# US 5,708,566 A · Solder bonded electronic module

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- Number: US 5,708,566 A
- Document ID: US5708566A
- Status: Granted
- Kind: A
- Application number: 08/742,110
- Filed: 1996-10-31
- Granted: 1998-01-13
- Earliest claimed: 1996-10-31
- Assignees: Motorola, Inc.
- Inventors: Roy E. Hunninghaus; Kevin M. Andrews; Gary L. Christopher; David J. Anderson; Joseph P. Tomase
- Web page: https://patentgrep.com/patent/US5708566A

## CPC

- H05K 7/20509: {Multiple-component heat spreaders; Multi-component heat-conducting support plates; Multi-component non-closed heat-conducting structures}
- H05K 1/0206: {by printed thermal vias}
- H05K 3/0061: {onto a metallic substrate, e.g. a heat sink (heat sinks for electric apparatus H05K7/20)}
- H05K 3/341: Surface mounted components
- H05K 3/42: Plated through-holes {or plated via connections}
- H05K 2201/066: Heatsink mounted on the surface of the printed circuit board [PCB]
- H05K 2201/10166: Transistor
- H05K 2201/10969: Metallic case or integral heatsink of component electrically connected to a pad on PCB
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

An electronic control module (10) includes a circuit substrate (12) containing a plurality of thermal vias (36) and a heat-generating electronic device (26) attached to the thermal vias (36). The circuit substrate (12) is attached to a mounting plate (18) by a plurality of electrically-isolated, thermal attachment pads (20) located at selected positions on an electrically insulating layer (16) overlying a metal baseplate (14). A solder layer (22) functions to both mechanically attach the plurality of thermal vias (36) to the plurality of thermal attachment pads (20), and to provide a thermal dissipation pathway for heat generated by the electronic devices (26). The heat is transferred from the circuit substrate (12) through the plurality of thermal attachment pads (20) to the metal baseplate (14).

## Claims

### Claim 1

An electronic module comprising:
a circuit substrate having a thermal via disposed therethrough;
a heat-generating electronic component overlying an upper surface of the thermal via;
a metal baseplate;
an electrically insulating layer overlying the metal baseplate;
a thermal attachment pad overlying the electrically insulating layer; and
a solder layer overlying the thermal attachment pad, wherein the solder layer thermally couples the thermal via to the thermal attachment pad and attaches the circuit substrate to the metal plate.

### Claim 2 (depends on 1)

The electronic module of claim 1, wherein the thermal via comprises:
an opening in the circuit substrate, the opening having an inner surface extending from an upper surface of the circuit substrate to a lower surface of the circuit substrate; and
a metal plating layer overlying the inner surface and a portion of the upper and lower surfaces of the circuit substrate in proximity to the opening.

### Claim 3 (depends on 2)

The electronic module of claim 2 further comprising:
a solder mask overlying the portions of lower surface of the circuit substrate; and
an adhesive layer overlying the electrically insulating layer at positions intermediate to portions of the solder mask and the electrically insulating layer.

### Claim 4 (depends on 1)

The electronic module of claim 1 further comprising:
an interconnect trace disposed on the circuit substrate; and
a control circuit electrically coupled to the heat-generating electronic component by the interconnect trace,
wherein, the control circuit activates the heat-generating electronic component causing a thermal emission from the heat-generating electronic component that is dissipated through the thermal via to the mounting plate.

### Claim 5

An electronic module comprising:
a printed circuit board populated with a plurality of heat-generating electronic components,
wherein each heat-generating electronic component overlies a plurality of thermal vias extending through the printed circuit board;
a mounting plate including a metal baseplate having an electrically insulating layer thereon; and
a plurality of thermal attachment pads at selected locations on the electrically insulating layer thermally coupling the plurality of heat-generating electronic components to the mounting plate,
wherein each of the plurality of thermal attachment pads is bonded to the plurality of thermal vias by a solder layer, and
wherein the plurality of thermal attachment pads attach the printed circuit board to the mounting plate.

### Claim 6 (depends on 5)

The electronic module of claim 5 further comprising:
a control circuit electrically coupled to the plurality of heat-generating electronic components,
wherein the control circuit activates the plurality of heat-generating electronic components, and
wherein heat from the plurality of heat-generating electronic components is transferred to the mounting plate through the plurality of thermal vias.

### Claim 7 (depends on 5)

The electronic module of claim 5, wherein each thermal via comprises an opening in the circuit substrate, the opening having an inner surface extending from an upper surface of the circuit substrate to a lower surface of the circuit substrate, and a metal plating layer overlying the inner surface and a portion of the upper and lower surfaces of the circuit substrate in proximity to the opening, and wherein each of the plurality of power transistors is bonded to the plating layer.

### Claim 8

An electronic module comprising:
a multi-layer printed circuit board having a device surface opposite a mounting surface;
a plated via extending through the multi-layer printed circuit board from the device surface to the mounting surface;
a heat-generating electronic component attached to the plated via;
an aluminum mounting plate having a thermally conductive, electrically insulating material thereon;
a solderable metal layer overlying the thermally conductive, electrically insulating material; and
a solder layer overlying the solderable metal layer,
wherein the solder layer thermally couples the plated via to the copper layer, and
wherein the solder layer attaches the multi-layer printed circuit board to the aluminum mounting plate.

### Claim 9 (depends on 8)

The electronic module of claim 8 further comprising:
a control circuit disposed on the device surface of the multi-layer printed circuit board and electrically coupled to the heat-generating electronic component,
wherein the control circuit activates the heat-generating electronic component, and
wherein heat from the heat-generating electronic component is transferred to the aluminum mounting plate through the plated via and through the thermally conductive, electrically insulating material.

### Claim 10 (depends on 8)

The electronic module of claim 8, wherein the electronic module contains a plurality of plated vias, and wherein the solderable metal layer is configured as a plurality of copper pads residing on the thermally conductive, electrically insulating material at locations corresponding to the plurality of plated vias.

### Claim 11 (depends on 10)

The electronic module of claim 10, wherein each of the plurality of plated vias comprise:
an opening in the multi-layer printed circuit board, the opening having an inner surface extending from the device surface to the mounting surface; and
a metal plating layer overlying the inner surface and a portion of the device surface and a portion of the mounting surface in proximity to the opening.