Electronics Forum | Thu May 29 12:53:36 EDT 2003 | designchain
Managing items and BOMs, even for a small company, should not be done on spreadsheets - they're single user, prone to error, and hard to manage. There are relatively low-cost, very functional systems on the market that enable management and revision
Electronics Forum | Sun Dec 15 22:31:43 EST 2002 | craigj
Has anyone heard of vias cracking (barrel from pad) when being wave soldered. Was told this was a big problem by contract pcb designer, he always tent vias because of this. The reason was that the solder filling the vias caused stressing and then sep
Electronics Forum | Mon Dec 16 21:34:05 EST 2002 | grantp
Hi, Yes, the stencil does touch the PCB. Is there another method? Sorry to sound a bit dumb on that, however I don't have a lot of experience with automated stencil printing, and manual has been working well up to now with this BGA. Regards, Gra
Electronics Forum | Mon Dec 16 21:40:27 EST 2002 | grantp
Hi, Thanks for the info, and I will check it out. Do you know where the IPC 7525 spec is? Does it explain why square is better? I know there is some theory I am missing here, and that's why we have problems. I am just freaking out trying to establi
Electronics Forum | Tue Dec 17 08:46:59 EST 2002 | Randy Villeneuve
Personaly I would try a different solder paste. Give Indium a call and get a sample of their SMQ92J No clean. You will be impressed. Alpha and Kester also have good products but we have a long history with this paste and we have printed millions of b
Electronics Forum | Wed Dec 18 01:37:39 EST 2002 | Steve
I dont know what kind of screener you use but my 1st impression is that the board and stencil are separating too fast,the paste doesn't have enough surface tension to stay on the board, you're tearing the paste off the board. If you can, slow down th
Electronics Forum | Wed Dec 18 08:19:00 EST 2002 | cyber_wolf
One thing that will also cause this is very slight stencil mis-alignment. Sometimes the paste will have a tendency to hang up in the apertures if you are over hanging just a little on the solder mask. Some solder mask are very slick and will not pull
Electronics Forum | Thu Dec 19 13:20:55 EST 2002 | russ
Your area ratio for this aperture is fine (.78) usually any value greater than .66 will provide a reliable paste release. I would make sure however that the stencil is polished. I agree with other posts regarding your setup and/or paste type is prob
Electronics Forum | Thu Dec 19 16:15:26 EST 2002 | Dreamsniper
Hi Grant Petty, I read about your problem, You might have problem with the design. First on the pad. What is the diameter of the BGA pad in your PCB. We have the same size of PCB and we use 0.584mm Pad dia. and a 10% reduction on our aperture. We us
Electronics Forum | Mon Dec 16 15:00:56 EST 2002 | sueph
We have always baked our assembled boards prior to wave solder, but have recently learned that there are some companies out there who don't. I checked with one of my supervisors, and he said that baking is recommended but not required. I'm wonderin
