Electronics Forum | Wed Nov 06 16:31:59 EST 2002 | slthomas
I would also consider paste control (don't take it personally...I always have to get after people about this one), time on the stencil, time between print and reflow, solderability of the component leads, paste volume (that one really got us once....
Electronics Forum | Thu Nov 07 09:23:05 EST 2002 | russ
What would the considerations be in utilizing a type 4 paste as opposed to type 3? We have an assembly that has a large amount of uBGAs (12 mil diam pad)along with 50 mil pitch BGAs assorted fine pitch etc... We are experiencing difficulty in paste
Electronics Forum | Thu Nov 21 07:57:37 EST 2002 | gramsey
The information you are seeking is found in IPC-7525. Section 3.3 describes an equation for calulating the solder paste volume required to produce a desireable fillet. I simplified it a bit. V=1/s[Tb(Ah-Ap) + Ft + Vp] - Vh V is the volue of paste
Electronics Forum | Thu Nov 21 06:36:30 EST 2002 | Ben
I'm doing SMT of lead-free solder BGA on FR4 Ni-Au PCB. The solder paste I'm using is Sn/Ag/Cu and reflow with peak temp at 240C. I found there are voids(1-2) in almost every solder joint(500 micron in dia) under xray. And the void size is violate th
Electronics Forum | Fri Jan 03 12:01:46 EST 2003 | jax
Alot of the companies out there use Standards developed internally, centered around there paste, equipment, and reflow processes. Normally you will see either 5mil or 6mil stencils used for everything in house with the exceptions of specific boards.(
Electronics Forum | Thu Feb 06 14:27:18 EST 2003 | MA/NY DDave
Hi You already have some good answers. Let me add just a little of what I know. You might want to check the IPC and obtain their guides on this technology. Also SMTA, NEPCON and others have technical proceedings on this technology. Checking with e
Electronics Forum | Mon Jan 13 18:22:55 EST 2003 | davef
100 sec) and decrease reflow temp to 205C. * Understand that voids are primarily process indicators. There is experimental evidence that voids retard crack propagation locally around the void on a temporary basis. There is no standard, IPC or otherw
Electronics Forum | Mon Jan 20 22:39:46 EST 2003 | davef
Hi Stevo, Most paste suppliers say something like, �above 183*C for 45 to 60 seconds.� The problem we have with statements like that is that they seem to assume that the pads, component leads, and solder paste are all near eutectic 60/40 solder. A
Electronics Forum | Wed Jan 29 14:22:56 EST 2003 | russ
Most bowing I see is caused by an asymetrical layer stackup of the PCB. (different copper thicknesses throughout the stackup) e.g. for a 4 layer board - 2 oz. copper on layer 1, 1 oz. copper on layer 4, etc... I would doubt that is the V-score since
Electronics Forum | Wed Feb 05 20:56:23 EST 2003 | jonfox
I think you just answered a questioned that I never thought to ask. Are bulk parts manufactured differently than standard tape and reel parts? That would explain why there is a bigger price difference in parts from Murata and not from others. As I
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