10
\$\begingroup\$

A recent question asking how to deal with a missing pin on a specific IC (Use the heatsink tab which is connected to ground) made me curious. What is the industry term for a pin that is physically missing or otherwise non-connectable pins?

I know these are common in the DPAK/TO252, and sometimes on SOT packages.

Some research shows that the TO252 has both a -3 and a -3+ variation, where the -3 has the truncated pin, while the -3+ version has all three pins at regular length. Same goes for the -5 and -5+ versions.

But what is this type of truncated pin called? There has to be an industry term.

enter image description here

\$\endgroup\$

1 Answer 1

Reset to default
3
\$\begingroup\$

What is typical for these types of packages is that the leadframes are ordered in and come in a flat stamped sheet like reel of metal, the leads are shaped and placed in the mold for the epoxy injection. If you want to reuse an existing mold but want to leave out a pin or leg then you need to have a vestigal lead in there to prevent the epoxy from squeezing out during molding. It is either than or get a new mold made. Here is what a untrimmed lead frame looks like before forming (but for a different product/package type).

enter image description here

I am unaware of what a generic term might be for this. I've heard variously, dropped/missing/blank pin. But I am sure it's not industry standard.

\$\endgroup\$
1
  • 2
    \$\begingroup\$ You just pulled out your phone and took a picture of it while writing this answer, didn't you? :) \$\endgroup\$
    – abdullah kahraman
    Commented May 29, 2013 at 21:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.