Measurement Definitions

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Measurement Definitions

This section defines how each solder machine parameter is measured and or calculated:

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PREHEAT:

Preheat Max Temp: The temperature of the Top Foil Thermocouple (Coupon Top) at the time when the Speed Sensor hits the first solder wave (chip wave or main wave).  This records the change in temperature imposed by the preheat system on the top foil of a typical circuit board.

Preheat Min Temperature: The temperature of the Top Foil Thermocouple (T/C) at the first data point taken after the start button is pressed.  This records the starting temperature of the top foil of the circuit board.

Preheat Max Slope: The largest temperature slope (positive or negative) seen on the Top Foil T/C between start and the Speed Sensor hitting the first wave (chip or main wave).

Equation

Slope is measured over a 1 second time interval using a “linear regression” technique (m = Slope).

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Conveyor (speed): The conveyor speed is found by dividing 9.75” (distance between C and Speed sensors) by the time measured between the C and Speed sensors hitting the main wave.

 

SOLDER WAVE:

Delta T at Wave: The maximum overall temperature seen on the Top Foil T/C after the Speed Sensor hits the main wave minus the temperature of the Top Foil T/C as the Speed Sensor hits the main wave. This records the change in temperature imposed by the main wave on the top foil of a typical circuit board.

Contact Temperature: The maximum temperature seen on the Coupon Solder T/C after the Speed Sensor hits the solder wave to a user settable distance after the Speed Sensor disconnects from the main wave. This settable distance is typically the distance from the solder wave to the Hot air knife but may be less if it is seen that the hot air knife influences this temp prematurely. Range is from 0 to 30.5 cm (0 to12.0 in). The default is that this filter is off so the solder contact temp max is looked for to the end of the profile data.

Dwell Time (A, B, C): The time measured between the respective sensors entering and exiting the main wave.  This records the total time each of the three sensors (A, B, C) spends in contact with the main wave.

Contact Length: The Dwell Time at A, B, and C times the measured Conveyor Speed.  This records the total length of circuit board in contact with the main wave at any given instant while in the wave.

Immersion Depth: This is a function of Contact Length and is calculated based on a known basic wave shape. This records the height of a free flowing solder wave relative to the bottom of the WaveRIDER® NL 2 pallet.

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Parallelism: The Dwell Time at sensor C minus the Dwell Time at sensor A.  This records the contact time difference between the left and right sides of the circuit board, which is a function of how parallel the bottom of the WaveRIDER® NL 2 pallet is to the crest of the wave.

 

CHIP WAVE:

Delta T at Wave: The maximum overall temperature seen on the Top Foil T/C between the time the Speed Sensor hits the chip and main solder waves minus the Max Preheat Temp.  This records the change in temperature imposed by the chip wave on the top foil of a typical circuit board.

Contact Temp: The maximum temperature seen by the Exposed T/C between the time the Speed Sensor hits the chip and main waves.  This records the surface temperature of the chip wave.

Dwell Time (A, B, C); Contact Length; and Parallelism: These parameters are measured using the same techniques as those for the solder wave Dwell Times, except they are relative to the chip wave.

 

Chip Detection:

Chip wave data is determined in the same manner as the solder wave. The presence of a chip wave is automatically detected when two solder contact points are detected on sensors A or B, or four solder contact points measured by sensor “C” / Speed Sensor. The solder contact time between the chip and solder wave for the C sensor must be greater than 1.0 seconds to be counted as separate wave contacts. If less than 1.0 seconds, the multiple solder contacts are considered “noise” or contact bounce and are counted as one wave contact rather than two.

 

In addition, as the distance between the chip and solder wave gets larger, the time between the C sensor leaving the solder wave and the Speed sensor hitting the chip wave must also be less the 1.0 seconds. If not, these two solder contacts will be seen as one wave for the same reasons stated above.

 

The illustration displays the interaction between the two waves and the WaveRIDER® NL 2 pallet sensors as described above.

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The graph should be used to determine the maximum conveyor speed you may use to avoid violating the 1.0 second minimum travel time between sensors and waves. This is a function of the distance between the chip and solder waves and the average solder wave contact length.

Locate the curve that represents your average contact length. Locate the Chip to Solder wave separation on the X-axis of the graph. Move up vertically until it intersects the contact length or the fixed curve. Look to the left to determine the maximum conveyor speed you may run.

 

COUPON TEMPERATURE STATISTICS:

For all three coupon T/C’s, the following is recorded:

(exception: solder sensor slopes are not calculated since they are normally very fast).

Min°: Lowest temperature seen throughout the data set.

Max°: Highest temperature seen throughout the data set.

Max (-) Slope: Greatest negative (falling) temperature change seen throughout the data set.

Max (+) Slope: Greatest positive (rising) temperature change seen throughout the data set.

Equation

Slope is measured over a 1 second time interval using a “linear regression” technique (m = Slope).

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Time > 361°F (183°C) = The total time spent above the typical solder melting point.