JP2007294932A - Metal core printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal core printed wiring board for acquiring superior productivity and quality of a product, and further eliminating the use of an expensive process for improving adhesion properties between a metal core layer and an insulating layer; and to provide a method for manufacturing it. <P>SOLUTION: A part of side edges 1a of the metal core printed wiring board 1 is exposed by the metal core layer 2, and the residual part is sealed by the insulating layer 3. In more concrete terms, the overall shape of the metal core printed wiring board 1 is formed into a rectangle, a part of non-corner parts of the side edges 1a is exposed by the metal core layer 2, and the residual part of the non-corner parts and corners 1b are sealed by the insulating layer 3. Consequently, since the insulating layers 3 are made to adhere to each other in most parts, superior adhesion properties can be acquired between the metal core layer 2 and the insulating layer 3. Since the corner 1b is often brought into contact with outside, there are points where the metal core layer and the insulating layer are easy to peel, so that it is preferable that the insulating layer 3 is formed at the corner part 1b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal core printed wiring board and a manufacturing method thereof, and more particularly to a metal core printed wiring board in which a metal core layer is exposed at a part of a side edge and a manufacturing method thereof.

  With the recent high performance and miniaturization of electronic devices, the need for heat dissipation has increased due to the increased capacity of components mounted on the printed wiring board and the higher density of the printed wiring board itself. Therefore, for example, a metal core printed wiring board provided with a metal core layer excellent in heat dissipation and soaking properties is used (see, for example, Patent Document 1).

  Moreover, in order to improve the productivity of a product, the manufacturing method of the printed wiring board which cut | disconnects one connection wiring board along a predetermined cutting line, and isolate | separates into several printed wiring boards is known. For example, see Patent Document 2).

  7A to 7E are side cross-sectional views for explaining a method for manufacturing a metal core printed wiring board according to Conventional Example 1, and FIG. 8A illustrates a method for manufacturing a metal core printed wiring board according to Conventional Example 1. (B) is a B7-B7 line sectional view of (A), (C) is a side sectional view showing a metal core printed wiring board of conventional example 1.

  In the manufacturing method of the metal core printed wiring board of Conventional Example 1, first, a metal core layer 50 is prepared as shown in FIG. The metal core layer 50 is a plate material made of a metal foil with good thermal conductivity such as copper, aluminum, or an alloy containing them as a main component.

  Next, as shown in FIG. 7B, a through hole 50a penetrating the surface and back surface (upper surface and lower surface) of the metal core layer 50 is formed by etching, punching, or the like.

  Next, as shown in FIG. 7C, an insulating layer 51 made of a prepreg (a glass cloth or other cloth impregnated with an epoxy resin) and an insulating layer formed on the upper and lower surfaces of the metal core layer 50 are formed. A first conductor layer 52 and a second conductor layer 53 made of metal foil (for example, copper foil) are formed on 51, and are heated and subjected to pressing (thermocompression bonding) to integrate them.

  Next, as shown in FIG. 7D, a through hole 54 penetrating through the first conductor layer 52 and the second conductor layer 53 is formed, and a plating film 55 is formed on the inner surface thereof. The conductor layer 52 and the second conductor layer 53 are electrically connected.

  Next, as shown in FIG. 7E, the first conductor layer 52 and the second conductor layer 53 are etched to form a circuit pattern, and the connection wiring board 56 is obtained.

  Thereafter, the connection wiring board 56 is cut by a predetermined cutting line CL shown in FIGS. 8A and 8B using a cutting blade (not shown) or the like, as shown in FIG. 8C. To obtain a metal core printed wiring board 57.

  9A is a side sectional view for explaining a method of manufacturing a metal core printed wiring board of Conventional Example 2, FIG. 9B is a sectional view taken along line B8-B8 of FIG. 9A, and FIG. 9C is a metal core of Conventional Example 2. It is side surface sectional drawing which shows a printed wiring board.

In the manufacturing method of the metal core printed wiring board of the conventional example 2, as shown to FIG. 9 (A) and (B), the metal core layer 50 is not exposed in the side edge part of a board | substrate, but several core parts 50b are included. A connecting wiring board 58 having a configuration in which an insulating layer 51 is formed on the insulating layer 51 is manufactured at a predetermined interval, and the connecting wiring board 58 is cut along a predetermined cutting line CL. As shown in C), a plurality of metal core printed wiring boards 59 are obtained by separation.
JP-A-8-293659 JP 2000-133913 A

  Usually, a rolled metal foil having a thickness of 200 μm or more is used for the metal core layer 50 used for the metal core printed wiring board in order to improve heat dissipation and heat uniformity. Unlike the electrolytic metal foil used for the conductor layer or the like, the rolled metal foil is not formed with a roughened surface. Therefore, in order to improve the adhesion with the insulating layer 51, a roughened surface is formed on the metal core layer 50. It was.

As a method of forming the roughened surface,
(1) Method of forming oxide on metal foil surface (2) Method of maintaining the shape of the oxide layer and reducing it to metal with a reducing agent (3) Method of etching metal surface into needle shape with etchant 4) A method of forming a metal surface having a coarse particle diameter by electroless plating or electrolytic plating is known.

  Although the above methods (1) and (2) are relatively inexpensive methods, the entire side surface of the metal core layer 50 is exposed from the side edge portion of the metal core printed wiring board 57 of the conventional example 1, so that the metal core The adhesion between the layer 50 and the insulating layer 51 is weak.

  For example, regarding the peel strength between the copper foil and the insulating resin of the printed wiring board, JIS-C-6484 (copper-clad laminate for printed wiring boards, flame-resistant glass cloth base epoxy resin), JIS-C-6486 (printed wiring) As shown in (Copper-clad laminate for glass, glass cloth base epoxy resin), a peel strength of 1.4 kN / m or more is required. However, the methods (1) and (2) have a problem that it is difficult to satisfy a peeling strength of 1.4 kN / m or more.

  In the method (3) above, the crystal grain boundary on the surface of the metal foil is corroded by the etching solution to form a needle-like rough surface. In order to increase the adhesion between the insulating resin and the surface of the metal foil, Therefore, there is a problem that it is necessary to refine the crystal grains and increase the crystal grain boundary portion, which requires manufacturing time and manufacturing cost.

  In the method (4), very good adhesion can be obtained. However, since the processing cost is expensive, there is a problem that the manufacturing cost increases.

  In Conventional Example 2, since the adhesion between the insulating layers 51 is strong, a process for obtaining high adhesion between the metal core layer 50 and the insulating layer 51 is not necessary.

  However, since it is necessary to arrange the core part 50b at a predetermined position before the thermocompression bonding process between the metal core layer 50 and the insulating layer 51, the metal core layers corresponding to the core parts of a plurality of wiring boards are collectively arranged. Compared with the manufacturing method which performs, productivity was remarkably inferior and the metal core printed wiring board had the subject that cost increased as a result.

  Further, when the insulating layer 51, the first conductor layer 52, and the second conductor layer 53 are pressed, the resin constituting the insulating layer may be dissolved, and the core portion 50b may be misaligned. There was a problem that the quality varied.

  The present invention has been made to solve the above-described problems, and improves the productivity and quality of products, and does not require expensive processing for improving the adhesion between the metal core layer and the insulating layer. An object of the present invention is to provide a metal core printed wiring board and a manufacturing method thereof.

  The metal core printed wiring board of the present invention includes a metal core layer, a first conductor layer formed on an insulating layer on the upper surface or the lower surface of the metal core layer, and the insulating layer on the upper surface or the lower surface. In the metal core printed wiring board having a second conductor layer formed on the insulating layer on the opposite side through the layer, the metal core layer is exposed at a part of the side edge portion of the metal core printed wiring board, An insulating layer is formed on the remaining portion.

  The upper surface of the metal core printed wiring board is formed in a polygonal shape, the side edge portion includes a corner portion including a corner and a non-corner portion, and the metal core layer is exposed in a part of the non-corner portion, It is preferable that an insulating layer is formed on the remaining part of the corner part and the corner part.

  The total width of the insulating layer on one side of the side edge is preferably substantially the same as or greater than the total width of the exposed metal core layer. Further, the width of the insulating layer formed between the corner and the exposed metal core layer and the width of the insulating layer between the exposed metal core layers are substantially the same as or the width of the exposed metal core layer. The above is preferable.

  The width of the exposed metal core layer is preferably at least twice the thickness of the metal core layer.

  It is preferable that the exposed metal core layers are disposed at symmetrical positions on the surfaces facing each other.

  The peel strength between the metal core layer and the insulating layer may be less than 1.4 kN / m.

The manufacturing method of the metal core printed wiring board of the present invention,
A metal plate layer is formed by punching a metal plate and including a frame portion, a plurality of core portions disposed inside the frame portion, and a connecting portion that connects the core portions to each other and the core portion and the frame portion. Process,
Forming an insulating layer on the metal core layer;
A first conductor layer is formed on the insulating layer on the upper surface or the lower surface of the metal core layer, and a second conductor layer is formed on the insulating layer opposite to the insulating layer on the upper surface or the lower surface through the metal core layer. Forming each of
Forming a circuit pattern on each of the first conductor layer and the second conductor layer;
Cutting along a cutting line passing through the connecting portion of the metal core layer, and separating into a plurality of metal core printed wiring boards;
It is characterized by having.

  According to the first aspect of the present invention, since the insulating layer is continuous in most parts, good adhesion can be obtained between the metal core layer and the insulating layer.

  The invention according to claim 2 is preferable because the insulating layer is formed at the corner portion that often comes into contact with the outside and the metal core layer and the insulating layer are easily peeled off.

  According to the invention of claim 3, there are many portions where the insulating layers are continuous, and higher adhesion can be obtained between the metal core layer and the insulating layer.

  According to the invention which concerns on Claim 4, the part which an insulating layer continues becomes more, and higher adhesiveness is obtained between a metal core layer and an insulating layer.

According to the fifth aspect of the present invention, when the metal core layer, the insulating layer, and the conductor layer are subjected to pressure bonding processing, the metal core layer is displaced from a predetermined position, or the substrate after the metal core printed wiring board is manufactured. The occurrence of local warping is suppressed.
According to the invention which concerns on Claim 6, the expensive process for improving the peeling strength of a metal core layer and an insulating layer becomes unnecessary.

  According to the invention of claim 7, since good adhesion can be obtained between the metal core layer and the insulating layer, it is expensive to form a roughened surface on the metal core layer in order to obtain high adhesion. No processing is required. As a result, the manufacturing time can be shortened and the manufacturing cost can be reduced.

  In addition, when the metal core layer and the insulating layer are thermocompression bonded, since the core portions of the metal core layer are connected by the connecting portion, a plurality of metal core printed wiring boards can be manufactured in a lump. Good.

  Furthermore, even when the insulating resin constituting the insulating layer is melted during thermocompression bonding of the insulating layer and the conductor layer, the core portion of the metal core layer is not likely to be displaced, resulting in variations in the quality of each substrate. Also disappear.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an appearance of a metal core printed wiring board according to an embodiment of the present invention. 2A is a sectional view taken along line A1-A1 in FIG. 1, FIG. 2B is a sectional view taken along line B1-B1 in FIG. 1A, FIG. 2C is a sectional view taken along line C1-C1 in FIG. Is a front view thereof.

  As shown in FIGS. 1 and 2, a metal core printed wiring board 1 according to an embodiment of the present invention includes a metal core layer 2, an insulating layer 3 formed on the metal core layer 2, and the metal core layer. A first conductor layer 4 (a circuit pattern is omitted in FIGS. 1 and 2) formed as a predetermined circuit pattern on an insulating layer 3 formed on an upper surface (front surface), and a lower surface of the metal core layer It has the 2nd conductor layer 5 (The circuit pattern is abbreviate | omitted in FIG.1 and FIG.2) formed as a predetermined circuit pattern on the insulating layer 3 formed in the (back surface).

  In order to electrically connect the first conductor layer 4 and the second conductor layer 5, the first conductor layer 4 and the second conductor layer 5 are penetrated, and the inner surface thereof is coated with the plating film 7. A through hole 6 is formed. (See FIG. 2C).

  The metal core layer 2 is a plate material made of a metal foil with good thermal conductivity such as copper, aluminum, or an alloy containing them as a main component, and has a thickness of 200 μm or more.

  The insulating layer 3 is made of, for example, an epoxy resin.

  The 1st conductor layer 4 and the 2nd conductor layer 5 are the board | plate materials made from metal foil with favorable heat conductivity, such as copper, aluminum, or an alloy which has them as a main component, for example, about 18-70 micrometers. Having a thickness of

  A part of the side edge portion 1a of the metal core printed wiring board 1 according to the embodiment of the present invention is characterized in that the metal core layer 2 is exposed and the insulating layer 3 is formed in the remaining portion (see FIG. 2 (D)). Thereby, since the insulating layer 3 is continuous in most parts, good adhesion can be obtained between the metal core layer 2 and the insulating layer 3. Therefore, even if the peeling strength between the metal core layer 2 and the insulating layer 3 is as low as less than 1.4 kN / m, good adhesion between the metal core layer 2 and the insulating layer 3 can be obtained.

  Further, the metal core printed wiring board 1 is formed so that each surface has a rectangular shape, the metal core layer 2 is exposed at a part of the non-corner portion 1c of the side edge portion 1a, and the remaining portion of the non-corner portion 1c and An insulating layer 3 is formed on the corner portion 1b. Since the corner portion 1b often contacts the outside and is a fragile portion, it is preferable that the insulating portion 3 is formed on the corner portion 1b.

  Here, as shown in FIG. 2B, the total width (e × 2 + c) of the insulating layer 3 on the lateral side of the side edge portion 1a is the total width (f) of the exposed end face of the metal core layer 2. It is preferably substantially the same as or more than x2).

  Further, the total width (g × 2 + d) of the insulating layer 3 in the vertical side of the side edge portion 1a is substantially equal to or greater than the total width (h × 2) of the exposed end surface of the metal core layer 2. Is preferred.

  Further, on the lateral side of the side edge portion 1a, the width e of the insulating layer 3 from the corner to the exposed metal core layer 2 and the width c of the insulating layer 3 between the exposed metal core layers 2 are as follows. The width f is preferably substantially the same as or larger than the width f. Further, in the vertical side of the side edge portion 1a, the width g of the insulating layer 3 from the corner to the exposed metal core layer 2 and the width d of the insulating layer 3 between the exposed metal core layers 2 are the exposed metal core layer 2 The width h is preferably substantially the same as or larger than the width h. Furthermore, on all sides, the width of the insulating layer 3 from the corner to the exposed metal core layer 2 and the width of the insulating layer 3 between the exposed metal core layers 2 are substantially the same as the width of the exposed metal core layer 2 or More than that is preferred.

  By comprising as mentioned above, the part in which the insulating layer 3 continues increases, and higher adhesiveness is obtained between the metal core layer 2 and the insulating layer 3.

  The widths f and h of the exposed metal core layer 2 are preferably at least twice the thickness i of the exposed metal core layer. As a result, when the metal core layer, the insulating layer, and the conductor layer are subjected to pressure bonding, the metal core layer is displaced from a predetermined position, or the substrate is locally warped after the metal core printed wiring board is manufactured. It is suppressed.

  The dimensions of the above-described parts in the embodiment of the present invention are, for example, a is 150 mm, b is 110 mm, c is 40 mm, d is 30 m, e is 45 mm, f is 10 mm, g is 30 mm, h is 10 mm, i is 0.4 mm. However, the above numerical values are examples and are not limited to these.

  Moreover, it is preferable that the exposed metal core layer 2 is symmetrically disposed on the surfaces facing each other. As a result, when the metal core layer, the insulating layer, and the conductor layer are subjected to pressure bonding, the metal core layer is displaced from a predetermined position, or the substrate is locally warped after the metal core printed wiring board is manufactured. It is suppressed.

  Next, the manufacturing method of the metal core printed wiring board 1 which concerns on the embodiment of this invention is demonstrated. 3A is a side cross-sectional view for explaining a method of manufacturing the metal core printed wiring board 1 according to the embodiment of the present invention, FIG. 3B is a cross-sectional view taken along the line B2-B2 of FIG. FIGS. 5A to 5D are side sectional views showing a metal core printed wiring board 1 according to an embodiment of the present invention, and FIG. 5A illustrates a method for manufacturing the metal core printed wiring board 1 according to an embodiment of the present invention. (B) is a B4-B4 line sectional view of (A).

  First, as shown in FIGS. 3A and 3B, a metal plate is punched out, and a frame portion 2a, a plurality of core portions 2b arranged inside the frame portion 2a, the core portions 2b, and a core A metal core layer 2 including a connecting portion 2c that connects the portion 2b and the frame portion 2a is formed.

  Next, as shown in FIG. 4A, a through hole 2d that penetrates the upper surface and the lower surface (front surface and back surface) of the core portion 2b of the metal core layer 2 is formed by etching, punching, or the like.

  Next, as shown in FIG. 4B, the insulating layer 3 is stacked on the upper surface and the lower surface of the core portion 2b, and the first conductor layer 4 and the second conductor layer 5 are stacked on the insulating layer 3, and heated. Then, press processing (thermocompression processing) is performed and integrated.

  Next, as shown in FIG. 4C, a through hole 6 that penetrates the first conductor layer 4 and the second conductor layer 5 and passes through the through hole 2d is formed, and the inner surface and the opening of the through hole 6 are further formed. A plating film 7 is formed around the part to electrically connect the first conductor layer 4 and the second conductor layer 5.

  Next, as shown in FIG. 4D, the first conductor layer 4 and the second conductor layer 5 are etched to form a circuit pattern, and the connection wiring board 8 is obtained.

  Thereafter, the connecting wiring board 8 is cut along a predetermined cutting line CL shown in FIGS. 5A and 5B by using a cutting blade (not shown), etc. The metal core printed wiring board 1 is obtained.

  According to the method for manufacturing the metal core printed wiring board 1 according to the embodiment of the present invention, good adhesion can be obtained between the metal core layer 2 and the insulating layer 3, so that high adhesion can be obtained. An expensive process for forming a roughened surface on the core layer 2 is unnecessary, and an inexpensive process is sufficient. As a result, the manufacturing time can be shortened and the manufacturing cost can be reduced.

  Moreover, since the core parts 2b of the metal core layer 2 are connected by the connecting part 2c before the thermocompression bonding of the metal core layer 2 and the insulating layer 3, there is no need to arrange a plurality of core parts 2b. Since the connection wiring boards can be manufactured in a lump, productivity is improved.

  Further, when the insulating layer 3, the first conductor layer 4 and the second conductor layer 5 are subjected to thermocompression bonding, the core portion 2b is not likely to be displaced even if the insulating resin is dissolved. There is no variation in quality.

  FIG. 6 is a cross-sectional view taken along line B1-B1 of FIG. 2 (A) showing a modification of the metal core printed wiring board 1 according to the embodiment of the present invention.

  In this modification, only one connecting portion 2 c is connected to the vertical side of the core portion 2 b of the metal core layer 2. Thereby, it becomes easy to cut | disconnect the connection part 2c along the vertical cutting line CL.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical matters described in the claims. For example, the shape of the metal core printed wiring board 1 of the present invention is not limited to a rectangle, and may be any shape such as a triangle, five or more polygons, and a circle. Moreover, the number of the metal core layers 2 exposed to the side edge 1a is not limited to 2, and may be 1 or 3 or more.

  The present invention is used for metal core printed wiring boards used in various electronic devices and their manufacture.

It is a schematic diagram showing appearance of a metal core printed circuit board according to an embodiment of the present invention. 1A is a cross-sectional view taken along line A1-A1 in FIG. 1, FIG. 1B is a cross-sectional view taken along line B1-B1 in FIG. 1A, FIG. 1C is a cross-sectional view taken along line C1-C1 in FIG. FIG. (A) is side surface sectional drawing for demonstrating the manufacturing method of the metal core printed wiring board which concerns on the example of embodiment of this invention, (B) is B2-B2 sectional view taken on the line of (A). (A)-(D) are side surface sectional drawings which show the metal core printed wiring board which concerns on the example of embodiment of this invention. (A) is side surface sectional drawing for demonstrating the manufacturing method of the metal core printed wiring board based on the embodiment of this invention, (B) is B4-B4 sectional view taken on the line of (A). It is a B1-B1 line sectional view of Drawing 1 (A) showing a modification of a metal core printed wiring board concerning an example of an embodiment of the present invention. (A)-(E) are side surface sectional drawings for demonstrating the manufacturing method of the metal core printed wiring board of the prior art example 1. FIG. (A) is side sectional drawing for demonstrating the manufacturing method of the metal core printed wiring board of the prior art example 1, (B) is the B7-B7 sectional view taken on the line of (A), (C) is the metal core printed wiring of the prior art example 1. It is side surface sectional drawing which shows a board. (A) is side surface sectional drawing for demonstrating the manufacturing method of the metal core printed wiring board of the prior art example 2, (B) is the B8-B8 sectional view taken on the line of (A), (C) is the metal core printed wiring of the prior art example 2. It is side surface sectional drawing which shows a board.

Explanation of symbols

1: Metal core printed wiring board 1a: Side edge portion 1b: Corner portion 2: Metal core layer 2a: Frame portion 2b: Core portion 2c: Connection portion 3: Insulating layer 4: First conductor layer 5: Second conductor layer 6: Through hole 7: Plating film 8: Connection wiring board CL: Cutting line

Claims (7)

The metal core layer, the first conductor layer formed on the insulating layer on the upper surface or the lower surface of the metal core layer, and the insulating layer on the upper surface or the lower surface are insulated on the opposite side via the metal core layer In a metal core printed wiring board having a second conductor layer formed on the layer,
The metal core printed wiring board, wherein the metal core layer is exposed at a part of a side edge of the metal core printed wiring board, and an insulating layer is formed at the remaining part.   The upper surface of the metal core printed wiring board is formed in a polygonal shape, the side edge portion includes a corner portion including a corner and a non-corner portion, and the metal core layer is exposed in a part of the non-corner portion, The metal core printed wiring board according to claim 1, wherein an insulating layer is formed on the remaining part of the corner part and the corner part.   The width of the insulating layer formed between the corner and the exposed metal core layer and the width of the insulating layer between the exposed metal core layers are substantially equal to or greater than the width of the exposed metal core layer. The metal core printed wiring board according to claim 2.   4. The metal core printed wiring board according to claim 1, wherein the width of the exposed metal core layer is at least twice the thickness of the metal core layer. 5.   5. The metal core printed wiring board according to claim 1, wherein the exposed metal core layers are arranged at symmetrical positions on mutually facing surfaces. 6.   The metal core printed wiring board according to any one of claims 1 to 5, wherein a peel strength between the metal core layer and the insulating layer is less than 1.4 kN / m. A metal plate layer is formed by punching a metal plate and including a frame portion, a plurality of core portions disposed inside the frame portion, and a connecting portion that connects the core portions to each other and the core portion and the frame portion. Process,
Forming an insulating layer on the metal core layer;
A first conductor layer is formed on the insulating layer on the upper surface or the lower surface of the metal core layer, and a second conductor layer is formed on the insulating layer opposite to the insulating layer on the upper surface or the lower surface through the metal core layer. Forming each of
Forming a circuit pattern on each of the first conductor layer and the second conductor layer;
Cutting along a cutting line passing through the connecting portion of the metal core layer, and separating into a plurality of metal core printed wiring boards;
A method for producing a metal core printed wiring board, comprising:

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