HI TECHIES
One solution to the problems reported is the use of vapour phase or,
as some prefer, condensation soldering.
The advantage being that the temperature delta can be maintained at
something around 12C assuming SAC at 219C and the fluid boiling at
230C. Of course the process permits a more uniform heati transfer
within less than 2 seconds between the outer and inner solder spheres
on BGA.
So to the original problem sufferer Poh Kong Hui, you might want to
investigate this process route and do some comparative analyses. This
is a really cool solution - sorry Dewey, couldn't resist that one!
Kindest regards
Graham Naisbitt
[log in to unmask]
GEN3 SYSTEMS
Unit B2, Armstrong Mall
Southwood Business Park
Farnborough Hampshire
GU14 0NR - UK
ENGINEERING RELIABILITY
IN ELECTRONICS
On 18 Aug 2006, at 08:13, Ingemar Hernefjord (KC/EMW) wrote:
> " By the way, such kind of issue happened only to one customer..."
> see
> my comments to 'Immersion Au vs Immersion Ag'..Poh's case is typically
> what I meant: supplier dependency.
>
> Richard's words about a dewetting caused by a phosphorous rich barrier
> is also what I think. Therefore, KH, send your sample(s) to a
> qualified
> lab for confirmation of what Richard proposed. And, if you have
> accepted
> results from other board suppliers, then be happy, and skip the bad
> one
> until they show improvements.
> Inge
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Poh Kong Hui
> Sent: den 17 augusti 2006 16:24
> To: [log in to unmask]
> Subject: Re: [TN] LEADFREE BGA ISSUE
>
> Hi Technetters,
> Could someone advise me the reasons to following issue.
>
> 1. There are total 25 boards for the evaluation purpose.
> 2. Round 1, we assemble d11 units SAC BGA onto board of ENIG. The
> result
> was 10 passed functioonal, 1 piece was not working. There was no
> signal
> & power to the BGA unit.
>
> 3. Round 2, 4 boards were being assembled, 3 passed, 1 was not
> working
>
> 4. Round 3, 10 boards were biring assembled, 1 was working, 9 not
> working.
>
> The above-stated boards undergo the same temperature profile.
>
> At the beginning, we were suspecting the board of ENIG. When 1 BGA was
> being removed from the failed board, and intend to perform the
> reballing, we realise the not all BGA substrate pads were able to
> solder. Certain pads were very dull and when solder is applied on
> it, it
> seened there was dewetting issue.
>
> My question is, if the failure of the BGA that was due to BGA's
> substrate or otherwise.
>
> By the way, such kind of issue happened only to one customer...
> Thanks
>
> KH Poh
>
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