HKJ Package Direct Mount?

Andrew Gibson

Hi - is it practical to directly solder an HKJ package with shortened but otherwise unmodified leads to a suitable PCB pattern? Any life-over-temperature implications? Or is it necessary to have some lead-forming to allow for thermal expansion mismatch between the board and the package? Or for some other reason I hope you will name?

In many cases it is tempting to apply the HKJ package to an extended version of the SOIC footprint e.g. for the TPS40200SHKJ in place of the TPS40200SHD. If possible, please list a few reasons why this is not a good idea, if this is the case.

Thank you in advance.

over 9 years ago

0 Richard Biddle over 9 years ago

TI__Expert 5570 points

The gull wing and other formations are there to provide stress relief as you mentioned. There are a number of lead-forming references at the www.fancort.com website. FANCORT specializes in lead-forming.

0 Andrew Gibson over 9 years ago in reply to Richard Biddle

Intellectual 640 points

Hi Richard,

So it would be a bad approach to cut the leads HKK & HKJ short and solder the parts straight onto the pads without any lead forming?

0 R.A. Pauley over 9 years ago in reply to Andrew Gibson

TI__Intellectual 1130 points

Good afternoon, Andrew. If I may interject... cutting the leads and soldering the parts directly to the PCB pads would essentially convert these packages into LCCC's which would not have the thermal fatigue or shock life required for many programs.

In addition, since thermal dissipation is primarily through the package body for these devices, forming the leads to allow ~.015" to .030" package bottom to board space clearance where epoxy underfill can be applied will improve dissipation.

Space & High Reliability (Read Only)

Space & High Reliability Forum (Read Only)

HKJ Package Direct Mount?