JP2008172128A - Circuit module and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal component unit having high heat dissipation effect, in which a heating part and a printed circuit board with a signal system electronic part mounted thereon are mounted. <P>SOLUTION: In a conductive heat transfer board, a metallic plate 12, a sheet-shaped heat transmission layer 14, a lead wire 11 made up of a lead frame, more than a part of which is embedded therein, and the like, are provided. In a module, a printed circuit board 15 is connected with the lead wire 11. Since a part of the lead wire 11 has a chimney structure having chimney formation 13, air with specific gravity, which becomes smaller because of heat generated from heating elements, such as the electronic part, is moved up positively. At the same time, cold air is drawn inside through suction force generated there, and the electronic component can be cooled, thereby raising cooling property of the circuit module. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a circuit module used for a power supply circuit, a drive circuit, and the like using a power semiconductor of an electronic device and a manufacturing method thereof.

  In recent years, with the demand for higher performance and miniaturization of electronic devices, further miniaturization is required for power supply circuits and drive circuits (for example, sustain circuits for plasma televisions) using a power semiconductor or the like. However, since power system electronic components (for example, power semiconductor elements) generate large current and high heat generation, it is necessary to mount them on a heat conductive substrate corresponding to large current and high heat dissipation. Compared with such power electronic components, signal electronic components (for example, signal semiconductor elements and various chip components) do not generate much heat and can be mounted with high density. For this reason, a power system electronic component is conventionally mounted on a heat conductive substrate and is mounted on a heat component unit (for example, a heat component unit 7 in FIG. 9 described later), and a signal system electronic component is a general printed wiring board (for example, in FIG. 9 described later). Japanese Patent Application Laid-Open No. H10-228561 proposes mounting on a printed wiring board 8) and electrically connecting a plurality of substrates thus created to form one circuit module. Next, an example of a conventional circuit module will be described with reference to FIGS.

  FIG. 9 is a perspective view for explaining a conventional circuit module, which is one of the circuit modules used in a plasma display device, for example. This circuit module includes a thermal component unit and a printed wiring board fixed on the thermal component unit via a plurality of lead wires.

  In FIG. 9, the thermal component unit 7 is formed of an insulator 5 fixed on a metal plate 4, a metal pattern 6, a lead wire 1, and the like. On the metal pattern 6, the heat generating component 3 is soldered via the terminal 2. Further, a hole 9 is formed in a part of the printed wiring board 8 so that the lead wires 1 can be inserted all together. The lead wire 1 of the thermal component unit is inserted into the hole 9 of the printed wiring board 8 and integrated into one circuit module.

  Next, the heat dissipation mechanism in this circuit module will be described with reference to FIG.

FIG. 10 is a perspective view illustrating a heat dissipation mechanism of a conventional circuit module. In FIG. 10, the circuit module stands up substantially vertically. This is because products (such as plasma televisions or liquid crystal televisions) in which such circuit modules are used are required to be large and thin, and circuit modules are also used in order to reduce the floor area. . In FIG. 10, an arrow 10 indicates a state in which heat is released from the heated circuit module to the outside by the air flow. In FIG. 10, the heat generated in the heat generating component 3 (not visible because it is behind the printed wiring board 8) leads to the space between the thermal component unit 7 and the printed wiring board 8 as indicated by the arrow 10. It is discharged (or air-cooled) as a random air flow to the outside through the gap of the line 1.
JP 2006-308620 A

  However, in the configuration shown in FIG. 10, it is difficult to increase the air flow rate because the air-cooled air flow is not constant as indicated by the arrow 10. As a result, the cooling efficiency decreases. Even if forced air cooling is attempted using a fan or the like, the cooling effect is low because the air flow escapes through the gap because of the structure with many gaps. Further, when the air volume is increased, the forested lead wire 1 may cause a wind noise or the like.

  Accordingly, the present invention surrounds the gap between the thermal component unit and the printed wiring board with a chimney forming body to form a kind of chimney structure, and the chimney structure is generated by heat generated from a heat generating component mounted inside the chimney structure. To heat the air inside the air, actively move the air with a lower specific gravity upward (or generate an updraft), draw in the cold air with the suction force generated there, and cool the heat generating parts Thus, the object is to increase the heat dissipation effect (or cooling effect) of the circuit module.

  In order to achieve the above object, the present invention is a circuit module comprising a heat conductive substrate, a printed wiring board fixed to the heat conductive substrate, and a lead wire, and is fixed to the heat conductive substrate side. A circuit in which a gap between the printed wiring board and the heat conductive substrate is formed by the lead wire, and a chimney forming body is provided on the lead wire arranged from the lower side to the upper side of the lead wire. It is a module.

  As described above, according to the present invention, a gap is formed using a lead wire between the heat conductive substrate and the printed wiring board portion, and a chimney forming body is formed on a part of the lead wire forming the gap. The amount of air flowing through the space sandwiched between the heat conductive substrate and the printed wiring board can be increased by a chimney effect, and the heat conductive substrate is mounted on the surface of the printed wiring board. It is possible to increase the cooling efficiency of the electronic components and the like. As a result, various circuit modules and electronic devices can be reduced in size and noise.

  Note that some of the manufacturing steps shown in the embodiments of the present invention are performed using a molding die or the like. However, the molding die is not shown unless it is necessary for explanation. Further, the drawings are schematic views and do not show the positional relations in terms of dimensions.

(Embodiment)
Hereinafter, a circuit module according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a circuit module according to an embodiment of the present invention. In FIG. 1, 11 is a lead wire, 12 is a metal plate, 13 is a chimney forming body, 14 is a heat transfer layer, 15 is a printed wiring board, and 16 is an arrow. In FIG. 1, the circuit module is erected in order to explain the chimney effect in a circuit module incorporated in a plasma television or the like.

  In FIG. 1, a circuit module comprising a heat conductive substrate (details of the heat conductive substrate will be described later with reference to FIGS. 2 to 8), a printed wiring board fixed to the heat conductive substrate, and a lead wire, A gap between the printed wiring board and the heat conductive substrate is formed by the lead wire fixed to the heat conductive substrate side, and a chimney is formed on the lead wire arranged from below to above the lead wire. A circuit module provided with a formed body will be described.

  In FIG. 1, a kind of chimney structure is formed by a surface formed by the metal plate 12 and the heat transfer layer 14, a surface formed by the printed wiring board 15, and a chimney forming body 13 that closes the gap. And the circuit module in this Embodiment has a chimney structure positively part or more. The air whose specific gravity is reduced by the heat generated from the heat generating component (not shown) by the chimney structure thus formed is moved above the chimney structure (or an upward air flow is generated), and the suction generated there The cold air is newly supplied to the heat generating component by force, and the heat radiation effect of the circuit module is enhanced. And by forming the chimney forming body 13 between the heat transfer layer 14 and the printed wiring board 15, the air gap is prevented and the chimney effect is enhanced.

  Next, an example of a method for forming a chimney structure in a circuit module will be described with reference to FIGS. In FIG. 2, 17 is a heat conductive substrate, and 18 is a hole.

  FIG. 2 is a perspective view for explaining how the heat conductive substrate 17 and the printed wiring board 15 are integrated. In FIG. 2, a heat conductive substrate 17 is configured by fixing a sheet-like heat transfer layer 14 on a metal plate 12 and embedding part or more of a lead frame in the heat transfer layer 14. (Note that the lead frame is not shown in FIG. 2. In FIG. 2, only a part of the lead frame that is bent substantially perpendicularly from the heat transfer layer 14 to become the lead wire 11 is shown. The lead frame and the like will be described later with reference to FIGS. A hole 18 is formed in a predetermined portion of the printed wiring board 15. Then, as shown by an arrow 16, the lead wire 11 formed on the heat conductive substrate 17 is inserted into the hole 18 formed on the printed wiring board 15.

  FIGS. 3A and 3B are perspective views for explaining how the gap between the heat conductive substrate 17 and the printed wiring board 15 is closed. FIG. 3A is a perspective view showing a state in which the heat conductive substrate 17 and the printed wiring board 15 are integrated, for example, as shown in FIG. In FIG. 3A, the heat conductive substrate 17 and the printed wiring board 15 are integrated via the lead wire 11. Next, as shown in FIG. 3B, the gap between the heat conductive substrate 17 and the printed wiring board 15 is closed. FIG. 3B is a perspective view for explaining a state in which a gap between the heat conductive substrate 17 and the printed wiring board 15 is closed. In FIG. 3 (B), the chimney forming body 13 is, for example, a heat-resistant film (for example, a polyimide tape). By forming the chimney forming body 13 between the heat conductive substrate 17 and the printed wiring board 15, a chimney structure is obtained. The chimney forming body 13 is formed so as to close the left and right gaps between the heat conductive substrate 17 and the printed wiring board 15. By closing the gaps on the left and right sides, you can reduce the gap wind and enhance the chimney effect.

  As shown in FIG. 3B, the chimney structure 13 is formed by utilizing the lead wire 11 (for example, fixing a member constituting the chimney formation body 13 to the lead wire 11). Can be stabilized.

  Next, an example of the manufacturing method of a heat conductive board | substrate is demonstrated using FIGS.

  4A and 4B are cross-sectional views illustrating a method for manufacturing a heat conductive substrate. 4 (A) and 4 (B), 19 is a press and 20 is a film for preventing dirt. Reference numeral 21 denotes a lead frame, which is obtained by processing a copper plate or the like into a wiring shape by pressing or the like. First, as shown in FIG. 4A, the metal plate 12, the heat transfer layer 14, the lead frame 21, and the antifouling film 20 are set on the press 19. 4 (A) and 4 (B), a mold set on the press 19 is not shown.

  As shown in FIG. 4A, the heat transfer layer 14 and the metal plate 12 are pressed and laminated in the direction of the arrow 16 using a press 19. Here, the heat transfer layer 14 is obtained by preforming a heat transfer material, which will be described later, into a sheet shape, for example. In FIG. 4A, the heat transfer layer 14 may have a slightly convex central portion so that air can be easily removed during pressing.

  FIG. 4B is a cross-sectional view illustrating a state after the press is completed. As shown in FIG. 4B, by using the film 20, the heat transfer layer 14 does not adhere as dirt on the surface of the press 19 or a mold (not shown). Further, by using the film 20 as a cushioning material (or packing or sealing material) between the press 19 or the mold and the lead frame 21, the heat transfer layer 14 is prevented from wrapping around the surface of the lead frame 21. Or press pressure can be increased. As a result, the heat transfer layer 14 is circulated to a plurality of lead frames 21. Thus, a part or more of the lead frame 21 is embedded in the heat transfer layer 14. By doing so, the mountability of parts is improved and the formability of solder resist and the like is improved. 4A and 4B, the heat transfer layer 14 and the like are heated at the time of pressing, whereby the heat transfer layer 14 can be softened and the adhesion effect with the metal plate 12 is enhanced.

  Then, as shown in FIG. 4B, after forming into a predetermined shape, the film 20 is peeled off from the surface of the heat transfer layer 14. Then, the heat transfer layer 14 in which the lead frame 21 is embedded and integrated on the metal plate 12 is heated and cured in a heating device to form a heat conductive substrate 17. In addition, by heat-curing the heat transfer layer 14 in a state where the film 20 is peeled off, the heat shrinkage (wrinkle generation) of the film 20 can be made without affecting the hardening of the heat transfer layer 14.

  Here, as the sheet-like heat transfer layer 14, a heat transfer composite material made of a thermosetting resin and a filler can be used. For example, the member is desirable from 70% to 95% by weight of the inorganic filler and 5% to 30% by weight of the thermosetting resin. Here, the inorganic filler has a substantially spherical shape, and its diameter is suitably 0.1 μm or more and 100 μm or less (if it is less than 0.1 μm, it becomes difficult to disperse in the resin, and if it exceeds 100 μm, the thickness of the heat transfer layer 14 is increased Will increase the thermal diffusivity). Therefore, the filling amount of the inorganic filler in the heat transfer layer 14 is filled at a high concentration of 70 to 95% by weight in order to increase the thermal conductivity. In particular, in the present embodiment, the inorganic filler is a mixture of two types of alumina having an average particle diameter of 3 μm and an average particle diameter of 12 μm. By using alumina having two kinds of large and small particle diameters, it is possible to fill the gaps between the large particle diameters of alumina with small particle diameters, so that alumina can be filled at a high concentration to nearly 90% by weight. As a result, the heat conductivity of the heat transfer layer 14 is about 5 W / (m · K). The inorganic filler may include at least one selected from the group consisting of alumina, magnesium oxide, boron nitride, silicon oxide, silicon carbide, silicon nitride, and aluminum nitride.

  When an inorganic filler is used, the heat dissipation can be improved, but in particular when magnesium oxide is used, the linear thermal expansion coefficient can be increased. Further, when silicon oxide is used, the dielectric constant can be reduced, and when boron nitride is used, the linear thermal expansion coefficient can be reduced. Thus, the heat transfer layer 14 having a thermal conductivity of 1 W / (m · K) or more and 20 W / (m · K) or less can be formed. In addition, when heat conductivity is less than 1 W / (m * K), it influences the heat dissipation of a heat conductive board | substrate. Moreover, when it is going to make thermal conductivity higher than 20 W / (m * K), it is necessary to increase the amount of fillers and may affect the workability at the time of a press.

  The thermosetting resin contains at least one kind of resin among epoxy resin, phenol resin and cyanate resin. These resins are excellent in heat resistance and electrical insulation. If the thickness of the heat transfer layer 14 is reduced, the heat of the lead frame 21 can be easily transmitted to the metal plate 12, but conversely, the withstand voltage becomes a problem. Further, if the thickness of the heat transfer layer 14 is too thick, the thermal resistance increases. Therefore, the optimum thickness may be set to 50 μm or more and 1000 μm or less in consideration of the withstand voltage and the thermal resistance.

  In addition, as the heat transfer layer 14, a heat conductive sheet material made by a casting method or the like made of an inorganic filler and a resin (thermosetting resin or thermosoftening resin) can also be used.

  Next, a method for mounting the electronic component on the heat conductive substrate 17 will be described with reference to FIG. 5A and 5B are cross-sectional views illustrating a method for mounting an electronic component on the heat conductive substrate 17. 5A and 5B, reference numeral 22 denotes an electronic component, for example, a heat generating component such as a power semiconductor. Reference numeral 23 denotes a dotted line. The electronic component 22 is mounted on the lead frame 21 as indicated by an arrow 16a in FIG. 5A and 5B, the solder resist formed on the lead frame 21 is not shown. After that, as indicated by an arrow 16b in FIG. 5B, a part of the lead frame 21 (for example, a part shown by a dotted line 23) is peeled off from the heat transfer layer 14, and bent substantially vertically to form the lead wire 11. . The electronic component 22 and the like are mounted on the heat conductive substrate 17 thus created.

  In this way, by forming a part of the lead frame 21 as the lead wire 11, the lead wire 11 and the lead frame 21 can be integrated, and the number of connection points between the lead frame 21 and the lead wire 11 can be reduced. . Further, it is possible to increase the connection strength between the lead wire 11 and the heat transfer resin 14 and to obtain an effect that the lead wire 11 is not easily disturbed when the electronic component 22 is mounted.

  It is also useful to previously form a solder layer or a tin layer on the mounting surface of the lead frame 21 such as the electronic component 22 so as to improve solderability. It is desirable that no solder layer be formed on the surface of the lead frame 21 that contacts the heat transfer layer 14. If a solder layer or a tin layer is formed on the surface in contact with the heat transfer layer 14 in this way, this layer becomes soft during soldering, which affects the adhesion (or bond strength) between the lead frame 21 and the heat transfer layer 14. May give.

  The metal plate 12 is made of aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity. In particular, in the present embodiment, the thickness of the metal plate 12 is 1 mm (desirably 0.1 mm or more and 50 mm or less), but the thickness can be designed according to product specifications (note that the thickness of the metal plate 12 is 0.2 mm). If the thickness is less than 1 mm, heat dissipation and strength may be insufficient, and if the thickness of the metal plate 12 exceeds 50 mm, it is disadvantageous in terms of weight). The metal plate 12 is not only a plate-like one, but also a fin portion (or uneven portion) for increasing the surface area on the surface opposite to the surface on which the heat transfer layer 14 is laminated in order to further improve heat dissipation. May be formed. The total expansion coefficient is 8 to 20 ppm / ° C., and warpage and distortion of the heat conductive substrate of the present invention and the entire power supply unit using the same can be reduced. In addition, when these components are surface-mounted, matching the thermal expansion coefficients with each other is also important in terms of reliability.

  Next, a state in which the heat conductive substrate 17 and the printed wiring board 15 are laminated and integrated will be described with reference to FIG. FIGS. 6A and 6B are cross-sectional views illustrating a state in which the heat conductive substrate 17 and the printed wiring board 15 are stacked and integrated via the lead wires 11. 6A, the heat conductive substrate 17 is composed of a metal plate 12, a heat transfer layer 14 fixed thereon, and a lead frame 21 in which a part or more is embedded in the heat transfer layer 14. Further, a part of the lead frame 21 is bent substantially vertically to form a lead wire 11. A hole 18 is formed at a predetermined position of the printed wiring board 15. In the printed wiring board 15, wiring patterns, through holes, solder resists, various electronic components mounted, and the like formed on the surface and inside thereof are not shown.

  First, as shown by an arrow 16a in FIG. 6A, a hole 18 of a printed wiring board 15 is inserted into a lead wire 11, and fixed and integrated with solder or the like to constitute a module. FIG. 6B is a cross-sectional view of the module thus created. Then, as shown in FIG. 6 (B), the chimney forming body 13 created using a predetermined insulating member is set as shown by an arrow 16b, and the gap between the heat conductive substrate 17 and the printed wiring board 15 is closed, and the chimney structure Form. And by setting this module vertically, the chimney effect shown in FIG. 1 is utilized.

  FIG. 7 is a perspective view showing a state in which the heat conductive substrate 17 and the printed wiring board 15 are integrated to constitute a circuit module. In FIG. 7, reference numeral 24 denotes a terminal, which corresponds to a terminal (or external terminal) for mounting the electronic component 22. As shown in FIG. 7, a sheet-like heat transfer layer 14 is fixed on the surface of the heat conductive substrate 17, and a part or more of the lead frame 21 is embedded in the heat transfer layer 14. A plurality of lead wires 11 are fixed to the heat conductive substrate 17 side. The lead wires 11 may be formed in a plurality of rows substantially in parallel as shown in FIG. For example, the lead wires 11 are formed on the left and right sides of the heat conductive substrate 17, and the chimney formation body 13 (not shown) is provided on the lead wires 11 to obtain a chimney structure. A part of the lead frame 21 can be bent substantially vertically to form the lead wire 11. The electronic component 22 is mounted on the lead frame 21 via the terminal 24. In FIG. 7, solder resist and solder are not shown. Also, the wiring pattern and solder resist of the printed wiring board 15 and electronic components mounted on the surface thereof are not shown. An arrow 16 indicates a state in which the hole 18 of the printed wiring board 15 is inserted into the lead wire 11.

  Next, the chimney forming body 13 will be described with reference to FIG. FIG. 8 is a perspective view showing a state in which the heat conductive substrate 17 and the printed wiring board 15 are integrated via the chimney forming body 13. In FIG. 8, a hole 18 is formed in the chimney forming body 13. By inserting the lead wire 11 formed on the heat conductive substrate 17 into the hole 18 formed in the chimney forming body 13, variations in the lead wire 11 (for example, variations in inclination, etc.) can be suppressed, and a plurality of leads The wires 11 can be easily inserted into the hole 18 in a lump. In addition, the arrow 16 in FIG. 8 shows the insertion direction of the chimney formation body 13 or the printed wiring board 15. In addition, the chimney formation body 13 can be formed with resin. Further, by using an elastic body for the chimney forming body 13 (or the surface of the chimney forming body 13 or the like), the adhesion with the heat transfer layer 14 or the printed wiring board 15 can be enhanced, and a gap (or a gap air) is created. The effect of reducing is obtained.

  In addition, the chimney formation body 13 is formed with an insulator. This is because the lead wires 11 and the like do not short-circuit each other. Further, the height of the chimney forming body 13 (the distance between the heat conductive substrate 17 and the printed wiring board 15) may be optimized and designed in terms of electric circuit or aerodynamics. The height of the chimney forming body 13 is desirably 5 mm or more (preferably 10 mm or more) and 200 mm or less (preferably 150 mm or less). When the height of the chimney forming body 13 is less than 5 mm, the thickness of the electronic component 22 mounted in the gap between the heat conductive substrate 17 and the printed wiring board 15 may be limited. Moreover, when the height of the chimney forming body 13 exceeds 200 mm, the depth of the plasma television or the like is affected. For this reason, the height of the chimney forming body 13 can be designed in consideration of the height of a component mounted in the gap and the amount of heat generated.

  In addition, it is desirable that the lead wire 11 is formed by peeling a part of the lead frame 21 from the heat transfer layer 14. By doing so, the lead frame 21 forming the wiring pattern on the heat conductive substrate 17 and the lead wire 11 can be integrated, and the effect of improving the reliability can be obtained. Further, the lead frame 21 is peeled off from the heat transfer layer 14 to form the lead wire 11, whereby the distance between the metal plate 12 and the lead wire 11 can be set as a creepage distance, and the electrical insulation can be improved.

The lead frame 21 may be a metal plate mainly made of copper or a copper alloy and punched into a predetermined shape. The material of the metal plate constituting the lead frame 21 will be described. Here, the metal material of the lead frame 21 is preferably a material mainly composed of copper (for example, copper foil or copper plate). This is because copper has both excellent thermal conductivity and electrical conductivity. As the copper plate for the lead frame 21, for example, a thickness of 100, 200, 300, 500 μm or the like can be used. As such a copper plate for the lead frame 21, for example, tough pitch copper (alloy symbol: C1100), oxygen-free copper (alloy symbol: C1020), or the like is desirably used. Such a material is produced by melting the raw material copper. Here, tough pitch copper is refined copper in which oxygen remains in copper, and is excellent in electrical conductivity and workability. For example, tough pitch copper is preferably 99.90 wt% or more of Cu, and oxygen free copper is preferably 99.96 wt% or more of Cu, for example. When the purity of copper is less than these numbers, it is affected not only by workability but also by thermal conductivity and electrical conductivity due to the influence of impurities (for example, the content of Cu ₂ O due to the influence of oxygen increases) There is. Such a member is inexpensive and excellent in mass productivity. Etching may be used as a patterning method for the lead frame 21, but punching with a press 19 (or a mold) is suitable from the viewpoint of pattern identity and mass productivity.

  Various copper alloys can be selected as the lead frame 21. For example, in order to improve the workability and thermal conductivity of the lead frame 21, at least one or more selected from the group of at least Sn, Zr, Ni, Si, Zn, P, Fe, etc. other than copper is used as the copper material. It is also possible to use an alloy made of any of the above materials. For example, it is possible to use a copper material (hereinafter referred to as Cu + Sn) in which Cu is mainly used and Sn is added thereto. In the case of a Cu + Sn copper material (or copper alloy), for example, by adding Sn to 0.1 wt% or more and less than 0.15 wt%, the softening temperature can be increased to 400 ° C. For comparison, when Sn-free copper (Cu> 99.96% by weight) is used and the lead frame 21 or a part of the lead frame 21 is a bent lead wire 11, the conductivity is low, but it is particularly formed on the finished heat conductive substrate. There was a case where distortion occurred in the part. As a result, the softening point of the material was as low as about 200 ° C., and it was expected that the material could be deformed during subsequent component mounting (soldering). On the other hand, when a copper-based material with Cu + Sn> 99.96% by weight was used, it was not particularly affected by the heat generation of various mounted parts. There was no effect on solderability and die bondability. Therefore, when the softening point of this material was measured, it was found to be 400 ° C. Thus, it is desirable to add some elements mainly composed of copper. As an element added to copper, in the case of Zr, the range of 0.015 wt% or more and 0.15 wt% is desirable. When the addition amount is less than 0.015% by weight, the effect of increasing the softening temperature may be small. On the other hand, if the amount added is more than 0.15% by weight, the electrical characteristics may be affected. Also, the softening temperature can be increased by adding Ni, Si, Zn, P or the like. In this case, Ni is 0.1 wt% or more and less than 5 wt%, Si is 0.01 wt% or more and 2 wt% or less, Zn is 0.1 wt% or more and less than 5 wt%, and P is 0.005 wt% or more. Less than 0.1% by weight is desirable. And these elements can make the softening point of a copper raw material high by adding single or multiple in this range. In addition, when there are few addition amounts than the ratio described here, the softening point raise effect may be low. Moreover, when there are more than the ratio described here, there exists a possibility of affecting the electrical conductivity. Similarly, in the case of Fe, 0.1% by weight to 5% by weight is desirable, and in the case of Cr, 0.05% by weight to 1% by weight is desirable. These elements are the same as those described above.

  The tensile strength of the copper material used for the lead frame 21 is desirably 600 N / square mm or less. In the case of a material having a tensile strength exceeding 600 N / square mm, the workability of these lead frames 21 may be affected. On the other hand, by setting the tensile strength to 600 N / square mm or less (and if these lead frames 21 require fine and complicated processing, desirably 400 N / square mm or less), the spring back (pressure even if bent to the required angle) is achieved. The occurrence of rebound by reaction force is suppressed, and the formation accuracy can be improved. As described above, the material of these lead frames 21 is mainly composed of Cu, whereby the electrical conductivity can be lowered, and further softening can improve the workability, and further the heat dissipation effect by these lead frames 21 can be enhanced. The tensile strength of the copper alloy used for these lead frames 21 is desirably 10 N / square mm or more. This is because the copper alloy used for the lead frame 21 needs to have a strength higher than the tensile strength (about 30 to 70 N / square mm) of general lead-free solder. When the tensile strength of the copper alloy used for these lead frames 21 is less than 10 N / square mm, when the electronic component 22 is soldered and mounted on these lead frames 21, it is not the solder portion but the portion of the lead frame 21. There is a possibility of cohesive failure.

  It is also useful to previously form a solder layer or a tin layer on the mounting surface of the lead frame 21 such as the electronic component 22 so as to improve solderability. It is desirable that no solder layer be formed on the surface of the lead frame 21 that contacts the heat transfer layer 14. If a solder layer or a tin layer is formed on the surface in contact with the heat transfer layer 14 in this way, this layer becomes soft during soldering, which affects the adhesion (or bond strength) between the lead frame 21 and the heat transfer layer 14. May give.

  The metal plate 12 is made of aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity. In particular, in the present embodiment, the thickness of the metal plate 12 is 1 mm (desirably 0.1 mm or more and 50 mm or less), but the thickness can be designed according to product specifications (note that the thickness of the metal plate 12 is 0.2 mm). If the thickness is less than 1 mm, heat dissipation and strength may be insufficient, and if the thickness of the metal plate 12 exceeds 50 mm, it is disadvantageous in terms of weight). The metal plate 12 is not only a plate-like one, but also a fin portion (or uneven portion) for increasing the surface area on the surface opposite to the surface on which the heat transfer layer 14 is laminated in order to further improve heat dissipation. May be formed. The total expansion coefficient is 8 to 20 ppm / ° C., and warpage and distortion of the heat conductive substrate of the present invention and the entire power supply unit using the same can be reduced. In addition, when these components are surface-mounted, matching the thermal expansion coefficients with each other is also important in terms of reliability.

  When the lead frame 21 is bent to form the lead wire 11, the bending angle is preferably substantially vertical (preferably vertical ± 20 degrees or less, desirably ± 10 degrees or less, and further ± 5% or less). If the vertical angle exceeds ± 20 degrees, there is a possibility of affecting the insertability of the printed wiring board 15 into the hole 18. Or since the hole 18 needs to be enlarged, the printed wiring board 15 is affected in downsizing.

  A circuit module comprising a heat conductive substrate 17, a printed wiring board 15 fixed to the heat conductive substrate 17, and a lead wire 11, wherein the printed wire is fixed by the lead wire 11 fixed to the heat conductive substrate 17 side. A circuit module is formed in which a gap is formed between the wiring board 15 and the heat conductive substrate 17 and the chimney forming body 13 is provided on the lead wire 11 arranged from the lower side to the upper side of the lead wire 11. Thus, the air cooling effect of the electronic component 22 mounted on the heat conductive substrate 17 side or the printed wiring board 15 side can be obtained, and the circuit module can be downsized and improved in performance. The reason why the chimney forming body 13 is provided on the lead wire 11 arranged from below to above among the lead wires 11 is to form the side surface (or chimney wall) of the chimney structure. This is because if the chimney forming body 13 is provided on the lead wires 11 arranged on the left and right, the chimney structure may be covered.

  A circuit module including a heat conductive substrate 17, a printed wiring board 15 fixed to the heat conductive substrate 17, and a lead frame 21, and the printed wiring is formed by the lead frame 21 bent from the heat conductive substrate 17 side. A circuit module is provided in which a gap is formed between the plate and the heat conductive substrate 17 and the chimney forming body 13 is provided on the lead frame 21 arranged from below to above the bent lead frame 21. Thus, the air cooling effect of the electronic component 22 mounted on the heat conductive substrate 17 side or the printed wiring board 15 side can be obtained, and the circuit module can be downsized and improved in performance.

  The heat conductive substrate 17 is a circuit comprising a metal plate 12, a sheet-like heat transfer layer 14 fixed on the metal plate 12, and a lead frame 21 having a part or more embedded in the heat transfer layer 14. By using the module, the air cooling effect of the electronic component 22 mounted on the heat conductive substrate 17 side or the printed wiring board 15 side can be obtained, and the circuit module can be downsized and improved in performance.

  By making the heat conductive substrate 17 and the printed wiring board 15 fixed to the heat conductive substrate 17 a circuit module fixed substantially in parallel, an air cooling effect of the electronic component 22 mounted on the circuit module can be obtained. This makes it possible to reduce the size and performance of the circuit module. Here, the reason why the fixing is substantially parallel is to realize a reduction in size and thickness of a device incorporating the circuit module. By fixing substantially parallel, the floor area when the circuit module is installed in an upright state can be increased, and the chimney efficiency can be increased.

  The heat conductive substrate 17 is composed of a metal plate 12, a sheet-like heat transfer layer 14 fixed on the metal plate 12, and a lead frame 21 having a part or more embedded in the heat transfer layer 14. The lead wire 11 that connects the heat conductive substrate 17 and the printed wiring board is a circuit module in which a part of the lead frame 21 embedded in the heat transfer layer 14 is bent substantially vertically, thereby providing heat conduction. The air-cooling effect of the electronic component 22 mounted on the substrate 17 side or the printed wiring board 15 side can be obtained, and the circuit module can be reduced in size and performance.

  The lead wire 11 or the lead frame 21 connecting the heat conductive substrate 17 and the printed wiring board portion is a circuit module formed in a plurality of substantially parallel rows, so that the electronic circuit mounted on the circuit module side or the printed wiring board is provided. The air cooling effect of the component 22 is obtained, and the circuit module can be reduced in size and performance.

  The heat transfer layer 14 is made of at least one resin selected from the group consisting of epoxy resins, phenol resins, and isocyanate resins, and alumina, magnesium oxide, boron nitride, silicon oxide, silicon carbide, silicon nitride, and aluminum nitride. By using at least one kind of inorganic filler selected from the group consisting of and a circuit module, the air cooling effect of the electronic component 22 mounted on the circuit module side or the printed wiring board 15 side can be obtained, and the circuit module can be downsized, High performance is possible. Further, heat generated in the electronic component 22 is transmitted to the metal plate 12 through the heat transfer layer 14, and is further radiated to a chassis (for example, a metal chassis of a plasma television) or a fin fixed to the metal plate 12. Can do. Thus, both the chimney effect and the heat dissipation by heat conduction can be used together.

  The lead frame 21 or the lead wire 11 is a circuit module made of copper foil, tough pitch copper, or oxygen-free copper, so that the lead wire 11 connecting the printed wiring board 15 and the heat conductive substrate 17 is part of the lead frame 21. By forming a chimney structure that uses this as a part of the structure of the chimney forming body 13, the air cooling effect of the electronic component 22 mounted on the circuit module can be obtained, and the circuit module can be reduced in size and performance. Is possible.

  In the lead frame 21 or the lead wire 11, Sn is 0.1 wt% or more and 0.15 wt% or less, Zr is 0.015 wt% or more and 0.15 wt% or less, Ni is 0.1 wt% or more and 5 wt% or less. In the following, Si is 0.01% to 2% by weight, Zn is 0.1% to 5% by weight, P is 0.005% to 0.1% by weight, and Fe is 0.1% by weight. It is a metal material mainly comprising copper, including at least one selected from the group of 5% by weight or less, and a printed circuit board according to any one of claims 1 to 4, 15 and the heat conductive substrate 17 can be formed by a part of the lead frame 21, and a chimney structure that forms a part of the structure of the chimney forming body 13 is formed. Air cooling effect of parts 22 etc. is obtained Miniaturization of the circuit module, thereby enabling high performance.

  At least the step of integrating the metal plate 12, the lead frame 21, and the heat transfer layer 14, the step of curing the heat transfer layer 14, and mounting the electronic component 22 on the lead frame 21, Bending part of the lead frame 21 substantially vertically to form the lead wire 11, fixing part of the lead wire 11 to a printed wiring board, and part of the lead frame 21 or part of the lead wire 11 The circuit module manufacturing method including the step of forming the chimney forming body 13 makes it possible to create a circuit module having a chimney structure capable of obtaining an air cooling effect such as the electronic component 22 mounted on the circuit module. Miniaturization and high performance are possible. Although it is effective to use the lead wire 11 for fixing the chimney forming body 13, the lead frame 21 portion may also be used together.

  As described above, the circuit module and the manufacturing method thereof according to the present invention enable downsizing and high performance of plasma televisions, liquid crystal televisions, various in-vehicle electrical components, or industrial devices that require heat dissipation. Become.

The perspective view of the circuit module in embodiment of this invention The perspective view explaining a mode that a heat conductive substrate and a printed wiring board are integrated. (A) (B) is a perspective view explaining a mode that a gap between a heat conduction board and a printed wiring board is plugged up together. (A) (B) is sectional drawing explaining the manufacturing method of a heat conductive board | substrate both (A) (B) is sectional drawing explaining the mounting method of the electronic component on a heat conductive board. (A) (B) is sectional drawing explaining a mode that a heat conductive board and a printed wiring board are laminated | stacked and integrated via a lead wire. The perspective view which shows a mode that a heat conductive substrate and a printed wiring board are integrated, and a circuit module is comprised. The perspective view which shows a mode that a heat conductive board and a printed wiring board are integrated via a chimney formation body. The perspective view explaining the conventional circuit module The perspective view explaining the heat dissipation mechanism of the conventional circuit module

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Lead wire 12 Metal plate 13 Chimney formation body 14 Heat transfer layer 15 Printed wiring board 16 Arrow 17 Heat conduction board 18 Hole 19 Press 20 Film 21 Lead frame 22 Electronic component 23 Dotted line 24 Terminal

Claims (10)

A circuit module comprising a heat conductive substrate, a printed wiring board fixed to the heat conductive substrate, and a lead wire,
By the lead wire fixed on the heat conductive substrate side, a gap between the printed wiring board and the heat conductive substrate is formed,
The circuit module which provided the chimney formation body in the lead wire arrange | positioned toward the upper direction from the downward direction among the said lead wires. A circuit module comprising a heat conductive substrate, a printed wiring board fixed to the heat conductive substrate, and a lead frame,
By the lead frame bent from the heat conductive substrate side, a gap between the printed wiring board and the heat conductive substrate is formed,
The circuit module which provided the chimney formation body in the lead frame arrange | positioned toward the upper direction from the downward direction among the bent lead frames. 3. The heat conduction substrate includes a metal plate, a sheet-like heat transfer layer fixed on the metal plate, and a lead frame in which a part or more is embedded in the heat transfer layer. A circuit module according to any one of the above. The circuit module according to claim 1, wherein the heat conductive substrate and the printed wiring board fixed to the heat conductive substrate are fixed substantially in parallel. The heat conductive substrate is composed of a metal plate, a sheet-like heat transfer layer fixed on the metal plate, and a lead frame embedded in part or more in the heat transfer layer,
2. The circuit module according to claim 1, wherein the lead wire connecting the heat conductive substrate and the printed wiring board portion is formed by bending a part of the lead frame embedded in the heat transfer layer substantially vertically. The circuit module according to claim 1, wherein the lead wires or lead frames connecting the heat conductive substrate and the printed wiring board are formed in a plurality of substantially parallel rows. The heat transfer layer includes at least one resin selected from the group consisting of an epoxy resin, a phenol resin, and an isocyanate resin;
At least one inorganic filler selected from the group consisting of alumina, magnesium oxide, boron nitride, silicon oxide, silicon carbide, silicon nitride, and aluminum nitride;
The circuit module according to claim 1, comprising: The circuit module according to claim 1, wherein the lead frame or the lead wire is copper foil, tough pitch copper, or oxygen-free copper. In the lead frame or lead wire, Sn is 0.1 wt% or more and 0.15 wt% or less, Zr is 0.015 wt% or more and 0.15 wt% or less, Ni is 0.1 wt% or more and 5 wt% or less, Si is 0.01 wt% or more and 2 wt% or less, Zn is 0.1 wt% or more and 5 wt% or less, P is 0.005 wt% or more and 0.1 wt% or less, Fe is 0.1 wt% or more and 5 wt% or less. 3. The circuit module according to claim 1, wherein the circuit module is a metal material mainly composed of copper, including at least one selected from the group of wt% or less. at least,
A step of integrating the metal plate, the lead frame, and the heat transfer layer;
Curing the heat transfer layer;
After mounting an electronic component on the lead frame, bending a part of the lead frame substantially vertically to form a lead wire;
Fixing the lead wire to a printed wiring board;
Providing a chimney forming body on a part of the lead frame or lead wire;
Of manufacturing a circuit module.

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