Electronics Forum | Tue Mar 03 02:39:56 EST 2015 | sarason
I would presume you reflow the top of the board first. Use tented vias. As you have worked out, vias have surface tension, which sucks the solder up the hole during reflow of the bottom of the board. Good luck! regards sarason
Electronics Forum | Tue Mar 03 03:11:57 EST 2015 | vb7007
Hi I also forgot to mention, top side is reflowed first at SMT. Tenting vias is good option. we are looking into it. Can you please also suggest any solution to avoid solder balls at bottom side in other places than vias. Thanks
Electronics Forum | Mon Mar 02 23:48:22 EST 2015 | vb7007
Hi We are using Universal carrier for a 2 sided PCB, where the bottom side goes for hand solder the switches after wave. Our issue is, we are getting micro solder balls all over PCB bottom after wave, whereas we got numerous vias, which also turns
Electronics Forum | Tue Mar 03 09:29:48 EST 2015 | rgduval
A couple of things that have helped me with solder ball issues at wave in the past: 1. Flux. Insure good flux coverage on the bottom of the board. 2. Preheat. Insure that the board is sufficiently preheated for the wave operation. Since you're
Electronics Forum | Wed Mar 24 23:12:48 EDT 2021 | grahamcooper22
0.66 area aspect ratio...so for example...if the device is 0.5mm pitch QFP, the pcb pad may be 12 thou wide..make the aperture 9 to 10 thou wide...and reduce it's length by 10 % overall compared to the pcb pad.... Depending on device pitch, select ap
Electronics Forum | Thu Mar 25 18:09:36 EDT 2021 | grahamcooper22
I think between us we've not missed too many points...
Electronics Forum | Thu Mar 25 20:09:35 EDT 2021 | grahamcooper22
What is the QFP pitch ? What aperture dimensions have you chosen ? Is the stencil laser cut then polished ? Your AFTER stencil size looks promising...your BEFORE stencil aperture size looks disastrous...would surely give bridges.. Your pcb pad siz
Electronics Forum | Thu Mar 25 16:29:39 EDT 2021 | jdengler
Your missing the point. The placement machine is the primary issue. Does this toy even say it can handle that component? If you have the ability try slowing the machine down when it is placing that component. Slow X, Y, and Theta axis. Jerry
Electronics Forum | Thu Apr 29 10:24:15 EDT 2021 | oxygensmd
I have the same issue but with one customer only. All the other have smaller or more difficult QFPs with really low bridging issues - close to no-one. I think the PCB and PCB design also an issue - other customers are using 32/64/100/144 QFPs and we
Electronics Forum | Tue Mar 23 23:17:12 EDT 2021 | llawrence
Hello everyone, I work for a company that, up until now, has done everything using through-hole components. This has been fine for years, but we have been pushed into the world of surface mount manufacturing by a new product that is far cheaper and
