Electronics Forum | Thu Feb 18 17:29:54 EST 1999 | Stefan Witte
The circle is not a "good" fiducial. The gradually change in contrast of a circle versus a cross makes it difficult to find the center of the fiducial. By pre-tinning the fiducials there will be a convex mirror surface distorting the edges even more.
Electronics Forum | Mon Sep 22 15:32:20 EDT 2008 | davef
We see this fairly often. It doesn't affect solderability. Our analysis makes us think this coloration is copper. The reason copper appears on the surface may be that heat cycles increase the thinness and porosity of the immersion silver [IAg] coatin
Electronics Forum | Thu Jul 31 15:41:23 EDT 2003 | davef
Q: Could any of you guys tell me what exactly is this greenish thing ? A: No, but is not copper oxide. Copper oxide is brown, the color of a penny [here in the US] or an untreated copper laminated trace on a board. Many copper salts are greenish in
Electronics Forum | Mon May 18 13:30:15 EDT 1998 | Earl Moon
| I'm reviewing my board fab spec. It calls for a minimum SnPb thickness of 50 microinches on HASL PWB's. I've looked at other specs that call out anything from 30 to 80 microinches, and others that just say the copper pad must be covered and solde
Electronics Forum | Thu Apr 20 02:27:11 EDT 2017 | pavel_murtishev
Mile, Please tell me more about your soldering process: - Are soldering process parameters the same for all three pins? - Is unsoldered pin connected to thermal heavy copper polygon? - What is your board surface finish? HASL? - Sn/Pb or LF process?
Electronics Forum | Wed Apr 28 11:47:34 EDT 1999 | Frank Boyko
| | We use Immersion Gold (AuNi) for our 20 mil pitch and BGA boards. | | Lately, we have been having solderability problems with boards with this surface from some of our suppliers. | | | | We are considering trying boards with White Tin solderable
Electronics Forum | Mon Feb 22 14:02:17 EST 1999 | Michael Allen
We have resorted to adding a ring (or donut) around our 0.040" round fiducials. The donut acts as a "plating thief" to minimize the thickness of the copper plating (in the case of HASL finish) and of the solder plating (in the case of solder-plated
Electronics Forum | Fri Aug 20 12:18:11 EDT 1999 | Earl Moon
| I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | Can any one tell me what I have to change in my SMT | process (paste, reflow, etc) If any? | I ran one P.C.Boar
Electronics Forum | Fri Aug 20 12:54:11 EDT 1999 | Carol Zhang
| | I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | | Can any one tell me what I have to change in my SMT | | process (paste, reflow, etc) If any? | | I ran one
Electronics Forum | Fri Aug 20 14:22:02 EDT 1999 | Earl Moon
| | | I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | | | Can any one tell me what I have to change in my SMT | | | process (paste, reflow, etc) If any? | | | I
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