So I’ve done a few emitter swaps over the years. Almost always used Arctic Alumina thermal epoxy except for once when I mixed arctic silver in to make a semi-permanent bond. Last couple I did I really was racing the AA to get stuff lined up and reassembled before it set up which got my thinking, when is a thermal compound better to use under a mcpcb? Does it detract for any durability? Seems like most to all LEDs are centered by a ring which mounts against the reflector and are pressed down by this reflector so is a thermal adhesive even needed? Would I be better off using a thermal paste in the future?
Thermal paste, if you use the good ones, is better than thermal epoxy.
Unless you’re overwdriving your LEDs a lot though you won’t notice a difference.
Unless you have a need for adehesion, thermal paste is transfers heat better
If the pill/shelve is not alu but cu or brass, i solder mcpcb every time. The best heatsinking. Ever.
if alu, ti or ss without retaining screws then thrmal epoxy is still nr.1.
If mcpcb retaining screws are available then IC Diamond Karat24 thermal paste.
So to me the question remains. In your most commonly seen construction where the LED’s MCPCB is sandwiched between the shelf and the reflect, does this require thermal adhesive for the best durability or is nothing lost by going with a thermal paste/compound?
I use paste exclusively because I like to take stuff apart, and it just works great! Use good thermal paste though! The fit between yhe thermal interface is important though. The flatter each are, the better (machined, lapped, remove oxidization, etc.). It’s easier to disassemble than if things are glued. The only argument for adhesive is longevity. All thermal paste has a useful life span, so it needs to be refreshed eventually. If you have a good mating surface and clamping force from screwing down the reflector, thermal paste is fine.
Unless you have screws to clamp the MCPCB i would use glue. But if there are screws fixing the board then quality paste is OK.
I have OCD so i solder every MCPCB to heatsink as long if it is Cu or Brass.
Use adhesive only if there is no mechanical means to hold the mcpcb firmly on the mounting shelf or whatever the mcpcb is attached to.