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Subject:	Re: Lead Free BGAs
From:	John Maxwell <[log in to unmask]>
Reply To:	TechNet E-Mail Forum <[log in to unmask]>, John Maxwell <[log in to unmask]>
Date:	Wed, 23 Nov 2005 11:20:04 -0800
Content-Type:	text/plain
Parts/Attachments:	text/plain (44 lines)

Joel:
I came out of building high density Dc-Dc converters in volume. When one
adds high mass components like ferrite cores, ENIG board finish,
components with PdAu lead finish,  and 10 layer 2 oz inner layer boards,
temperatures are up. Otherwise parts lift out of solder joints, solder
joints fail on large parts at the ENIG surface due to incomplete
dissolution of the gold/palladium and other fun problems. There is no
simple answer as it depends on many issues. If I was running an .062"
thick double sided assembly with HASL pad finish then you bet 205C
absolute minimum is just peachy. If I have a high thermal mass assembly
using an ENIG board and PdAu components then temperatures go up.

John Maxwell

>The article indicates that a typical Sn/Pb profile peaks at 220degC. I don't
>think anyone should be running Sn/Pb that hot. You don't need to be 40degC
>above reflow to form a reliable solder joint. I think a Sn/Pb profile should
>max at 205degC.
>
>I wonder if the experimental results would change if he ran a cooler (and in
>my opinion more appropriate) profile.
>
>Joel Mearig
>Delta Tau Data Systems, Inc.
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
>Sent: Wednesday, November 23, 2005 7:07 AM
>To: [log in to unmask]
>Subject: [TN] Lead Free BGAs
>
>
>

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