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Mon, 13 Jun 2005 17:30:43 -0400 |
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Hi Werner,
if I got it right, one should design the landpattern the same size as the chip? That is for a 1206, the landpattern should be 120 mils overall length and 60 mils wide.
Then, I am wondering how can one inspect the workmanship, not to mention eventual rework?
And secondly, how could one control the height of the solder joint?
Regards,
Ioan
> -----Original Message-----
> From: TechNet [SMTP:[log in to unmask]] On Behalf Of Werner Engelmaier
> Sent: Monday, June 13, 2005 5:15 PM
> To: [log in to unmask]
> Subject: Re: [TN] Ceramic MLCs and Leadfree, John Maxwell case?
>
> Hi John,
> LF-solder are stronger, less ductile, and creep slower--all of these add up
> to higher stresses in LF-SJs; ergo higher flex crack sensitivity.
> For chip components I suggest getting rid of the fillets--they cause
> component cracking, increasing the solder joint height under CCs and CRs, and reflow
> soldering them.
>
> Werner Engelmaier
>
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