Electronics Forum | Fri Oct 28 04:56:12 EDT 2016 | lilybell
I read a few posts here about resistor in led applications. The thing is, the resistor has clarified as this shows:was always use with a power source delivering a higher forward voltage than the led could tolerate(ex: a 9volt battery hook up to a 3w
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 | 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 | 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 | Fri Mar 26 15:48:31 EDT 2021 | grahamcooper22
Leaded HASL on small pads can be quite difficult to print on...the HASL tends to be domed rather than flat..and that can affect print quality...you really need a perfectly flat pcb pad to print paste on when you are assembling 0.5mm QFPs. If the pcb
Electronics Forum | Thu Mar 25 20:50:50 EDT 2021 | stephendo
A couple more things. The PCB. What size are the pads? One time a board shop had difficulty putting masking between the pads of a QFP and the pads suffered as a result. When I told them they didn't have to have masking between the pads, the pads w
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
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 | Mon Dec 17 15:11:35 EST 2007 | chef
Blew chunks - thanx for thinking outside the box. Of course there's two sides to every story. Just last week I had a new operator "splash" a couple of boards. Top solder was great, it was all one big solder bridge. Come to find out, the operator forg
