>Jerry,

If the capacitor is ceramic boy will you have fun keeping it from cracking
during reflow cool down and PWA handling.

John Maxwell

>Hello all,
>
>Don't worry, ... you can read on. I am not posting any links!
>I wonder if anyone can shed some light on the following topic:
>         Using IPC-SM-782 Land Pattern program one has to input Solder Joint
>Design Goals (Min.) for Toe, Heel and Side for any SMD part. However the
>Surface Mount Design and Land Pattern Standards states that those dimensions
>"have been determined based on industry empirical knowledge and reliability
>testing".
>That is fine, but how about those parts that are either too new or used very
>rarely?
>I am attempting to design a pattern for a Chip Capacitor 5550 with a
>thickness of 2.5mm.
>Could anyone share his/her SMD assembly empirical knowledge and know-how and
>answer the following questions:
>- what would be an optimum number (mm) for each parameter for that
>particular part?
>- what are those numbers based on?
>- is there a formula that determines the correct ratio between the part's
>dimension(s) and Solder Joint size?
>
>Thanks in advance
>
>Jerry

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