JP4621432B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a printed wiring board and a manufacturing method thereof, and more particularly to a printed wiring board having a structure in which interlayer conduction is obtained by a metal bump and a manufacturing method thereof.

  Conventionally, a metal bump (protrusion) is formed on a metal layer by etching or the like, and an adhesive sheet to be an interlayer insulating layer is bonded to the bump forming surface of the metal layer so that the bump top portion is exposed. There is a printed wiring board having a structure in which another metal layer is bonded on top of each other, a conductive circuit is formed on both surfaces by etching these metal layers, and the bumps form interlayer conductive portions (for example, Patent Document 1, 2).

  Such a printed wiring board can be mounted on both sides of an IC chip or the like by a flip chip mounting method. In addition, the adhesiveness between the conductor circuit and the interlayer insulating layer (insulating base layer) is high. As a result, the conductor circuit that is miniaturized with high-density mounting is peeled off from the insulating base layer even if an IC chip or the like is mounted. It is required not to.

As a method for improving the adhesion between the insulating base layer and the conductor circuit, (1) a method of bonding the conductor circuit and the insulating base layer using an adhesive, and (2) a bonding surface of the conductor to the insulating base layer. And (3) forming an organic film on the bonding surface of the conductor to the insulating base layer to chemically bond the conductor circuit and the insulating base layer. There are ways to get power, etc.
JP 2001-1111189 A JP 2002-359471 A

  However, all the conventional methods have problems.

  That is, (1) the method of bonding using an adhesive is limited to use in a relatively low temperature range, and cannot be used when there is a processing step at a high temperature.

  In addition, (2) the method of using the physical anchor effect by roughening the conductor surface improves the adhesion by increasing the amount of roughening, but is disadvantageous for fine circuit (fine circuit) formation, Roughening has a limit and increases the number of manufacturing steps of the printed wiring board.

  Furthermore, (3) the method of obtaining an organic bonding force by forming an organic film on the surface of a conductor cannot be expected to have a bonding effect depending on the material of the insulating base layer, and increases the production process of the printed wiring board. become.

  An object of the present invention is to improve the adhesion between the insulating base layer and the conductor circuit by eliminating the problems of the conventional one and supplementing the adhesion between the insulating layer (insulating base layer) and the conductor circuit. An object of the present invention is to provide a printed wiring board that can be used and a method for manufacturing the same.

  This invention solves the said subject, The invention which concerns on Claim 1 is the 1st metal layer in which the several conductive bump was formed in the single side | surface, and the 2nd metal layer, A printed wiring board in which one or more reinforcing bumps are provided on a printed wiring board that is overlapped with an insulating layer disposed in a region excluding the bumps, and the top of each bump and the second metal layer are combined. It is a wiring board.

  The invention according to claim 2 is the invention according to claim 1, wherein the reinforcing bump is a land electrically independent from a circuit formed on one of the first and second metal layers. It is a printed wiring board.

  The invention according to claim 3 is the step of forming a plurality of conductive bumps on one side of the first metal layer, and forming an insulating layer on the bump forming surface of the first metal layer except for each bump. A step of superimposing the second metal layer on the first metal layer with the insulating layer sandwiched therebetween, and bonding the top of each bump to the second metal layer; and the first and second layers Forming a circuit on the metal layer, forming at least one reinforcing bump.

  According to a fourth aspect of the present invention, in the step of forming a plurality of conductive bumps on one side of the first metal layer, and in the region excluding the bumps on the bump forming surface of the first metal layer, A step of forming an insulating layer having a thickness corresponding to the height of the bump, and a second metal layer superimposed on the first metal layer with the insulating layer interposed therebetween, and the top of each bump and the second metal layer A circuit in which at least one of the bumps is formed on one of the first and second metal layers when the circuit is formed on the first and second metal layers; Forming a land that is electrically independent of the printed wiring board.

  As described above, according to the present invention, a first metal layer having a plurality of conductive bumps formed on one side and a second metal layer sandwich an insulating layer disposed in a region excluding each bump. Since the printed wiring board in which the tops of the bumps and the second metal layer are combined with each other has one or more reinforcing bumps, such reinforcing bumps are connected to the interlayer conductor. By using it as a bump to supplement the adhesion between the insulating base layer and the conductor circuit, not as a common bump, the adhesion between the insulating base layer and the conductor circuit can be compensated. There exists an effect which can improve the adhesiveness of a layer and a conductor circuit.

  In addition, since the bumps for supplementing the close contact between the insulating base layer and the conductor circuit can be formed at the same time in the bump forming process for interlayer conduction, the manufacturing process of the printed wiring board is not increased. Moreover, it can be used without any problems even when there is a processing step at high temperature, when forming a fine circuit (fine circuit), or when the insulating layer is a material with poor chemical bonding force. .

  An embodiment of a printed wiring board and a method for manufacturing the same according to the present invention will be described with reference to FIG.

  First, as shown in FIG. 1A, three layers of a copper foil plate-shaped first metal layer (conductor layer) 11, an etching barrier layer 12 made of nickel or the like, and a copper bump forming layer 13 are formed. The material 10 is prepared as a starting material.

  As shown in FIG. 1B, the bump forming layer 13 of the three-layer material 10 is etched to form interlayer conduction bumps 14 at each position where interlayer conduction should be performed, and adhesion reinforcement is provided at the adhesion reinforcement position of the conductor. A bump 15 is formed. The bump 14 and the bump 15 can be formed by the same etching process. The bumps 14 and the bumps 15 can also be formed on the first conductor layer 11 by copper plating.

  Next, as shown in FIG. 1C, an insulating layer (insulating property) is formed in a region excluding the bumps 14 and 15 on the bump forming surface of the first conductor layer 11 (specifically, the surface of the etching barrier layer 12). Base layer) 16 is formed.

  The insulating base layer 16 can be formed by attaching a thermoplastic polyimide sheet, applying a thermoplastic polyimide precursor, or the like. The insulating base layer 16 has a thickness equivalent to the height of the bumps 14 and 15, and as shown in the drawing, the top surfaces of the bumps 14 and 15 are not covered without covering the top surfaces 14A and 15A of the bumps 14 and 15. The surfaces 14A and 15A are formed so as to be exposed.

  Next, as shown in FIG. 1 (d), a plate-like second metal layer (conductor layer) 17 made of copper foil is disposed on the insulating base layer 16, and the second is cured by press curing by heating and pressing. The conductor layer 17 is bonded to the insulating base layer 16. That is, the second conductor layer 17 and the top surfaces 14A and 15A of the bumps 14 and 15 are combined. This bonding method can be performed by plating as well as pressing.

  As a result, the second conductor layer 17 is formed with the insulating base layer 16 and the bumps 14 and 15 provided at portions other than the bump placement portion sandwiched therebetween.

  Next, as shown in FIG. 1 (e), the first conductor layer 11 and the etching barrier layer 12 are etched so that the conductor circuit 18 connected to the bumps 14 and 15 is electrically independent of the conductor circuit 18. An independent conductor portion 19 connected to the bump 15 is formed. In addition, the second conductor layer 17 is etched to form a conductor circuit 20 connected to the bumps 14 and 15 and an independent conductor portion 21 that is electrically independent of the conductor circuit 20 and connected to the bump 15. Thereby, one printed wiring board (double-sided wiring board) 30 is completed.

  In the printed wiring board 30, the conductor circuit 18 on the upper surface side and the conductor circuit 20 on the lower surface side are conductively connected by the bump 14, and the bump 14 forms an interlayer conductive conductor. Since the bumps 14 are coupled to the conductor circuits 18 and 20 at both ends, the bumps 14 exhibit excellent conductivity.

  On the other hand, the bumps 15 are respectively coupled to the independent conductor portion 19 existing on the upper surface side of the insulating base layer 16 and the conductor circuit 20 existing on the lower surface side of the insulating base layer 16, or the insulating base layer 16 The independent conductor portion 21 existing on the lower surface side of the insulating base layer 16 and the conductor circuit 18 existing on the upper surface side of the insulating base layer 16 are coupled to each other. The bump 15 can be installed in any place as long as the conductor circuits 18 and 20 are not short-circuited.

  Thereby, the bump 15 forms a bump for reinforcing the adhesion between the conductor and the insulating base layer, and the conductor circuit 18 on the upper surface side is lined with the independent conductor portion 21 on the lower surface side and the bump 15 for adhesion reinforcement. In addition, the conductor circuit 20 on the lower surface side is configured to be lined with the independent conductor portion 19 on the upper surface side and the bumps 15 for adhesion reinforcement, and each has a degree of bonding to the insulating base layer 16. Increase.

  Thereby, the adhesiveness of the conductor circuits 18 and 20 with respect to the insulating base layer 16 is improved. In addition, the present invention can be applied to the printed wiring board 30 with the insulating base layer 16 having a poor chemical bondability without being increased in the manufacturing process, limited to high temperature atmosphere and circuit miniaturization, and effective. is there.

  FIG. 2 shows a printed circuit board 40 in which an IC chip 42 is flip-chip mounted by solder balls 41 on the conductor circuit 18 of the printed wiring board 30. FIG. 3 is a schematic plan view showing a main part of the printed circuit board of FIG.

It is sectional drawing which shows one Embodiment of the printed wiring board by this invention, and its manufacturing method. FIG. 2 is a cross-sectional view showing a printed circuit board in which an IC chip is flip-chip mounted on the printed wiring board of FIG. 1. FIG. 3 is a schematic plan view showing a main part of the printed circuit board of FIG. 2.

Explanation of symbols

10 Three-layer material 11 First metal layer (conductor layer)
12 Etching barrier layer 13 Bump forming layer 14, 15 Bump 16 Insulating layer (insulating base layer)
17 Second metal layer (conductor layer)
18 Conductor Circuit 19 Independent Conductor 20 Conductor Circuit 21 Independent Conductor 30 Printed Wiring Board 40 Printed Circuit Board 41 Solder Ball 42 IC Chip

Claims (6)

A first metal layer having a plurality of conductive bumps formed on one side and a second metal layer are overlapped with an insulating layer disposed in a region excluding the bumps, and the top of each bump. And a printed wiring board in which the second metal layer is bonded,
The first metal layer includes one or more reinforcing bumps, and the reinforcing bumps enhance adhesion between the insulating layer and the first or second metal layer . Printed wiring board characterized by   2. The printed wiring board according to claim 1, wherein the reinforcing bump is a land electrically independent from a circuit formed on one of the first and second metal layers. Forming a plurality of conductive bumps on one side of the first metal layer;
Forming an insulating layer excluding each bump so that the top surface of each bump is exposed on the bump forming surface of the first metal layer;
A step of superimposing a second metal layer on the first metal layer with the insulating layer in between, and bonding a top of each bump and the second metal layer;
When forming a circuit on the first and second metal layers, at least one reinforcing bump capable of enhancing adhesion between the first or second metal layer and the insulating layer is formed. Process,
A method for producing a printed wiring board, comprising: Forming a plurality of conductive bumps on one side of the first metal layer;
Forming an insulating layer having a thickness corresponding to the height of each bump in a region excluding each bump so that a top surface of each bump of the bump forming surface of the first metal layer is exposed ;
A step of superimposing a second metal layer on the first metal layer with the insulating layer in between, and bonding a top of each bump and the second metal layer;
When a circuit is formed on the first and second metal layers, at least one of the bumps is used as a land that can enhance adhesion between the first or second metal layer and the insulating layer. A step of forming the reinforcing bump, the step of forming the reinforcing bump so as to be electrically independent from a circuit formed on one of the first and second metal layers;
A method for producing a printed wiring board, comprising: The metal layer of at least one of the first and second forms a conductor circuit and an independent conductor portion electrically independent of the conductor circuit;
  The printed wiring board according to claim 1, wherein the independent conductor portion and the reinforcing bump line a metal layer opposite to the independent conductor portion with the insulating layer interposed therebetween. 6. The printed wiring board according to claim 1, 2, or 5, wherein a conductor circuit is formed on the first and / or second metal layer and can be mounted on the conductor circuit by a flip chip mounting method. Printed wiring board.

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