There are a number of different methods used in this thread - I used Permatex Ultra Black gasket maker to secure the heat shield after doing the mod myself. SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod

Repo Man11 wrote on 2024-03-03, 00:55:

There are a number of different methods used in this thread - I used Permatex Ultra Black gasket maker to secure the heat shield after doing the mod myself. SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod

Ultra Black and Ultra Grey are great, I use them on cars all the time when needed. But I've always heard the curing solvents in RTV were extremely corrosive to electronics.

RTVs are also all sealants rather than adhesives, so have about the same sticking power as that peel off glue that's sometimes used to stick products to packaging.

Also if your CPU is running hotter than McDonald's serves coffee, you've probably killed it, so something just a bit over slightly more heat resistant than candle wax is gonna be fine, but sure, use the epoxy putty petrol heads use to build up exhaust ports if you think you are ever going to want to MIG weld a heatsink onto it. I would consider commercial temperature hot glue, but figure the lower temp craft stuff is not quite past the slightly more resistant than wax so might creep.

Urethane based glues seem like the best bet, but finding non gallon quantities in hardware stores is a bit of a challenge.

BitWrangler wrote on 2024-03-03, 03:16:

RTVs are also all sealants rather than adhesives, so have about the same sticking power as that peel off glue

You've obviously never tried to get off an oil pan stuck on with ultra black before.

Didn't have to try. Swift whack with a mallet breaks the sticktion.

Edit: bear in mind in that situation you've got about a square inch of contact per 2 or 3 linear inches around the gasket, so larger pan that gets up to as much as 15 square inches or so, if you stuck a sandwich plate to your counter with sticky tack or bluetack type stuff over the whole bottom area you'd have as much trouble getting it off. On this you're not even gonna have a square inch to hold.

kingcake wrote on 2024-03-03, 02:16:

Repo Man11 wrote on 2024-03-03, 00:55:

There are a number of different methods used in this thread - I used Permatex Ultra Black gasket maker to secure the heat shield after doing the mod myself. SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod

Ultra Black and Ultra Grey are great, I use them on cars all the time when needed. But I've always heard the curing solvents in RTV were extremely corrosive to electronics.

Could be, but the four dots I used are spaced well away from the CPU core. The heat shield won't come off easily, and the clamping force of the heatsink compresses everything and hold it in place. It's been over a year, and it works fine.

There would be a concern about the adhesion of the thermal paste overcoming the adhesion of the RTV when you take it off though.

BitWrangler wrote on 2024-03-03, 04:26:

There would be a concern about the adhesion of the thermal paste overcoming the adhesion of the RTV when you take it off though.

That's what happened when I tried J.B. Weld epoxy. As strong as that stuff is, it was too inflexible. The RTV has withstood numerous heat sink removals, and I'm pretty generous with the thermal paste.

Repo Man11 wrote on 2024-03-03, 04:44:

BitWrangler wrote on 2024-03-03, 04:26:

There would be a concern about the adhesion of the thermal paste overcoming the adhesion of the RTV when you take it off though.

That's what happened when I tried J.B. Weld epoxy. As strong as that stuff is, it was too inflexible. The RTV has withstood numerous heat sink removals, and I'm pretty generous with the thermal paste.

I've never been impressed with JB Weld. It's let me down multiple times.

Kahenraz wrote on 2024-03-03, 00:34:

Is there a recommended type and brand of glue or epoxy to bond the metal heat spreader to the ceramic substrate? It would have be to be heat resistant as well.

My favorite was 5200 marine adhesive.

The best however may be the stuff they use on windshields (which may be the same stuff as 5200) it’s considered a “structural adhesive” but I haven’t tried that yet.

kingcake wrote on 2024-03-03, 05:20:

Repo Man11 wrote on 2024-03-03, 04:44:

BitWrangler wrote on 2024-03-03, 04:26:

There would be a concern about the adhesion of the thermal paste overcoming the adhesion of the RTV when you take it off though.

That's what happened when I tried J.B. Weld epoxy. As strong as that stuff is, it was too inflexible. The RTV has withstood numerous heat sink removals, and I'm pretty generous with the thermal paste.

I've never been impressed with JB Weld. It's let me down multiple times.

J.B. Weld (the original, the quick set version is not good IMO) has worked very well for me over the years for certain repairs. I once used it to fill on a dent in my small block Chevrolet's oil filter mount. Some careless handling of the engine block had put a divot right where the oil filter seal fits against the block; I filled it in with J.B. Weld, and it never leaked again. It has also worked very well for me for repairing broken plastic computer case bits. But it wasn't the right thing for reattaching a CPU heat shield.