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I want to bond a PCB (2 layer & 0.6mm thickness) to a metal (copper & 4mm thickness.) Could anyone help me with the process of bonding it? There is a power amplifier that has to be soldered with the metal and also to the PCB.

I found a few options, but still unaware of implementation part.

Like thermally & electrically conductive adhesive (TECA) like coolspan from Rogers.

Is there any other way to bond the metal and PCB?

Like soldering (sweat soldering/sandwich soldering?

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    \$\begingroup\$ Just get a metal core PCB to begin with. \$\endgroup\$
    – DKNguyen
    Commented Dec 26, 2020 at 4:31
  • \$\begingroup\$ How much power are you talking about? Do you know what thickness of metal would be sufficient to carry the required current? \$\endgroup\$
    – user4574
    Commented Dec 26, 2020 at 4:35
  • \$\begingroup\$ Thermal dissipation of around ~400W, and need the metal cald of around 3 to 4mm thickness which will be fixed to my mechanical heatsink. \$\endgroup\$
    – Vineeth
    Commented Dec 26, 2020 at 5:53
  • \$\begingroup\$ @DKNguyen , Yes I have that option, but i'm trying to optimize the cost of manufacturing. Because I can get a copper metal block of 4mm thickness in standard market and 2 layer PCB for low cost too. But the cost of metal clad processed PCB is higher. \$\endgroup\$
    – Vineeth
    Commented Dec 26, 2020 at 5:55

2 Answers 2

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From first principles:

Just glue the board to the copper sheet with regular epoxy. As long as you respect the temperature limits of the glue, and the bottom of the board is clean and flat. Keep the glue line as thin as possible by applying the minimum and then compressing it in a press to squeeze most of it out before it sets.

Reasoning: 0.1 mm of epoxy will have about 5 x less thermal resistance than the 0.5 mm of fibreglass in your board, so you don't need to optimise much more.

It won't be electrically connected to the copper so you might also need some screws near the RF connectors.

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Sweat Soldering is the optimum way to bond the board and the metal clad. Just solder paste is required.

Going with adhesive will increase the cost of fabrication and also the cure temperature requirement for the adhesive will make the fabrication more complex.

Thank you all.

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  • \$\begingroup\$ Soldering is a tricky process. Temperature control is critical, and not on the table for most amateurs. The way to apply heat is to heat the metal surface from the other side. However, this will heat the entire pc board and keep it at soldering temperature for a long time. This, in turn, will very likely cause the pcb copper foil adhesive to fail - it's not magic stuff. So what you want to do is get the metal hot, apply the pc board with a coating of solder past, then cool the metal quickly - but not so quickly you distort the metal. Like I say, not for the beginner. \$\endgroup\$
    – WhatRoughBeast
    Commented Dec 27, 2020 at 14:45

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