JP2011228512A - Mounting structure for heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure for a heat sink, which has a less influence on a structrue of a circuit on a circuit board or on its inner layer, and enables easy mounting.SOLUTION: A mounting structure for a heat sink 3 includes: the heat sink 3 that is press-contacted to a surface, which is opposite to a circuit board 1, of an electronic component 2 mounted on the circuit board 1, and thus radiates heat from the electronic component 2; a pedestal 4 having a press-fit pin for fixing to the circuit board 1; a coil spring 6; and fastening means 9 for fastening the heat sink 3 to the pedestal 4 through the coil spring 6. Fixing the pedestal 4 to the circuit board 1 with the press-fit pin results in that the heat sink 3 is fixed to the circuit board 1.

Description

  The present invention relates to a seat sink mounting structure used for cooling various components.

  Electronic components such as integrated circuits that are attached to a substrate and constitute a circuit that generate significant heat during use must be cooled. A heat sink is often used for this cooling. The heat sink is pressed against the surface of the electronic component, which is a heating element, the heat from the electronic component is transferred to the heat sink by heat transfer, and the heat conduction in the heat sink is used to provide the surface opposite to the surface pressed against the electronic component. The electronic component is cooled by dissipating heat through the heat dissipating fins (Patent Documents 1 and 2).

  In Patent Document 1, a heat sink having a plurality of mounting portions on the outside for dissipating heat by having a contact surface on the upper surface of a semiconductor element provided on one surface of the substrate, a socket having screws inside, A heat sink mounting structure including a stud penetrating from a surface side and projecting to one surface side and a socket screw and screwed therein is shown. The socket and the guide have an engaging portion that engages with each other, and after temporarily fixing with the engaging portion, the screw and the stud are screwed together and fastened. A coil spring is inserted between the screw and the stud. The guide is fixed to a fixed plate disposed on the lower surface of the substrate.

  In Patent Document 2, in order to attach a heat sink to an electronic component mounted on a substrate, a heat sink in which four corners of the heat sink are fixedly supported on the substrate by a two-stage screw installed in the coil spring in combination with the coil spring. The mounting structure is shown.

JP 2007-258464 A JP-A-5-243439

  In Patent Document 1, since the guide having a large diameter penetrates the substrate, the influence on the circuit arrangement on the substrate or its inner layer is large, and the restriction on the circuit design is large. Furthermore, installation is not easy. Further, since the guide is fixed to a fixing plate installed under the substrate, it is difficult to attach the heat sink with such a structure to a limited place where the mounting area is narrow.

  In Patent Document 2, the heat sink is fixed to the substrate using a two-stage screw that penetrates the substrate. Therefore, a large diameter screw is used. Therefore, the influence on the circuit arrangement on the substrate or its inner layer becomes large, and the restriction on the circuit design is large. Furthermore, since it is attached using screws, it cannot be said to be a simple attachment.

  The present invention has been made in view of such a situation, and provides a heat sink mounting structure that has a small influence on the circuit arrangement of the substrate or its inner layer and can be easily mounted in a narrow place. With the goal.

The mounting structure of the heat sink according to the present invention is as follows:
A heat sink that dissipates heat from the electronic component by being pressed against and brought into contact with the surface opposite to the substrate of the electronic component mounted on the substrate;
A cradle having a press-fit pin for fixing to the substrate;
Spring,
Fastening means for fixing the heat sink to the cradle via the spring;
Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the influence which it has on the circuit arrangement | positioning on a board | substrate or its inner layer is small, and the attachment structure of a heat sink which can be easily attached to a narrow place can be provided.

It is a perspective view which shows the example of the outline | summary of the attachment structure of the heat sink which concerns on embodiment of this invention. It is a perspective view which shows the example of the cradle which concerns on embodiment. It is a figure which shows the example of the press fit pin which concerns on embodiment. It is a perspective view which shows the example of the holding screw which concerns on embodiment. It is sectional drawing which shows the example of the attachment structure of the heat sink which concerns on embodiment. (A) Sectional drawing which shows the example of the attachment structure of the heat sink with respect to the electronic component of thickness D which concerns on embodiment, (b) The example of the attachment structure of the heat sink with respect to the electronic component of thickness D '(> D) which concerns on embodiment FIG. (A) It is sectional drawing which shows the structure of the cradle of the modification concerning embodiment, (b) It is sectional drawing which shows the cradle after the assembly of the modification concerning embodiment.

(Embodiment)
FIG. 1 is a perspective view showing an outline of an example of a heat sink mounting structure according to an embodiment of the present invention. In FIG. 1, an electronic component 2 to be cooled by a heating element is attached on a substrate 1, and is cooled via a heat sink 3 attached in contact with the surface of the electronic component 2. The cradle 4 is attached and fixed to the attachment hole 5 of the substrate 1. A holding screw 9 as a fastening means is screwed into a screw portion provided on the cradle 4 via a coil spring 6, a spacer 7 inserted as necessary, and a washer 8. By this screwing, the heat sink 3 is pressed against the electronic component 2 with a predetermined force via the coil spring 6 and is fixed to the substrate 1. The sheet sink mounting structure includes a heat sink 3, a cradle 4, a coil spring 6, a spacer 7 that is inserted as necessary, and a holding screw 9. A washer 8 may be included.

  The heat sink 3 includes a contact portion 30 that is in contact with the surface of the electronic component 2 opposite to the surface attached to the substrate 1, and a plurality of heat radiation fins 31 provided on the surface of the contact portion 30 opposite to the substrate 1. In addition, at the end of the contact portion 30, there are through-holes 32 provided at four positions where there is no radiation fin 31.

  FIG. 2 is a perspective view showing an example of the cradle 4 according to the embodiment. The cradle 4 includes a fastening support portion 40, a press-fit pin 41, and a pedestal 43 positioned between the two. A female screw portion 42 is provided at the end of the fastening support portion 40 opposite to the pedestal 43. The fastening support portion 40 has a size that can penetrate the through hole 32 of the heat sink 3. In the example of FIG. 2, two press-fit pins 41 are provided per one cradle 4.

  FIG. 3 is a diagram illustrating an example of the press-fit pin 41 according to the embodiment. The press-fit pin 41 is configured by being surrounded by a plurality of elongated plates having spring properties whose side surfaces are curved outward. The diameter of the mounting hole 5 of the substrate 1 is slightly smaller than the outer diameter of the press-fit 41 pin. By pressing and inserting the press-fit pin 41 into the mounting hole 5 of the substrate 1 shown in FIG. The inner wall of the mounting hole 5 is pushed by a plurality of long and narrow side plates. The press-fit pins 41 are fixed to the substrate 1 by this force, and as a result, the cradle 4 is fixed to the substrate 1.

  The area of the pedestal 43 when projected onto the mounting surface of the substrate 1 is usually larger than the area of the fastening support portion 40 projected onto the mounting surface of the substrate 1 as shown in FIG. At this time, the thickness of the pedestal 43 is made smaller than the thickness of the electronic component 2 to be cooled that is mounted on the substrate 1.

  The outer diameter of the press-fit pin 41 is significantly smaller than screws and other fixing means conventionally used for fixing the heat sink 3 to the substrate 1. Therefore, the diameter of the mounting hole 5 of the substrate 1 for inserting the press fit pin 41 is also smaller than before.

  FIG. 4 is a perspective view showing an example of a holding screw 9 according to the embodiment. The holding screw 9 includes a screw head 90, a stepped portion 91, a male screw portion 92, and a slit portion 93. The male screw portion 92 is screwed to the female screw portion 42 provided in the fastening support portion 40 shown in FIG. 2 via the coil spring 6, the spacer 7 inserted as necessary, and the washer 8. The slit 93 is used to rotate the holding screw 9 during screwing, but is not an essential element. It is only necessary that the holding screw 9 has a rotatable structure for screwing the male screw portion 92 into the female screw portion 42.

  Next, the assembly and operation of the heat sink mounting structure configured as described above will be described. FIG. 5 is a cross-sectional view showing an example of the mounting structure of the heat sink 3 according to the embodiment, which is parallel to the XZ plane shown in the upper part of FIG. 1 including the longitudinal axis of the cradle 4 and the holding screw 9. It is sectional drawing when it cut | disconnects in a smooth surface. 5 indicates that the same reference numerals as those in FIGS. 1 to 4 are the same. The stepped portion 91 of the holding screw 9 has an outer diameter smaller than the inner diameter of the coil spring 6, and the outer diameter of the lower surface of the screw head 90 is larger than the outer diameter of the coil spring 6. The length of the coil spring when no load is applied is L.

  First, the press-fit pins 41 of the cradle 4 are pressed and inserted into the mounting holes 5 of the substrate 1. The cradle 4 is fixed to the substrate 1 by this simple operation. In the example shown in FIGS. 1, 2, and 5, one cradle 4 is equipped with two press-fit pins. In the example shown in FIG. 1, four cradles 4 are fixed to the substrate 1 at four locations in the vicinity of the electronic component 2.

  Next, the fastening support portion 40 of the cradle 4 is passed through the through hole 32 provided in the contact portion 30 of the heat sink 3. Thereby, the fastening support part 40 protrudes to the heat radiating fin 31 side of the heat sink 3. The coil spring 6 is put on the protruding fastening support portion 40. Next, the male screw portion 92 of the holding screw 9 is inserted inside the coil spring 6 through the washer 8 and a spacer 7 having a predetermined thickness to be inserted when necessary, and the female screw portion of the fastening support portion 40 is inserted. 43 is screwed.

  When the male screw portion 92 of the holding screw 9 is screwed into the female screw portion 43 of the fastening support portion 40, the lower surface of the screw head 90 of the holding screw 9 first comes into contact with the end surface of the coil spring 6. When the screwing with the fastening support part 40 is advanced, the lower surface of the stepped part 91 comes into contact with the end face of the fastening support part 40 through the washer 8 and the spacer 7 introduced when necessary. In this state, the screwing of the male screw portion 92 of the holding screw 9 and the female screw portion 43 of the fastening support portion 40 is completed. By carrying out this operation on all of the cradle 4, the attachment of the heat sink 3 to the substrate 1 is completed.

  FIG. 6 shows an example of a state where the attachment of the heat sink 3 to the substrate 1 is completed. 6A is a cross-sectional view showing an example of a heat sink mounting structure for an electronic component having a thickness D according to the embodiment, and FIG. 6B is a cross-sectional view of the heat sink for an electronic component having a thickness D ′ (> D) according to the embodiment. It is sectional drawing which shows the example of attachment structure. In FIG. 6A, the spacer 7 is not used, and in FIG. 6B, the spacer 7 is used. The thickness T of the spacer 7 is equal to the difference between D 'and D.

  The length of the coil spring 6 after the heat sink 3 is attached to the substrate 1 is the same length L ′ in both cases of FIGS. This L ′ is substantially equal to the sum of the length of the portion of the fastening support portion 40 protruding from the through hole 32 of the heat sink 3, the thickness of the spacer 7, and the length of the stepped portion 91. Since the length of the protruding portion of the fastening support portion 40 is determined depending on the thickness of the electronic component 2 to be cooled, by selecting the thickness of the spacer 7, Even if the thickness of the electronic component 2 differs, the length after attachment can be made constant length L '. Selecting the thickness of the spacer 7 includes making the thickness zero, that is, not introducing the spacer. Assuming that the spring constant of the coil spring 6 is k, the heat sink 3 is pressed against the substrate 1 with a force of k × (L−L ′) in both cases of FIGS. Therefore, the electronic component 2 fixed to the substrate 1 is in contact with the surface of the contact portion 30 of the sheet sink 3 opposite to the cooling fin 31 while being pressed with a force of k × (LL ′). To do. That is, the contact state between the heat sink 3 and the electronic component 2 is constant regardless of the thickness of the electronic component 2. Therefore, the heat transfer rate from the electronic component 2 to the heat sink 3 can also be maintained at a constant value regardless of the thickness of the electronic component 2. In the example of FIGS. 6A and 6B, the thickness D of the electronic component 2 when the spacer 7 of FIG. 6A is not introduced is controlled to a constant pressing force in the heat sink mounting structure according to this embodiment. The smallest possible thickness.

  The heat transferred to the heat sink 3 by heat transfer reaches the cooling fins 31 by heat conduction in the heat sink 3. A plurality of cooling fins 31 are provided on the heat sink 3, and heat is radiated from the cooling fins 31. Thus, the heat generated in the electronic component 2 is efficiently radiated by the heat sink 3 and the electronic component 2 is cooled. Since the pressing force of the heat sink 3 against the electronic component 2 is constant regardless of the thickness of the electronic component 2, the cooling capability of the electronic component 2 by the heat sink 3 is also constant regardless of the thickness of the electronic component 2.

  In the example shown in FIGS. 1, 2, 5, and 6, there are two press-fit pins 41 provided on one cradle 4. However, the number of press-fit pins 41 is not limited to this and may be one or more.

  In the example shown in FIGS. 1, 2, 5, and 6, the cradle 4 includes a pedestal 43. However, the press-fit pin 41 may be directly attached to the fastening support portion 40 without the pedestal 43.

  As a modification of the cradle 4 provided with the pedestal 43, the pedestal 4 may be configured by separately forming the pedestal 43 and assembling it together with the fastening support portion 40. Fig.7 (a) is sectional drawing which shows the structure of the cradle of the modification which concerns on embodiment, FIG.7 (b) is sectional drawing which shows the cradle after the assembly of the modification which concerns on embodiment. In the example shown in FIG. 7, the press-fit pin 41 is attached to the fastening support portion 40, and the fastening support portion 40 is inserted into a pedestal 43 having a through hole for the press-fit pin 41 and a recessed portion for storing the fastening support portion 40. The cradle 4 is formed by pressing and inserting the press fit pin 41 into the through hole 43 and penetrating it. By pressing and inserting the press-fit pins 41 protruding from the pedestal 43 into the mounting holes 5 of the substrate 1, the cradle 4 according to this modification is fixed to the substrate 1.

  In the example shown in FIG. 1, one heat sink 3 is fixed by four cradles, but may be plural instead of four. For example, two cradles may be installed on the diagonal line of the heat sink 3 to fix the heat sink 3 to the substrate 1.

  In the description so far, the fastening support portion 40 has the female screw portion 42, and the holding screw 9 has the male screw portion 92. However, the male screw portion 40 and the female screw portion 42 may be reversed.

Since the heat sink mounting structure is configured as described above, it has the following effects.
(1) Since the press-fit pins 41 are used to fix the cradle 4 to the substrate 1, compared to the conventional case of attaching the corresponding one to the cradle 4 to the substrate 1 with screws or the like, The mounting hole 5 for the substrate 1 may be small. Accordingly, the influence on the surface of the substrate 1 and the circuit formation area of the inner layer is reduced, so that restrictions on circuit design on the substrate 1 are reduced. In addition, since it is not necessary to use the fixing plate employed in the heat sink mounting structure described in Patent Document 1, the heat sink 3 can be mounted in a narrow place.
(2) Using the holding screw 9 having the stepped portion 91, the spacer 7 having an appropriate thickness determined by the thickness of the electronic component 2 to be cooled is inserted between the stepped portion 91 and the fastening support portion 40. Thus, even if the thickness of the electronic component 2 to be cooled is different, the heat sink 3 can be easily attached to the substrate 1 with the same pressing force with a simple configuration. Therefore, it is possible to provide a simple heat sink 3 mounting structure that has a constant cooling capacity regardless of the thickness of the electronic component 2.
(3) When the pedestal 4 includes the pedestal 43 and the area of the pedestal 43 projected onto the surface of the substrate 1 is larger than the area projected onto the surface of the substrate 1 of the fastening support portion 40, the heat sink 3 The pressing force per unit area on the substrate 1 can be reduced by the difference between the projected areas of the two. Therefore, adverse effects due to stress on the substrate 1 can be reduced.
(4) When the fastening support portion 40 and the pedestal 43 of the cradle 4 are formed as separate parts, the fastening support portion 40 and the pedestal 43 can be formed in a simple shape. It becomes easy. Furthermore, when manufacturing the cradle 4 having different heights, since the pedestal 43 can be made common, the manufacturing process can be simplified.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1) A heat sink that dissipates heat from the electronic component by being pressed against and brought into contact with a surface opposite to the substrate of the electronic component to be mounted on the substrate,
A cradle having a press-fit pin for fixing to the substrate;
Spring,
Fastening means for fixing the heat sink to the cradle via the spring;
A heat sink mounting structure characterized by comprising:

(Appendix 2) The heat sink includes a plurality of through holes at an end portion,
The cradle includes a fastening support portion having a screw portion, and passes the fastening support portion through the through-hole,
The fastening means is a holding screw that is screwed with a screw portion of the cradle,
The spring includes a portion of the fastening support portion that protrudes through the through hole and is disposed between the heat sink and the holding screw, and the spring screw is connected to the screw portion of the fastening support portion. A coil spring that is compressed by being pressed by the holding screw by being screwed to the heat sink and generating a pressing force against the heat sink,
The heat sink mounting structure according to Appendix 1, wherein the heat sink is attached.

(Appendix 3) The holding screw has a stepped portion,
The outer diameter of the stepped portion is smaller than the inner diameter of the coil spring.
The heat sink mounting structure according to Supplementary Note 2, wherein:

(Additional remark 4) Between the said fastening support part and the said holding screw, the inside of the said coil spring is larger than the outer diameter of the screw part of the said holding screw, and a through-hole with a diameter smaller than the outer diameter of the said stepped part A spacer having
The heat sink mounting structure according to Supplementary Note 3, wherein:

(Supplementary Note 5) The thickness of the spacer is the sum of the length of the portion of the fastening support portion that protrudes through the through hole, the thickness of the spacer, and the length of the stepped portion of the holding screw. The thickness is a predetermined value smaller than the length of
The heat sink mounting structure as set forth in Appendix 4, wherein

(Appendix 6) The cradle has a pedestal having a projected area on the substrate larger than the fastening support portion between the fastening support portion and the press-fit pin.
The heat sink mounting structure according to any one of appendices 2 to 5, characterized in that:

(Additional remark 7) As for the said stand, the said fastening support part and the said base are separate bodies, and both are formed and assembled,
The heat sink mounting structure according to Supplementary Note 6, wherein:

(Appendix 8) A heat sink that includes a plurality of through holes at an end portion, and dissipates heat from the electronic component by being pressed against and brought into contact with a surface opposite to the substrate of the electronic component mounted on the substrate,
A fastening support part having a screw part, and a fixing means for fixing to the substrate, and a cradle for penetrating the fastening support part through the through hole;
A holding screw having a stepped portion and screwed with a screw portion of the cradle;
A portion of the fastening support portion that protrudes through the through-hole is disposed on the inside thereof, and is disposed between the heat sink and the holding screw, and the holding screw is screwed into the screw portion of the fastening support portion. A coil spring that is pressed and compressed by the holding screw to generate a pressing force against the heat sink,
The outer diameter of the stepped portion is smaller than the inner diameter of the coil spring;
A heat sink mounting structure characterized by that.

(Additional remark 9) Between the said fastening support part and the said holding screw, a through-hole of a diameter larger than the outer diameter of the screw part of the said holding screw and smaller than the outer diameter of the said stepped part inside the said coil spring A spacer having
The heat sink mounting structure according to appendix 8, wherein

(Supplementary Note 10) The thickness of the spacer is the sum of the length of the portion of the fastening support portion that protrudes through the through hole, the thickness of the spacer, and the length of the stepped portion of the holding screw. The thickness is a predetermined value smaller than the length of
The heat sink mounting structure according to appendix 9, characterized in that:

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Electronic component 3 Heat sink 4 Receptacle 5 Mounting hole 6 Coil spring 7 Spacer 8 Washer 9 Holding screw (fastening means)
DESCRIPTION OF SYMBOLS 30 Contact part 31 Radiation fin 32 Through-hole 40 Fastening support part 41 Press fit pin 42 Female thread part 43 Base 90 Screw head 91 Stepped part 92 Male thread part 93 Slot part

Claims (7)

A heat sink that dissipates heat from the electronic component by being pressed against and brought into contact with the surface opposite to the substrate of the electronic component mounted on the substrate;
A cradle having a press-fit pin for fixing to the substrate;
Spring,
Fastening means for fixing the heat sink to the cradle via the spring;
A heat sink mounting structure characterized by comprising: The heat sink includes a plurality of through holes at an end,
The cradle includes a fastening support portion having a screw portion, and passes the fastening support portion through the through-hole,
The fastening means is a holding screw that is screwed with a screw portion of the cradle,
The spring includes a portion of the fastening support portion that protrudes through the through hole and is disposed between the heat sink and the holding screw, and the spring screw is connected to the screw portion of the fastening support portion. A coil spring that is compressed by being pressed by the holding screw by being screwed to the heat sink and generating a pressing force against the heat sink,
The heat sink mounting structure according to claim 1. The holding screw has a stepped portion,
The outer diameter of the stepped portion is smaller than the inner diameter of the coil spring.
The heat sink mounting structure according to claim 2. A spacer having a through-hole having a diameter larger than the outer diameter of the screw portion of the holding screw and smaller than the outer diameter of the stepped portion inside the coil spring between the fastening support portion and the holding screw. Deploy,
The heat sink mounting structure according to claim 3. The thickness of the spacer is such that the total value of the length of the portion of the fastening support portion that protrudes through the through hole, the thickness of the spacer, and the length of the stepped portion of the holding screw is greater than the length of the coil spring. A thickness that is a small predetermined value,
The heat sink mounting structure according to claim 4. The cradle has a pedestal having a larger projected area on the substrate than the fastening support portion between the fastening support portion and the press-fit pin.
The heat sink mounting structure according to any one of claims 2 to 5, wherein the heat sink is attached to the heat sink. The cradle is formed by assembling both the fastening support part and the pedestal,
The heat sink mounting structure according to claim 6.

Images