Electronics Forum | Mon Dec 31 08:11:23 EST 2001 | hany_khoga
Dear all : We are suffering a severe curvature in our boards when coming out of the wave solder m/c. An Engineer suggested to enter them again for a second pass in the m/c expecting board were thermally mistreated just after the W.S. Can this real
Electronics Forum | Mon Dec 31 08:59:36 EST 2001 | Don Adams
The second pass in the wave is pretty extreme and will probably aggravate the conditions which caused warpage in the first place. Areas to look for problems, The lay up of the boards at fabrication or the materials used can lead to warpage. Work wi
Electronics Forum | Tue Feb 11 10:51:20 EST 2020 | slthomas
To predict whether or not a first pass part is going to come off during the second pass you need to calculate the ratio of weight/soldered surface area. According to a couple of different sources that I've dug up, maximum is around 44 grams/in.^2. I
Electronics Forum | Thu Nov 17 21:46:48 EST 2005 | C. Kolokoy
With DIP type components, a sub-par fluxing method (foaming a no-clean), and a chip wave where one is not needed are formulas for bridging and insufficient wetting. If you have SMD's on the wave solder side of the board greater than 0603, and no SOT
Electronics Forum | Wed Mar 24 08:36:58 EST 2004 | Evtimov
Hi! What exatly you do? Do you reflow the both sides of the board at the same time or you reflow your second side? I think in both cases you should decrease you bottom zones. If you reflow both sides - with 10-20C(F) If you reflow the second side - w
Electronics Forum | Mon Apr 13 12:06:53 EDT 2009 | jefflkupkt
BoardHouse, Thanks for the reply. The board supplier did cover the cost of the bare boards. Five years ago I saw a different part pass ET only to fail at final assembly test as well. One engineer called it "acid trap" on the inner layers where the
Electronics Forum | Thu May 05 08:14:45 EDT 2011 | kahrpr
Where black pad exists, it is not a common problem. When I read it is totally random I doubt that. You have defiantly something going on that is unique with the process. It is either your board manufacturer or your solder paste or your profile. It c
Electronics Forum | Mon Oct 05 04:55:42 EDT 2009 | pengliang
we suggest as below : the first : check the soldering(solder ball and pad) by X-ray ; second: to do dye analyse (note:pls confrm is there have crack )
Electronics Forum | Fri Apr 09 15:00:04 EDT 2010 | davef
So for your SMT1/SMT2/PTH boards, you have poor solderability during SMT2. [Even if you have no SMT2 and only ST1/PTH, our answer is the same.] We assume this occurs on one board part number only. We guess that your bare boards have insufficient gol
Electronics Forum | Thu Jun 27 11:56:40 EDT 2019 | slthomas
It seems to me that it would be easier to manually apply a little bit of chipbonder on the edge of the part after the first reflow than to tape the part down. The epoxy would cure sufficiently before the second reflow to secure the part after the s
