Hi All,
I've been reading the responses to this thread with interest since I'm one
of those designers that was designing boards way back then. You guys and
gals are sooooo much more knowledgeable about fab and assembly than I and
many other designers (and engineers). You all make good points about
concurrent engineering. Believe it or not, many designers have been asking
for this many years and it's taken this long to become reality (in some
organizations, anyway). So, to get to my point already -- what might help
is for some of you gurus to share your expertise not only on this forum but
in some other way, say in a reference containing "do's and don'ts" from
actual experience. I'm not asking for a text book, just practical
experience on how designers can make boards easier to fab and assemble -
like maybe your top 10 list. I know you don't have anything better to do,
right? : ) So, at the risk of being branded by the list as a total jerk,
what do you think? IPC standards are good and I use them as much as is
practical. You understand that we must also balance your input with what
engineering, the product and the customer demands. So, if you think this
is a decent request, go ahead and let me have it between the eyes (if you
don't think this is a decent request, be kind.) Things change very rapidly
these days. A lot of us just need more practical info.
Sue James
IPC Certified Interconnect Designer
815-624-5444 Direct Line
--------Original Message------------
Date: Wed, 16 Aug 2000 18:08:27 -0400
From: joyce <[log in to unmask]>
Subject: Re: Wave soldering ancient designs...
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
few tricks may help:
(1) use Lonco flux to activated your PWB before wave (Lonco=pink water
soluable flux can eat your forks for lunch). Make sure you clean the
PWB on
time with the neutralizer and hot water....
(2) as suggested by others, bake and wave immediately.
A lot of problem with the old design is that process changed in late
80s:
(1) eliminate CFC ==> can not use RA flux
(2) cost cutting ===> use FR4 instead of polyimide board ==> can not go
high
temperature wave
(3) cost cutting ===> use non-mil temp range components ===> can not go
to
high temperature wave
(4) cost cutting ==> use non-nitrogen or low grade nitrogen and/or
shorter
preheat zone (cycle time improvement)...
(5) others...(you want to know? no, no, you do not really want to
know...).
It is sad you find out on production line...someone (designer) should
spot
it...(back to Brain's point of concurrent engineering...with the fast
turn
around workforce...you may have difficult time to "concurrent"...copycat
without true knowledge is scary in design...)...(i think i better shut
up
before someone kills me)...
jk
At 10:20 AM 8/16/00 EDT, you wrote:
>In a message dated 08/16/2000 8:44:10 AM Central Daylight Time,
>[log in to unmask] writes:
>
>> We usually wave solder the easy components, clean, apply the heat
sinks,
>> clean again, bake, and hand solder the toughies. Would a rework
station be
>> any help? That's a guess, we're looking at getting a mini-wave
system next
>> fiscal.
>>
>> How ancient - 70's, 80's, or early 90's?
>>
>> Hans
>
>Hi Hans!
>
>Wish I could that, but the heatsinks are bonded to the top of the
boards and
>cover the entire surface of the board, except where the barrels are for
the
>components. Then you install the components straddling the
heatsink...they
>don't make it easy brother!
>
>-Steve Gregory-
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