JP2008199720A - Power supply module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the heat dissipation performance of a coil portion of a transformer in a power supply module in which the transformer is integrated with a semiconductor element. <P>SOLUTION: This power supply module is provided with a first heat dissipation plate 8, a transformer 9 and semiconductor elements 10, 11 which are integrated with the first heat dissipation plate 8, wherein the transformer 9 has a core portion 12 and a coil portion 13 for generating magnetic field using the core portion 12 as an axis, the one surface of the coil portion 13 is thermally joined to the first heat dissipation plate 8 and a second heat dissipation plate 17 is thermally joined to the other surface of the coil portion 13. Thus, in the power supply module 7 in which the transformer 9 and the semiconductor elements 10, 11 are integrated, the second heat dissipation plate 17 can efficiently dissipate heat of the coil portion 13, and the heat dissipation performance of the coil portion 13 can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply module in which a transformer and a semiconductor element are integrated.

  As shown in FIG. 4, in order to meet the recent demand for standardization of modules, a power supply module 4 in which a transformer 2 and a semiconductor element 3 are mounted on a heat sink 1 can be considered.

  4 includes a heat sink 1 and a transformer 2 and a semiconductor element 3 integrated with the heat sink 1. The transformer 2 includes a core portion 5 and the core portion 5 as an axis. The heat sink 1 and the transformer 2 are integrated by having a coil portion 6 that generates magnetic flux and joining one surface of the core 5 and the heat sink 1.

  By integrating electronic components as much as possible in this way, it is not necessary to mount each individual electronic component or design the circuit layout, etc., reducing design man-hours and contributing greatly to productivity improvement. To do.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2005-80382 A

  The power supply module 4 having the above configuration has a problem that the heat dissipation of the coil portion 6 of the transformer 3 is low.

  Generally, the core part 5 of the transformer 2 has lower thermal conductivity than the coil part 6, and therefore, when the core part 5 and the heat radiating plate 1 are joined as shown in FIG. 4, the heat of the coil part 6 is efficiently radiated. This is because it is not transmitted to the plate 1. And if the heat dissipation of the coil part 6 is low in this way, the electrical resistance increases due to the temperature rise of the coil part 6 and the temperature of the entire module rises, making it difficult to reduce the size and density, etc. Various problems arise.

  Therefore, an object of the present invention is to improve heat dissipation of a coil portion of a transformer in a power supply module in which a transformer and a semiconductor element are integrated.

  In order to achieve this object, the present invention includes a first heat radiating plate, a transformer and a semiconductor element integrated with the first heat radiating plate, and the transformer includes a core portion and the core portion as an axis. A coil portion for generating a magnetic field, and one surface of the coil portion and the first heat radiating plate are thermally bonded, and a second heat radiating plate is thermally bonded to the other surface of the coil portion. It was supposed to be.

  Thereby, the present invention can improve the heat dissipation of the coil portion of the transformer in the power supply module in which the transformer and the semiconductor element are integrated.

  This is because the highly heat-generating semiconductor element and the coil part are thermally joined to the first heat sink, so that heat is conducted quickly, so that the thermal uniformity of the entire power supply module is improved and the coil part is joined. This is because the heat from the coil portion can be efficiently released by the second heat radiating plate. As a result, in the power supply module in which the transformer and the semiconductor element are integrated, the heat dissipation of the coil portion of the transformer can be improved.

  Hereinafter, a power supply module in which a transformer and a semiconductor element in an embodiment of the present invention are integrated will be described.

(Embodiment 1)
First, the structure in the present embodiment will be described.

  A power supply module 7 shown in FIG. 1 includes a first heat radiating plate 8, a transformer 9, an FET 10 (semiconductor element), and a diode 11 (semiconductor element) integrated with the first heat radiating plate 8. 9 includes core portions 12 </ b> A and 12 </ b> B (hereinafter collectively referred to as a core portion 12) and a coil portion 13.

  In the present embodiment, the core portion 12 includes middle legs 14A and 14B (hereinafter collectively referred to as the middle legs 14) and both upper and lower ends of the middle legs 14 so as to be substantially perpendicular to the middle legs 14. And back legs 15A and 15B (hereinafter collectively referred to as back legs 15). The coil portion 13 generates a closed magnetic field around the middle leg 14 as an axis, and is disposed between the upper and lower back legs 15 on the outer periphery of the middle leg 14. In FIG. 1, the core portion 12 is not disposed on the outer surface of the coil portion 13 and is an open system. However, the outer leg covers the outer surface of the coil portion 13 and is substantially parallel to the middle leg 14. If (not shown) is provided, the magnetic flux can flow more smoothly.

  Moreover, in this embodiment, since the core part 12 in which the back legs 15 are formed at both ends of the middle leg 14 is used, the core part 12 in which the magnetic flux forms a closed circuit shape can be formed. The back leg 15 is formed so as to cover the middle leg 14 and the coil portion 13, and is opposed to the other back leg 15. Further, the core portion 12 of the present embodiment is divided into an upper core portion 12 and a lower core portion 12.

  Hereinafter, the upper core portion 12 will be described as a core portion 12A, and the lower core portion 12 will be described as a core portion 12B. The upper core portion 12A of the present embodiment includes an intermediate leg 14A and an upper end of the intermediate leg 14A. The middle leg 14A and the substantially perpendicular back leg 15A are provided in the lower part, and the lower core part 12B is similarly provided with the middle leg 14B and the lower leg 15B of the middle leg 14B. The middle leg 14A and the middle leg 14B are magnetically joined. When the core portion 12 is divided in this way, the coil portion 13 can be easily inserted.

  In the present embodiment, a winding coil is used as the coil portion 13, and this winding coil is wound in the bobbin 16. The lower surface of the coil portion 13 and the upper surface of the first heat radiating plate 8 are joined, so that the first heat radiating plate 8 and the transformer 9 are integrated, and the upper surface of the coil portion 13 is A second heat radiating plate 17 is arranged. That is, the first heat radiating plate 8 is disposed between the lower back leg 15B and the coil portion 13, and the second heat radiating plate 17 is disposed between the upper back leg 15A and the coil portion 13. . The second heat radiating plate 17 can be bent and stretched.

  In the present embodiment, a transformer 9 is joined to the center of the first heat radiating plate 8, and a semiconductor element such as an FET 10 or a diode 11 is mounted on the outer periphery thereof. The FET 10 and the diode 11 are soldered and mounted on a lead frame 19 formed on the first heat radiation plate 8 via a first adhesive layer 18.

  The coil portion 13 and the first heat radiating plate 8 are bonded with a second adhesive layer 20. In the present embodiment, the second adhesive layer 20 has a smaller elastic modulus (softer) than the first adhesive layer 18. Further, the back legs 15B of the core portion 12B and the first heat radiating plate 8 are bonded with a third adhesive layer 21, and the second adhesive layer 20 has a thermal conductivity higher than that of the third adhesive layer 21. It was expensive.

  Further, in the present embodiment, the first heat radiating plate 8 and the lower back leg 15B facing the first heat radiating plate 8 are bonded by the third adhesive layer 21, but the second heat radiating plate 17 and The adhesive layer is not formed between the second heat radiation plate 17 and the upper back leg 15A facing the second heat radiating plate 17, and a space is provided to reduce the thermal conductivity.

  Further, in the present embodiment, the first heat radiating plate 8 has a lower surface (surface opposite to the side on which the FET 10 or the diode 11 is mounted) and a chassis at a portion where semiconductor elements such as the FET 10 and the diode 11 are joined. 22 is bent between a portion in surface contact with the coil portion 13 and a portion to which the FET 10 and the diode 11 are joined.

  The power supply module 7 formed in this way is mounted by inserting the lead frame 19 into the main board 23 arranged above and arranging the transformer 9 in the through hole 24 provided in the main board 23. The transformer 9 induces a magnetic flux in the core portion 12 when a current is passed through the primary side coil portion 13, and receives the change in the magnetic flux at the secondary side coil portion 13 to convert it into a voltage. .

  The material of the member used by this Embodiment is demonstrated below.

  As the first heat radiating plate 8 and the second heat radiating plate 17, an aluminum plate or a copper plate having a thickness of about 1.0 mm to 5.0 mm was used. In the present embodiment, the winding of the coil portion 13 is a copper wire coated with an insulating layer, but may be formed of a copper plate or the like. The core 12 (12A and 12B) was made of soft magnetic ferrite obtained by sintering a metal oxide such as iron or manganese. The core portion 12 may be other than ferrite as long as it is a magnetic material.

  Further, as a metal plate for forming the lead frame 19, tough pitch copper having a thickness of 0.5 mm was used. The thickness of the metal plate is preferably 0.1 mm or more in order to sufficiently increase the heat diffusibility and heat dissipation from the lead frame 19.

As the first adhesive layer 18, it was used to fill a filler made of Al ₂ O ₃ in the epoxy resin 70 to 95 wt%. The epoxy resin is used because it is excellent in heat resistance and electrical insulation. In addition to the epoxy resin, an insulating thermosetting resin such as a phenol resin or a cyanate resin, or a thermoplastic resin such as a liquid crystal polymer or PPS (polyphenylene sulfide) may be used.

  Moreover, in this embodiment, the pregel material which consists of thermoplastic resin powder was previously added to this epoxy resin with a filler. This pregel material absorbs the liquid component of the uncured thermosetting resin, expands, and quickly gels. Therefore, the pregel material can be solidified before the epoxy resin of the first adhesive layer 18 is polymerized. It can be easily removed from the mold.

As the filler, in addition to Al ₂ O ₃ , an inorganic powder made of at least one of MgO, SiO ₂ , BN, and AlN, or a powder made of a metal oxide may be used. These fillers can increase the thermal conductivity. In particular, when MgO is used, the linear thermal expansion coefficient can be increased, and when BN is used, the linear thermal expansion coefficient can be decreased. Thus, by adjusting the thermal expansion coefficient of the resin with the type of filler to be filled, the thermal expansion coefficient of the metal used for the lead frame 19 and the first heat radiating plate 8 and the first adhesive layer 18 is approximated, The thermal reliability of the entire module can be improved.

The filler made of Al ₂ O ₃ used in this embodiment is a mixture of two types of Al ₂ O ₃ having an average particle size of 3 microns and an average particle size of 12 microns. By using the Al ₂ O ₃ of the large and small two types of particle size, can fill the Al ₂ O ₃ of small particle size in the gap Al ₂ O ₃ of large particle size, the Al ₂ O ₃ to about 95 wt% Can be filled to a high concentration. As a result, the thermal conductivity of the first adhesive layer 18 is about 5 W / m · K.

  And if this filler is as small as possible with a diameter in the range of 0.1 to 100 μm and is filled to a high concentration of about 70 to 95% by weight, the thermal conductivity can be increased. If the filling rate of the filler exceeds 95% by weight, it becomes difficult to mold, and the adhesiveness between the first adhesive layer 18 and the metal plate serving as the lead frame 19 or the first heat radiating plate 8 is also reduced. It is better to keep it below%. As the first adhesive layer 18, a thermoplastic resin such as a liquid crystal polymer having high thermal conductivity or PPS may be used.

  Further, in the present embodiment, the thickness of the first adhesive layer 18 is formed to be a maximum of 0.6 mm in consideration of the withstand voltage and the thermal resistance.

  In the present embodiment, the second adhesive layer 20 is configured to have a filler content smaller than that of the first adhesive layer 18 so that both the thermal conductivity and the elastic modulus are reduced.

  Further, the third adhesive layer 21 has a smaller filler content than that of the second adhesive layer 20 so that the thermal conductivity is further reduced.

  And the chassis 22 in this Embodiment used the aluminum plate about 2.0 mm thick. If fins are arranged in place of the chassis 22, the surface area increases and the heat dissipation can be further improved.

  Next, the manufacturing method of the power supply module 7 in this Embodiment is demonstrated.

  First, the filler-filled resin mass is collected into a round shape (or a bowl shape, a trapezoidal shape, a cylindrical shape, a spherical shape) so that the center is convex, and placed on both sides of the first heat radiation plate 8 shown in FIG. Then, this filler-containing resin is stretched to form a sheet by a heat press or a vacuum heat press.

  Next, this 1st heat sink 8 is heated at 100 degreeC for 1-2 minutes, the 1st contact bonding layer 18 is solidified, and it removes from a metal mold | die. Then, it is placed in a furnace at 200 ° C. for several hours, and the epoxy resin of the first adhesive layer 18 is polymerized and finally cured. In the present embodiment, before the first adhesive layer 18 is cured, the lead frame 19 is disposed on the first adhesive layer 18 in advance and integrated before being cured. When a pattern is formed on the lead frame 19 here, if the lead frame 19 is embedded until it is substantially flush with the first adhesive layer 18, filler-filled resin also enters between the patterns to improve electrical insulation. In addition, electronic components can be easily mounted on the lead frame 19. The lead frame 19 may be disposed on the first adhesive layer 18 with a highly heat conductive adhesive or the like after the first adhesive layer 18 is cured.

  A solder layer or a tin layer (not shown) may be formed on the upper surface of the lead frame 19 by electroplating. Thus, the 1st contact bonding layer 18 can be formed except the center part of a heat sink.

  Next, the 1st heat sink 8 is bent so that a center part may become convex shape. As shown in FIG. 2, a through hole 25 is provided at the center of the first heat radiating plate 8, and a slit 26 is provided from the through hole 25 toward the outer surface of the first heat radiating plate 8. This slit 26 is for preventing a short circuit current from being generated in the first heat radiating plate 8 due to a magnetic flux generated by a current flowing through the primary winding, and generating a reverse magnetic flux due to the generation of the short circuit current. .

  Thereafter, the coil portion 13 wound in the bobbin 16 is disposed on the outer periphery of the middle leg 14 </ b> B of the core portion 12 of the transformer 9. Here, a notch 27 is provided below the bobbin 16. This is because the coil part 13 exposed from the notch part 27 and the first heat radiating plate 8 are bonded by the second adhesive layer 20.

  Then, the second heat radiating plate 17 is bonded to the upper surface of the coil portion 13 of the transformer 9 with an adhesive or the like. At this time, the second heat radiating plate 17 is bent. The second heat radiating plate 17 is also provided with a through hole similar to the through hole 25 of the first heat radiating plate 8.

  Next, as shown in FIG. 1, the middle leg 14 </ b> B of the lower core portion 12 </ b> B is inserted from below the through hole 25 of the first heat radiating plate 8, and is bonded by the third adhesive layer 21.

  Thereafter, the upper core portion 12A is disposed so as to face the lower core portion 12B.

  Finally, semiconductor components such as the FET 10 and the diode 11 are mounted on the lead frame 19 and the outer portion of the lead frame 19 is bent.

  The power supply module 7 formed in this way is mounted by inserting the lead frame 19 into the main board 23.

  The main board 23 is provided with a through hole 24 in the transformer 9 portion, and the transformer 9 is fitted into the through hole 24 portion. Inserting in this way leads to a reduction in the overall height of the module. At this time, the second heat radiating plate 17 may not pass through the through hole 24 in order to increase the heat radiating area. In this case, if the second heat radiating plate 17 is bent in advance, the transformer 9 can be easily fitted into the through hole 24 of the main board 23. And if this 2nd heat sink 17 extends after arrange | positioning the main board | substrate 23, it will not inhibit a low profile.

  If one end of the lead frame 19 is electrically connected to the lead terminal of the coil part 13 and the other end is inserted into the main board 23, the electrode of the coil part 13 can be drawn to the surface of the mounting board.

  The effect in this Embodiment is demonstrated below.

  In the power supply module 7 in which the transformer 9 and the semiconductor element (FET 10 and diode 11) are integrated, the heat dissipation of the coil portion 13 of the transformer 9 can be improved.

  Because the semiconductor element (FET 10, diode 11) and the coil portion 13 with high exothermic properties are thermally bonded to the first heat radiating plate 8 via the first and second adhesive layers 18, 20, This is because heat is efficiently conducted, soaking power of the entire power supply module 7 is improved, and heat of the coil portion 13 can be efficiently released by the second heat radiating plate 17 joined to the coil portion 13.

  That is, the heat generating part of the transformer 9 is mainly the coil part 13, but when the core part 12 of the transformer 9 is joined to the first heat radiating plate 8 as shown in FIG. In addition to being unable to escape efficiently, the heat conductivity of the core portion 12 is smaller than the heat conductivity of the coil portion 13, so that it is difficult to diffuse the heat of the coil portion 13 to the core portion 12. In addition, as shown in FIG. 3, by simply joining the coil portion 13 of the transformer 9 to the first heat radiating plate 8, the heat from the FET 10 and the diode 11 having extremely high heat generation properties causes the first heat radiating plate 8 to flow. Therefore, there arises a problem that the temperature of the coil part 13 is raised instead.

  On the other hand, in the present embodiment, as shown in FIG. 1, one surface of the coil portion 13 is joined to the first heat radiating plate 8, and the second heat radiating plate 17 is disposed on the surface opposite to the joined surface. Yes. Therefore, when the FET 10 or the diode 11 becomes hotter than the coil part 13, the heat transmitted to the coil part 13 can be released from the second heat radiating plate 17, and the coil part 13 is temporarily less than the FET 10 or the diode 11. If the temperature is too high, the heat of the coil portion 13 can be quickly released from the second heat radiating plate 17, and the transfer of heat to the FET 10 and the diode 11 can be suppressed. Thus, in this Embodiment, the heat dissipation of the coil part 13 can be improved.

  Further, in the present embodiment, since the coil portion 13 having high heat generation and the FET 10 and the diode 11 are integrated by sharing the first heat radiating plate 8, the heat uniformity inside the module is improved, and the entire module is improved. Thermal reliability can be improved.

  In general, the coil portion 13 (winding) mainly composed of copper has higher thermal conductivity than the semiconductor element (FET 10 or diode 11) packaged with a plastic material. Rather than disposing on the element, disposing on the coil portion 13 as in the present embodiment can dissipate heat more efficiently.

  In the present embodiment, since the elastic modulus of the second adhesive layer 20 is smaller (softer) than the elastic modulus of the first adhesive layer 18, the second adhesive layer 20 is vibrated even if the coil portion 13 vibrates. Can be absorbed by elastically deforming, and reliability of vibration of the entire module can be improved. Note that, when the elastic modulus is decreased, the thermal conductivity is generally decreased. Therefore, in the present embodiment, the first adhesive layer 18 has a higher thermal conductivity than the second adhesive layer 20. Here, since semiconductor elements such as the FET 10 and the diode 11 are damaged by heat, the heat is released to the first heat radiating plate 8 as quickly as possible through the lead frame 19 and the first adhesive layer 18. There is a need. Therefore, it is very effective to improve the thermal conductivity of the first adhesive layer 18 as in the present embodiment.

  In the present embodiment, the thermal conductivity of the second adhesive layer 20 is made higher than the thermal conductivity of the third adhesive layer 21, so that the thermal resistance from the first heat radiating plate 8 to the coil portion 13 is increased. A series of heat transfer paths connecting the first heat radiating plate 8 to the second heat radiating plate 17 through the coil portion 13 can be formed.

  That is, this embodiment suppresses heat from the coil part 13, the FET 10, and the diode 11 from being transmitted to the core part 12 having a low thermal conductivity as much as possible, and achieves heat equalization of the heat generating part by the first heat radiating plate 8. By releasing the heat of the coil portion 13 from the second heat radiating plate 17, the entire power supply module 7 can be efficiently radiated.

  In the present embodiment, in order to integrate the first heat radiating plate 8 and the transformer 9, the first heat radiating plate 8 and the back leg 15B are bonded by the third adhesive layer 21. A space is provided between the second heat radiating plate 17 and the back leg 15A facing the second heat radiating plate 17. Thereby, it can suppress that the heat of the 2nd heat sink 17 is transmitted to the core part 12, and can thermally radiate efficiently to the module exterior. The second heat radiating plate 17 may be bonded to the back leg 15A with an adhesive, but it is desirable to use an adhesive having as low a thermal conductivity as possible in order to suppress heat conduction.

  In the present embodiment, a winding coil is used for the coil portion 13. However, if the coil portion 13 and the first and second heat radiating plates 8 and 17 are directly joined, a flat shape is used. However, it may be configured to be incorporated in the core portion. The shape of the core portion 12 may be a split type (EE type), an EI type, or a UU type combining a so-called E type and E type, or may be a non-split type so-called toroidal core.

  The present invention is a power supply module in which a transformer and a semiconductor element are integrated, and the heat dissipation of the coil portion can be improved. Therefore, the power supply module can be greatly used for a power supply module for large currents such as for PDP and in-vehicle use.

Sectional drawing of the power supply module in one embodiment of this invention The top view which shows the manufacturing process of the power supply module in the same embodiment Sectional drawing of the power supply module for contrast with one embodiment of this invention Cross section of power supply module for comparison

Explanation of symbols

7 Power supply module 8 First heat sink 9 Transformer 10 FET (semiconductor element)
11 Diode (semiconductor element)
12, 12A, 12B Core part 13 Coil part 14, 14A, 14B Middle leg 15, 15A, 15B Back leg 16 Bobbin 17 Second heat sink 18 First adhesive layer 19 Lead frame 20 Second adhesive layer 21 Third Adhesive layer 22 Chassis 23 Main board 24 Through hole 25 Through hole 26 Slit 27 Notch

Claims (6)

A first heat sink;
A transformer and a semiconductor element integrated with the first heat sink;
The transformer is
The core,
A coil part that generates a magnetic field around the core part,
One surface of the coil portion and the first heat radiating plate are thermally bonded,
A power supply module in which a second heat sink is thermally joined to the other surface of the coil portion. The core part is
Middle legs,
At both ends of the middle leg, the middle leg has a back leg formed substantially perpendicular to the middle leg,
The coil portion is
Between the back legs and disposed on the outer periphery of the middle leg,
The first heat sink is
It is arranged between one of the back legs and the coil part,
The second heat sink is
The power supply module of Claim 1 arrange | positioned between the other side of the said back leg, and the said coil part. A first adhesive layer is formed between the semiconductor element and the first heat dissipation plate,
A second adhesive layer is formed between the coil portion and the first heat dissipation plate,
The power supply module according to claim 1, wherein the second adhesive layer has a smaller elastic modulus than the first adhesive layer. A second adhesive layer is formed between the coil portion and the first heat dissipation plate,
A third adhesive layer is formed between the back leg and the first heat radiating plate,
The second adhesive layer is
The power supply module according to claim 2 or 3, wherein the thermal conductivity is higher than that of the third adhesive layer. Than the thermal conductivity between the first heat sink and the back leg facing the first heat sink,
5. The power supply module according to claim 2, wherein a thermal conductivity between the second heat radiating plate and a back leg facing the second heat radiating plate is lower. 6. A chassis is joined on the first heat sink,
The power supply module according to claim 1, wherein the first heat radiating plate is bent so as to be in surface contact with the chassis.

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