LISTSERV - TECHNET Archives - LISTSERV.IPC.ORG

TECHNET Archives

January 2001

TechNet@IPC.ORG

	LISTSERV Archives
	TECHNET Home
	TECHNET January 2001

	Log In
	Register

	Subscribe or Unsubscribe

	Search Archives

Options:	Use Monospaced Font Show Text Part by Default Show All Mail Headers
Message:	[<< First] [< Prev] [Next >] [Last >>]
Topic:	[<< First] [< Prev] [Next >] [Last >>]
Author:	[<< First] [< Prev] [Next >] [Last >>]

Subject:	Re: PCB Baking
From:	Robert Lazzara <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Thu, 25 Jan 2001 19:40:21 EST
Content-Type:	text/plain
Parts/Attachments:	text/plain (38 lines)

In a message dated 1/25/01 5:53:14 PM Eastern Standard Time,
[log in to unmask] writes:

Q: Is there any standard (IPC or otherwise) that details the requirements and
the process of baking bare PC boards prior to assembly?
A: Not the IPC. The various "How-To-Assemble" handbooks may have a reference
but none qualify as a standard.

Q: It is standard practice to bake boards that have been stored in high
humidity conditions for long periods. These boards will have absorbed
moisture and will need drying before wave soldering to prevent outgassing.
A: HASL finishes can stand a typical dehydration bake without real liability
to reduced solder ability associated with the accelerated aging effects of
the dehydration bake. The increase of intermetalic is likely slight compared
to the mass of HASL solder on the copper and thus of little consequence.
Immersion coatings, especially white tin, should not be baked, and OSPs
aren't famous for withstanding pre-assembly baking without degradation of the
coating (I'm bracing for rebuttals).

When in-doubt, ask your friendly PWB supplier to take the boards back to
perform a dehydration bake. Should be cheap. Follow with a representative
solder ability test (ala the IPC-S-804)...then, and only then, can you trust
the boards to the expense of assembly.

Bob Lazzara
Circuit Connect  -  Atlanta
+1 706.245.4232

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2

LISTSERV.IPC.ORG