Electronics Forum | Fri Dec 04 20:26:34 EST 1998 | kallol Chakraborty
| | | | Hi folks , | | | | Lately we are seeing a lot of rawcards with black spots on the pads - most of them have Au finish(immersion gold) . We did a lot of inspecton after wave solder and found that only (fine pitch) QFP are affected the most. Ou
Electronics Forum | Fri Dec 04 20:37:45 EST 1998 | kallol chakraborty
| | | | | Hi folks , | | | | | Lately we are seeing a lot of rawcards with black spots on the pads - most of them have Au finish(immersion gold) . We did a lot of inspecton after wave solder and found that only (fine pitch) QFP are affected the most
Electronics Forum | Tue May 19 12:54:55 EDT 1998 | Richard Jackson
| We had a similar problem. But whenever the solder came from the screen printer the solder would wet to the gold fingers, with the help of residual flux. But the problem is balls, that I assume are not wetted to the gold fingers but instead are jus
Electronics Forum | Mon May 18 21:29:38 EDT 1998 | D.Lange
| I've tried every thing I can think of. Do you have any | Ideas? | What I have is micro balls on the gold fingers of | panelize boards. These balls only appear on the gold | finger. Or at least I can only find them on the gold | fingers. | What I
Electronics Forum | Tue May 19 12:29:59 EDT 1998 | Richard Jackson
| Richard, | You may be encountering solder paste contamination | on the assembly during the printing process. Solder | will reflow on tin/lead plated lands therefore invisible. | If you are washing the assembly prior to inspection | then you are
Electronics Forum | Fri May 28 17:44:51 EDT 1999 | Glenn Robertson
| I discovered that we have some gold plated (30 mico in.) through hole connectors which were Paste In Hole soldered (60 sec at reflow) on a HASL PCB. Do we have an embrittlement reliability issue? The calculated volume % of gold in the joints is abo
Electronics Forum | Tue May 19 10:23:06 EDT 1998 | Mike C
| Howdy Richard, | Welcome to the club! I now dub thee a full fledged member of the "Spotty Gold Finger and Bleeding Ulcer Society"...or SGFBUS for short... (GRIN) | I know it's not funny to be in that position, but there's so many different places t
Electronics Forum | Wed Jan 26 14:33:47 EST 2000 | Glenn Robertson
Tuan - How about Sn/0.7Cu? It's M.P. is 227 and it's readily available. If the leads are Gold plated you might consider pre-tinning them. If you need a higher temp alloy any of the major solder companies can help - I suggets you start with Ind
Electronics Forum | Thu Jan 27 14:49:53 EST 2000 | Glenn Robertson
Tuan - One of the reasons I suggested pre-tinning (aside from the negative effects of Gold on appearance and reliability) is the known slower wetting of Sn/Ag and Sn/Cu alloys as compared to Sn/Pb. If you don't have to be Lead-free, the high Lead
Electronics Forum | Mon Aug 27 15:06:29 EDT 2001 | davef
This otta push Wolfgang over the top ... Recommended reading G.G. Harman, Wire Bonding in Microelectronics : Materials, Processes, Reliability, and Yield, 2nd edition, McGraw-Hill Electronic Packaging and Interconnection Series, 1997. G.G. Harman, R
