Electronics Forum | Fri Nov 09 10:37:38 EST 2007 | devajj
We have started using QFN packages in large volume and are having problems with no-solders. We are using 6mil stencil with 1x1 paste print to pad. These also have thermal pads with thru vias that we reduce the stencil aperture by 1/4. Board also ha
Electronics Forum | Sat Nov 10 23:46:36 EST 2007 | mika
BTW, The surrounded QFN fine pitch terminals should have the normal aperture reduction of 7 % in case of RoHS Senju solder paste. This works for our Telecom customer. The vias in the ground pad will be somewhat filled with solder and makes it diffi
Electronics Forum | Mon Nov 26 20:11:41 EST 2007 | shy
Yes, i'm agree with you davef but i'm not put the chipbonders onto pads. i'm put the chipbonders at the beneath component (center between both component terminals) which the idea is to hold the component during wave soldering which might cause the co
Electronics Forum | Thu Dec 20 08:29:52 EST 2007 | cdsullivan
I figured as much. The exacto method is what we've been doing. We did send some back to the fab house and they really "fubar"ed the pads. So we decided to do it ourselves. You are exactly right... it should have been caught before it ever made it to
Electronics Forum | Mon Jan 07 11:17:21 EST 2008 | ehess
I am looking for some pads for a Universal VCD, PN 23502000. It is the pad that goes on top of the knurled nut that sets the anvil height (bottom of clinch base on the piston). Universal mfg machine is down so I'm looking for someone who might have
Electronics Forum | Fri Feb 15 07:19:22 EST 2008 | floydf
Currently when we get a new screen, we inspect it by holding a pcb or artwork under it and confirming that there are pads underneath all of the holes. The flaw with this approach is that if there are pads on the board with no corresponding hole in th
Electronics Forum | Thu Mar 13 09:22:08 EDT 2008 | scotceltic
Don't waste your time or your repair technicians time on 100 PCBA's. Order the correct part size for the pads and return the old part. There shouldn't be much of a cost difference. This will save you a massive amount of time on rework not to menti
Electronics Forum | Wed Apr 09 22:58:10 EDT 2008 | davef
We wonder about: * Solder mask encroaching onto the component pads. Please describe the solder coverage on pads where there is tombstoning. * History of the issue. How long has this been going on? Have you ever produced non-tombstone board consisentl
Electronics Forum | Fri Apr 25 12:36:52 EDT 2008 | fsw
All, Does anyone on the forum have experience with underfill? We have a component with QFN pkg on one of the new products. It has a thermal pad in the centre. Customer wants this component to have an underfill. Questions - 1) Does one normally req
Electronics Forum | Thu May 29 17:19:51 EDT 2008 | dyoungquist
On 0402s we use 20x25 mil pads with a 15 mil gap between the pads on the pcb with ENIG finish, 5 mil stencil with a 1:1 aperture (20x25 mil) and SAC305 lead free solder paste. We very rarely see any tombstoning on 0402s using this setup.
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