QFN soldering
T Chap
Posts: 4,223
I have a product that uses several QFN's, and I need a reliable way to solder them without having to rework them every time. Removing the bridges with a fine pencil and flux is easy but I need to get past this hurdle. I use a high quality stainless stencil from a popular company. There are always bridges though, so I think I need to revisit the stock Eagle QFN package and maybe reduce the pad sizes since there is obviously too much solder for the requirement. The other problem is getting the flux out from under of the part. Flux causes issues when there is some remaining. It is almost like it is easier just to screen and reflow all the parts except the QFN's, then manually come back and place them with air. Using air what works decently is to place some flux on the pads, then use some fine solder to coat the pads, then remove the flux. Then place the part with air. This can take a minute or two which is too long. Anyone have any success with fast reliable placement for these parts?
Comments
1. change the paste you are using.
2. Have the pads cut smaller ON THE STENCIL and make sure you are wiping it down with a firm stroke to reduce the thickness of the paste.