Well Inge , you sure play hard to get ; spend midnight heating my pyrex
glass plates ;
depleting my chemical fridge of polymers and the precious substrates stocks
.
Soooo, hate to break the news to you , yo're totally sane (doesn't help
hey?);
mother Gaia with sea level atmospheric pressures does indeed tolerate little
intrusions .
No idea how far you went on heat, pressure and vacuum ; my home lab is
limited ;
the best results (least amount of bubbles seen under pyrex[100x
magnification]) seen after
heating (went to 150'C; 1/2 hour) ; vacuum (relative, 1/2h), and assembly
under vacuum ;
than pulled out of cylinder and clamped .
Bit impractical for volumes ; but (as you know)the moment you pull it from
vacuum you have all the air soup back just about instantly .
But with your budget, if it is volume (Matthias caught me on wrong foot);
with one or two rotational manipulators and clear cylinder you can apply the
polymer on heated substrate under vacuum ;
tedious (one by one, unless you'd develop in line serial movement in glass
tube).
Nice project ; let me know the volumes ; polymer specs , etc.
I'll mail you the chamber sketch.
It would be simple enough ; all the mechanics on linear slide ;
with glass tube sliding over for vacuum ; say open 2 meters; closed 1 meter
.
Sorry not to answer specifically ; but how much of gas is in this case in
the category of how many of molecules is too much when it is obviously too
much . But yo' know that .
You'll have to apply in vacuum , only way , not that daunting , you'll gain
on bond strength on return to atmosphere as the polymer seeps back in .
I'll team up if you let me (building coincidentally much longer chamber for
one of my arty projects);
in return you can let us know the intermittence and silver flakes
conclusions .
Deal ?
pk
-----Original Message-----
From: Ingemar Hernefjord (EMW)
[mailto:[log in to unmask]]
Sent: Wednesday, 6 October 1999 16:36
To: 'TechNet E-Mail Forum.'; 'Paul Klasek'
Subject: RE: [TN] Cold solder
Coming Aussilek, if you can give me this: how much gas and water (maybe even
Mango Tea) is included in a CuMo carrier with electroless Au/Ni? Size 1"x2"
and 0.05" thick. We mount this carrier on a Al part by means of a polymer
transfer (heat+pressure) and observe numerous gas bubbles. Brush-Wellman
recommends isostatic highpressure CuMo instead with higher (nearly
100%)metal content (less voids). Alpha Metals say there is no volatiles in
their transfer, they think it's the CuMo carrier that behave badly.
Vacuumbake in heat may help temporarily, but a couple of hours in the
assembly environment, and I think mother Gaia will put back the gas, water
and tea into the structure. Insane?/Ingemar
What's this non tech rumble mate ? lets get back to work :
Inge, you still owe us the analysis method adopted on those intermittents
you battled with (please) .
I'd love to know if that dye line worked ; or whatever else .
And , Kelly, the minute traces of Darjeeling tea in bulk of Jamaican rum
compromised in my grog (heated capped) should not sway you to deluded
assumptions.
Otherwise I agree with you ; takes a seriously confused lord to "improve"
otherwise decent tea with something like bergamon oil, some of us use as a
solvent (orange , ok , close enough).
And Swedes boil tea in milk !
As Carey says 'enough blabbering'
paul
PS
the PCB manufacturing saga was most enlightening ; thanks fellows
PPS
Do you have a picture Ioan , of that "cold" joint ?
Watch it Earl - that stuff'll rust your bloomin' plumbing!! For all I know,
that might be what's wrong with our Aussie friend.
>I resemble that remark.
>
>> Earl Grey is a good tea, I agree,
>> Now, Joan, are you sure it's about cold soldering at all? As you describe
>it could as well be dewetting. If it's dewetting, your trouble shooting can
>leave the wavesolder for a while. Again, I wonder why you don't do a
wetting
>test on the terminals.
>> Good Lunch
>> Ingemar Hernefjord
>> Ericsson Microwave Systems
>>
>> ----------------------------------------------------------------------
>> Earl and all,
>>
>> the soldering was a lot better before. We've always had the QA on our
>back,
>> checking the flux density and the settings for the problem assemblies.
>> Myself, I don't recall having seen so much cold solder.
>>
>> The machine had been calibrated last saturday during the monthly
>> maintenance, when the pot is thoroughly cleaned.
>>
>> It's possible that the solder mask changed, since it's darker now.
>Together
>> with the soldering problems we started experiencing discoloration of the
>> solder mask on the solder side. But wouldn't this randomly affect any
>place
>> on the surface? I still get the connectors OK, with bad solder joints on
>the
>> caps and resistor networks.
>>
>> There has been no artwork change. However, could some changes in the
>> materials or manufacturing of the board affect somehow the thermal mass
>here
>> and there? I mean, maybe the connectors drain somehow the heat from the
>> adjoining components.
>>
>> And anyway, what on earth generates cold solder in the waving process?
>>
>> Ioan
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe: SUBSCRIBE TECHNET <your full name>
To unsubscribe: SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################
|
