Thermal profiling is always necessary — no matter what. Or is it? If this sounds like a contradiction, there are currently ways of profiling that provide alternatives to the most time-consuming or labor-intensive methods. For example, oven verification may in some cases replace repeated board profiles, but only if strict parameters are met. The trick is in knowing when to profile the board or verify the oven performance.
Thermal Profiling is a recognized necessity. As mid-to-high volume production continues to dominate in many areas, it is beneficial to understand the available choices in profiling, and which ones will work best under what circumstances. One of the main distinctions to be made is between board profiling and oven profiling. Having said that, it must be clear as to exactly when it is possible to effectively replace board profiling with oven profiling, the benefits of doing so, and the parameters that are required for successful implementation.
There is no doubt that in today’s more sophisticated electronics market, with boards populated with everything from BGAs to SiPs (System in Package), process control is more important than ever. At the center of achieving that control, you will find thermal management. And since thermal management cannot be achieved, or documented, without thermal profiling, thermal profiling brings us to the heart of the matter.
After BGA removal for repair, there typically is an excess of solder remaining on the board side, which can cause short circuits by bridging between adjacent joints and/or open circuits by preventing the complete collapse of all joints. It is imperative that the excess solder be removed to present a uniform surface across the site for proper component attachment, as BGA rework can be both time consuming and costly.
Thermal profiling is a critical function in printed circuit board assembly. This article describes thermal profiling hardware and process management software solutions as used at EMS provider Axiom Electronics LLC to meet the thermal profiling challenges of today’s microelectronics environment. Reflow challenges include thermal inequalities of high layer count circuit boards that have uneven mass distribution, components of varying sizes, micro BGAs, high ball-count BGAs, LGAs, etc. These easy to use thermal profiling tools help to improve yields by providing a stable repeatable process while saving time and providing necessary supporting documentation.
As the electronics industry prepares for the possibility of Pb-free Printed Circuit Board Assembly (PCBA) processing without the
The goal of thermal profiling is to always increase quality and reduce waste. Three case histories - covering powder coating, baking and solder reflow applications - show you how three manufacturers achieved these goals.
Characterization of the thermal performance of modern convection reflow ovens is important in
ascertaining the process window for a particular product or application. This is especially true
for lead free processes. Using typical manufacturing materials such as FR4 can be problematic
in that the product changes thermal characteristics after a relatively short number of thermal
excursions. Other potential test vehicles such as a stainless steel or aluminum plate are more
robust and able to withstand repeated thermal cycles, however, introduce significantly different
thermal conductivities that masks potential weaknesses in oven design. Trying to match these
physical properties within a single test vehicle is necessary in order to characterize the various
oven parameters. Such materials exist in composites with highly insulating properties similar to
typical FR4 material as well as a high tolerance to numerous thermal excursions. This paper
investigates the performance of three ...
With accurate monitoring of a reflow oven's operating parameters, SPC can track product quality and increase yields.