a few questions:

-exactly WHAT get tarnished, dielectric, copper, solder?
-WHAT will be "grounded"? 
-you can't decide RF ground with a multimeter.
-WHAT microwave product do you work with? Sometimes, a board in a
microwave set is not a RF board at all, but driver or logics etc.

Inge
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kong Hui Poh
Sent: den 12 december 2007 13:43
To: [log in to unmask]
Subject: Re: [TN] Tarnished on the bottom side (Teflon Board)


Hi Technetterers,

I am facing with board that after reflow, it turned tarnished.
The board is of tin-lead plating.

The top side of the board consists of the circuitry & components.
The bottom side of the board is a complete plane.

My customers said that there will be grounding due to the tarnished.
However, I try using Multimeter, and probe the bottom side very lightly.
The measurement I got is less than 0.5 Ohm.

Somehow, the measurement shows otherwise.

I wandered if there is an issue with the grounding if the board is
tarnished.

Can someone advise me if any of the IPC spec states that board of
tin/lead plating, if found tarnished is a reject/defect.

Is any of the IPC spec. defines the solder surface requirement for the
Microwave end product (if after reflow).

Thanks you in advance.

Regards,
Poh

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 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
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
-----------------------------------------------------