Hey,
One issue with a very custom project I'm working on is the special board material we use doesn't handle higher temperature very well during the reflow soldering process. Anything above 130C starts to cause board warping and delamination. The longer its above the temperature and the higher the temperature the worse it gets. We are currently having the boards made with regular lead solder (I believe 63/37), and they turn out acceptable and we successfully use them, but are noticeably warped.
Got me to thinking. I know low temp solder exists for specialized applications, but does it exist and is it supported at all by board houses for PCB fabrication. Does anyone have any experience having a board made with a special low temp solder as opposed to traditional lead or lead-free solder options? The plating we use is ENIPIG which is a must, if that matters. The board utilizes a hybrid mix of 0201 caps/resistors and a few BGAs, which we have a board house place. Then we manually place bare dies and wire bond them to the board. We then encapsulate the whole PCB. My point being if a low-temp solder has weaker mechanical strength that is no big deal. Our wire bonds are already orders of magnitude more fragile than solder joints and we have the tools and techniques in place to deal with it.
Thanks!
Edit: The ideal melting point would be around 160C. The wire bonding process keeps the board sitting at 130C, so I wouldn't want to be on the hairy edge of the parts reflowing during bonding. Also another step involves a thermoplastic tape to melt and adhere the bare dies to the PCB, which melts at 140C. Again wouldn't want the hot plate to reflow the parts accidentally. I have found at 140C the board doesn't warp worse despite the spec. I'm hoping around 160C would show similar results or at least less warping then we get from the 220C or so reflow process currently done by the board house.
One issue with a very custom project I'm working on is the special board material we use doesn't handle higher temperature very well during the reflow soldering process. Anything above 130C starts to cause board warping and delamination. The longer its above the temperature and the higher the temperature the worse it gets. We are currently having the boards made with regular lead solder (I believe 63/37), and they turn out acceptable and we successfully use them, but are noticeably warped.
Got me to thinking. I know low temp solder exists for specialized applications, but does it exist and is it supported at all by board houses for PCB fabrication. Does anyone have any experience having a board made with a special low temp solder as opposed to traditional lead or lead-free solder options? The plating we use is ENIPIG which is a must, if that matters. The board utilizes a hybrid mix of 0201 caps/resistors and a few BGAs, which we have a board house place. Then we manually place bare dies and wire bond them to the board. We then encapsulate the whole PCB. My point being if a low-temp solder has weaker mechanical strength that is no big deal. Our wire bonds are already orders of magnitude more fragile than solder joints and we have the tools and techniques in place to deal with it.
Thanks!
Edit: The ideal melting point would be around 160C. The wire bonding process keeps the board sitting at 130C, so I wouldn't want to be on the hairy edge of the parts reflowing during bonding. Also another step involves a thermoplastic tape to melt and adhere the bare dies to the PCB, which melts at 140C. Again wouldn't want the hot plate to reflow the parts accidentally. I have found at 140C the board doesn't warp worse despite the spec. I'm hoping around 160C would show similar results or at least less warping then we get from the 220C or so reflow process currently done by the board house.
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