<p>Problems with bubbles in conformal coating</p> <p>We operate a troubleshooting, repair, fabrication facility. The circuit cards we see are between 5 to 10 years old. They are exposed to extremes in weather and humidity. After repair/rework we apply low VOC silicone as a conformal coating. Our problem is bubbles.</p> <p>We´ve tried heating the boards to varying degrees, as well as keeping them cooler. We used various types of brushes to apply the coating, but continue to have bubbles between and behind the legs of surface mount components. Can you suggest low cost ideas we can try to reduce bubbles as the coating cures?</p>
Contamination Prior to Conformal Coating When moving PCB assemblies through the factory we use a tray that is not made of anti-static material. In order to minimize static issues we will place a layer of pink antistatic bubble material on the tray placing the boards on it. There is a "rumor" that the pink material can leave a residue on the PCB creating a contamination, inhibiting good adhesion of conformal coating. We have contacted several suppliers of this pink bubble material and none of them believe this could be a problem. Has anyone seen evidence of this problem or have some data to support or deny this rumor? Thanks for any help.
Re-plating lead-free components for tin/lead assembly We work with an aerospace manufacturer on a PCB assembly that includes Pb-free components (no BGAs). The device is processed using SnPb (60-40) solder, but this does not solve the issue of Sn plating on the leads and the risk of tin whiskers. According to information on this website http://nepp.nasa.gov/whisker/ tin whisker formation is an issue on the exposed component leads outside of the solder region. Is there a process that can be used to re-plate component leads to add Pb?
Epoxy Bonding Problems on RoHS Boards We are having problems with epoxy bonding components to RoHS circuit boards. We never had this problem on non RoHS boards. We´re sure the epoxy has not changed. Is there something about RoHS compliant boards that makes them more difficult to bond to? The boards look sparkling clean to the eye!
Affects of Silicone Migration We are researching the affects of silicone migration onto electronic circuitry. We have heard of military contractors not allowing silicone materials in certain parts of the factory. Are you familar with any potential hazards to health or long-term product reliability due to products exposed to silicone materials?
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