Electronics Forum | Mon Oct 15 10:51:49 EDT 2001 | davef
On over printing, the general issues are: * Paste deposits being so large that when reflowing, collapse onto many, rather than a single solder mass. * Paste expanding during heating and being close to other solder deposits and bridging [as you say].
Electronics Forum | Tue Oct 16 06:08:12 EDT 2001 | wbu
Hi Dave, tweaking, oh yes, we did like it to have that job done and not have people sitting around waiting for work or beeing able to deliver on schedule. Nonconformity report, ...ummmmh, weren�t that big that we thought we needed it, actually the t
Electronics Forum | Wed Oct 24 18:09:44 EDT 2001 | davef
Allowing the board fabricator to define the board you expect to receive is fine, as long as they do a good job. Regardless of the existence of a clear product definition or not, it�s reasonable for you to argue that your receipts must meet the requi
Electronics Forum | Thu Nov 01 12:13:10 EST 2001 | jonathan
I guess this clarifies the defect more then looks at the process, but I�ll just through it out there for the sake of learning something new. If anyone would comment on this please feel free�. There are many different varieties of dewetting defects.
Electronics Forum | Mon Nov 05 20:34:03 EST 2001 | davef
What�s the problem? There area many heat related failure mechanisms in bare boards. You can damage boards with heat several ways. A couple favorites [Don�t try this at home. Perform on a closed track by professional solders only.] are: * Put a
Electronics Forum | Tue Nov 06 18:39:08 EST 2001 | MikeF
Also, check the website for Assembly magazine, http://www.assemblymag.com, they have some good information on the basics of torque. Determining the "correct" torque value can become very complicated very quickly. The same size screws made from differ
Electronics Forum | Mon Nov 19 20:10:49 EST 2001 | davef
We print glue with a thick stencil on one product. Although it works �correctly�, we don�t like it because the process flow is goofy. So on a high mix line, it ends-up being a burden. Also, there is no rocket science behind making the stencils for
Electronics Forum | Wed Nov 21 05:06:31 EST 2001 | frha
Thanks Mr Parker! I understand that the basic "demming-wheel" needs to be on place first. My contract manufacturers list ALL adjustments, failures etc during the production, and we also discuss the statistics (pareto) and corrective actions for all d
Electronics Forum | Fri Nov 23 14:47:35 EST 2001 | kgroen
Some comments on the previous post: Be careful when looking at the proportion of SMT defects that are solder defects - you may very well find that only a small few of them originate at the screen printing step. As for specification limits for pas
Electronics Forum | Wed Nov 28 20:14:50 EST 2001 | ianchan
Hi, i'd second that choice of enineering degree in electronics as monkey says, coz of variable options open to you IF you decide to rotate in your field of applicable enggr interests... IT courses are abundant in today's "open Uni" learning "econom
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