Electronics Forum | Tue Aug 21 03:42:55 EDT 2001 | mugen
SMT community, My Fellows, 1) why is No-clean (NC) the preferred process, for BGA mounting by SMT? 2) why is water-soluble (WS) not a hot choice? 3) All I know, *is in layman terms*, that BGA has tendency to trap water, should WS process be the c
Electronics Forum | Wed Aug 22 10:57:59 EDT 2001 | wbu
Hi Steven, BGA�s are known for their ability to self align and from own experiance they do. There�s enough documentation on this one available (...don�t have the links present like Dave but I�m sure he will give you enough to spend some evenings rea
Electronics Forum | Thu Aug 23 15:45:48 EDT 2001 | slthomas
So, we've already addressed the tombstoning on these guys by adopting the mfr's (Pana.) recommendations for pad size and spacing. Problem is, we have pretty bad wetting of some of these parts. The rest of the board we use them on looks great, nice
Electronics Forum | Thu Aug 23 16:41:06 EDT 2001 | slthomas
Naw, the rest of the BOARD we use them on. Same assembly. Actually we use them on one other assembly and have the same problem. Same oven, same line, same paste, same problem. I've tried to get the production super. to move them to another line w
Electronics Forum | Wed Nov 28 09:17:17 EST 2001 | Dave G
I've heard of reliabilty problems caused by wave soldering melf's as well. We don't put Melfs on the bottom of our PCB's on newer designs. We only have to deal with gluing & putting them through the wave on some of our older legacy designs. Increasi
Electronics Forum | Wed Nov 28 20:45:03 EST 2001 | dougk
We�ve also had glass diode difficulties- poor adhesion while all other parts are fine (including tall parts). I�ve received some interesting information from Heraeus: It seems the newer glues create a much stronger bond to SMD�s, except glass diodes.
Electronics Forum | Tue Aug 28 12:05:42 EDT 2001 | mparker
The advantage of DPMO is that the numbers used are PPM, (Part Per Million), rather than percentage. Percentage can distort, depending on volume. For instance, 100 units processed, 25 defects found = 75 percent yield. 4 units processed, 1 defect found
Electronics Forum | Thu Aug 30 14:14:27 EDT 2001 | dougt
James Take a board with double sided tape and run it with all the other parts "shorted". Make sure that the part is being placed by the head/spindle that will be used during a full run. Inspect the part after it is placed and carefully remove it a
Electronics Forum | Thu Oct 11 10:51:27 EDT 2001 | MikeF
Sean I have to agree with Dave on this issue. As a frequent reader of this forum I appreciate it when company reps clearly note their affiliation, but I like it much better when they are also willing to identify the companies they compete against, "o
Electronics Forum | Thu Sep 06 10:58:49 EDT 2001 | davef
If your words imaged correctly, it seems a bit strange to have a trace that is wider than the pad where it connects, because we�re used to seeing a narrower trace connecting to a wider pad. It�s tough to determine what the designer was thinking abou
