Electronics Forum | Mon Sep 13 06:23:06 EDT 1999 | Earl Moon
| | We have a product, with various PWBs, with over 600 parts each one (We are a low Volume/high mix company with an average component placement per PCB between 250 to 300 parts). This PWBs have 7 to 10, 20 mils pitch parts. We are having problems wi
Electronics Forum | Thu Dec 08 07:55:16 EST 2005 | davef
Your understanding of the situation is correct. In both cases, you solder to the nickel. The gold [Au] protects the nickel from oxidation. When soldering, the gold moves into solution in the solder and forms an intermetallic compound [IMC] with th
Electronics Forum | Thu Feb 18 22:49:49 EST 1999 | Chris G.
| We are using .040" diameter fiducials (global and local) on our boards. They are solder covered and HASL. I get batches of boards where the p&p vision system has trouble reading the fiducial. The fiducial looks dark on the screen. The board ven
Electronics Forum | Fri Feb 19 00:32:40 EST 1999 | ZEEK
| We are using .040" diameter fiducials (global and local) on our boards. They are solder covered and HASL. I get batches of boards where the p&p vision system has trouble reading the fiducial. The fiducial looks dark on the screen. The board ven
Electronics Forum | Thu Aug 21 22:10:07 EDT 2003 | adlsmt
Well, for some reason the board house will pay for the boards but has some issue with paying for the parts on them. Why am I not supprised? Perhaps I have mis-diagnosed the problem. We have found two different board p/n's with the same type of defec
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 | Tue Aug 20 18:15:02 EDT 2002 | davef
Haaaaa!!!! Soldering to plastic!!!! An apt analogy!!! I like to compare it to soldering to dirt. Some thing. In fact, you are soldering on nickel, when soldering on many things. It�s just that the gold, er Pd, flash enables the wetting mechanism
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 | Fri Feb 19 09:20:01 EST 1999 | Stefan Witte
If the fiducials are rejected from the vision system, I would not relay on the accuracy of the position. Again, I would like to point out that the circle shape has a somewhat sinoid contrast in X- and Y- direction ( same as a diamond shape, but recta
Electronics Forum | Fri Feb 19 14:44:24 EST 1999 | Lance A. Smalley
You don't say what kind of machine you are using but several just use the edge of fiducials to determine area (and centers). If you are teaching in binary and have the ability to select a decision level (threshold), use a level half way between loss
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