The latest video on the Huntron YouTube channel discusses testing conformal coated PCBs with the Huntron Access Prober.
One of the toughest challenges when testing printed circuit boards with protective coatings is penetrating the coating to make good contact with the test point. Achieving good contact is necessary when capturing a test measurement you can trust.
Probe type for testing conformal coated PCBs
The most important way to achieve good conformal coating penetration is by selecting the best probe. Most spring probes can successfully penetrate thinly applied coatings. However, as the conformal coating gets thicker more aggressive probe types are needed. Huntron supplies a very sharp, high spring force needle probe well suited to penetrating thicker, pliable coatings. QA Technologies supplies this probe but most spring probe manufacturers will have similar options.
The Huntron Workstation software has several features to assist you with checking and fixing open circuit signatures caused by bad contact. You can access these features when viewing the Troublesheet after the test is run. The menu displayed when you right-click on the signature box lets you access methods to retest a point. These methods are grouped together at the top of the menu. Once you have retested the point you can save the new signature or signatures.
Several options are available to have the Access Prober rescan selected pins. You can also have the Prober rescan all displayed open pins by selecting “Reprobe Opens”.
We have created a video on testing conformal coated PCBs. View the embedded video below or go to the Huntron YouTube channel to watch this and other videos published by Huntron Technical Support.