GB2316235A - Heat sink and grounding arrangement - Google Patents
Heat sink and grounding arrangement Download PDFInfo
- Publication number
- GB2316235A GB2316235A GB9616793A GB9616793A GB2316235A GB 2316235 A GB2316235 A GB 2316235A GB 9616793 A GB9616793 A GB 9616793A GB 9616793 A GB9616793 A GB 9616793A GB 2316235 A GB2316235 A GB 2316235A
- Authority
- GB
- United Kingdom
- Prior art keywords
- heat sink
- power amplifier
- circuit board
- contact
- soldered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
- H01L23/433—Auxiliary members in containers characterised by their shape, e.g. pistons
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Cooling Or The Like Of Electrical Apparatus (AREA)
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
Abstract
A heat producing component such as a power amplifier (27) is mounted on a heat sink (10) which is in turn mounted on a circuit board (26). The heat sink is made of a single piece of metal folded into the shape shown, and includes a resilient member (22), formed by cutting and bending the metal, which cooperates with lugs (20,21,Fig.1, not shown) to urge the component into contact with a surface of the heat sink. The component is soldered to the heat sink, which is also soldered to the circuit board. The assembly is then placed in a case, the top half of which (32) is a further heat sink which abuts the protruding arms (11,12) of the heat sink and also serves as a ground plane.
Description
APPARATUS AND METHOD FOR SOLDERING
Field of the Invention
This invention relates to apparatus for mounting a heat producing circuit component to a heat sink and a circuit board and a method of soldering.
Background of the Invention
Radio transmitters use a power amplifier (PA) as the last stage of their transmitter section to amplify a signal to be transmitted before the signal is passed to an antenna. The PA produces heat and needs a good ground plane to ensure proper operation. A heat sink is usually used to absorb heat from the power amplifier and to dissipate the heat. It is common in radio transmitter design for the chassis to be used as a ground plane. The radio transmitter chassis can also be used as a heat sink as well as the ground plane.
There are several known methods for assembling the power amplifier to the heat sink, to the ground plane and to the PCB. In one of these known methods, the first step is to solder all the components on to the
PCB in a reflow oven. The second step is to manually assemble the power amplifier to the PCB and the third step is to assemble the power amplifier to the heat sink using screws. The disadvantage of the method described above is that there are many manual steps involved after the first automated step and that the use of screws increases the component count required. Further, if it is necessary to provide an additional connection between the power amplifier and the ground plane.
Another method for assembly is to make a hole in the PCB for the ground plan of the power amplifier then to solder the power amplifier to the
PCB and to then attach the PCB with the power amplifier to the radio chassis using screws. The power amplifier ground plane is connected to the radio chassis to function as a heat sink as well as a ground plan. The disadvantage of the above method is that the hole in the PCB reduces the usable area of the PCB and the assembly of the power amplifier to the PCB and to the radio chassis is done manually.
This invention seeks to provide a heat sink, a method for assembling and a method for soldering the heat sink to the PCB which mitigates the above mentioned disadvantages.
Sllmmarv of the Invention
According to the to a first aspect of the invention there is provided an apparatus for mounting a heat producing circuit component to a circuit board. The apparatus includes a first heat sink having integrally formed therewith a spring for resiliently urging the circuit component into contact with a first portion of the first heat sink.
By providing an integrally formed spring, the heat producing circuit component is maintained in contact with the heat sink with the need for screws thereby reducing the component count. In the preferred embodiment of the invention, the heat producing circuit component is also soldered to the heat sink It is envisaged that for some applications the spring alone may be used to secure the component to the heat sink.
It will now be appreciated that a heat sink incorporating a spring will enable a component to be retained in position on the heat sink during a subsequent soldering step. Soldering tends to cause component dislocation and the invention is therefore particularly advantageous where the component is to be subsequently soldered.
The resilient nature of the spring also confers the advantage of assisting in the correct placement of the component because of the "urging" effect.
In the preferred embodiment, the integrally formed spring comprises a an elongate resiliently biased spring arm. This is preferred because such an arm can be easily formed in the heat sink by, for example, a stamping operation.
In the preferred embodiment, the circuit component is soldered to the first portion of the heat sink. This is preferred because soldering ensures good thermal conductivity.
In the preferred embodiment, at least the first portion of the heat sink is provided with surface which has an affinity for solder. This enables the component to be easily soldered.
The surface may conveniently be an electroplated surface although other ways of providing the surface may be used.
In the preferred embodiment, the apparatus further includes a second portion for retaining, in use, the apparatus to the circuit board.
The second portion may, in use, be soldered to the circuit board.
In the preferred embodiment, the apparatus further includes a contact arm for making electrical contact to another circuit component.
In the second aspect of the present invention a power amplifier module is provided in which the circuit component is a power amplifier.
The another circuit component may be a ground plane and preferably, the ground plane is used as a further heat sink.
Preferably, the circuit board is located in a first half of a case and the ground plain is located in a second half of the case such that when, the halves are brought together the contact arm makes electrical with the ground plane. Thus a module is provided where the necessary connections to the ground plane are made by the assembly into a case. It will be appreciated that this confers a yet further advantage during disassembly for servicing in that the connection to the ground plane is automatically broken. Further, the use of additional components such as plugs and sockets is avoided.
According to the to a third aspect of the invention there is provided a method for soldering a power amplifier to a heat sink and circuit board.
The method comprising the steps of: applying a solder formulation to the printed circuit, applying a solder formulation to an upper side of a first part of the heat sink, placing the power amplifier on the upper side of the first part of the heat sink, placing the heat sink on the printed circuit board, placing the printed circuit board having the heat sink and the power amplifier in a reflow oven and conducting a single reflow operation such that the power amplifier is soldered to the heat sink and the heat sink is soldered to the circuit board.
Preferably, the first heat sink is provided with legs to be placed in the printed circuit board for preventing movement of the heat sink during a soldering process.
A preferred embodiment of the invention will now be described by way of example only, with reference to the drawings.
Brief Description of the Drawings
FIG. 1 is an isometric view shown an apparatus in two positions according to the preferred embodiment of the invention;
FIG. 2 is a section view , showing the apparatus assembled to the power amplifier and to the printed circuit board in a case according to the preferred embodiment of the invention; and
FIG. 3 is a flow chart of a method of soldering and assembling the heat sink, the power amplifier and the printed circuit board according to the preferred embodiment of the invention.
Detailed DescnDtlon of the Drawings Referring firstly to FIG. 1 and FIG. 2, an apparatus for mounting a power amplifier 24 to a printed circuit board (PCB) 22 according to the preferred embodiment of the invention is now will be described. The apparatus includes a heat sink 10. The heat sink 10 is formed in a stamping and folding process from a copper blank and comprises three major parts. The parts are two contact arms a first contact arm 11 and a second contact arm 12 interconnected by a first flat portion 13. By reference to the figures it will be seen that the three major parts are connected by a first end bend 14 which is 'IJ' shaped such that the first flat portion 13 is a first arm of the "IJw' and the first contact arm 11 is the other arm of the 'raj".
Thus it will be appreciated that during the folding process the copper blank is folded back on itself.
A second end bend 15 marks the boundary between the first flat portion 13 and the second contact arm 12. The bend 15 does not form a "Ut' shape because the blank is not folded back on itself. Rather a "lazy S" shape is formed in which the arm 12 projects beyond the boundary and away from the first flat portion The stamping process is utilised to form a number of features on the heat sink. By stamping a suitable set of projections onto a front face 16 of the first flat portion 13 as pair of legs 17 and 18 are formed which project out of a rear face 19 of the flat portion 13. These are used to locate the heat sink in a manner to be described later.
Similarly, a pair of location lugs 20 and 21 are also provides These are used to aid in the location of a heat producing component in a way to be later described.
During the stamping process a longitudinal cut is made partly along the long dimension of the first contact arm 11 at its peripheral edge. This is folded to provide a downwardly directed spring arm 22. (By downwardly directed it is meant that the spring arm 22 is bent towards the front face 16 of the first flat portion 13.)
As may be seen from the figures, the arms are provided at their extreme ends with curved faces 23, 24 and 25. These ensure that an effective non-scoring contact is made by the arms.
The copper used is half hard, lmm thick having a tensile strength of 37 to 46 KSI. This is electroplated with nickel to a thickness of 0.00152 to 0.00254 mm and tin to a thickness of 0.00254 to 0.00640mm. This produces a heat sink which may be easily soldered and the heat sink is also resilient, that is to say the arms are resiliently deformable.
The way in which the heat sink is utilised will now be described with reference Fig. 3 in addition to Fig.s 1 and 2.
In a first step, step 100, a solder paste is applied to a printed circuit board 26.
In a next step, step 102, solder paste is applied to the heat sink 10. In step 104, the heat producing component, in this case a power amplifier 27, is then located on the heat sink 10. This is achieved by inserting an end 28 of the power amplifier 27 between the curved face 25 of the spring arm 22 and the front face 16 of the flat portion 13. The curved face 25 aids the insertion by a "ramping" effect in which the insertion motion causes the spring arm to be forced away from the face 16. Insertion is limited by the location lug 21 but in a resilient manner such that the lug 21 is forced partially back into the end bend 14. The end 29 of the power amplifier 27 is brought into intimate contact with the face 16 over its complete length. The resilience of the lug 21 then urges the end 29 against the second location lug 20. Thus, it will be appreciated that the power amplifier 27 is "clicked into place and is firmly retained to the heat sink 10.
In a next step, step 106, the heat sink 10 and power amplifier 27 are placed on the circuit board the legs 17 and 18 being inserted into holes in the board. This forms a power amplifier module or sub-assembly.
In step 108, the power amplifier module is then placed in a re-flow oven and heated to cause solder reflow. This results in one operation in all three components, that is to say, the power amplifier the printed circuit board and the heat sink to be soldered together.
In step 110, the power amplifier module is then assembled into a case. The case comprises a first half 31 and a second half 32.
The second half 32 includes an additional heat sink 33 which in addition acts as a ground plane. In the assembly process the arms 11 and 12 abut the heat sink 33 automatically making good thermal and electrical contact. The case is dimensioned such that the arms 11 and 12 are forced resiliently downwards. Their resilience then ensures that an effective
contact is maintained.
Claims (17)
1. An apparatus for mounting a heat producing circuit component to a circuit board comprising:
a first heat sink having integrally formed therewith a spring for resiliently urging the circuit component into contact with a first portion of the first heat sink
2. An apparatus as claimed in claim 1 wherein the integrally formed spring comprises a an elongate resiliently biased spring arm.
3. An apparatus as claimed in claim 1 or claim 2 wherein the circuit component is soldered to the first portion of the heat sink.
4. An apparatus as claimed in claim 3 wherein at least the first portion of the heat sink is provided with surface which has an affinity for solder.
5. An apparatus as claimed in claim 4 wherein the surface is an electroplated surface.
6. An apparatus as claimed in any preceding claim further comprising a second portion for retaining, in use, the apparatus to the circuit board.
7. An apparatus as claimed in claim 6 wherein the second portion is, in use soldered to the circuit board.
8. An apparatus as claimed in any preceding claim further comprising at least one contact arm for making electrical contact to another circuit component.
9. A power amplifier module comprising an apparatus as claimed in any one of claims 1 to 7 wherein the circuit component is a power amplifier.
10. A power amplifier module comprising an apparatus as claimed in claim 8 wherein the another circuit component is a ground plane.
11. A power amplifier module as claimed in claim 10 wherein the ground plane is a further heat sink.
12. A power amplifier module as claimed in any preceding claim wherein the circuit board is located in a first half of a case and the ground plain is located in a second half of the case such that when the halves are brought together the contact arm makes electrical contact with the ground plane.
13. A method for soldering a power amplifier to a heat sink and circuit board comprising the steps of:
applying a solder formulation to the printed circuit board;
applying a solder formulation to an upper side of a first part of the heat sink;
placing the power amplifier on the upper side of the first part of the heat sink;
placing the heat sink on the printed circuit board;
placing the printed circuit board having the heat sink and the power amplifier in a reflow oven; and
conducting a single reflow operation such that the power amplifier is soldered to the heat sink and the heat sink is soldered to the circuit board.
14. A method as claimed in claim 13 wherein the power amplifier is retained on the heat sink by a resiliently deformable spring.
15. The method according to claim 13 or 14, wherein the first heat sink is provided with an elongate heat sink member having a contact portion to, in use, make contact with a second heat sink.
16. The method according to any one of the preceding claims, wherein the first heat sink is provided with legs to be placed in the printed circuit board for preventing movement of the heat sink during a soldering process.
17. A method as claimed in claim 17 wherein the sub-assembly is located in a first half of a case and the second heat sink is located in a second half of the case and the step of abutting is achieved by assembly of the halves of the case.
17. A method of assembling a power amplifier module comprising the steps of soldering a power amplifier to a heat sink to as claimed in any preceding claim to form a suSassembly and further comprising the steps of:
providing a second heat sink; and
abutting the contact portion of the first heat sink against the second heat sink.
18. A method as claimed in claim 17 wherein the sub-assembly is located in a first half of a case and the second heat sink is located in a second half of the case and the step of abutting is achieved by assembly of the halves of the case.
Amendments to the claims have been filed as follows
Claims 1. An apparatus for mounting a heat producing circuit component to a circuit board comprising:
a first heat sink having integrally formed therewith a spring for resiliently urging the circuit component into contact with a first portion of the first heat sink and at least one contact arm for making electrical contact to another circuit component.
2. An apparatus as claimed in claim 1 wherein the integrally formed spring comprises a an elongate resiliently biased spring arm.
3. An apparatus as claimed in claim 1 or claim 2 wherein the circuit component is soldered to the first portion of the heat sink.
4. An apparatus as claimed in claim 3 wherein at least the first portion of the heat sink is provided with surface which has an affinity for solder.
5. An apparatus as claimed in claim 4 wherein the surface is an electroplated surface.
6. An apparatus as claimed in any preceding claim further comprising a second portion for retaining, in use, the apparatus to the circuit board.
7. An apparatus as claimed in claim 6 wherein the second portion is, in use soldered to the circuit board.
8. A power amplifier module comprising an apparatus as claimed in any one of claims 1 to 7 wherein the circuit component is a power amplifier.
9. A power amplifier module comprising an apparatus as claimed in claim 8 wherein the another circuit component is a ground plane.
10. A power amplifier module as claimed in claim 10 wherein the ground plane is a further heat sink 11. A power amplifier module as claimed in any preceding claim wherein the circuit board is located in a first half of a case and the ground plain is located in a second half of the case such that when the halves are brought together the contact arm makes electrical contact with the ground plane.
12. A method for soldering a power amplifier to a heat sink and circuit board comprising the steps of:
applying a solder formulation to the printed circuit board;
applying a solder formulation to an upper side of a first part of the heat sink;
placing the power amplifier on the upper side of the first part of the heat sink;
placing the heat sink on the printed circuit board;
placing the printed circuit board having the heat sink and the power amplifier in a reflow oven; and
conducting a single reflow operation such that the power amplifier is soldered to the heat sink and the heat sink is soldered to the circuit board.
13. A method as claimed in claim 13 wherein the power amplifier is retained on the heat sink by a resiliently deformable spring.
14. The method according to claim 13 or 14, wherein the first heat sink is provided with an elongate heat sink member having a contact portion to, in use, make contact with a second heat sink.
15. The method according to any one of the preceding claims, wherein the first heat sink is provided with legs to be placed in the printed circuit board for preventing movement of the heat sink during a soldering process.
16. A method of assembling a power amplifier module comprising the steps of soldering a power amplifier to a heat sink to as claimed in any preceding claim to form a sub-assembly and further comprising the steps of:
providing a second heat sink; and
abutting the contact portion of the first heat sink against the second heat sink.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9616793A GB2316235A (en) | 1996-08-09 | 1996-08-09 | Heat sink and grounding arrangement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9616793A GB2316235A (en) | 1996-08-09 | 1996-08-09 | Heat sink and grounding arrangement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9616793D0 GB9616793D0 (en) | 1996-09-25 |
| GB2316235A true GB2316235A (en) | 1998-02-18 |
Family
ID=10798290
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9616793A Withdrawn GB2316235A (en) | 1996-08-09 | 1996-08-09 | Heat sink and grounding arrangement |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2316235A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0142400A1 (en) * | 1983-09-27 | 1985-05-22 | Compagnie Europeenne De Composants Electroniques Lcc | Housing for an electronic component, especially for telephone protection |
| GB2184887A (en) * | 1985-12-21 | 1987-07-01 | Marston Palmer Ltd | Heat sink |
| US4945401A (en) * | 1987-07-20 | 1990-07-31 | The Staver Company Inc. | Heat dissipator for semiconductor unit |
| GB2236213A (en) * | 1989-09-09 | 1991-03-27 | Ibm | Integral protective enclosure for an assembly mounted on a flexible printed circuit board |
| GB2270207A (en) * | 1992-08-27 | 1994-03-02 | Dsk Technology International L | Cooling of electronics equipment |
| US5381041A (en) * | 1994-04-05 | 1995-01-10 | Wakefield Engineering, Inc. | Self clamping heat sink |
-
1996
- 1996-08-09 GB GB9616793A patent/GB2316235A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0142400A1 (en) * | 1983-09-27 | 1985-05-22 | Compagnie Europeenne De Composants Electroniques Lcc | Housing for an electronic component, especially for telephone protection |
| GB2184887A (en) * | 1985-12-21 | 1987-07-01 | Marston Palmer Ltd | Heat sink |
| US4945401A (en) * | 1987-07-20 | 1990-07-31 | The Staver Company Inc. | Heat dissipator for semiconductor unit |
| GB2236213A (en) * | 1989-09-09 | 1991-03-27 | Ibm | Integral protective enclosure for an assembly mounted on a flexible printed circuit board |
| GB2270207A (en) * | 1992-08-27 | 1994-03-02 | Dsk Technology International L | Cooling of electronics equipment |
| US5381041A (en) * | 1994-04-05 | 1995-01-10 | Wakefield Engineering, Inc. | Self clamping heat sink |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9616793D0 (en) | 1996-09-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |