|
|||||||||||||||
|
Ask the Experts
Ask the Experts Panel share experiences, theories and practices to help solve problems associated with advanced electronics manufacturing and assembly.
Expert Panel Contributors:
|
Is PCB Baking Necessary?
Comments Try the IPC-1601 Printed Board Handling and storage guidelines. S.F. I couldn't agree with R.M. more! Dupont, Isola, and NASA have done extensive studies which show that flexible circuit materials, lead free resin systems, and ANY laminate if you want the highest reliability, should be baked to remove moisture prior to ANY thermal stress. It has nothing to do with whether they are "good" IPC 6012 boards. If the boards are vacuum sealed from the fabricator, that's great for the first reflow, but what about second reflow, wave, secondary hand soldering, selective soldering, and rework? What if the vacuum seal is broken for inspection? The key is there should be minimial or no moisture in the boards prior to any thermal stress which has the potential to vaporize the moisture in the board. Just as Rich points out, boards should be treated just like any other MSD. J.H. Get some different experts. Have them study material mositure absorbtion charteristics. It is obvious they are in the assemble end of the business. Why not ask the people that make the material and look at their charts. The guy in marketing knows more than the two guys in manufacturing operations. Lord help us. R.M. Do IPC documents require vacuum package for all PCBs? What IPC document covers this? We often receive PCB in unsealed packaging. P.U.
|
Submit a Comment |
|||||||||||||
| |||||||||||||||
