|Ask the Experts|
September 21, 2017
Wave soldering LCDs
We are currently hand soldering a 25 pin 51x29x2.75mm standard LCD onto a double sided board. The bottom surface of the display is positioned 7mm above the board. We would like to wave solder this display for two reasons; improve solder quality and to increase throughput. Our main concern is thermal damage. What is the best way to wave solder this LCD without causing thermal damage?
|Expert Panel Responses|
Assuming the LCD is not going face down into the wave, wave soldering should not be a problem for this type of component. Make sure the wave system provides the correct preheat to the assembly prior to soldering and that you profile the assembly so that it meets the thermal characteristics of the component without exceeding them.
Regional Sales Manager
OK International Inc.
Have you considered using a selective soldering machine for this process? You can consistently control the process, and the heat.
National Sales and Marketing Manager, North America
Business Development Manager, DAGE | X-Ray component counting
Many of our customers wave solder LCD displays on their circuit boards without any problems of thermal damage. All of the devices I have seen are rated for wave soldering but the biggest concern I would have is over preheating. Typical topside board temperature as the board leaves the preheat is 210-220 F and I would avoid using topside preheat. Depending on flux type, lead layout, orientation and lead length bridging could be a issue. If the leads are all inline keep them parallel to the conveyor. If you keep the preheat temperature in spec and dwell time in the wave to the minimum needed for good hole fill you should not have any issues with thermal damage to the LCD display.
Senior Applications Engineer
There is another option other than wave solder. EFD developed a system that dispenses solder then uses a laser to heat the solder at the joint for reflow. This is much slower than wave solder, but should improve your quality and have even less thermal impact than hand soldering.
Director of Application Engineering
I would think selective wave soldering systems or selective soldering stations would be able to handle this application quite well. Spacers could be used to keep the LCD off the board and the board could be process through the equipment. Since this is a double sided board, I would not believe you would need too much top side preheat to get the solder to flow to the top side of the board, so this would be helpful in preventing the component from overheating during the soldering operation. If you are currently manually soldering these components, you are applying more heat to each lead than they will see going over any wave solder system. Hence the heat from the wave or mass soldering system will be less than the heat from the solder iron, which should also help in improving the quality of the product. I say this because soldering irons are typically set at 650 to 750 F while soldering systems are typically set at 500F, quite a different. If more information is needed please ask more questions
Vice President, Technical Director
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