What are the bake out conditions for Polyimide?
-----Original Message-----
From: Blomberg, Rainer (FL51) [mailto:[log in to unmask]]
Sent: Tuesday, August 17, 1999 10:44 AM
To: [log in to unmask]
Subject: Re: [TN] Baking out PCBs?
Mr. Talbert,
In response to your questions,
1) Boards in Florida (and most other places except Arizona) acquire moisture
over a short time that causes measeling when suddenly exposed to high heat.
The moisture turns to vapor and seeks to escape. The moisture content also
causes dimensional changes that can cause warp and bow of boards with
integral heatsinks.
2)We use polyamide boards of 9 to 16 layers. The baking spec I provided
just happened to be from the wave solder process. The bake-out for manual
processing is the same. Master Interconnect Boards (MIB) of up to 16 layers
are vacuum baked longer (16 hours).
3) The process was developed from our experience and process development
experiments.
Hope this is helpful.
R. G. Blomberg
Honeywell -SASSO
Staff Production Engineer
-----Original Message-----
From: Talbert, Marvin [mailto:[log in to unmask]]
Sent: Monday, August 16, 1999 4:03 PM
To: [log in to unmask]
Subject: FW: [TN] Baking out PCBs?
Hello Mr. Blomberg,
This is interesting. We take similar precautions for moisture sensitive
packages but not for the boards.
What is your concern with the bare board? What type of board material did
you have the problems on? How many layer and can you tell me who the vendor
is?
You said specifically wave but not reflow. Why?
Did you devise these specs yourself or were these taken from MIL-SPECs?
Marvin Talbert
Data General PCB Engineer
919-387-5134 Direct
919-387-5292 Fax
919-871-6598 Beeper
The most successful people in life are generally those who have the best
information. [Benjamin Disraeli]
> -----Original Message-----
> From: Blomberg, Rainer (FL51) [SMTP:[log in to unmask]]
> Sent: Friday, August 13, 1999 11:47 AM
> To: [log in to unmask]
> Subject: Re: [TN] Baking out PCBs?
>
> Here's a cut out of our process spec: "Prior to wave soldering, the boards
> shall be baked in a vacuum oven (28.5 inches of mercury, minimum) at 95?C
?
> 5?C for six hours minimum. The boards shall be soldered within 4 days
after
> removal from the oven or maintained at 54?C ? 5?C minimum or stored in a
dry
> nitrogen box. If these conditions are not maintained, the baking cycle
> shall be repeated." The cleaning method is up to you, but we use Axarel
32
> in an ECD batch cleaner followed by water and IPA rinse then oven drying @
> 150 deg. F. for 2 hours.
>
> Rainer G. Blomberg
> Staff Production Engineer
>
> -----Original Message-----
> From: Rick Thompson [mailto:[log in to unmask]]
> Sent: Friday, August 13, 1999 10:28 AM
> To:
> Subject: [TN] Baking out PCBs?
>
>
> Hi,
>
> As a small contract manufacturer, we receive a lot of bare PCBs consigned
> from our customers. Many times these PCBs are of questionable cleanliness
> and the storage conditions are unknown to us, so we routinely wash and
bake
> these boards out overnight. My question is this: Are there any industry
> specifications or recommendations for this type of process? Anybody care
to
> share how they handle this? I've looked in IPC-A-600, IPC-6011 and
IPC-6012
> and don't find anything specific to this topic.
>
> Thanks in advance.
>
>
> Rick Thompson
> Ventura Electronics Assembly
> 2665A Park Center Dr.
> Simi Valley, CA 93065
>
> +1 (805) 584-9858 voice
> +1 (805) 584-1529 fax
> [log in to unmask]
>
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