Heat sink lock in retaining spring

I don't know anything about these clips, but it's not uncommon for heat sinks to be rather hard to attach. They want to keep it as low cost as possible, while keeping pressure on the heat sink for a good fit. Ease of use seems to be secondary. The factory knows how to make it all work.

An image of heat sink might help. Is there a bracket that bolts to the mother board?

They look somewhat similar to SS clips used to hold glass onto metal-framed greenhouses here in the UK. They require considerable force to put in place with the added hazard of trying to avoid breaking the glass!

As I check through my records, I find that the devices at risk were nothing like as expensive as I'd thought. Still removing a 5 lead device and replacing it is a tiresome exercise.

In future I'll stick with heat sinks that accept a bolt through the (TO220-5) device.

Sylvia.

I'm actually using

While that force is being applied to allow the clip to pass in front of the device, the friction at the pivot point is much increased, making it difficult to slide the clip sideways.

Sylvia.

Some big mosfets don't have a mounting hole. That leaves more room for silicon. We clip mount them, but with screws.

No insulator?

Must the clip be loaded from the end or can it be loaded from the face, possibly by using wide mouth pliers as a press.

It can be placed into the slot in the face easily - no force required - but with only about 2mm clearance between the clip and face. Significant force is then required to pull it outwards to clear the device being cooled.

No doubt a special tool could be devised.

Sylvia.

In this case the heat sink was isolated, and the device was an audio frequency power amplifier. Built onto a home-etched board[*], two have worked without incident for many years.

Sylvia

For insertion, an oversized pair of pincing pliers will work.

For removal, a screw driver pry. Don't re-use the clip.

Helps if the heatsink and clips are designed for each other, and the right size for the package and mounting height intended.

If it's too difficult to get a reliable and secure mount, use a different mounting method. This stuff is not intended for one-off projects.

RL

RL

Eventually one gets tired of the hassle and mess, especially with ferric chloride under ones fingernails.

Multilayer, plated-thru, solder masked, silkscreened boards are cheap now, thank Goodness.

There is an instant-set (modestly) thermally conductive Locktite.

I like surface-mount fets with surface-mount heat sinks.

Standing up, just bolt a TO220 or TO247 to an isolated heat sink.