Heat transfer apparatus suitable for use in a circuit board assembly

• US 5,831,826 A
• Filed: 09/20/1996
• Issued: 11/03/1998
• Est. Priority Date: 09/20/1996
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Van Ryswyk, James Edward
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): CHERVINSKY, BORIS LEO
• Application Number:
  US08/717,055
• Time in Patent Office: 774 Days
• Field of Search: 361/704, 361/707, 361/709, 361/719, 361/720, 361/753, 165/185, 165/80.1, 174/16.3, 174/51, 257/717, 379/428, 379/429
• US Class Current: 361/719
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 1/11 Printed elements for providing electric connections to or between printed circuits
• CPC Class Codes: H05K 2201/0373 Conductors having a fine structure, e.g. providing a plurality of contact points with a structured tool providing micro- or nanometer scale roughness on a metal surface H05K2203/0307
• CPC Class Codes: H05K 2201/066 Heatsink mounted on the surface of the PCB heatsink inserted in the PCB H05K2201/10416
• CPC Class Codes: H05K 2201/0939 Curved pads, e.g. semi-circular or elliptical pads or lands
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254
• CPC Class Codes: H05K 2203/043 Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste
• CPC Class Codes: H05K 3/0061 onto a metallic substrate, e.g. a heat sink heat sinks for electric apparatus H05K7/20
• CPC Class Codes: H05K 3/325 by abutting or pinching, i.e. without alloying process; mechanical auxiliary parts therefor adaptations of leads inserted in holes for press-fit connections H05K3/308
• CPC Class Codes: H05K 3/3468 Applying molten solder
• CPC Class Codes: H05K 7/20445 the coupling element being an additional piece, e.g. thermal standoff

Abstract

A heat transfer apparatus is carried on a substrate (204) having top and bottom surfaces (212, 214). The heat transfer apparatus includes a pad (220/222), at least one via (224/226), and a plurality of pads (302). The pad (220/222) is carried on the top surface (212) of the substrate (204) to electrically connect to an electronic component (228/230). The via (224/226) intersects the pad (220/222) and extends between the top and bottom surfaces (212, 214) of the substrate (204). The plurality of pads (302) are carried on the bottom surface (214) of the substrate (204) beneath the pad (220/222). The via (224/226) intersects one of the plurality of pads (302) to transfer heat generated during operation of the electronic component (228/230) thereto.

Claims

1. A heat transfer apparatus carried on a substrate, the substrate having top and bottom surfaces, the heat transfer apparatus comprising:

a part placement region described in the top surface of the substrate, the part placement region being rectangular;

a ground pad carried on the top surface of the substrate and contained in the part placement region, the ground pad to receive an electronic component;

at least one via extending through the ground pad and extending orthogonally between the top and bottom surfaces of the substrate;

a heat transfer region described in the bottom surface of the substrate, the heat transfer region being rectangular, the heat transfer region and the part placement region similarly sized and juxtaposed with one another, the heat transfer region defined by a first longitudinal axis and a first transverse axis orthogonal to the first longitudinal axis; and

a plurality of rows of a plurality of ground pads carried on the bottom surface of the substrate and confined to the heat transfer region, each of the plurality of ground pads being an elongated shape and defined by a second longitudinal axis and a second transverse axis orthogonal to the second longitudinal axis, the second longitudinal axis oriented at an angle with respect to the first transverse axis, the angle greater than 0 degrees and less than 90 degrees, the at least one via extending through one of the plurality of ground pads.

2. The heat transfer apparatus according to claim 1 wherein each of the plurality of ground pads are similarly shaped.

3. The heat transfer apparatus according to claim 1 wherein each of the plurality of ground pads are uniformly spaced with respect to one another.

4. The heat transfer apparatus according to claim 1 wherein the angle is approximately 45 degrees.

5. The heat transfer apparatus according to claim 1 wherein each of the plurality of ground pads employ rounded corners.

6. The heat transfer apparatus according to claim 5 wherein each of the plurality of ground pads comprise a rectangular midsection and semicircular ends.

7. A heat transfer apparatus carried on a substrate, the substrate having top and bottom surfaces, the heat transfer apparatus comprising:

a pad carried on the top surface of the substrate to receive an electronic component;

at least one via intersecting the pad and extending between the top and bottom surfaces of the substrate; and

a plurality of pads carried on the bottom surface of the substrate beneath the pad, each of the plurality of pads being an elongated oval shape, the at least one via intersecting one of the plurality of pads to transfer heat generated during operation of the electronic component thereto.

8. The heat transfer apparatus according to claim 7 wherein each of the plurality of pads is slanted.

9. A heat transfer apparatus carried on a substrate, the substrate having top and bottom surfaces, the heat transfer apparatus comprising:

a pad carried on the top surface of the substrate to receive an electronic component;

at least one via intersecting the pad and extending between the top and bottom surfaces of the substrate; and

a plurality of pads carried on the bottom surface of the substrate beneath the pad, a dimension of the plurality of pads is varied to hold comparatively larger and smaller predetermined amounts of solder extending to comparatively larger and smaller predetermined heights thereabove the at least one via intersecting one of the plurality of pads to transfer heat generated during operation of the electronic component thereto.

10. A circuit board assembly comprising:

a circuit board having top and bottom surfaces;

a part placement region described in the top surface of the circuit board, the part placement region being rectangular;

a heat transfer region described in the bottom surface of the circuit board, the heat transfer region being rectangular, the heat transfer region and the part placement region similarly dimensioned and juxtaposed with one another, the heat transfer region defined by a first longitudinal axis and a first transverse axis orthogonal to the first longitudinal axis;

a ground pad carried on the top surface of the circuit board and contained in the part placement region;

an electronic component coupled to the ground pad via a first solder fillet;

at least one via coupled to the first solder fillet and extending orthogonally between the top and bottom surfaces of the circuit board, the at least one via filled with solder; and

a plurality of rows of a plurality of ground pads carried on the bottom surface of the circuit board and confined to the heat transfer region, each of the plurality of ground pads being an elongate shape and defined by a second longitudinal axis and a second transverse axis orthogonal to the second longitudinal axis, the second longitudinal axis oriented at an angle with respect to the first transverse axis, the angle greater than 0 degrees and less than 90 degrees, each of the plurality of ground pads having a second solder fillet carried thereon, the at least one via extending through one of the plurality of ground pads and coupled to the second solder fillet thereof.

11. The circuit board assembly according to claim 10 further comprising a housing adapted to receive the circuit board, the housing including a mating surface for juxtaposition with the heat transfer region to directly contact the second solder fillet of each of the plurality of ground pads.

12. The circuit board assembly according to claim 11 wherein

the circuit board is substantially planar,

each of the plurality of ground pads is similarly dimensioned, and

the mating surface is horizontally level.

13. The circuit board assembly according to claim 12 wherein each of the plurality of ground pads are similarly shaped.

14. The circuit board assembly according to claim 12 wherein each of the plurality of ground pads are uniformly spaced with respect to one another.

15. The circuit board assembly according to claim 12 wherein each of the plurality of ground pads employ rounded corners.

16. The circuit board assembly according to claim 15 wherein each of the plurality of ground pads comprise a rectangular midsection and semicircular ends.

17. A circuit board assembly comprising:

a circuit board having top and bottom surfaces, the circuit board being substantially planar;

a ground pad carried on the top surface of the circuit board;

a part placement region described in the top surface of the circuit board, the part placement region containing the ground pad;

an electronic component coupled to the ground pad via a first solder fillet;

at least one via coupled to the first solder fillet and extending between the top and bottom surfaces of the circuit board, the at least one via filled with solder;

a plurality of pads carried on the bottom surface of the circuit board beneath the ground pad, dimensions of the plurality of pads vary, each of the plurality of pads having a second solder fillet carried thereon, the second solder fillet of at least one of the plurality of pads coupled to the at least one via;

a heat transfer region described in the bottom surface of the circuit board, the heat transfer region populated by the plurality of pads, the heat transfer region and the part placement region similarly dimensioned and juxtaposed with one another; and

a housing adapted to receive the circuit board, the housing including a mating surface for juxtaposition with the heat transfer region to directly contact the plurality of pads, the mating surface being curved.

18. A communication device comprising:

an antenna;

a user interface;

a transceiver coupled to the antenna and the user interface, the transceiver to amplify signals received from the user interface for transmission by the antenna, the transceiver comprising a circuit board assembly, the circuit board assembly comprising;

a metal housing having a mating surface;

a circuit board for seating in the metal housing, the circuit board having top and bottom surfaces;

a part placement region described in the top surface of the circuit board;

a heat transfer region described in the bottom surface of the circuit board, the heat transfer region, the part placement region and the mating surface of the metal housing similarly shaped, similarly dimensioned and aligned with one another, the heat transfer region defined by a first longitudinal axis and a first transverse axis orthogonal to the first longitudinal axis;

a ground pad carried on the top surface of the circuit board and contained in the part placement region;

an amplifier circuit positioned in the part placement region, the amplifier circuit having an amplifier component coupled to the ground pad, the amplifier component generating heat at the ground pad during operation thereof;

at least one filled via coupled to the ground pad and extending orthogonally between the top and bottom surfaces of the circuit board; and

a plurality of rows of a plurality of ground pads carried on the bottom surface of the circuit board and confined to the heat transfer region, each of the plurality of ground pads being an elongate shape and defined by a second longitudinal axis and a second transverse axis orthogonal to the second longitudinal axis, the second longitudinal axis oriented at an angle with respect to the first transverse axis, the angle greater than 0 degrees and less than 90 degrees, the plurality of ground pads coupled to the mating surface of the metal housing, the at least one via extending through one of the plurality of ground pads, the at least one via delivering heat generated by the amplifier component to the metal housing and the plurality of ground pads for dissipation.