Is anyone using a laser to selectively solder components to a board?
I'm just starting to research selective soldering methods for the company i work for as we're looking to replace our current hand soldering processes for lead- and lead free- products. At the moment i don't think a mini-wave would be suitable for our application due to the need to apply the solder on the top side of the board.
An idea of the price for this kind of equipment would be appreciated, and any process limitations that people may have encountered or know of.
My advice is the technology is not there unless your boards have been designed for laser soldering. Even then there are too many limitations to go into it. We tried a unit for almost a year and were never able to get consistent, not even going to mention quality, production out of the unit.
I agree with James. Granted there are a variety of lasers to try, we too could not get a consistent power setting. Plus when paste turns liquid, you get some reflection. Also the mask around the pad has to be pulled back or burning may occur.
Well, there seems to be many opinions, many of which could be correct, however... With the proper laser they can be quite good for soldering.
Here are a few guidelines I would like to suggest. 1) Have your product soldered first (by the vendor) 2) Try to spec in a 960 to 980 nm rated laser. These diodes are more penetrative and less refelective. 3) Use a wire or paste that has a 3 to 3.5% flux content. They seem to solder better. 4) If you can get variable beam, it is a great feature. This allows you to have a range that the beam can be adjusted for various pad sizes. and finally 5) Vision is a good feature. While it costs more, it allows to you precisely target the pad each time.
If the goal is selective soldering (not to raise the substrate temperature too high), consider the use of microwaves. Our company has been working on this technology for selectively bonding substrates. For example, we use the process to bond ROHS metallizations bumps at far lower temps than what's applied in the industry.