Hello fellow TechNet'rs,

I'm clueless about ac voltage breakdowns along cracks in the solder resist
of flex PCBs. The breakdown voltage is much lower than on those flex PCBs
without solder resist.

With limited current one can watch the arc above, not down in the crack. The
crack is definitely a precondition for the breakdown and defines the
position and direction of the arc.

No problem with dc!

I'd be grateful for hints.

No crack - no arc. So we will try to avoid the cracks
- with improved layout,
- with a thin flex layer instead of solder resist and
- with more careful handling of the PCBs.

But I still want to understand.

Thomas

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------