Clipping vs Screwing Down Power Chips

[CarlosT]

Here's a cool heat sinking subtopic...screwing down versus clipping the chip to the heatsink. There would seem to be a lotta pluses to clipping.

Pros of Clipping TO220s:

1- Even clamping pressure over a greater surface area of the chip

2- No doubleguessing about how tight to screw things

3- No additional concerns over the screw making contact with the metal and shorting the chip

4- No screw and nut to figure out

5- No holes to drill into a nice virginal heatsink

6- Quick and easy...easy to undo

Cons of Clipping TO220s:

1- Maybe...not enough pressure to make good thermal contact?

2- Maybe...clip may come off under jarring or shock to amp chassis?

3- ...

I'm grasping for cons here...

In particular, I'm talking about Aavid Thermalloy's very Max Clip system

http://www.aavidthermalloy.com/produ...ip/index.shtml

I'm seriously considering using these "Clip Over Edge" clips with my Wakefield 401-K heatsink...call me lazy

http://www.aavidthermalloy.com/cgi-b...Search1=Search

[v-bro]

The only minor thing I can think of is the messy way to mount it with paste or silicon patch, never found the right tool to keep the spring open.. The system in the slideshow-picture in your first link looks interesting in that perspective...

Here's what I once did to attach a slab of aluminum to a T-amp chip:

[CarlosT]

Nice...but is that clip for retaining or cooling?

I don't think that clipping changes the grease mess much other than there's no reason to grease either side of the "clipover the edge" clip...it's not really intended to add any cooling in my application although it prolly does by a nominal amount.

[v-bro]

Retaining and cooling, here's how it looked aprox. (it used to be a larger slab...)

[falcott]

Somewhere, sometime, I saw a clip that screwed at one end into the heatsink, supporting the chip by the other end.

I know this almost defeats the purpose of "clipping" that you're talking about, but it does allow the chip to be mounted on a chunky heatsink, and it will hold the chip more evenly on the sink than simply a screw at one end.

I've been trying to find something similar for my LM amp chips, but haven't managed yet... Let me know if you do!

[falcott]

Originally posted by CarlosT

Cons of Clipping TO220s:

1- Maybe...not enough pressure to make good thermal contact?

2- Maybe...clip may come off under jarring or shock to amp chassis?

3- ...

I'm grasping for cons here...

3- Limited to using a thin, small heatsink?

[peranders]

Only cons for clips _if_ the design is made for it.

[heater]

In the Genelec monitors I opened the LM3886s are pressed against the heatsink with a spring clips. Mind you the heatsink in this case is the entire speaker box which is cast aluminium. There is not much air flow inside those boxes (only from the port) but they don't seem to have any problem with heat.

[CarlosT]

I sorta eyed it up and the heatsink I'm using is .190" thick where the LM3875 would clip/screw to. The other factor that motivated me is that the 401-A version of this heatsink with a hole for the TO220 is $12something while the non-holy 401-K version is $8something. $4 a hole? That's too much $$$. So you see...both laziness and cheapness combined to have me look at the Max Clips

[Minion]

I find I get best thermal contact useing a Screw with a Big washer which helps apply an even presure over the whole chip...

Works 4 me!!