A mounting assembly for a multiple chip module or other circuit module, which includes a board having a surface including an array of board contacts, such as a printed wiring board in a computer system. A circuit module, such as a multiple chip module, having a first surface and a second surface is included. The circuit module includes an array of circuit contacts on the first surface of the circuit module. An interposer between the board and the first surface of the circuit module, includes conductors between the circuit contacts in the array of circuit contacts on the circuit module and board contacts in the array of board contacts on the board. A thermal bridge member contacts the second surface of the circuit module. A heat spreader contacts the thermal bridge member to dissipate the heat over a large region. A fastener fastens the board, interposer, circuit module, thermal bridge member, and heat spreader together, such that thermal contact is made between the circuit module and the thermal bridge member and between the thermal bridge member and the heat spreader, and electrical contact is made between the array of circuit contacts and the conductors in the interposer, and between the conductors in the interposer and the array of board contacts. The fastener comprises a releasable mechanism which allows the circuit module to be easily inserted or removed. A circuit module may include the host processor and supporting circuitry for a computer. Also, the circuit module may include more than one multiple chip substrate, or a multiple chip substrate combined with a printed wiring board substrate on which contact areas are formed.