SMT007 Magazine

SMT-July2016

Issue link: https://iconnect007.uberflip.com/i/699765

Contents of this Issue

Navigation

Page 49 of 123

50 SMT Magazine • July 2016 can be seen to failing in either single or double coated condition. Hence the geometry chal- lenge of the 3-oz copper tracks for the acrylic-1 coating has been shown by it failing the con- densation test. From above this coating passed the humidity test at 40°C/93%RH, and the same coating with the 1oz copper tracks also passed. Thus the incremental geometry challenge and the fine control of the condensing condition in this experimental arrangement allows detailed and robust characterization of coating perfor- mance. Discussion It is well known that water films will lead to anodic corrosion on powered circuitry and that conformal coatings are a suitable mitiga- tor. However, this requires complete coverage of all the parts so that the water film has no ac- cess to the energized parts of the boards. Hence there is an issue with achieving complete per- fect conformal coating coverage. The technique described here that has just been developed and offers a wide range of flex- ibility in the test conditions. In the current setup controlled levels of condensation can be achieved above 30°C and a range of humidities. A crucial aspect of any condensation technique is the ability to achieve a number of aims: re- peatability, controllable and stable conditions, and maintain those conditions over any desired time period. Within the many existing testing methods that were mentioned above there is a great challenge to achieve a fully controlled condensing condition across the wide range of equipment manufacturers, and hence there is a struggle to achieve all four aims in the wider context of standards testing. However, the ap- proach described here has this ability, and fur- thermore these four aims are easily met. CONDENSATION TESTING—A NEW APPROACH Figure 12: Condensing conditions with the 3oz copper tracks with the acrylic-1 and polyurethane coatings.

Articles in this issue

Archives of this issue

view archives of SMT007 Magazine - SMT-July2016