How to Do a Wave Solder Profile

Wave solder machines process high volumes of printed circuit boards.

Since the 1950s, wave solder machines have been the workhorses of high-volume electronics production. An inclined conveyer feeds circuit boards into a wave solder machine and over a heated solder bath. The bath contains a submersible pump that creates a wave of molten solder. As each board contacts the wave, the solder flows into every joint, processing circuits at a much higher rate than is possible by hand. The optimal profile for conveyor speed and preheat ramp-up rate takes into account the specified solder temperature and contact time, or dwell time, for each circuit design.

Things You'll Need

• Manufacturing specification for circuit board
• Operator’s manual for wave solder machine
• Wave solder machine
• Sample circuit boards
• Temperature sensor

Instructions

1. Review the manufacturing specification for the circuit board for which you need a wave solder profile. Note the specified values for contact time in seconds, immersion depth in mils, solder temperature and preheat temperature.

2. Refer to the operator’s manual for the wave solder machine. Check the wave profile and note the wave contact length in inches at the specified immersion depth.

3. Calculate the conveyor speed. Divide the wave contact length by the contact time and note the result, which is the conveyor speed in inches per second. Multiply by five to convert to feet per minute. For example, if the wave contact length is 4 inches and the contact time is five seconds, the conveyor speed is .8 inches per second or 4 feet per minute.

4. Set up the preheaters on the machine. Mount a temperature sensor on a sample circuit board. Switch on the preheaters and allow the preheat temperature to stabilize. Set the conveyor speed to the calculated value and run the board through the preheat zone.

5. Note the temperature of the circuit board on exiting the preheat zone. If it is below the specified preheat temperature, increase the power to the preheaters. If it is too hot, decrease the power. Repeat the temperature measurement until a sample board reaches the specified temperature on exiting the preheat zone.

6. Record all the settings you have established for the wave solder profile. Bring the machine up to operating temperature. Run one or more circuit boards through the machine and check that the results are acceptable before running production boards.

Tips & Warnings

• Use an instrumented data logger if you want to monitor the temperature profile through the entire length of the wave solder machine.

• Do not attempt this task unless you have received appropriate training and you are proficient in the use of wave soldering machines. Serious injury can result from incorrect use of this type of equipment.

References

• Indiana University-Purdue University Indianapolis: Wave Soldering
• Speedline Technologies: Effect of Contact Time on Lead-Free Wave Soldering
• Technology Information Corporation: Wave Solder Optimizer
• Practical Components: Lead-Free Wave Soldering of High Complexity PWB’s

Resources

• OCI Materials: History of the Wave Solder Machine
• University of Michigan: Wave Soldering
• Electronic Controls Design: WaveRIDER NL 2