JP2016197691A - Print circuit board and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-manufacture print circuit board having a metal member for heat radiation capable of enhancing heat radiation performance.SOLUTION: A print circuit board 10 formed of an insulator includes: a base material 11 formed in a plate-like shape; wiring patterns 5b, 5c, 5e, 5f, 5h, 5 p, 5 s, 5 t which are formed on the surface of the base material 11; and a metal core 3 which is embedded in the base material 11 for radiating the heat generated by FETs 9a, 9b which are mounted on the wiring patterns 5b, 5c, 5e, 5h. A lower part of the metal core 3 is exposed from the bottom of the base material 11. The metal core 3 exposed from the bottom of the base material 11 and the wiring patterns 5p, 5 s, 5 t are covered with a metal plating 12 of an identical material which is formed in the same process.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a structure in which heat generated in an electronic component mounted on a printed board is radiated by a metal member embedded in the printed board.

  In order to dissipate heat generated by electronic components mounted on a printed circuit board, various techniques for embedding a metal member in the printed circuit board have been proposed.

  For example, in the printed circuit boards of Patent Documents 1 to 4, a metal member such as copper is embedded in a base material made of an insulator, and an electronic component that generates heat is mounted above the metal member.

  In Patent Documents 1 to 3, a wiring pattern is provided on the upper surface of the metal member exposed from the upper surface of the substrate, and an electronic component is mounted on the wiring pattern. In Patent Document 2, the upper surface of the wiring pattern is covered with gold plating.

  In Patent Documents 1 and 2, the lower surface of the metal member is covered with an insulating layer. In Patent Document 2, a metal layer made of copper foil is provided on the lower surface of the insulating layer. In Patent Documents 3 and 4, a wiring pattern is provided around the lower surface of the metal member exposed from the lower surface of the substrate or the exposed portion thereof. In Patent Document 4, the wiring pattern is a ground pattern formed by copper plating.

  In Patent Documents 1 and 3, a metal radiator is attached below a metal member or base material via a wiring pattern, an insulating layer, or a heat conductive sheet. Moreover, in patent document 1, 3, the wiring patterns provided in the upper surface and lower surface of the base material are connected by the through hole which penetrates a base material around the metal member. In Patent Document 3, the wiring pattern is extended from the lower surface of the metal member and its periphery to the periphery of the through hole on the lower surface of the base material, and the thickness of the wiring pattern is increased in the vicinity of the metal member. The thickness of the wiring pattern is reduced around the periphery.

  In Patent Documents 2 to 4, a metal member is embedded in a double-sided substrate in which a conductor layer is provided on the upper and lower surfaces of the base material. However, in Patent Document 1, in addition to the upper and lower surfaces of the base material, a conductor is also provided inside. A metal member is embedded in a multilayer substrate having three or more layers provided with layers.

  In the multilayer substrate, for example, as disclosed in Patent Document 5, a base insulating layer and a conductor layer are constituted by a plurality of double-sided wiring substrates and prepregs. By sandwiching the prepreg between multiple double-sided wiring boards and heating and pressing, the thermosetting resin contained in the prepreg is melted, and then the thermosetting resin is cured, so that the multiple double-sided wiring boards and the prepreg are integrated. It has become.

JP 2007-36050 A JP 2008-251671 A JP 2010-109036 A JP 2010-258260 A JP 2003-17862 A

  When a metal member is exposed from the surface of the printed circuit board, such as the top or bottom surface of the base material, heat dissipation performance is achieved by mounting electronic components that generate heat on the exposed portion of the metal member, or by bringing a wiring pattern or radiator into contact with it. Can be increased.

  On the other hand, a wiring pattern provided on the surface of a printed circuit board is generally used to form a through hole in the printed circuit board, prevent corrosion of the wiring pattern, and facilitate mounting of electronic components on the wiring pattern. Covered with metal plating, such as copper, gold, or solder. At that time, if only the wiring pattern is covered with the metal plating, it is necessary to perform a masking process for covering the metal member exposed from the surface of the printed board, which increases the manufacturing process of the printed board.

  An object of the present invention is to facilitate the manufacture of a printed circuit board provided with a metal member for heat dissipation and to improve heat dissipation performance.

  The printed circuit board according to the present invention is for dissipating heat generated by a base plate made of an insulator, a wiring pattern provided on the surface of the base material, and an electronic component mounted on the wiring pattern. And a metal member embedded in the base material. Then, a part of the metal member is exposed from the surface of the base material on which the wiring pattern is provided, and the exposed portion of the metal member and the wiring pattern are covered with the same material metal plating applied in the same process. Yes.

  According to the present invention, the metal member exposed from the surface of the substrate and the wiring pattern are covered with the same material metal plating applied in the same process. For this reason, it becomes unnecessary to mask the exposed part of a metal member beforehand, and it can suppress that the manufacturing process of a printed circuit board increases, and can manufacture a printed circuit board easily. In addition, since a part of the metal member is exposed from the surface of the base material and is covered with the metal plating, the heat dissipation performance of the metal member can be improved while preventing the metal part from being corroded. .

  In the present invention, the printed circuit board may further include a through conductor that is provided so as to penetrate the base material and connects the wiring patterns provided on the upper surface and the lower surface of the base material. In this case, the exposed portion of the metal member, the wiring pattern, and the end portion of the through conductor are covered with the same material metal plating applied in the same process.

  In the present invention, in the printed board, the base material includes a first insulating layer provided with a wiring pattern for mounting an electronic component on the upper surface, and a second insulating layer provided on the lower surface of the first insulating layer. The first insulating layer has a higher thermal conductivity than the second insulating layer, and a recess is provided so as to reach the lower surface of the first insulating layer from the lower surface of the second insulating layer. The member may be inserted into the recess. In this case, the metal member exposed from the lower surface of the second insulating layer, the wiring pattern, and the end portion of the through conductor are covered with the same metal plating applied in the same process.

  In the present invention, a base material made of an insulator and formed into a plate shape, a wiring pattern provided on the surface of the base material, and a base material for radiating heat generated in an electronic component mounted on the wiring pattern In the printed circuit board including the metal member embedded in the substrate, a part of the metal member is exposed from the surface on which the wiring pattern of the base material is provided, and the exposed portion of the metal member and the wiring pattern are formed by metal plating. The height including the metal plating of the exposed part of the metal member and the wiring pattern with respect to the substrate may be the same. Moreover, the height including the metal plating of the exposed portion of the metal member, the wiring pattern, and the end portion of the through conductor with respect to the base material or the second insulating layer may be the same.

  Further, an electronic device according to the present invention includes the above-described printed circuit board, an electronic component that generates heat mounted on the printed circuit board so as to overlap with a metal member provided on the printed circuit board, and a metal exposed from the lower surface of the printed circuit board. And a heat radiating body provided to come into contact with the lower surface of the member.

  ADVANTAGE OF THE INVENTION According to this invention, manufacture of the printed circuit board provided with the metal member for heat dissipation can be made easy, and heat dissipation performance can be improved.

It is the figure which showed the upper surface layer in the upper surface of the printed circuit board of this invention. It is the figure which showed the AA cross section of FIG. It is the figure which showed the inner layer of the printed circuit board of FIG. It is the figure which showed the lower surface layer of the printed circuit board of FIG. It is the figure which showed the recessed part and metal core which were provided in the printed circuit board of FIG. It is the figure which showed the manufacturing process of the printed circuit board of FIG. It is the figure which showed the continuation of the manufacturing process of FIG. 6A. It is the figure which showed the continuation of the manufacturing process of FIG. 6B.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same reference numerals are given to the same parts and corresponding parts.

  First, the structure of the printed circuit board 10 and the electronic device 100 according to the embodiment will be described with reference to FIGS.

  FIG. 1 is a view showing the upper surface layer L1 on the upper surface of the printed circuit board 10. FIG. 2 is a diagram showing a cross section taken along the line AA of FIG. FIG. 3 is a view showing the inner layers L2, L3, and L4 inside the printed circuit board 10. As shown in FIG. FIG. 4 is a view showing the lower surface layer L5 on the lower surface of the printed circuit board 10. FIG. 5 is a view showing the recess 11 k and the metal core 3 provided in the printed circuit board 10.

  1 and 3 show the state viewed from above the printed circuit board 10, and FIGS. 4 and 5 show the state viewed from below the printed circuit board 10. In each figure, only a part of the printed circuit board 10 and the electronic device 100 is shown for convenience.

  The electronic device 100 includes a DC-DC converter mounted on, for example, an electric vehicle or a hybrid car. The electronic device 100 includes a printed circuit board 10, electronic components 9 a to 9 j, and a heat sink 4.

  As shown in FIG. 2, the printed circuit board 10 is a multilayer (five layers) substrate in which surface layers L1 and L5 are provided on both the upper and lower surfaces, and a plurality of inner layers L2, L3, and L4 are provided therein. . The printed circuit board 10 includes a base material 11, a metal core 3, a heat sink 4, wiring patterns 5a to 5w, and through holes 6a to 6e.

  The substrate 11 is made of an insulator and is formed in a plate shape. Specifically, the substrate 11 is composed of a first insulating layer 1 and a second insulating layer 2.

  The first insulating layer 1 is composed of a highly thermally conductive prepreg. The high thermal conductivity prepreg is, for example, a prepreg having high thermal conductivity and insulation produced by mixing alumina into epoxy. Alumina is a reinforcing material, and epoxy is a thermosetting resin.

  The first insulating layer 1 is formed in a flat plate shape having a predetermined thickness (about 100 μm). An upper surface layer L1 is provided on the upper surface of the first insulating layer 1 exposed to the outside. As shown in FIG. 1, electronic components 9a to 9g and wiring patterns 5a to 5i are provided on the upper surface layer L1.

  The wiring patterns 5a to 5i are made of copper foil having conductivity and thermal conductivity. A part of the wiring patterns 5a to 5i functions as a land for soldering the electronic components 9a to 9g. The electronic components 9a to 9g include FETs (field effect transistors) 9a and 9b, discrete components 9c, and chip capacitors 9d to 9g.

  The FETs 9a and 9b are surface-mounting electronic components that generate a large amount of heat. The source terminal s1 of the FET 9a is soldered on the wiring pattern 5a. The gate terminal g1 of the FET 9a is soldered on the wiring pattern 5b. The drain terminal d1 of the FET 9a is soldered on the wiring pattern 5c. The source terminal s2 of the FET 9b is soldered on the wiring pattern 5c. The gate terminal g2 of the FET 9b is soldered onto the wiring pattern 5d. The drain terminal d2 of the FET 9b is soldered to the wiring pattern 5e.

  As illustrated in FIG. 2, the discrete component 9 c is an electronic component including lead terminals t <b> 1 and t <b> 2 (FIG. 1) that penetrate the printed circuit board 10. The main body of the discrete component 9 c is mounted on the upper surface of the first insulating layer 1. The lead terminals t1 and t2 of the discrete component 9c are inserted into the through holes 6c and 6d, respectively, and then soldered.

  The chip capacitors 9d to 9g are surface mount type electronic components. As shown in FIG. 1, the chip capacitor 9d is soldered onto the wiring patterns 5b and 5h. The chip capacitor 9e is soldered on the wiring patterns 5e and 5f. The chip capacitor 9f is soldered on the wiring patterns 5d and 5i. The chip capacitor 9g is soldered on the wiring patterns 5e and 5g.

  As shown in FIG. 2, a second insulating layer 2 is provided on the lower surface of the first insulating layer 1. The second insulating layer 2 is formed in a flat plate shape thicker than the first insulating layer 1 and has a laminated structure. In detail, the 2nd insulating layer 2 is comprised by adhere | attaching the copper clad laminated board 2a on the upper and lower surfaces of the normal prepreg 2b, respectively.

  The normal prepreg 2b is a prepreg that is a material of a general printed circuit board, and is a plate material formed by impregnating glass fiber with epoxy, for example. The copper-clad laminate 2a is obtained by adhering copper foil to the upper and lower surfaces of a plate-like core material 2c formed by impregnating glass fiber with epoxy, for example. The glass fiber and the epoxy constituting the normal prepreg 2b and the copper clad laminate 2a have different components in this example, but as another example, the components may be the same. Glass fiber is a reinforcing material.

  As another example, instead of glass fiber, a plate material made of another reinforcing material such as carbon fiber and a thermosetting resin other than epoxy may be used as the second insulating layer 2.

  An inner layer L2 is provided between the first insulating layer 1 and the second insulating layer 2 using the copper foil portion of each copper-clad laminate 2a of the second insulating layer 2, and the inner layer L3, L4 is provided, and a lower surface layer L5 is provided on the lower surface of the second insulating layer 2.

  As shown in FIG. 3, the inner layers L2 to L4 are provided with wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n". Each of the wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" is made of a copper foil having conductivity and thermal conductivity.

  In this example, the wiring patterns 5j, 5k, 5l, 5m, and 5n of the inner layer L2, the wiring patterns 5j ′, 5k ′, 5l ′, 5m ′, and 5n ′ of the inner layer L3, and the wiring patterns 5j ″ and 5k of the inner layer L4 are used. “5l”, “5m”, and “5n” have the same shape. As another example, the shapes of the wiring patterns of the inner layers L2, L3, and L4 may be different.

  As shown in FIG. 4, the lower surface layer L5 is provided with electronic components 9h to 9j and wiring patterns 5o to 5w. The wiring patterns 5o to 5w are made of copper foil having conductivity and thermal conductivity. A part of the wiring patterns 5p, 5q, 5s, 5t, 5v, and 5w functions as a land for soldering the electronic components 9h to 9j.

  The electronic components 9h to 9j are surface mount type chip capacitors. The chip capacitor 9h is soldered on the wiring patterns 5p and 5q. The chip capacitor 9i is soldered on the wiring patterns 5t and 5s. The chip capacitor 9j is soldered on the wiring patterns 5v and 5w.

  As shown in FIG. 2 and the like, a recess 11k is provided on the lower surface of the substrate 11. Specifically, the recess 11 k is provided in the second insulating layer 2 so as to be recessed from the lower surface of the second insulating layer 2 in the thickness direction and reach the lower surface of the first insulating layer 1. The metal core 3 is fitted into the recess 11k. That is, the metal core 3 is embedded in the base material 11 so as to reach the lower surface of the first insulating layer 1 from the lower surface of the second insulating layer 2.

  Further, the metal core 3 is provided on the lower surface of the first insulating layer 1 so as to overlap with at least the FETs 9a and 9b. Specifically, as shown in FIG. 1, when viewed from above the printed circuit board 10, the metal core 3 includes a plurality of electronic components 9a, 9b, 9d, 9f provided on the upper surface of the first insulating layer 1 and a plurality of wiring patterns. 5a to 5e, 5h, and 5i are provided over a wide range so as to be wholly or partly overlapped. In other words, the electronic components 9a, 9b, 9d, and 9f are mounted on the wiring patterns 5a to 5e, 5h, and 5i on the printed circuit board 10 so as to overlap the metal core 3 in the vertical direction.

  The metal core 3 is made of a metal body such as copper having thermal conductivity. As shown in FIGS. 1, 4, and 5, the metal core 3 is formed in a rectangular shape when viewed from above or below. The recess 11k is formed in a substantially rectangular shape when viewed from above or below. The area of the recess 11 k is wider than the area of the metal core 3.

  As shown in FIG. 2, the upper surface of the metal core 3 is covered with the first insulating layer 1. The lower part of the metal core 3 is exposed from the lower surface of the second insulating layer 2. The metal core 3 radiates heat generated by the electronic components 9a, 9b, 9d, and 9f mounted on the wiring patterns 5a to 5e, 5h, and 5i on the upper surface layer L1 directly above. In addition, the metal core 3 radiates heat generated in the electronic components 9 a to 9 j and transmitted to the base material 11. The metal core 3 is an example of the “metal member” in the present invention.

  The thermal conductivity of the first insulating layer 1 and the metal core 3 is higher than the thermal conductivity of the second insulating layer 2. Further, the thermal conductivity of the metal core 3 is higher than the thermal conductivity of the first insulating layer 1. Specifically, for example, the thermal conductivity of the second insulating layer 2 is 0.3 to 0.5 W / mK (mK: meter · Kelvin), whereas the thermal conductivity of the first insulating layer 1 is 3 to 5 W / mK. Moreover, when the metal core 3 is made of copper, the thermal conductivity of the metal core 3 is about 400 W / mK.

  In each of the inner layers L2 to L4, an insulator (epoxy or glass fiber) of the second insulating layer 2 is interposed between the wiring patterns 5j to 5n, 5j ′ to 5n ′, 5j ″ to 5n ″ and the metal core 3. (FIGS. 2 and 3). For this reason, the metal core 3 and the wiring patterns 5j to 5n, 5j 'to 5n', 5j "to 5n" are insulated.

  In the lower surface layer L5, a predetermined insulation distance is provided between the wiring cores 5o, 5p, 5r, 5s, and 5u in the vicinity of the metal core 3 and the metal core 3 (FIGS. 2 and 4). For this reason, the metal core 3 and each wiring pattern 5o-5w are insulated.

  In the upper surface layer L1, the first insulating layer 1 is interposed between the wiring cores 5a to 5e, 5h, and 5i immediately above the metal core 3 and the metal core 3 (FIGS. 1 and 2). In other words, the wiring patterns 5a to 5e, 5h, and 5i are provided above the metal core 3 with the first insulating layer 1 interposed therebetween. For this reason, the metal core 3 and each wiring pattern 5a-5e, 5h, 5i are insulated. In addition, wiring patterns 5a, 5e, 5f, 5g, 5i, and 5h are provided above the second insulating layer 2 with the first insulating layer 1 interposed therebetween. Therefore, the wiring patterns 5j to 5n on the inner layer L2 and the wiring patterns 5a, 5e, 5f, 5g, 5i, and 5h on the upper surface layer L1 are insulated.

  The through holes 6a to 6e penetrate the first insulating layer 1 and the second insulating layer 2 of the substrate 11 and the wiring patterns in the both insulating layers 1 and 2 around the metal core 3 (FIG. 2). The inner surfaces of the through holes 6a to 6e are covered with a metal plating 14. The through holes 6a to 6e connect the wiring patterns provided in the upper surface layer L1, the inner layers L2 to L4, and the lower surface layer L5 of the base material 11. The through holes 6a to 6e are examples of the “through conductor” in the present invention.

  A plurality of through holes 6a are provided so as to penetrate through the wiring patterns 5a of the insulating layers 1, 2 and the upper surface layer L1, the wiring patterns 5j, 5j ′, 5j ″ of the inner layers L2 to L4, and the wiring pattern 5o of the lower surface layer L5. Each through hole 6a connects the wiring patterns 5a, 5j, 5j ′, 5j ″, and 5o.

  The plurality of through holes 6b penetrate through the insulating layers 1 and 2, the wiring pattern 5e of the upper surface layer L1, the wiring patterns 5m, 5m ', 5m "of the inner layers L2 to L4, and the wiring pattern 5s of the lower surface layer L5. Each through hole 6b connects the wiring patterns 5e, 5m, 5m ′, 5m ″, and 5s.

  The through hole 6c is provided so as to penetrate the insulating layers 1 and 2, the wiring pattern 5e of the upper surface layer L1, the wiring patterns 5m, 5m ', 5m "of the inner layers L2 to L4, and the wiring pattern 5s of the lower surface layer L5. One lead terminal t1 of the discrete component 9c is soldered to the through hole 6c, and the lead terminal t1 is connected to the wiring patterns 5e, 5m, 5m ′, 5m ″, and 5s through the through hole 6c. Has been.

  The through hole 6d is provided so as to penetrate the insulating layers 1 and 2, the wiring pattern 5f of the upper surface layer L1, the wiring patterns 5n, 5n ′, 5n ″ of the inner layers L2 to L4, and the wiring pattern 5r of the lower surface layer L5. The other lead terminal t2 of the discrete component 9c is soldered to the through hole 6d, and the lead terminal t2 is connected to the wiring patterns 5f, 5n, 5n ′, 5n ″, 5r via the through hole 6d. Has been.

  The through hole 6e is provided so as to penetrate the insulating layers 1 and 2, the wiring pattern 5h of the upper surface layer L1, the wiring patterns 5k, 5k ′, 5k ″ of the inner layers L2 to L4, and the wiring pattern 5p of the lower surface layer L5. The through holes 6e connect the wiring patterns 5h, 5k, 5k ′, 5k ″, and 5p.

  As shown in FIG. 2, the lower surfaces of the wiring patterns 5p, 5s, and 5t of the lower surface layer L5 and the lower ends (lower edges) of the through holes 6b, 6c, and 6e are flush with the lower surface of the metal core 3. . The lower surfaces of the wiring patterns 5o, 5q, 5r, 5u to 5w of the lower surface layer L5 shown in FIG. 4 and the lower ends of the through holes 6a and 6d are also flush with the lower surface of the metal core 3.

  The exposed portion of the metal core 3 exposed from the lower surface of the base material 11, the wiring patterns 5o to 5w, and the lower end portions of the through holes 6a to 6e are covered with the same metal plating 12 applied in the same process. (See FIG. 2; FIG. 4 omits illustration of the metal plating 12). Thereby, the height including the metal plating 12 of the metal core 3, the wiring patterns 5o to 5w, and the lower end portions of the through holes 6a to 6e with respect to the lower surface of the second insulating layer 2 of the substrate 11 is the same. .

  The upper surfaces of the wiring patterns 5a to 5i on the upper surface layer L1 and the upper ends (upper edges) of the through holes 6a to 6e are flush with each other. The wiring patterns 5a to 5i and the upper end portions of the through holes 6a to 6e are covered with the same metal plating 13 made in the same process (see FIG. 2, the metal plating 13 is not shown in FIG. 1). . Thereby, the height including the metal plating 13 of the wiring patterns 5a to 5i and the upper end portions of the through holes 6a to 6e with respect to the upper surface of the first insulating layer 1 of the substrate 11 is the same.

  The metal platings 12 to 14 are all copper plating in this example. As another example, you may comprise the metal plating 12-14 by plating of other metals, such as gold | metal | money and a solder.

  As shown in FIG. 2, a heat sink 4 is provided below the second insulating layer 2 and the metal core 3. The heat sink 4 is made of metal such as aluminum, and releases the heat generated in the printed circuit board 10 to cool the printed circuit board 10. The heat sink 4 is an example of the “heat radiator” in the present invention.

  On the upper surface of the heat sink 4, convex portions 4 a and 4 b projecting upward are formed. The upper surfaces of the convex portions 4 a and 4 b are parallel to the plate surface of the printed circuit board 10.

  A screw hole 4h is formed in the convex portion 4b of the heat sink 4 in parallel with the thickness direction of the printed circuit board 10 (vertical direction in FIG. 2). In each of the insulating layers 1 and 2, a through hole 7 is provided at a position that does not overlap the electronic components 9a to 9j and the wiring patterns 5a to 5w. The through hole 7 communicates with the screwing hole 4 h of the heat sink 4.

  The screw 8 is passed through the through hole 7 from above the first insulating layer 1 and screwed into the screw hole 4 h of the heat sink 4, whereby the convex portion 4 b of the heat sink 4 is fixed to the lower surface of the second insulating layer 2. The The heat sink 4 is attached below the printed circuit board 10 by providing a plurality of such screwing points.

  In a state where the convex portion 4 b of the heat sink 4 is fixed to the lower surface of the second insulating layer 2, the lower surface covered with the metal plating 12 of the metal core 3 and the upper surface of the convex portion 4 a of the heat sink 4 are in contact. In this example, the area of the upper surface of the convex portion 4a of the heat sink 4 is reduced due to a predetermined insulation distance between the wiring pattern 5o, 5p, 5r, 5s, 5u on the lower surface layer L5 and the metal core 3. It is slightly narrower than the area of the lower surface of the metal core 3.

  As another example, the area of the upper surface of the convex portion 4a of the heat sink 4 is made the same as or slightly wider than the area of the lower surface of the metal core 3 in consideration of the wiring pattern of the lower surface layer L5 and the arrangement of electronic components. May be.

  Thermal grease (not shown) having high thermal conductivity may be applied to the upper surface of the convex portion 4a of the heat sink 4, or a thermal conductive sheet may be attached. Thereby, the adhesiveness of the upper surface of the convex part 4a and the lower surface covered with the metal plating 12 of the metal core 3 is enhanced, and the thermal conductivity from the metal core 3 to the heat sink 4 is enhanced.

  Next, a method for manufacturing the printed circuit board 10 will be described with reference to FIGS. 1 to 5, FIGS. 6A, 6B, and 6C.

  6A to 6C are diagrams illustrating manufacturing steps of the printed circuit board 10. In FIGS. 6A to 6C, each part of the printed circuit board 10 is simplified for convenience.

  6A, of the two copper-clad laminates 2a, the copper foils on both upper and lower surfaces of one copper-clad laminate 2a are subjected to etching or the like to form wiring patterns 5j to 5n, 5j ′ to the inner layers L2, L3. 5n ′ (reference numerals omitted in FIGS. 6A to 6C). Further, the copper foil on the upper surface of the other copper-clad laminate 2a is etched to form wiring patterns 5j ″ to 5n ″ (reference numerals are omitted in FIGS. 6A to 6C) of the inner layer L4 (( 1)).

  Next, a through hole 2h for fitting the metal core 3 into each copper clad laminate 2a is formed ((2) in FIG. 6A). Further, a through hole 2h ′ for fitting the metal core 3 is also formed in the normal prepreg 2b ((3) in FIG. 6A).

  The through holes 2h and 2h 'are formed in a substantially rectangular shape as shown in FIG. 5A when viewed from the thickness direction of the copper-clad laminate 2a and the normal prepreg 2b. A plurality of convex portions 2t projecting inward are formed at predetermined intervals on the inner peripheral surfaces of the through holes 2h and 2h '. As shown in FIG. 5B, the protruding length of each convex portion 2t is set to a length that reaches the outer peripheral surface of the metal core 3 in a state where the metal core 3 is fitted in the through holes 2h and 2h '.

  Thereby, in a state where the metal core 3 is fitted in the through holes 2h and 2h ′, the contact portion 2t ′ in which the outer peripheral surface of the metal core 3 and the inner peripheral surface of the through holes 2h and 2h ′ are in contact with each other is separated from each other. Part 2s is formed. A plurality of contact portions 2t 'and spacing portions 2s are alternately formed at predetermined intervals in the circumferential direction of the metal core 3 and the through holes 2h, 2h'.

  For this reason, the contact area between the metal core 3 and the inner peripheral surfaces of the through holes 2h and 2h 'is reduced, and the metal core 3 can be easily fitted into the through holes 2h and 2h'. However, once the metal core 3 is inserted into the through holes 2h and 2h ′, the metal core 3 is inserted into the through holes by the frictional resistance of the contact portions 2t ′ between the inner peripheral surfaces of the through holes 2h and 2h ′ and the outer peripheral surface of the metal core 3. It is possible to make it difficult to escape from 2h and 2h ′.

  Moreover, the highly heat conductive prepreg 1a which has predetermined | prescribed thickness, and the copper foil 5 which has predetermined | prescribed thickness for affixing on the upper surface of this prepreg 1a are prepared ((4) of FIG. 6A). Further, a metal body such as copper is processed to form a metal core 3 having a predetermined shape ((5) in FIG. 6A).

  Then, as shown in FIG. 6B (6), from the bottom, one copper-clad laminate 2a, a normal prepreg 2b, the other copper-clad laminate 2a, a highly heat-conductive prepreg 1a, and a copper foil 5 are sequentially arranged. After stacking and inserting the metal core 3 into the through holes 2h and 2h ′, the metal core 3 is pressed in the vertical direction (thickness direction of each member) while being heated (lamination press).

  Thereby, the epoxy of each prepreg 2b, 1a and the copper clad laminated board 2a melt | dissolves, and it penetrates into the clearance gap between these members 1a, 2a, 2b. Thereafter, the epoxy is cured, so that the members 1a, 2a, and 2b are bonded to each other, and the first insulating layer 1, the second insulating layer 2, the inner layers L2 to L4, and the recess 11k of the base material 11 are configured ( (6 ') of FIG. 6B). The inner peripheral surface of the recess 11k is formed by the inner peripheral surfaces of the through holes 2h and 2h ', and the bottom surface of the recess 11k is formed by the lower surface of the prepreg 1a having high thermal conductivity.

  Further, the melted epoxy of each prepreg 2b, 1a and the copper clad laminate 2a is filled in the gap between the metal core 3 and the recess 11k or the separation portion 2s. Thereafter, the base material 11 and the metal core 3 are integrated by curing the epoxy. That is, the upper surface of the metal core 3 is held by the first insulating layer 1. At the contact portion 2t 'between the metal core 3 and the recess 11k, the metal core 3 is held by the glass fiber and epoxy of the copper-clad laminate 2a and the prepreg 2b. Moreover, in the space | interval part 2s of the metal core 3 and the recessed part 11k, the metal core 3 is hold | maintained by the epoxy 2j after hardening of the copper clad laminated board 2a and the prepreg 2b (FIG.5 (c), FIG.1, FIG.3, FIG.4). . Furthermore, the lower part of the metal core 3 is exposed from the lower surface of the second insulating layer 2, and the copper foil of the copper clad laminate 2 a at the lowermost part and the lower surface of the metal core 3 are flush with each other. The upper surface of the uppermost copper foil 5 is also flush.

  Next, as shown to (7) of FIG. 6C, the through-hole 6 'for through-holes is formed in the copper foil 5 and the base material 11 in the predetermined location. Then, as shown in FIG. 6C (8), the inner surface of each through hole 6 ′ is covered with a metal plating 14. Further, the copper foil 5 of the first insulating layer 1 of the substrate 11 is covered with a metal plating 13. Furthermore, the copper foil 2d of the second insulating layer 2 (copper foil on the lower surface of one copper-clad laminate 2a) and the lower part of the metal core 3 are covered with the metal plating 12. Thus, through holes 6a to 6e (indicated by reference numeral 6 in FIG. 6C) are formed, and the lower end, the upper end, and the inner surface of the through holes 6a to 6e are covered with metal platings 12, 13, and 14, respectively (FIG. 2). . Metal plating 12-14 is performed simultaneously in the same plating process.

  Moreover, the height including the metal plating 13 of the upper ends of the wiring patterns 6a to 6i and the through holes 6a to 6e with respect to the upper surface of the first insulating layer 1 of the substrate 11 is the same. Moreover, the height including the metal plating 12 of the metal core 3, the wiring patterns 6o to 6w, and the lower end portions of the through holes 6a to 6e with respect to the lower surface of the second insulating layer 2 of the substrate 11 is the same.

  Next, the copper foil 2d (FIG. 6C (8)) at the bottom is etched to form the wiring patterns 5o to 5w (not shown in FIG. 6C) of the lower surface layer L5 on the lower surface of the second insulating layer 2. ((9) in FIG. 6C). In addition, the uppermost copper foil 5 is etched to form wiring patterns 5a to 5i (not shown in FIG. 6C) of the upper surface layer L1 on the upper surface of the first insulating layer 1.

  Thereafter, the exposed upper surface of the first insulating layer 1, the wiring patterns 5a to 5i, the lower surface of the second insulating layer 2, the wiring patterns 5o to 5w, and the like are subjected to a surface treatment such as resist or silk. (10) in FIG. 6C). Then, the outer shape is processed by cutting excess ends of the insulating layers 1 and 2 ((11) in FIG. 6C). Thus, the printed circuit board 10 is formed.

  According to the embodiment, in the printed circuit board 10 in which the metal core 3 for heat dissipation is embedded in the base material 11, the metal core 3 exposed from the lower surface of the second insulating layer 2 of the base material 11, the wiring patterns 5o to 5w, and the through holes The lower end portions of 6a to 6e are covered with the same metal plating 12 made in the same process. And the height with respect to the lower surface of the 2nd insulating layer 2 of the metal core 3, wiring pattern 5o-5w, and the lower end part of the through holes 6a-6e is made the same. For this reason, it is not necessary to mask the exposed portion of the metal core 3 in advance, and an increase in the manufacturing process of the printed board 10 can be suppressed, and the printed board 10 can be easily manufactured. Moreover, since the lower part of the metal core 3 is exposed from the lower surface of the base material 11 and covered with the metal plating 12, the heat dissipation performance of the metal core 3 can be enhanced while preventing the lower part of the metal core 3 from corroding. .

  Moreover, in the said embodiment, the electronic components 9a, 9b, 9d which generate heat | fever via the 1st insulating layer 1 with high heat conductivity, wiring pattern 5a-5e, 5h, 5i, and the metal plating 13 directly on the metal core 3. FIG. 9f are mounted, and the heat sink 4 is brought into contact with the lower surface of the metal core 3 exposed from the second insulating layer 2 through the metal plating 12. For this reason, the heat sink 4 can be adhered to the lower surface of the metal core 3 while preventing the lower surface of the metal core 3 from corroding. The heat generated in the electronic components 9a, 9b, 9d, and 9f can be easily transferred to the heat sink 4 through the first insulating layer 1 and the metal core 3, and can be efficiently radiated from the heat sink 4 to the outside.

  In the present invention, various embodiments other than those described above can be adopted. For example, in the above embodiment, the example in which the through holes 9a to 9e are provided in order to connect the wiring patterns on the surface layers L1 and L5 and the inner layers L2 to L4 of the printed circuit board 10 has been described. It is not limited to only. In addition to this, for example, a through hole that connects only the wiring patterns on the upper surface and the lower surface of the printed board may be provided. Further, in addition to the through hole, for example, a through conductor that penetrates a base material such as a copper terminal or a pin may be provided, and the wiring patterns of different conductor layers of the printed circuit board may be connected by the through conductor.

  Further, the present invention may be applied to a printed circuit board in which through conductors such as through holes are omitted. In this case, the exposed portion of the metal core 3 and the wiring patterns 5o to 5w are covered with the metal plating 12 of the same material applied in the same process, and the metal plating 12 of the metal core 3 and the wiring patterns 5o to 5w on the base material 11 is covered. It is sufficient to make the heights including the same.

  Moreover, in the above embodiment, although the example which exposed only the lower part of the metal core 3 from the lower surface of the base material 11 was shown, this invention is not limited only to this. In addition to this, for example, the upper part of the metal core 3 may also be exposed from the upper surface of the substrate 11. In this case, the upper part of the metal core 3 exposed from the upper surface of the base material 11, the wiring patterns 5a to 5i, and the edges of the upper ends of the through holes 6a to 6e are covered with the metal plating 13 of the same material applied in the same process. Thus, the metal core 3 and the wiring patterns 5a to 5i with respect to the upper surface of the substrate 11 may have the same height including the metal plating 13.

  In the above embodiment, an example in which the shape of the metal core 3 when viewed from above is rectangular has been described. However, the shape is not limited to this, and the metal core 3 is viewed from above according to the arrangement position and shape of the electronic components that generate heat. The shape of the metal core can be any shape.

  Moreover, although the example using the heat sink 4 was shown as a heat radiator in the above embodiment, it may replace with this and may use the radiator using an air cooling type or a water cooling type, or a refrigerant | coolant. . Moreover, you may use not only a metal heat radiator but the heat radiator formed with resin with high heat conductivity.

  Moreover, although the example which applied this invention to the printed circuit board 10 in which the two surface layers L1 and L5 and the three inner layers L2-L4 were provided was given in the above embodiment, this invention is a wiring pattern on the upper surface or the lower surface. The present invention can also be applied to a single-layer printed board provided with a conductor such as, and a printed board provided with a conductor in two or more layers.

  Furthermore, in the above embodiment, although the DC-DC converter mounted in an electric vehicle or a hybrid car was mentioned as an example as the electronic apparatus 100, this invention is a printed circuit board, the electronic component which generate | occur | produces, and a heat radiator. It is applicable also to other electronic devices provided with.

DESCRIPTION OF SYMBOLS 1 1st insulating layer 2 2nd insulating layer 3 Metal core (metal member)
4 Heat sink (heat sink)
5a-5i Upper surface layer wiring pattern 5o-5w Lower surface layer wiring pattern 6a-6e Through hole (penetrating conductor)
9a, 9b FET (electronic parts)
9d, 9f Chip capacitors (electronic components)
DESCRIPTION OF SYMBOLS 10 Printed circuit board 11 Base material 11k Concave part 12 Metal plating 100 Electronic device L1 Upper surface layer L5 Lower surface layer

Claims (7)

A substrate made of an insulator and formed in a plate shape;
A wiring pattern provided on the surface of the substrate;
In a printed circuit board comprising: a metal member embedded in the base material for dissipating heat generated in an electronic component mounted on the wiring pattern,
From the surface of the substrate on which the wiring pattern is provided, a part of the metal member is exposed,
The printed circuit board, wherein the exposed portion of the metal member and the wiring pattern are covered with the same material metal plating applied in the same process. The printed circuit board according to claim 1,
A through conductor provided to penetrate the base material and connecting the wiring patterns provided on the upper surface and the lower surface of the base material;
An exposed portion of the metal member, the wiring pattern, and an end portion of the through conductor are covered with the metal plating. The printed circuit board according to claim 2,
The substrate is
A first insulating layer provided with a wiring pattern for mounting the electronic component on an upper surface;
A second insulating layer provided on the lower surface of the first insulating layer,
The thermal conductivity of the first insulating layer is higher than the thermal conductivity of the second insulating layer,
A recess is provided so as to reach the lower surface of the first insulating layer from the lower surface of the second insulating layer,
The metal member is inserted into the recess;
The printed circuit board, wherein the metal member exposed from the lower surface of the second insulating layer, the wiring pattern, and an end portion of the through conductor are covered with the metal plating. A substrate made of an insulator and formed in a plate shape;
A wiring pattern provided on the surface of the substrate;
In a printed circuit board comprising: a metal member embedded in the base material for dissipating heat generated in an electronic component mounted on the wiring pattern,
From the surface of the substrate on which the wiring pattern is provided, a part of the metal member is exposed,
The exposed portion of the metal member and the wiring pattern are covered with metal plating,
The printed circuit board, wherein the exposed portion of the metal member and the wiring pattern with respect to the base material have the same height including the metal plating. The printed circuit board according to claim 4,
A through conductor provided to penetrate the base material and connecting the wiring patterns provided on the upper surface and the lower surface of the base material;
The metal plating covers the metal member exposed from the surface of the substrate, the wiring pattern, and an end of the through conductor,
The printed circuit board, wherein the exposed portion of the metal member, the wiring pattern, and the end portion of the through conductor with respect to the base material have the same height including the metal plating. The printed circuit board according to claim 5,
The substrate is
A first insulating layer provided with a wiring pattern for mounting the electronic component on an upper surface;
A second insulating layer provided on the lower surface of the first insulating layer,
The thermal conductivity of the first insulating layer is higher than the thermal conductivity of the second insulating layer,
A recess is provided so as to reach the lower surface of the first insulating layer from the lower surface of the second insulating layer,
The metal member is inserted into the recess;
The metal plating covers the metal member exposed from the lower surface of the second insulating layer, the wiring pattern, and an end of the through conductor,
The printed circuit board, wherein the metal member, the wiring pattern, and the end portion of the through conductor with respect to the lower surface of the second insulating layer have the same height including the metal plating. A printed circuit board according to any one of claims 1 to 6,
An electronic component that generates heat and is mounted on the printed circuit board so as to overlap vertically with the metal member provided on the printed circuit board;
An electronic device comprising: a heat dissipating member provided to come into contact with the lower surface of the metal member exposed from the lower surface of the printed circuit board.

Images