Why this extreme requirement? BGA's use to be signal processing units, which
is normally maximum 48 VDC. If you mean 250 Volts AFTER the environmental
test and at room conditions, I think it's reasonable, but 250 Volts bias
under test condition is horrible, not to say madness.
/Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Steve Kelly
Skickat: den 15 april 2008 14:42
Till: [log in to unmask]
Ämne: Re: [TN] Possible flux contamination issue
Good Morning,
I need to ask some more questions on this thread.
One of the reasons our customer went to a water soluble paste was the high
voltage/damp heat test requirement on the finished assembly.
The test requirement is 1000 hours of damp heat test at 85C/85RH. The
voltage requirement is 250 volts. BGA pad spacing is .050. The customer was
concerned about passing this test.
Regards Steve Kelly
Steve Kelly
PFC Flexible Circuits Limited
PH: (416) 750-8433
Fax: (416) 750-0016
Cell: (416) 577-8433
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Kelly
Sent: Monday, April 14, 2008 1:58 PM
To: [log in to unmask]
Subject: Re: [TN] Possible flux contamination issue
Thanks everyone for the help. Regards Steve Kelly
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: April-11-08 11:50 AM
To: [log in to unmask]
Subject: Re: [TN] Possible flux contamination issue
24 years ago (yes 24!), I gave a paper at InterNepcon, in Brighton, UK,
entitled "Contamination on Components and Small Assemblies". I no
longer have a copy, but I'm fairly sure I evoked the need to have all
the components supplied clean to avoid just this kind of problem.
Brian
Steve Kelly wrote:
> Good Morning,
>
> We are assembling a BGA connector onto a flex circuit. The BGA has leaded
> balls and the BGA manufacturer uses a no-clean process to attach the balls
> to the connector and does not clean afterwards.
>
> When we assemble the BGA connector to the flex we use water soluble paste
> and then we clean. After damp heat cycling we have seen some shorts. When
we
> take off the connector we see flux residues on the underside of the
> connector but not on the flex. So my question is - what are the concerns
> about mixing no-clean and water soluble? Is the failure likely due to
> inadequate cleaning or is there something else I should be concerned
about.
> I realize this is probably not the way it should be done but some days you
> just do what the customer wants - good or bad. Thanks in advance. Steve
> Kelly
>
>
>
> Steve Kelly
>
> (416) 750-8433 (work)
>
> (416) 750-0016 (fax)
>
> (416) 577-8433 (cell)
>
>
>
>
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