Electronics Forum | Wed Mar 27 18:23:01 EST 2002 | kmorris
Does anyone have experience doing conformal coating over Plastic BGA in High-Rel PCB assembly? Is underfill necessary to avoid problems with entrapped air, etc? Our application is a 17x17mm BGA, 256 I/O. We are assembling with a water soluable pas
Electronics Forum | Tue Sep 21 13:10:10 EDT 1999 | Dave F
| Dear All, | | In order to understand the soldering technologies in SMT, I'd like to understand why some cards are soldered and then cleaned, or only soldered whitout water cleaning nor "ultra sound" wavelength. | | I mean that I wonder why we use
ASYMTEK Products | Nordson Electronics Solutions | https://www.nordson.com/en/divisions/asymtek/your-process/applications-corner/bubbles-and-conformal-coating
Bubbles occur when solvents or air become trapped and can’t escape conformal coating material. The presence of bubbles can lead to long-term product reliability issues including bridging of conductive paths, corrosion of exposed areas, and cracked coating due to temperature changes, shock or vibration
| https://www.smtfactory.com/PCBA-Cleaning-Machine-PCB-Defluxing-For-Best-Coating-and-Bonding-Effect-id43566387.html
. Otherwise the paint will peel off quickly. Conformal coating logic is the same as painting. To make matters worse, the coating is often semi-permeable, and moisture can get in and seep into the flux residue and cause corrosion
