JP2010219280A - Electronic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic substrate which efficiently dissipates heat generated in a substrate by a heat dissipating member inserted into a via hole of the substrate for suppressing the temperature rise of the substrate. <P>SOLUTION: An electronic substrate 100 electrically connects a conductor layer 3 to a via hole 5 with a conductor layer 3 at least in both sides of an insulating substrate 4, and includes a heat conduction component 1 inserted into the via hole 5 formed leaving a conductor outermost layer which is in at least one surface of the insulating substrate 4, and a fixing member 2 for fixing the heat conduction component 1 to the via hole 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic substrate that generates a large amount of heat.

  The DC-DC converter for automobiles is generally of a system composed of four parts: a switching MOS-FET, a voltage converting transformer, a rectifying diode, and a smoothing choke coil. A DC-DC converter for a hybrid vehicle is configured such that each component is individually cooled by a cooling component such as a water jacket because heat from each component increases due to high voltage and large current. That is, each is separately mounted on a cooling component, and each component is electrically connected by a bus bar or the like (for example, cited document 1).

  In the configuration as described above, not only the screw fastening work or welding work in the connection part is increased, but the number of assembling steps is increased, and in order to avoid an electrical problem caused by the contact resistance variation in the connection part, Also, it is necessary to add dedicated parts. As a countermeasure against such a problem, these components are formed by forming a coil constituting a voltage converting transformer and a smoothing choke coil with a circuit pattern of a substrate on which a switching MOS-FET and a rectifying diode are mounted. Can be integrated, thereby reducing the number of connection points.

JP 2005-143215 A

  However, when a switching MOS-FET, a rectifying diode, a voltage conversion transformer, and a smoothing choke coil are formed and integrated on the same substrate, they are routed through a wiring circuit that electrically connects the components. As a result, heat is easily conducted. FIG. 8 shows an example of an electronic board formed by integrating the above-described components on the same board. FIG. 8 is a cross-sectional view of a conventional electronic substrate 900 constituting a DC-DC converter. In order to suppress the temperature rise of the electronic substrate 900, the electronic substrate 900 is thermally connected to the cooling component 103 such as a water jacket via the heat conductive sheet 102.

  When the coils constituting the voltage conversion transformer 920 and the smoothing choke coil 940 are formed in a circuit pattern, the heat generation therein is larger than that of the switching MOS-FET 910 and the rectifying diode 930. As a result, heat generated by the transformer 920 and the choke coil 940 is transmitted to the MOS-FET 910 and the diode 930 via the wiring circuits 951 to 955, and these are heated to a high temperature. The MOS-FET 910 and the diode 930 have a problem that reliability cannot be ensured when the temperature becomes higher than a predetermined temperature.

  In addition, in order to form a coil constituting the voltage conversion transformer 920 and the smoothing choke coil 940 with a circuit pattern and to reduce the substrate area used therefor, it is necessary to use a multilayer substrate having at least four conductor layers. There is. When a four-layer multilayer substrate is used, it is preferable to reduce the thickness per conductor layer in order to suppress the total thickness and total weight of the substrate.

  However, if the thickness per layer is made too thin, the amount of heat generated from the coils constituting the voltage conversion transformer and the smoothing choke coil becomes large and the substrate temperature rises. If the substrate temperature rises too much, it becomes difficult to ensure the reliability of via holes, through holes, or interlayer insulating materials formed in the substrate. Furthermore, when the heat generated in the coil increases, the MOS-FET and the diode are further increased in temperature through the wiring circuit, making it difficult to ensure their reliability.

  Accordingly, the present invention has been made to solve these problems, and in order to suppress the temperature rise of the substrate, the heat generated by the substrate is efficiently radiated by the heat radiating member inserted into the via hole of the substrate. An object of the present invention is to provide an electronic substrate configured as described above.

  An aspect of the electronic substrate according to the present invention is an electronic substrate having a conductive layer on at least both surfaces of the insulating substrate, and the conductive layer is electrically connected by a via hole, and at least one surface of the insulating substrate A heat conductive component inserted into the via hole formed leaving the outermost conductor layer, and a fixing member for fixing the heat conductive component to the via hole.

  According to the present invention, the heat dissipation member is inserted into the via hole connecting the conductive layers to suppress the temperature rise of the substrate, and the flatness of the electronic substrate can be ensured by leaving the conductive outermost layer. Adhesion to a cooling component via a sheet or the like is enhanced, and the electronic substrate can be cooled with higher efficiency.

  According to another aspect of the electronic substrate of the present invention, the via hole is formed leaving only the outermost conductor layer on one surface of the insulating substrate, and the heat conducting component inserted into the via hole is formed on the other surface. The protrusion is formed so as to protrude from a certain conductor outermost layer.

  According to the present invention, it is possible to further suppress the temperature rise of the substrate by providing the heat conductive component with the protruding portion.

  According to another aspect of the electronic substrate of the present invention, the via hole is provided with a through-hole penetrating the outermost conductor layer having a diameter smaller than the diameter of the via hole.

  According to this invention, when filling a fixing member such as a copper powder paste containing plating, conductive resin, or copper nanoparticles in the via hole, the flow of the fixing member is improved, and the fixing time of the heat conducting component can be shortened. Become.

  Another aspect of the electronic substrate of the present invention is characterized in that an air hole penetrating the heat conducting component is provided in a direction perpendicular to the insulating substrate of the heat conducting component.

  According to the present invention, by providing an air hole penetrating the heat conducting component, air bubbles generated when filling a fixing member such as plating, conductive resin, or copper powder paste containing copper nanoparticles in the via hole are removed. Thus, the reliability of the electronic substrate can be improved.

  In another aspect of the electronic substrate according to the present invention, the via hole is formed so that the diameter of the via hole increases toward the opened outermost layer of the conductor, and the heat conducting component has a shape of the via hole. It is formed correspondingly.

  According to the present invention, the inclination angle of the side surface of the via hole becomes gentle, and the stress applied to the fixing member due to thermal expansion and contraction is reduced, whereby the reliability of the electronic substrate can be improved.

  Another aspect of the electronic substrate of the present invention is characterized in that another heat radiating member is thermally connected to the protruding portion.

  According to this invention, it is possible to further suppress the temperature rise of the substrate by thermally connecting another heat radiating member to the protruding portion.

  In another aspect of the electronic substrate of the present invention, the conductor layer has a thickness of 200 μm or more.

  Another aspect of the electronic substrate of the present invention is characterized in that there are at least four conductor layers.

  Another aspect of the electronic substrate of the present invention is characterized in that the inner surface of the via hole is plated, and the thickness of the plating is 40 μm or more.

  Another aspect of the electronic substrate of the present invention is characterized in that the electronic substrate is a substrate constituting a DC-DC converter.

  According to the electronic substrate of the present invention, it is possible to efficiently dissipate heat generated in the substrate by the conductive heat radiating member inserted into the via hole of the substrate in order to suppress the temperature rise of the substrate.

It is sectional drawing which shows 1st embodiment of the electronic substrate which concerns on this invention. It is sectional drawing shown in the same state as other 1st embodiment of the electronic substrate which concerns on this invention, FIG. It is sectional drawing shown in the same state as 2nd embodiment of the electronic substrate which concerns on this invention, and FIG. It is sectional drawing when another heat radiating member is connected to the electronic substrate of FIG. It is sectional drawing shown in the same state as 3rd embodiment of the electronic substrate which concerns on this invention, FIG. FIG. 5 is a cross-sectional view showing a fourth embodiment of the electronic substrate according to the present invention in the same state as in FIG. 1. FIG. 10 is a cross-sectional view showing the fifth embodiment of the electronic substrate according to the present invention in the same state as in FIG. 1. It is sectional drawing of the conventional electronic substrate.

  An electronic substrate according to a first embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are cross-sectional views of the electronic substrate. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  The electronic substrate 100 is mainly composed of an insulating substrate 4 formed of an insulating resin or the like and a conductive layer 3 having conductivity such as copper. The conductor layer 3 is composed of four layers, ie, conductor outermost layers 3a and 3d and conductor inner layers 3b and 3c. Further, in order to insulate each conductor layer 3 (3a, 3b, 3c, 3d), an insulating layer 4 (4a, 4b, 4c) is provided between each conductor layer 3 (3a, 3b, 3c, 3d). Each is arranged.

  The electronic substrate 100 is formed with via holes 5 for connecting the conductor layers 3a, 3b, 3c, and 3d. A thermal conductive component 1 having good thermal conductivity is inserted into the via hole 5, and the thermal conductive component 1 is fixed to the via hole 5 by a fixing member 2. Here, as the heat conduction component 1, a material having high heat conductivity such as copper or aluminum can be used. As the fixing member 2, a solder, a conductive resin, a copper powder paste containing copper nanoparticles, or the like. Those having electrical conductivity of can be used.

  As described above, by inserting the heat conductive component 1 having good heat conductivity into the via hole 5, it is possible to suppress the temperature rise of the electronic substrate 100. Furthermore, the conductor outermost layer 3d side of the electronic substrate 100 is thermally connected to the cooling component 12 such as a water jacket via the heat conductive sheet 6, and the via hole 5 is formed so as to leave the conductor outermost layer 3d. As a result, the flatness of the electronic substrate 100 connected to the cooling component 12 side can be ensured, so that the adhesion to the cooling component 12 via the heat conductive sheet 6 is enhanced, and the electronic substrate 100 can be cooled with higher efficiency. Possible

  As a method for forming the via hole 5, there are a laser processing method and a drill processing method. In the laser processing method, the laser beam intensity and irradiation time are adjusted, and the drill processing method is used. The depth of the via hole 5 can be appropriately adjusted by adjusting the push-in width of the drill. It is also possible to manufacture each of the conductor layers 3 individually, form the via holes 5 in each of the conductor layers 3, and then bond them together to manufacture the electronic substrate 100.

Next, the electronic substrate 200 which is other 1st embodiment is demonstrated using FIG.
The difference from FIG. 1 is that the conductor layers 3 b, 3 c and 3 d are electrically connected by the via hole 5, and the via hole 5 cannot be confirmed from the outside of the electronic substrate 200.

  Even in such a structure, the heat dissipation member is inserted into the via hole 5 to suppress the temperature rise of the substrate, and the flatness of the electronic substrate can be ensured by leaving the conductive outermost layer 3d. Adhesion to a cooling component via a sheet or the like is enhanced, and the electronic substrate can be cooled with higher efficiency.

  As a method for forming the via hole 5, the conductor layers 3b to 3d are formed, then the conductor layers 3b to 3d are processed by a laser or a drill, and finally the conductor layer 3a is formed to manufacture the electronic substrate 200. Can do. It is also possible to manufacture each of the conductor layers 3 individually, and form the via holes 5 in each of the conductor layers 3, and then bond them together to manufacture the electronic substrate 200.

  Next, an electronic substrate according to a second embodiment of the present invention will be described below with reference to FIGS. FIG. 3 is a cross-sectional view of the electronic substrate, and FIG. 4 is a cross-sectional view when another heat dissipation member 20 is connected to the electronic substrate 300 of FIG.

  Similar to the electronic substrates 100 and 200, the electronic substrate 300 is mainly composed of an insulating substrate 4 formed of an insulating resin or the like and a conductive layer 3 (3a to 3d) having conductivity such as copper. Yes. The conductor layer 3 is composed of four layers, ie, conductor outermost layers 3a and 3d and conductor inner layers 3b and 3c. Moreover, in order to insulate each conductor layer 3 (3a, 3b, 3c, 3d), the insulating layer 4 is arrange | positioned between each conductor layer 3 (3a, 3b, 3c, 3d).

  The electronic substrate 300 is formed with via holes 5 for connecting the conductor layers 3a, 3b, and 3d. A thermal conductive component 1 having good thermal conductivity is inserted into the via hole 5, and the thermal conductive component 1 is fixed to the via hole 5 by a fixing member 2. Here, as the heat conduction component 1, a material having high heat conductivity such as copper or aluminum can be used. As the fixing member 2, a solder, a conductive resin, a copper powder paste containing copper nanoparticles, or the like. Those having electrical conductivity of can be used. The inner layer 3c is not connected to the via hole 5.

  Further, the heat conducting component 1 is formed with a protruding portion 11 that is integrally formed so as to protrude outward from the conductor outermost layer 3a. In this manner, by integrally forming the protrusion 11 on the heat conducting component 1, it is possible to further suppress the temperature rise of the electronic substrate 300.

  In addition, as shown in FIG. 4, another heat radiating member 20 such as a heat sink can be connected to the protrusion 11 to further suppress the temperature rise of the electronic substrate 300. As shown in FIG. 4, the heat radiating members 20 may be connected to the protruding portions 11, or one heat radiating member 20 may be connected to the plurality of protruding portions 11.

  Next, an electronic substrate according to a third embodiment of the present invention will be described below with reference to FIG. FIG. 5 is a cross-sectional view of the electronic substrate.

  Similar to the electronic substrate 300, the electronic substrate 400 is mainly composed of an insulating substrate 4 formed of an insulating resin or the like and a conductive layer 3 (3a to 3d) having conductivity such as copper. The conductor layer 3 is composed of four layers, ie, conductor outermost layers 3a and 3d and conductor inner layers 3b and 3c. Moreover, in order to insulate each conductor layer 3 (3a, 3b, 3c, 3d), the insulating layer 4 is arrange | positioned between each conductor layer 3 (3a, 3b, 3c, 3d).

  In the electronic substrate 400, via holes 5 for connecting the conductor layers 3a, 3b, and 3d are formed. A thermal conductive component 1 having good thermal conductivity is inserted into the via hole 5, and the thermal conductive component 1 is fixed to the via hole 5 by a fixing member 2. Here, as the heat conduction component 1, a material having high heat conductivity such as copper or aluminum can be used. As the fixing member 2, a solder, a conductive resin, a copper powder paste containing copper nanoparticles, or the like. Those having electrical conductivity of can be used. The inner layer 3c is not connected to the via hole 5.

  Furthermore, a through hole 7 is formed in the via hole 5 so as to penetrate the conductor outermost layer 3d. The diameter of the through hole 7 is formed to be smaller than the diameter of the via hole. Specifically, a through hole diameter of Φ0.6 mm or less is preferable with respect to a Φ6 mm via hole diameter. By constructing in this way, by further forming a through hole 7 penetrating the conductor outermost layer 3d in the via hole 5, the fixing member 2 such as a copper powder paste containing plating, conductive resin, or copper nanoparticles is formed in the via hole. When filling, the flow of the fixing member is improved, and the fixing time of the heat conducting component can be shortened. Furthermore, since the flatness of the electronic substrate can be ensured if the diameter of the through hole is Φ0.6 mm or less, the adhesion to the cooling component can be ensured via a heat dissipation sheet, and the electronic substrate can be cooled with high efficiency. It becomes.

  Next, an electronic substrate according to a fourth embodiment of the present invention will be described below with reference to FIG. FIG. 6 is a cross-sectional view of the electronic substrate.

  Similar to the electronic substrate 300 of FIG. 3, the electronic substrate 500 is mainly composed of an insulating substrate 4 formed of an insulating resin and the like, and a conductive layer 3 (3a to 3d) having conductivity such as copper. ing. The conductor layer 3 is composed of four layers, ie, conductor outermost layers 3a and 3d and conductor inner layers 3b and 3c. Moreover, in order to insulate each conductor layer 3 (3a, 3b, 3c, 3d), the insulating layer 4 is arrange | positioned between each conductor layer 3 (3a, 3b, 3c, 3d).

  In the electronic substrate 500, via holes 5 for connecting the conductor layers 3a, 3b, and 3d are formed. A thermal conductive component 9 having good thermal conductivity is inserted into the via hole 5, and the thermal conductive component 9 is fixed to the via hole 5 by the fixing member 2. Here, as the heat conduction component 9, a material having high heat conductivity such as copper or aluminum can be used. As the fixing member 2, a solder, a conductive resin, a copper powder paste containing copper nanoparticles, or the like. Those having electrical conductivity of can be used.

  Further, an air hole 8 penetrating the heat conducting component 9 is provided in the direction perpendicular to the substrate of the heat conducting component 9. The diameter of the air hole 8 is preferably as small as possible. In this way, by providing the air holes 8 in the heat conducting component 9, the bubbles generated when the via hole 5 is filled with the fixing member 2 such as plating, conductive resin, or copper powder paste containing copper nanoparticles are removed. Thus, the reliability of the electronic substrate 500 can be improved.

  Next, an electronic substrate according to a fifth embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a cross-sectional view of the electronic substrate.

  The electronic substrate 600 mainly includes an insulating substrate 4 formed of an insulating resin and the like, and a conductive layer 3 (3a to 3d) having conductivity such as copper. The conductor layer 3 is composed of four layers, ie, conductor outermost layers 3a and 3d and conductor inner layers 3b and 3c. Moreover, in order to insulate each conductor layer 3 (3a, 3b, 3c, 3d), the insulating layer 4 is arrange | positioned between each conductor layer 3 (3a, 3b, 3c, 3d).

  In the electronic substrate 600, via holes 15 for connecting the conductor layers 3a, 3b, and 3d are formed. The via hole 15 is formed in a substantially trapezoidal cross section so that the via hole diameter increases toward the opened conductor outermost layer side 3a. Then, the heat conduction component 10 having good thermal conductivity formed so as to correspond to the shape of the via hole 15 is inserted into the via hole 15, and the heat conduction component 10 is fixed to the via hole 15 by the fixing member 2. Here, as the heat conduction component 10, a material having high heat conductivity such as copper or aluminum can be used. As the fixing member 2, a solder, a conductive resin, a copper powder paste containing copper nanoparticles, or the like. Those having electrical conductivity of can be used.

  Thus, the via hole 15 is formed in a substantially trapezoidal cross section so that the via hole diameter increases toward the opened conductor outermost layer side 3 a, and the via hole 15 corresponds to the shape of the via hole 15. By inserting the formed thermal conductive component 10 having good thermal conductivity, the inclination angle of the side surface of the via hole 15 becomes gentle, and the stress applied to the fixing member 2 due to thermal expansion and contraction is reduced. It becomes possible to improve the reliability.

  As a method for manufacturing the electronic substrate described above, the fixing members 2 may be filled after the heat conductive components 1, 9, 10 are inserted into the via holes 5, 15, and the fixing members 2 are filled in the via holes 5, 15. The heat conductive components 1, 9, 10 may be inserted into the via holes 5, 15 before filling and fixing member 2 is cured.

  By using an electronic substrate having such a structure, the current that can be passed through a four-layer substrate having a via hole with an inner diameter of Φ0.6 mm and a copper plating thickness of 20 μm, which is a typical representative substrate, was about 1 (A). As a large current substrate, a four-layer substrate having a conductor thickness of 200 μm, an inner diameter of Φ6 mm, and a copper conductive material inserted into the hole, and via holes formed so as to have a copper plating thickness of 40 μm As a result, a current of about 80 (A) can be passed. Note that a plurality of via holes according to the present invention can be provided as appropriate according to the thermal characteristics required for the electronic substrate.

100, 200, 300, 400, 500, 600 Electronic substrate 900 Electronic substrate 1, 9, 10 Thermal conduction component 2 Fixing member 3 Conductor layer 3a, 3d Conductor outermost layer 4 Insulating substrate 5, 15 Via hole 6 Thermal conduction sheet 7 Through hole 8 Air hole 11 Projection 12 Cooling component 20 Heat dissipation member

Claims (10)

An electronic substrate having a conductor layer on at least both surfaces of an insulating substrate, the conductor layer being electrically connected by via holes,
A heat-conducting component inserted into the via hole that is formed leaving the outermost conductor layer on at least one surface of the insulating substrate;
A fixing member for fixing the heat conducting component to the via hole;
An electronic substrate comprising: The via hole is formed leaving only the outermost conductor layer on one side of the insulating substrate,
The electronic board according to claim 1, wherein the heat conductive component inserted into the via hole is formed with a protrusion so as to protrude from the outermost conductor layer on the other surface.   3. The electronic substrate according to claim 1, wherein a through-hole penetrating the outermost conductor layer is provided in the via hole so as to have a diameter smaller than the diameter of the via hole.   4. The electronic substrate according to claim 1, wherein an air hole penetrating the heat conductive component is provided in a direction perpendicular to the insulating substrate of the heat conductive component.   The via hole is formed such that the diameter of the via hole increases toward the outermost layer side of the opened conductor, and the heat conducting component is formed corresponding to the shape of the via hole. The electronic substrate according to any one of claims 1 to 4.   The electronic board according to claim 1, wherein another heat radiating member is thermally connected to the protrusion.   The thickness of the said conductor layer is 200 micrometers or more, The electronic board | substrate of any one of Claims 1-6 characterized by the above-mentioned.   The electronic substrate according to any one of claims 1 to 7, wherein there are at least four conductor layers.   The electronic substrate according to claim 1, wherein an inner surface of the via hole is plated, and the thickness of the plating is 40 μm or more.   The electronic substrate according to any one of claims 1 to 9, wherein the electronic substrate is a substrate constituting a DC-DC converter.

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