Technical Abstracts

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ABSTRACTS

1. Basics of successful hand soldering - EIX 97-04 EIX97043430906
NDN- 017-0263-5411-5
Oh, Edwin
Circuits Assembly v 7 n 11 Nov 1996. 4pp 1996 DOCUMENT TYPE- JA,
Journal Article ISSN- >1054-0407< CODEN- CIATE5 AUTHOR AFFILIATION-
Metcal Inc, Menlo Park, CA, USA JOURNAL NAME- Circuits Assembly
LANGUAGE- English
: Solder material plays a key role in determining PCB solder joint strength; since it supplies one of the key elements that makes up the metallurgical; bond. The other element comes from the bonding surface(s) itself. There; are seven criteria commonly used to choose solder: required solder joint; strength; physical form; melting point; degree of wicking; flux; interaction; leaching; and cost. The three key factors which include; solder materials, wetting action, and connection temperature determine the; mechanical strength of a solder joint.

2. Successful BGA rework - EIX 96-25 EIX96253154730
NDN-017-0248-5600-2
Peck, Douglas J.; Lee, Thomas
Circuits Assembly v 7 n 4 Apr 1996. 4pp 1996 DOCUMENT TYPE- JA,
Journal Article ISSN- >1054-0407< CODEN- CIATE5 AUTHOR AFFILIATION-
Advanced Electronics Interconnect Cent (AEIC), Haverhill, MA, USA
JOURNAL NAME- Circuits Assembly LANGUAGE- English
: Successful BGA rework and repair is extremely operator dependent. It; requires operator knowledge of BGA construction, its thermal; characteristics and development of preheat and >reflow< profiles for both; the removal and replacement of the package. Correct use of rework; equipment processes will ensure consistent and successful BGA rework.


3. Applying Taguchi analysis to wave soldering - INS 99-40 6374404
B1999-11-2210D-039 (EEA) NDN- 174-0637-4403-7
Williams, M.; Raaijmakers, P.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 10 NO. 8 Aug. 1999 PP. 58-64 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CENTER CODE- 1054-0407/99/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: In early 1997, a project was begun at Panasonic TV to study an alternative; method of flow (wave) soldering. Although Panasonic's current "horizontal; process" is dependable and consistent with existing products, certain PCB; layouts were limited. Early experimentation with future technologies; highlighted the shortfalls in Panasonic's current equipment. Panasonic's; latest PCB designs needed to be coupled with the most robust soldering; process available. The addition of quad flat pack (QFP) and; multipositioned S028 and S050 devices to the bottom side of the PCBs in; some designs also complicated matters. This article describes installation; and testing of a new wave soldering system, including the use of a; debridging wave former and optimization of the process settings by the; Taguchi method. Initial defect rates on new technology products, with a; typical >reflow< layout, fell from 2,900 ppm to 240 ppm. The first pass; yield increased by 15%.

4. Pulse-heated >reflow< soldering of flexible circuits - INS 99-40
6374403 B1999-11-2210D-038 (EEA) NDN- 174-0637-4402-5
Brackell, P.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 10 NO. 8 Aug. 1999 PP. 52-7 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Unitek Equip., Monrovia, CA, USA COPYRIGHT OF
1054-0407/99/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: Pulse-heated >reflow< soldering is a process in which two prefluxed,; solder-coated parts are heated to a temperature sufficient to cause the; solder to melt, flow, and solidify, forming a permanent electromechanical; bond between the parts and solder. As opposed to traditional soldering,; pulse-heated soldering >reflows< solder by using a thermode that is; heated and cooled down for each connection. Pressure is applied during; the entire cycle, including heating, >reflow< and cooling. A pulse-heated; control delivers energy to the thermode, which is mounted on the >reflow<; soldering head. A thermocouple, attached to the thermode, provides; feedback to the control for repeatable, consistent heat generation. The; soldering head brings the two parts into intimate contact. At a precise; pressure, the head signals the control to begin the thermode heating; cycle. The thermode conducts heat to the parts, and the subsequent; thermal transfer melts the solder between the parts. The molten areas; begin to flow, resulting in coalescence between the two solder masses.; When the controller terminates the >reflow< cycle, the parts continue to; be held together during the cooling cycle so that the solder resolidifies; and a joint is formed. A good solder joint is defined as one in which the; solder adequately joins both surfaces and wetting has occurred on both; part surfaces.


5. Streamlining PCB assembly - INS 99-22 6263986 B1999-07-2210D-027
(EEA) NDN- 174-0626-3985-4
Robertson, R. G.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 10 NO. 4 April 1999 PP. 32, 34-5 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Alcatel USA, Richardson, TX, USA COPYRIGHT
1054-0407/99/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: Designers and assemblers of electronic equipment continue to be pressed; for products that are faster, more complex and more reliable, yet at a; lower price. Relentless competition has led many companies to work toward; elimination of wave soldering as an essential part of their PCB assembly; process. A number of reasons may be cited for this trend. Probably the; most obvious is reduced cost for capital equipment purchase and; maintenance. Design flexibility is greatly enhanced because many; surface-mount components are not compatible with wave soldering but can; be used on either side of a double-side >reflow< design. Cycle time is; often reduced, and the thermal shock of wave soldering is avoided.; Environmental concerns related to disposal of lead dross and to solvent; emissions from solvent-based fluxes are also eliminated.


6. Ensuring reliable solder joints in PCB rework - INS 99-12 6200077
B1999-05-2210D-001 (EEA); C1999-05-3350E-001 (CCA) NDN-
174-0620-0076-4
Russell, E.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 10 NO. 2 Feb. 1999 PP. 68, 70, 72-3 1
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Sierra Res. & Technol. Inc., Westford. MA, USA
CENTER CODE- 1054-0407/99/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: In reworking PCBs, the creation of >reflow< profiles typically requires a; combination of skill, luck, and extreme patience, especially in dealing; with assemblies consisting of fine-pitch components and area-array; devices. The traditional method of profiling a board is to guess at the; heater set points, measure the results and adjust the set points as; required. This process, however, can take hours to perfect and, to be; cost-effective, requires relevant experience from the technician; operating the rework system. Otherwise, the manufacturer may find that; the least expensive approach is to simply throw the boards away.; Auto-prediction software is a standard tool in >reflow< soldering as part; of the PCB assembly process. However, profiling software designed; specifically for rework has only recently become available. Since the; challenges are different for rework as compared to assembly, this article; takes a look at the set-up features and performance capabilities of; rework software now on the market.


7. Developing the through-hole >reflow< process - INS 99-02 6133436
B1999-02-2210D-046 (EEA) NDN- 174-0613-3435-0
Robertson, R. G.; Nguyen, N.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 9 NO. 11 Nov. 1998 PP. 32-4, 36, 38-9 6
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Alcatel USA, Richardson, TX, USA COPYRIGHT
1054-0407/98/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: During the past three to four years, Alcatel USA has been working to; eliminate the need for wave soldering for as many of its mixed-technology; PCBs as possible. The program for reduction of wave soldering has; provided significant improvements in cost and cycle time. Implementation; of the through-hole >reflow< process has been an essential part of this; program. This process involves printing of solder >paste< over the; locations where through-hole components are to be inserted. These; components are then installed immediately before the surface-mount; >reflow< oven and soldered with the other components. Component types; that are suited to this process include PGAs (pin grid arrays), DIPs; (dual in-line packages) and various connectors.


8. Reworking EMI/RF shields - INS 98-26 5957674 B9808-5230-010 (EEA)
NDN- 174-0595-7673-7
Zamborsky, E.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 9 NO. 5 May 1998 PP. 58, 60, 63 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- OK Int., Yonkers, NY, USA COPYRIGHT OF
1054-0407/98/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF): EMI/RF shields, once strictly through-hole parts assembled as a last step; by operators with huge 300 W soldering irons, have been replaced by; precision-formed surface mount shields. These shields are placed during; normal assembly operations and soldered with production >reflow< ovens; simultaneously with the components underneath. These EMI/RF shields, when; systematically approached, can be successfully reworked utilizing; existing manufacturing equipment. Using either conduction or convection; >reflow<, and the techniques associated with each, may provide a solution; to the challenge these odd-form components present to the current rework; and repair environment.


9. Keeping up with >reflow< soldering process constraints. II - INS 98-05
5820902 B9803-2210D-019 (EEA) NDN- 174-0582-0901-0
De Klein, F. J.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 12 Dec. 1997 PP. 52, 54, 56-7, 59 12
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Dover-Soltec, Oosterhout, Netherlands
CENTER CODE- 1054-0407/97/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: >Reflow< soldering of double-sided PCBs, through-hole components, ball; grid array (BGA) packages and flip-chip packages with more stringent; requirements on quality, yields, maintenance, reliability and the; environment is not easy in high-volume electronics manufacturing. More; users are "pushing the envelope" of process limits in an attempt to get; more production at higher quality yields out of >reflow< soldering; machines. >Reflow< oven manufacturers will continue to introduce product; features into their machines, but the most appropriate systems will; always be the most flexible ones. The number of machine features and; available retrofittable options reduce the risk of not being able to; rearrange the process for future technology. Perhaps not utilized; currently, additional features may be built now into a >reflow< machine; for use in the future as unanticipated process demands appear.


10. Keeping up with >reflow< soldering process constraints. I - INS 98-03
5806640 B9802-2210D-043 (EEA) NDN- 174-0580-6639-9
De Klein, F. J.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 11 Nov. 1997 PP. 56, 58-9 5
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Dover Soltec, Oosterhout, Netherlands
CENTER CODE- 1054-0407/97/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: Rapid growth in component technology has necessitated changes in mass; >reflow< soldering, both in the process and the equipment. Increasingly,; assembly professionals are seeking more flexible equipment that allows; new features to be retrofitted, so that the machines will be more capable; of handling changing component processing requirements. Some of the new; >reflow< technologies-double-sided, through-hole, direct-chip attach; (DCA) and ultrafine pitch-are in use, but much discussion about; technological constraints still exists. Most engineers generally agree; that the best insurance for the future is having the greatest number of; features/options available on a >reflow< soldering machine-and also; having the flexibility to use them.


11. Solder cream >reflow< thermal profiles - INS 97-36 5689151
B9710-2210D-041 (EEA) NDN- 174-0568-9150-4
Gilbert, B.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 7 July 1997 PP. 65, 68 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Multicore Solders, Richardson, TX, USA COPYRIGHT OF
1054-0407/97/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: While it is clear that thermal profile extremes can have a profound; effect on the performance of solder creams, in the majority of cases the; profile is determined by the requirements of the fully assembled board; and the capability of the >reflow< oven being used. There is no unique; profile for any cream, and information supplied with the product can only; be a guide. The use of a temperature profiler is one way to arrive at a; suitable process. A great deal has been written about the equipment used; in >reflow< soldering, namely convection >reflow<, which is in general; use and is the most acceptable means of achieving controlled, reliable; results. This article focuses on the solder cream material-what happens; at the various stages of >reflow<, the profiles they generate and their; effects on the various constituent materials of the solder cream.


12. Thermal considerations for large device rework - INS 97-31 5655697
B9709-0170J-032 (EEA) NDN- 174-0565-5696-0
Scheu, W. F.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 6 June 1997 PP. 38, 40, 43 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Automated Production Equip., Key Largo, FL,
CLEARANCE CENTER CODE- 1054-0407/97/$2.00+0.25 PUBLISHER- Miller
Freeman PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: Successful and safe rework of large devices, such as BGAs (ball grid; arrays), QFPs (quad flat packs), PGAs (pin grid arrays), 225 I/O BGA; packages and edge connectors, has become increasingly difficult due to; the increased mass and varying thermal requirements of the components; themselves. For example, there are a variety of BGA packages widely in; use today. The most common packages include the plastic ball grid array; (CPBGA), the ceramic ball grid array (CBGA) and ceramic column grid array; (CCGA). While methods of removing and replacing large surface-mount; packages such as QFPs are fairly well understood, there are significant; physical differences between traditional packages such as QFPs and BGAs.; Thermal requirements are different. Therefore, rework methods are also; different. Whereas QFP rework usually involves focusing or directing; heated air on the peripheral lead attach areas, BGA processing requires; concurrent heating and >reflow< of all underside solder balls. This is; achieved by heating the entire BGA package. Understanding how these; packages are constructed and the thermal considerations directly; affecting their removal and replacement can save a great deal of time and; trouble when rework is necessary. The prudent process engineer conducts; careful analysis of a given device's thermal requirements. This analysis; can help determine, for example, the amount of thermal energy required to; attain >reflow< before attempting rework of a device/assembly on a volume; basis.

13. Soldering: Why we're still struggling - INS 97-14 5544063
B9705-2210D-040 (EEA) NDN- 174-0554-4062-6
Engelmaier, W.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 2 Feb. 1997 PP. 68, 70, 72, 125 13
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Engelmaier Assoc. Inc., Mendham, NJ, USA
CENTER CODE- 1054-0407/97/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: After the thousands of years man has used solder, the electronics; industry still struggles with reliable PCB solder attachments, the; soldering process and the behavior of solder joints when stressed during; manufacture, testing, shipping and use in the field. The reasons for this; are many, but it's the rapid changes and innovations in technology that; deal the heaviest blows. Recently, statements have come to light in some; print media that need clarification. Changes in standards have led to an; almost continuous stream of revised standards from MIL-P-28809 to; DOD-2000 to MIL-STD2000 to IPC-S-815 to J-STD-001; most with numerous; revisions. These changes have also led to numerous changes in the; soldering process, from wave to vapor phase, IR (infrared) >reflow< to; forced convection and to manual soldering. And all of these processes; have their own peculiarities. Additionally, solder materials, including; differing tin-lead compositions. no-lead, high-melt and low-melt and; high-strength solders, have been introduced. These differences result in; different liquid and solid temperatures and, thus, differing process; requirements. Different base materials and surface preparations have; found their way onto PCBs and components.


14. Advances in >reflow< oven technology - INS 97-13 5538386
B9705-2210D-030 (EEA) NDN- 174-0553-8385-0
Bouchard, R.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 8 NO. 2 Feb. 1997 PP. 30-6 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- BTU Int., North Billerica, MA, USA COPYRIGHT OF
1054-0407/97/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: >Reflow< soldering is not often looked upon as the most interesting; process in PCB assembly, especially when compared with the chaotic speed; of a pick and place machine or the rhythmic pace of a stencil printer. A; box sitting quietly on the floor with a conveyor providing the only; visible sign of movement suggests that not much is happening. However,; the impression is indeed misleading, for multiple stages of precisely; controlled events are occurring inside the box-events as critical in; surface-mount assembly as any step preceding or following it.


15. Advanced surface-mount manufacturing methods - INS 96-43 5410186
B9612-2210D-009 (EEA) NDN- 083-0541-0185-0
Belmonte, J.; Zarrow, P.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 7 NO. 9 Sept. 1996 PP. 36, 38, 40-1 2
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- MPM Corp., Franklin, MA, USA COPYRIGHT OF
1054-0407/96/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199609)7:9L.36:ASMM;1-1 LANGUAGE-
English (DEF)
: Surface-mount manufacturing is continually being examined for ways to; streamline the process while maintaining process performance. In many; cases, process steps can be eliminated by incorporating advanced; surface-mount manufacturing methods. Two processes gaining interest are; single center >reflow< soldering (SCRS), or intrusive >reflow< soldering,; and double-sided >reflow< soldering. These processes are not new; various; companies have been working with them for years, and many have; incorporated them into at least a portion of their mixed-technology; assembly production. Among the more significant contributions is a; detailed study of >reflow< soldering of through-hole components,; undertaken in 1986 by a major US electronics manufacturer. Experiments; were conducted to examine and define all of the critical operating; parameters. Ten years and hundreds of millions of solder joints later,; there have been no documented field failures attributed to the use of the; process, which has maintained a consistent solder defect rate of 4 to 7; ppm.


16. A solder >paste< comparison - INS 96-32 5345738 B9609-2210D-034
(EEA) NDN- 083-0534-5737-4
Seelig, K.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 7 NO. 7 July 1996 PP. 32, 34-6 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- AIM Products, Smithfield, RI, USA COPYRIGHT OF
1054-0407/96/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199607)7:7L.32:SPC;1-5 LANGUAGE-
English (DEF)
: Medium-residue no-clean solder pastes are currently the most popular type; of no-clean material used in surface mount assembly. Sometimes, however,; a manufacturer may want to or need to move to a low-residue no-clean; material for any number of reasons. There are a number of differences; between the two types in terms of both processing requirements and; overall chemistry. Any user moving to a low-residue process should be; knowledgeable of the special requirements of low-residue solder pastes; because such knowledge can mean the difference between a costly; high-defect process and a high-yield, low-cost, low-defect one.


17. BGAs in the assembly process - INS 96-29 5327999 B9609-0170J-009
(EEA) NDN- 083-0532-7998-8
Zamborsky, E.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 7 NO. 5 May 1996 PP. 68, 70 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- OK Ind. Inc., Yonkers, NY, USA COPYRIGHT OF
1054-0407/96/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199605)7:5L.68:BAP;1-6 LANGUAGE-
English (DEF)
: This paper describes rework and repair concepts for BGAs. The paper looks; at how BGAs can be removed and the way in which the board is prepared for; resoldering. The paper then discusses how the BGAs are aligned and; resoldered. Finally the paper briefly discusses the inspection; techniques.

18. Surface-mount connectors in a no-clean environment - INS 96-29
5327991 B9609-2180E-002 (EEA) NDN- 083-0532-7990-3
McGuiggan, T.; Radabaugh, S.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 7 NO. 5 May 1996 PP. 34-6, 38 2 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Compaq Comput. Corp., Houston, TX, USA COPYRIGHT OF
1054-0407/96/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199605)7:5L.34:SMCC;1-N LANGUAGE-
English (DEF)
: To determine the compatibility of low-profile surface-mount connectors in; a no-clean manufacturing environment, several experiments were completed; with a focus on contact integrity. The project test vehicle was a; daisy-chained FR-4 test module populated with surface-mount connectors,; allowing both connector solder joints and contacts to be electrically; monitored. Processing conditions including IR >reflow< soldering, manual; rework, localized PCA cleaning and in-line cleaning were completed to; understand the process robustness of the connectors. Twenty-five assembly; pairs were soldered with surface-mount connectors using noclean RMA; (rosin, mildly activated) solder >paste< and an IR in-line >reflow<; process. Visual inspection at 30X magnification and electrical continuity; verified the connectors to be functional.


19. BGA rework system - INS 96-07 5193127 B9604-0170J-005 (EEA);
C9604-3350E-004 (CCA) NDN- 083-0519-3127-5
NO-AUTHOR
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 12 Dec. 1995 PP. 44, 46 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CENTER CODE- 1054-0407/95/$2.00+0.25 PUBLISHER- Miller Freeman
PUBLICATION COUNTRY- USA S I C I- 1054-0407(199512)6:12L.44:RS;1-F
LANGUAGE- English (DEF)
: This paper describes the BGA-2000 Micro Oven rework system. This system; has been engineered to allow safe, efficient rework of BGA (ball grid; array) components. Using a microprocessor profile controller, the; operator simply selects the appropriate removal or replacement profile; and starts the rework sequence. Each of the replacement profiles contains; four time/temperature zones (subzone, preheat, >reflow< and cooling) to; duplicate the original manufacturing >reflow< cycle. Removal and; replacement profiles can be stored, recalled and edited with the touch of; a button, or to enhance process control, the profiles can be locked in to; eliminate operator adjustment. The unit`s exclusive micro-oven design; encapsulates the BGA under rework ensuring that a constant; temperature-controlled environment is maintained throughout the >reflow<; cycle. The oven`s proprietary PCB seal combined with its elevated nozzle; vents protect surrounding components from adjacent heating damage; normally associated with nonfocused convection heating devices.


20. Attaching thermocouples for thermal profiling �PCB processing� - INS
96-07 5193126 B9604-2210D-005 (EEA) NDN- 083-0519-3126-3
Saunders, R.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 12 Dec. 1995 PP. 40-2 1 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Saunders Technol., Hollis, NH, USA COPYRIGHT OF
1054-0407/95/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199512)6:12L.40:ATTP;1-2 LANGUAGE-
English (DEF)
: Repeatable PCB thermal processing requires establishment of accurate,; precise thermal profiles based upon acquisition of reliable temperature; data obtained from key locations on the board. Acquiring such data; involves attaching thermocouples to the PCB so that critical temperatures; can be monitored during soldering. Choosing the best thermocouple; attachment method is largely dependent on the application. Obtaining an; accurate reading of board surface temperature requires the thermocouple; junction to be in firm, direct contact with the surface. If solder or; adhesive is used, it must be the minimum amount possible to minimize; thermal lag. Quick-setting adhesives are easy to use but are best suited; to lower temperature applications such as the "A" side in wave soldering; and in rework applications. High temperature solder and epoxy require; considerable skill and time to install properly and to remove without; damaging the board, but will provide accurate results for many profiles; in >reflow<, IR and wave soldering applications. They are well suited to; test boards but require too much time and effort to install and remove; for most rework applications. A mechanical thermocouple attachment device; can be quick and easy to install and remove without damaging the board or; component. It can provide accurate, reliable results in >reflow<, IR,; wave solder and rework applications, and can be used on any type of; surface and can reach into tight locations anywhere on the board.


21. Developing the paste-in-hole process �Dual mass >reflow< soldering� - INS
96-01 5150984 B9602-2210D-015 (EEA) NDN- 083-0515-0984-0
Gervascio, T.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 10 Oct. 1995 PP. 50, 52, 54 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Group Technol., Tampa, FL, USA COPYRIGHT OF
1054-0407/95/$2.00+0.25 PUBLISHER- Miller Freeman PUBLICATION
COUNTRY- USA S I C I- 1054-0407(199510)6:10L.50:DPHP;1-3 LANGUAGE-
English (DEF)
: This article discusses aspects of PCB design for the dual mass >reflow<; soldering process which must be considered in order to ensure that the; potential assembly cost savings from use of this process are made. The; article discusses candidate PCB selection from an assembly viewpoint, and; also looks at the selection of components, packaging and connector; materials which can withstand the the temperatures encountered in mass; >reflow< ovens. The most critical part of the design process is stencil; aperture design for connectors to ensure void-free hole filling. The; assembly sequence and tooling are also discussed, along with >reflow<; issues, and the article concludes with a look at future developments for; the "paste-in-hole" process.


22. Repairing BGA components - INS 95-39 5071233 B9511-2210D-029 (EEA)
NDN- 083-0507-1233-8
Abbagnaro, L.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 7 July 1995 PP. 44-7 1 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- PACE Inc., Laurel, MD, USA COPYRIGHT OF
1054-0407/95/$2.00+0.25 PUBLICATION COUNTRY- USA LANGUAGE- English
(DEF)
: BGA packages were investigated for repair feasibility. Hot-gas >reflow<; was readily accomplished and worked reliably over a wide range of gas; temperatures and flow rates. Conductive removal was readily accomplished; with a hand-held tool, but conductive installations would require a; machine approach. Preheat may reduce primary >reflow< time but usually; increases the total cycle time for a removal or installation, and its use; is recommended when >reflowing< thermally massive assemblies. Placement; was readily accomplished using a relatively simple nozzle/template; process. Components can be reprocessed, if necessary, using flow; desoldering to clean removed parts and preforms to replace solder balls.; BGA technology is still evolving and should provide more challenges to; the assembler in the future.


23. Plastic ball grid array repair procedures - INS 95-39 5071230
B9511-0170J-034 (EEA) NDN- 083-0507-1230-2
Miles, B.; Darveaux, R.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 7 July 1995 PP. 32-5 5 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Packaging Lab., Motorola, Ft. Lauderdale, FL, USA
CENTER CODE- 1054-0407/95/$2.00+0.25 PUBLICATION COUNTRY- USA
LANGUAGE- English (DEF)
: Plastic ball grid array (PBGA) packages are prone to die bond; delamination and "popcorn" failure during solder >reflow<. The primary; goal of this study was to significantly reduce or eliminate the need to; bake PCBs before performing any device repair procedures. It was found; that the moisture content in a saturated PBGA package could not be; decreased to an acceptable level through any type of reduction in a; standard bake-out procedure. Additional studies are planned to evaluate; the effect of bake-outs in a vacuum oven. The study continued by; evaluating various sizes of packages. It was determined that the maximum; safe temperature for a moisture-saturated PBGA package is 185 degrees C.; This information was used to establish hot-air repair profiles for a; typical radio board. The repair profile should be defined by a 45 to 60; second ramp time to a maximum temperature of 215 degrees C. By following; these general guidelines for hot-air repair stations, it has been shown; that board repairs can be performed without elevating the temperature of; any of the PBGA packages on either side of the board to 185 degrees C. It; is important to note that when removing a PBGA package from an unbaked; PCB, the package should be replaced due to the increased risk of popcorn; cracking.


24. PCMCIA assembly process development and characterization - INS 95-22
4965480 B9507-2210D-014 (EEA) NDN- 083-0496-5480-6
Zbranek, G. Jr.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 6 NO. 3 March 1995 PP. 46-50 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Texas Instrum. Inc., Austin, TX, USA COPYRIGHT OF
1054-0407/95/$2.00+0.25 PUBLICATION COUNTRY- USA LANGUAGE- English
(DEF)
: Customer inquiries on the production capability of PCMCIA (Personal; Computer Memory Card International Association) format PCB assemblies; continue to increase. To help answer the inquiries, a structured; development approach was established to identify key response variables; of the assembly process. The current level of customer sophistication has; typically established the structured development approach as a; requirement for a prospective manufacturer of PCMCIA board assemblies.; This article discusses the objectives of the process development program,; and examines aspects such as panel array size, array depanelization; methods, array handling, array >reflow< and cleaning, connector placement; and connector removal/replacement, and discusses the direction of future; development efforts.


25. Process control in surface-mounted >reflow< - INS 95-04 4862812
B9503-2210D-018 (EEA); C9503-3350E-005 (CCA) NDN- 083-0486-2812-5
Lange, R.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 5 NO. 10 Oct. 1994 PP. 64-7 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Micron Custom Manuf.Services Inc., Boise, ID, USA
CENTER CODE- 1054-0407/94/$2.00+0.25 PUBLICATION COUNTRY- USA
LANGUAGE- English (DEF)
: In any manufacturing environment, process control is crucial for; achieving high yields. The technical definition of process control is the; reduction of variation around a target mean. With this definition in; mind, it logically follows that any means implemented that will reduce; variation could be considered process control. Process control in the; area of surface-mount >reflow< may initially sound very difficult to; implement, but it is necessary for producing consistent solder joints.; The first step in process control is the identification of all variables; affecting the process. >Reflow< can be divided into the following; categories: solder >paste< qualification and characterization; >reflow<; oven qualification and characterization; definition and documentation of; profile parameters; data collection; oven recipe standardization;; >reflow< technology; and oven maintenance. Reducing the variation in each; category is essential for achieving control of the process. Once all of; these parameters are monitored and controlled, >reflow< defects can be; virtually eliminated.


26. Solder >paste< considerations - INS 95-04 4862809 B9503-2210D-015
(EEA) NDN- 083-0486-2809-5
Kopp, D.; Zarrow, P.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 5 NO. 10 Oct. 1994 PP. 46-7, 49-50 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- ITMI, Durham, NH, USA COPYRIGHT OF
1054-0407/94/$2.00+0.25 PUBLICATION COUNTRY- USA LANGUAGE- English
(DEF)
: >Reflow< soldering can best be described as a process in which various; thermal durations are matched to the chemical and metallurgical; characteristics of the solder >paste<. The parameters that drive the; profile, with respect to the interplay between the composition of the; solder >paste<, the PCB assembly and the >reflow< system, must be taken; into consideration. Due to the flux, solvents and rheology modifiers,; solder >paste< is a complex chemical compound. The analysis in this paper; shows that the processing parameters, especially in the >reflow<; soldering process, depend largely upon the chemistry of the solder; >paste< and the manufacturer's formulation. Hence, even within a specific; category such as no-clean, no two profiles will be identical. In; addition, processing parameters are further complicated by the PCB; assembly geometry and mass, as well as the thermal efficiency of the; >reflow< soldering system employed.


27. Establishing a >reflow< profile - INS 94-43 4798769 B9412-2210D-004
(EEA); C9412-7480-007 (CCA) NDN- 083-0479-8769-5
Marshall, P.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 5 NO. 8 Aug. 1994 PP. 58, 60, 62 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Surf Syst., Leicester, UK COPYRIGHT
CLEARANCE CENTER CODE- 1054-0407/94/$2.00+0.25 PUBLICATION COUNTRY- USA
LANGUAGE- English (DEF)
: Having established the required >reflow< profile for the formulation of; solder >paste< selected, this profile should then be used as a starting; point for future production boards. The advantage of a PC-controlled; system is that the original profile can be stored, recalled and then; superimposed on any new profile generated. Thus, the operator can; instantly see where any alterations may be required in order to control; the parameters. When specifying a >reflow< system, you should not only; evaluate the various types of heating mediums available, but you should; also evaluate the control systems offered. The latest generation of; PC-controllable systems with enhanced color graphics displays offers a; lot more than temperature control and belt speed.


28. No-clean soldering - INS 94-12 4640389 B9405-0170G-008 (EEA)
NDN- 083-0464-0389-6
Zarrow, P.; Kopp, D.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 4 NO. 10 Oct. 1993 PP. 40, 44-7 3
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Technol. Dev., GSS-Array Technol., San Jose,
CA, USA PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: No-clean soldering is gaining momentum as a viable method for electronic; assembly. It has been successfully adapted to hand, wave and >reflow<; soldering. While this article focuses on no-clean solder pastes for; >reflow< soldering, the concept and many of the nuances are applicable to; other types of soldering as well.


29. Open vs. closed >reflow< soldering - INS 93-37 4486332
B9311-2210D-008 (EEA) NDN- 083-0448-6332-6
de Klein, F. J.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 4 NO. 4 April 1993 PP. 54-7 4 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- Soltec B.V., Oosterhout, Netherlands PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: Using nitrogen as a protective gas in >reflow< soldering is a major issue; in the push toward fine-pitch technology, bare-copper PCBs and actual; no-clean solutions. The benefits of a nitrogen atmosphere result from the; interaction between screen printing of solder >paste<, insertion of; components and >reflow< soldering. Process control is required for all; process steps, and the quality of the solder >paste<, components and PCBs; must be controlled as well. The use of nitrogen in >reflow< soldering; will produce a more robust process-but only if temperature profiles and; oxygen levels are controlled.


30. Thermal profiling >reflow< solder - INS 92-56 4313944
B9302-2210D-020 (EEA) NDN- 083-0431-3944-6
Kazmierowicz, P. C.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 3 NO. 8 Aug. 1992 PP. 59-62 0 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: One of the main problems faced in PCB assembly applications is the; initial setup of the >reflow< process to obtain optimal process yields.; In addition, all variables in the solder >reflow< process must be; continuously controlled. Understanding how the modern >reflow< oven works; and the basic principles of conveyorized heat treatment can ease the jobs; of setup and control. The author shows how to choose the best profiling; system for your application.


31. Understanding solder >paste< fundamentals (for SMT) - INS 92-56
4313939 B9302-2210D-015 (EEA) NDN- 083-0431-3939-2
Park, C. H.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 3 NO. 8 Aug. 1992 PP. 31, 34-6 2 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: Identifying a reliable solder >paste< manufacturer requires more than a; cookbook approach. Sound process experience dealing with solder >paste<; and an understanding of theories relevant to solder >paste< rheology and; formulation are necessities. A person with some understanding of the; supplier's operational practices is a valuable plus. The most obvious; quality indicators of a solder >paste< are its visual appearance and; viscosity. One major performance measure is the solder paste's printing; quality, which is a function of the paste's rheological properties.; Therefore, it is important to understand the fundamentals of solder; >paste< rheology and their performance implications.


32. Managing the thermal tradeoffs (MCMs) - INS 92-34 4202229
B9209-0170J-017 (EEA) NDN- 083-0420-2229-8
Walcutt, J.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 3 NO. 3 March 1992 PP. 36, 39, 41 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- Compix Inc., Tigard, OR, USA PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: Multichip modules and digital hybrid circuits offer electrical engineers; many benefits: increased densities, higher operating speeds and greater; functionality and performance. Most engineers are aware of the increasing; complexity and sensitivity to variations in the manufacturing processes,; the complexity and cost of rework and the magnitude of scrap costs. But; an equally important tradeoff is the effect of higher temperatures on; multichip modules (MCMs). This tradeoff is significant because it can; degrade circuit reliability.


33. Developments in hot-bar >reflow< - INS 92-03 4043746
B9201-2210D-045 (EEA) NDN- 083-0404-3746-0
Roberts, L.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 2 NO. 8 Aug. 1991 PP. 56-8, 60, 62, 64 5
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- EPE Technol., Manchester, NH, USA
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: Details factors to be considered when establishing >reflow< profiles.; The process variables in hot-bar soldering of fine-pitch components,; such as QFPs and TAB devices, and the interdependency of these variables; are examined.


34. No-clean >reflow< process implementation. II - INS 92-03 4043741
B9201-2210D-040 (EEA) NDN- 083-0404-3741-0
Morris, J. R.; Conway, J. H.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 2 NO. 8 Aug. 1991 PP. 28-9, 31-2, 35 0
reference(s) DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN-
CIATE5 CORPORATE AUTHOR- AT&T Bell Labs., Princeton, NJ, USA
PUBLICATION COUNTRY- USA LANGUAGE- English (DEF)
: For pt.I see ibid., vol.2, no.7, p.38 (1991). For >reflow< processes,; cleaning is performed after >reflow< for testability or for cosmetic; reasons, even though the solder pastes used produce noncorrosive,; nonconductive residues. To eliminate the need for cleaning, residue must; be significantly reduced. This study identified several candidate; materials for scale-up and factory trial. The following sections; describe the development of a manufacturable no-clean >reflow< soldering; process.


35. No-clean >reflow< process implementation. 1 - INS 91-22 3996228
B91068795 (EEA) NDN- 083-0399-6228-0
Morris, J. R.; Conway, J. H.
JOURNAL NAME- Circuits Assembly ABBREVIATED JOURNAL TITLE- Circuits
Assem. (USA) VOL. 2 NO. 7 July 1991 PP. 38-42 11 reference(s)
DOCUMENT TYPE- Journal paper ISSN- >1054-0407< CODEN- CIATE5
CORPORATE AUTHOR- AT&T Bell Labs., Princeton, NJ, USA PUBLICATION
COUNTRY- USA LANGUAGE- English (DEF)
: One of the corporate goals at AT and T is to eliminate chlorofluorocarb-; ons (CFCs) from its manufacturing operations by the end of 1994. This; article describes the development of a no-clean >reflow< soldering; process using low-residue solder >paste< (LRSP).


36. STUDY OF THE >THERMAL< BEHAVIOR OF A PRINTED CIRCUIT BOARD DURING THE
>REFLOW< PROCESS INSIDE A SURFACE MOUNT TECHNOLOGY OVEN - DIS 99-01
AAI1391403 NDN- 135-0239-3732-0
PEREZ SOTO, HERIBERTO Chairperson: DAVID SERRANO
VOL. 37-01 1998 PP. 350 128 page(s) CORPORATE AUTHOR- UNIVERSITY
OF PUERTO RICO, MAYAGUEZ (PUERTO RICO) INSTITUTION CODE- 0553 Degree-
M.SC. SUBFILE CODE- MAI Document Order Number- AAI1391403 LANGUAGE-
English (DEF)
: This thesis presents the development of a numerical model to predict the; thermal behavior during the surface mount technology >reflow< process. The; >reflow< process is a heating process in which the solder paste is melted; and then solidified on printed circuit boards (PCBs). Various assumptions; were used during the development of the model to simplify the different; heat transfer modes present in the problem, including negligible; temperature gradient in the vertical direction. The final numerical model; was able to predict the temperature >profile< for an ideal PCB. The ideal; PCB consisted of a solid copper plate 0.3048 m by 0.2413 m with a 0.0635 m; thickness, dimensions similar to many actual motherboards. Experiments; were designed and executed with the objective of gathering data for model; calibration. Temperature distributions inside an actual >reflow< oven were; collected simultaneously with temperature measurements along a test board.; The >reflow< oven consisted of twenty heating panels symmetrically; distributed below and above the PCB conveyor, as used in actual; manufacturing applications. Two oven temperature conditions were; considered, namely, ideal and actual set-points, and two conveyor speeds,; 1.27 cm/s and 1.905 cm/s. Ideal set-points consisted of uniform; temperatures throughout the panels. Comparisons between the numerical and; experimental solutions show that the proposed model predicts transient,; multi-dimensional heat transfer trends in >reflow< processes reasonably; well. Results indicate that ideal set-point conditions are better; predicted by the model, with an average temperature difference of; 5.10\sp\circC. Actual set-point conditions are approximated by the model; within an average temperature difference of 9.51\sp\circC. Major; differences between the model and the experimental data were found in the; cooling section of the oven. (Abstract shortened by UMI.); Citations from ENGINEERING INDEX: EIX


37. Flux chemistries and >thermal< >profiling< considerations in SMT assembly
- EIX 99-48 EIX99484841739 NDN- 017-0330-2375-3
Biocca, Peter
National Electronic Packaging and Production Conference-Proceedings of the
Technical Program (West and East) v 2 1999. p 971-977 1999 DOCUMENT
TYPE- JA, Journal Article ISSN- 0470-0155 CODEN- NEPPAL AUTHOR
AFFILIATION- Multicore Solders Inc, Richardson, TX, USA CONFERENCE DATE-
19990221-19990225 CONFERENCE TITLE- Proceedings of the NEPCON WEST '99
CONFERENCE LOCATION- Anaheim, CA, USA CONFERENCE CODE NO.- 55713
JOURNAL NAME- National Electronic Packaging and Production
Conference-Proceedings of the Technical Program (West and East)
LANGUAGE- English
: This paper will address the importance of thermal >profiling< in today's; electronic assembly. It is a summary of the points presented at the; conference. Today's electronic assembly have tighter lead spacings and the; use of BGA components where it is difficult to visualize the condition of; the solder joint after the >reflow< process makes it even more essential; than ever to develop an understanding of the paste chemistry and what; occurs during the >reflow< process. This understanding can enable an; engineer to optimize the >reflow< conditions to suit the chemistry of the; solder paste. The net result of this optimization is increased yields,; less soldering defects, reduced costs, and increased reliability. The; electronic assembly market has, in fact, has become in the last decade; mature and surface mount assembly here in America is no different than; surface mount assembly in Mexico or other emerging markets. Maintaining an; efficient soldering operation is essential for overall competitiveness.; Solder paste chemistries have also undergone major changes, improvements; in formulation to accommodate the more stringent needs of the industry.; Today's solder pastes are more stable, have higher print repeatability and; greater open time on the stencil than older versions. New additives,; activators and resin systems have made the solder paste more user; friendly. This user friendliness however is only appreciated if an; understanding of the solder paste chemistry and how it reacts in the; thermal cycle it sees in the >reflow< is first obtained. (Author abstract)


38. Modeling tool for the >thermal< optimization of the >reflow< soldering of
printed circuit assemblies - EIX 98-43 EIX98434359196 NDN-
017-0306-1126-3
Sarvar, F.; Conway, P.P.
Finite Elements in Analysis and Design v 30 n 1/2 Jul 15 1998. p 47-63
1998 DOCUMENT TYPE- JA, Journal Article ISSN- 0168-874X CODEN-
FEADEU AUTHOR AFFILIATION- Loughborough Univ, Loughborough, UK JOURNAL
NAME- Finite Elements in Analysis and Design LANGUAGE- English
: Thermal history variation within printed circuit assemblies (PCAs) during; >reflow< soldering is considered one of the main drivers for manufacturing; defects. It is recognized that predictive tools could be used to identify; the temperature variations that arise during the >reflow< process and, in; conjunction with experimentally derived data, determine their impact on; manufacturing quality. A predictive model would also be useful to a; designer for rearranging component placement for thermal mass; distribution, hence enabling the optimization of the design for; manufacture prior to final design commitment. Likewise, such a predictive; tool could be utilized for off-line optimization of >reflow< oven; >profiles< and in the design of more thermally efficient production; equipment. This paper describes the development of representative process; models of the >reflow< soldering of PCAs and outlines some of the more; important parameters to consider for accurate simulation of the >reflow<; process. Furthermore, the utilization of the predictive model is presented; as a tool for a number of end uses applicable to different application; domains, namely: process configuration for any given PCA; selection of the; most appropriate process and as a product design or verification tool to; improve thermal mass distribution and hence temperature history during; processing. (Author abstract) 12 Refs.


39. Direct product >temperature< control during soldering - EIX 98-15
EIX98154076345 NDN- 017-0292-9807-0
Spigarelli, Donald J.
SMT Surface Mount Technology Magazine v 11 n 5 May 1997. p 88, 90-91
1997 DOCUMENT TYPE- JA, Journal Article ISSN- 0893-3588 CODEN-
SMTEEL AUTHOR AFFILIATION- Sierra Research & Technology Inc, Westford,
MA, USA JOURNAL NAME- SMT Surface Mount Technology Magazine LANGUAGE-
English
: New techniques of process control have been developed for application to; batch thermal processing which includes soldering in incremental-drive; systems, incremental-drive mass >reflow< and rework of assemblies. These; developments are due to the increased use of computerized process control; and to new software developments. The methods permit >profiles< to be; automatically generated based on the desired or `ideal' product; time/temperature pattern by using the product temperature to control the; system. A calibration run to determine system requirements to reproduce; the product >profile< in subsequent runs also permits linear; product-profile generation.


40. >Reflow< >profiling< - >temperature< measurement - EIX 98-15
EIX98154076339 NDN- 017-0292-9801-9
Hwang, Jennie S.
SMT Surface Mount Technology Magazine v 11 n 5 May 1997. p 22 1997
DOCUMENT TYPE- JA, Journal Article ISSN- 0893-3588 CODEN- SMTEEL
AUTHOR AFFILIATION- H-Technologies Group Inc, Cleveland, OH, USA JOURNAL
NAME- SMT Surface Mount Technology Magazine LANGUAGE- English
: The development of an optimal >reflow< >profile< demands continued effort; due to several factors including the increasing complexity of printed; circuit boards (PCBs). In this dynamic process, two of the most formidable; uncertainties are the accuracy of temperature measurement and the level of; temperature uniformity across the board. At a selected location on the; board and at a specific time, the accuracy of the temperature measured; during the >reflow< process is determined by three aspects: the `quality'; of the physical contact between the thermocouple and the board; the; consistency of the contact; and the temperature response efficiency of the; thermocouple used.


41. A knowledge-based >thermal< >profile< identification advisor for surface
mount PCB assembly - EIX 97-43 EIX97433784379 NDN- 017-0281-3993-1
Wu, C.-H.; Srihari, K.; Mclenaghan, A.J.
International Journal of Advanced Manufacturing Technology v 11 n 5 1996.
p 343-352 1996 DOCUMENT TYPE- JA, Journal Article ISSN- 0268-3768
CODEN- IJATEA AUTHOR AFFILIATION- Department of Systems Science and
Industrial Engineering, T.J. Watson School of Engineering and Applied
Science, State University of New York, Binghamton, United States JOURNAL
NAME- International Journal of Advanced Manufacturing Technology
LANGUAGE- English
: >Reflow< soldering of solder paste is a critical process in the surface; mount assembly of printed circuit boards (PCBs). Infrared (IR) radiation; and/or forced convection are often used in an oven to heat the PCB; assembly and the deposited solder paste to cause the solder to >reflow<; and subsequently form the interconnection between the component; terminations and the attachment pads. Control of the >reflow< soldering; process requires the understanding and regulation of several complex; variables. Understanding the interrelationships among process control; parameters is important in achieving a low defect rate and high yields in; >reflow< soldering. When a variety of components are soldered onto a; printed circuit board (PCB) simultaneously in an IR/convection oven; through >reflow< soldering, the process control variables that need to be; considered include the characteristics of solder paste used, the size,; type, and quantity of components placed on the PCB, the substrate used,; the mass and the thermal area of the workpiece, and the conveyor speed. A; prerequisite for the achievement of high process yields in the >reflow<; soldering process is the identification of the optimal temperature; >profile< and the range between which the >profile< is acceptable for the; specific assembly. This information is subsequently used by the process; engineer to arrive at the relevant temperature of power (wattage) settings; for the oven. The in-depth process knowledge required to study the process; variables and deduce thermal >profiles< is not commonly available.; Consequently, the objective of this research was to use an expert system; approach to help a manufacturing engineer with thermal >profile<; identification in surface mount PCB assembly. The system developed; considers the major process control parameters and the interrelationships; among them to deduce the optimal temperature >profile< and a range in; which the >profile< is considered 'acceptable'. The >profile<; identification expert system was developed using PROLOG on a personal; computer. Results are displayed using a combination of graphical and; textual output. The system was designed to function in a stand-alone; capacity. The >profile< identification expert system's architecture; integrates an inference mechanism with the knowledge (facts and rules); provided by the domain expert. It allows the user to update or delete the; facts and rules stored in the knowledge base. Consequently, it provides an; avenue to enhance the capacity of the system to incorporate domain; specific changes. 15 Ref.


42. Solder cream >reflow< >thermal< >profiles< - EIX 97-42 EIX97423795745
NDN- 017-0281-0340-7
Gilbert, Bob
Circuits Assembly v 8 n 7 July 1997. p 66, 68 1997 DOCUMENT TYPE- JA,
Journal Article ISSN- 1054-0407 CODEN- CIATE5 AUTHOR AFFILIATION-
Multicore Solders, Richardson, TX, USA JOURNAL NAME- Circuits Assembly
LANGUAGE- English
: A great deal has been written about the equipment used in >reflow<; soldering, namely convection flow. This equipment is in general use and; is the most acceptable means of achieving controlled, reliable results.; This article focuses on the solder cream material. In particular, it; shows what happens at the various stages of >reflow<, the >profiles< they; generate and their effects on the various constituent materials of the; solver cream.


43. Influence of preheat and maximum >temperature< of the solder-reflow
>profile< on moisture sensitive IC's - EIX 97-41 EIX97413790052
NDN- 017-0280-9334-7
Shook, R.L.; Sastry, V.S.
Proceedings - Electronic Components and Technology Conference 1997. IEEE,
Piscataway, NJ, USA,97CB36048. p 1041-1048 1997 DOCUMENT TYPE- CA,
Conference Artic ISSN- 0569-5503 CODEN- PECCA7 AUTHOR AFFILIATION-
Lucent Technologies, Allentown, PA, USA SPONSOR- IEEE CONFERENCE DATE-
19970518-19970521 CONFERENCE TITLE- Proceedings of the 1997 47th IEEE
Electronic Components & Technology Conference CONFERENCE LOCATION- San
Jose, CA, USA CONFERENCE CODE NO.- 46865 JOURNAL NAME- Proceedings -
Electronic Components and Technology Conference LANGUAGE- English
: The purpose of this work was to determine the influence of preheat and; maximum solder >reflow< temperature on the level of moisture induced; damage in plastic surface mount integrated circuits. Both an analytical; moisture diffusion model and Finite Element Modeling were applied to the; analysis of absorption/desorption behavior of plastic molding compounds.; The models were used to analyze the moisture ingress kinetics during; controlled environmental exposures and for the prediction of moisture; desorption characteristics during solder >reflow< conditions.; Moisture/reflow experiments were conducted on an 80-pin PQFP, 225-pin; PBGA's, and two TSOP's (a 56-pin and a 40-pin). Devices were evaluated; using C-mode Scanning Acoustic Microscopy. Effects of maximum >reflow<; temperature on measured damage response were determined showing that as a; rule the JEDEC/IPC moisture resistance drops by one level for every 20; degree C increase in maximum >reflow< temperature. The overall benefit of; extended preheat is shown to be beneficial for only thin packages that are; not saturated. Details of the method used for predicting the beneficial; effects of preheating are described. (Author abstract) 22 Refs.


44. Device >temperature< measurement and >profile< derivation in a >reflow<
soldering oven - EIX 96-40 EIX96403277581 NDN- 017-0255-2814-6
Rothe, Paul; Dow, Stephen; Silveri, Robert
National Electronic Packaging and Production Conference-Proceedings of the
Technical Program v 2 1996. Reed Exhibition Companies, Norwalk, CT, USA. p
724-752 1996 DOCUMENT TYPE- CA, Conference Artic ISSN- 0470-0155
CODEN- NEPPAL AUTHOR AFFILIATION- Creare Inc CONFERENCE DATE-
19960227-19960229 CONFERENCE TITLE- Proceedings of the NEPCON WEST'96.
Part 2 (of 3) CONFERENCE LOCATION- Anaheim, CA, USA CONFERENCE CODE
NO.- 45120 JOURNAL NAME- National Electronic Packaging and Production
Conference-Proceedings of the Technical Program LANGUAGE- English
: Thermocouple (TC) usage and operating fundamentals are reviewed.; Uncertainty factors associated with the use of thermocouples for surface; mount component device/solder interface temperatures are then discussed.; Tests are performed using various attachment techniques to demonstrate the; degree of accuracy associated with the use of thermocouples and various; surface attachment methods. Next, many interactive factors associated with; product >profile< derivation in the >reflow< soldering process are; discussed along with methods for determining the heating/cooling; efficiency of forced convection ovens used in this process. (Author; abstract) 17 Refs.


45. New techniques of >temperature< control enhance processing with
incremental drive and stationary soldering systems - EIX 96-40
EIX96403277539 NDN- 017-0255-2771-3
Spigarelli, Donald J.
National Electronic Packaging and Production Conference-Proceedings of
the Technical Program v 1 1996. Reed Exhibition Companies, Norwalk, CT,
USA. p 277-286 1996 DOCUMENT TYPE- CA, Conference Artic ISSN-
0470-0155 CODEN- NEPPAL AUTHOR AFFILIATION- Sierra Research &
Technology, Inc CONFERENCE DATE- 19960225-19960229 CONFERENCE TITLE-
Proceedings of the NEPCON WEST'96. Part 1 (of 3) CONFERENCE LOCATION-
Anaheim, CA, USA CONFERENCE CODE NO.- 45120 JOURNAL NAME- National
Electronic Packaging and Production Conference-Proceedings of the
Technical Program LANGUAGE- English
: New techniques of process control have been developed which may be; readily applied to batch thermal processing. In the area of electronics; assembly, this includes surface mount soldering in incremental drive; systems, incremental drive mass >reflow< and rework of surface mount; circuit assemblies. Other techniques include the method of automatic; >profile< generation and cross-calibration methods. These and other new; control technique