JP2006060047A - Wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reinforce peeling strength of a metal layer for forming a wiring film on an interlayer insulating film with respect to the interlayer insulating film or of the wiring film by reducing the number of press processes required for the manufacture of a wiring board to raise manufacturing efficiency and hence improve productivity. <P>SOLUTION: An embedding metal layer 12 is stacked with a press on the surface of a metal plate 6 for forming a wiring film, on one surface of which a metal bump 4 for interlayer connection is formed via an interlayer insulating film 10, and the surfaces of the metal layer 12 for embedding and the interlayer insulating film 10 are polished until the top surface 4a of the metal bump 4 is exposed to form the embedded metal layer 12a on the surface of the interlayer insulating film 10. Further, the metal layer 16 for forming a wiring film at least having a portion connected to the top surface 12a of the metal bump 12 is formed with plating on the surface of the interlayer insulating film 10c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wiring board using metal bumps as interlayer connection means and a method for manufacturing the same.

  The applicant company of the present application has developed various techniques for manufacturing a multilayer wiring board, and many of the developed techniques are techniques using metal bumps as interlayer connection means. As a specific example of the technique, an etching barrier layer (thickness, for example, 1 μm) made of nickel, for example, is formed on one main surface of a copper layer for bump formation (thickness, for example, 100 μm). A wiring circuit board forming member made of a metal plate having a three-layer structure in which a copper foil (thickness, for example, 18 μm) for forming a conductor circuit is formed on the main surface is used as a base, and the surface is processed, for example, between layers A wiring board having bumps which are fine projections for connection is obtained. Regarding this, for example, Japanese Patent Application Nos. 2000-230142 (2000-43506) and 2000-334332 (: 2002-141629), Japanese Patent Application No. 2002-66410 (Japanese Patent Laid-Open No. 2002-43506), and other technical proposals.

3A to 3E are cross-sectional views showing a typical example of a method of manufacturing a wiring board using such a technique in the order of steps.
(A) As shown in FIG. 3A, a metal plate 102 having a metal bump formed on one surface is prepared, and further, for example, a glass cloth or a glass mat in a B-stage state is used as a base material. The laminated body of the B stage resin 104 and the release sheet 106 made of epoxy resin is exposed.
The metal plate 102 is formed by forming bumps 112 made of, for example, copper on one surface of a wiring film forming metal film 108 made of, for example, copper via an etching barrier metal layer 110 made of, for example, nickel.

  The metal plate 102 is formed, for example, by forming an etching barrier layer (thickness, for example, 1 μm) made of nickel, for example, on one main surface of a copper layer for bump formation (thickness, for example, 100 μm). A metal plate having a three-layer structure in which a copper foil (thickness, for example, 18 μm) for forming a conductor circuit is formed on the main surface of the barrier layer is used as a wiring board forming member, and the bump forming copper layer is selectively etched. Then, the metal bump 112 is formed, and then the etching barrier layer 110 made of nickel, which has functioned as an etching stopper at the time of etching, is removed by etching using the metal bump 112 as a mask.

Regarding this method, for example, Japanese Patent Application No. 2000-230142 (Japanese Patent Laid-Open No. 2002-43506), Japanese Patent Application No. 2000-334332 (Japanese Patent Laid-Open No. 2002-141629), Japanese Patent Application No. 2002-66410 (: Japanese Patent Laid-Open No. 2002-41029). The technical proposal is made by the application such as No. 43506).
The resin 104 serves as an interlayer insulating film, has a sheet shape, and is made of an epoxy resin in a B-stage state. Reference numeral 106 denotes a release sheet which is superimposed on the epoxy resin 104.

When the resin 104 is formed on the bump forming surface side of the metal plate 102, the release sheet 106 appropriately protrudes the top of the metal bump 112 from the surface of the resin 104, and is laminated by pressurization and heating. This is to secure a shrinkage allowance in anticipation of the bump 112 being shrunk, and is to be peeled after the top surface is polished and the top surface of the metal bump 112 is exposed, and the resin 104 in the B stage state. It also serves to prevent contamination of the surface.
Although not shown, a cushion material is disposed on the laminate made of the release sheet 106 and the B stage resin 104, and the laminate is a metal plate via a pressure plate (not shown). The bump 102 is pressed and heated on the bump forming surface side. The heating temperature at this time is set to a temperature of 120 ° C. or lower so as to maintain the B stage state. FIG. 3A shows the metal plate 102 and the laminate composed of the release sheet 106 and the resin 104 in a state immediately before being pressurized and heated.

(B) When a laminate composed of the resin 104 and the release sheet 106 is laminated on the bump forming surface side of the metal plate 102 by pressurization and heating, the result is as shown in FIG.
(C) Next, as shown in FIG. 3C, the laminate composed of the resin 104 and the release sheet 106 is dry-polished until the top surface 112a of each metal bump 112 is exposed. Dry polishing is polishing performed without supplying a cooling liquid such as water to the polishing portion. The reason why the wet polishing, that is, the polishing performed while supplying the cooling liquid such as water to the polishing portion is not performed is that the resin 104 gradually deteriorates due to the liquid such as moisture entering the B-stage resin 104, and the resin 104 This is to avoid the loss of the original resin physical properties.

(D) Next, as shown in FIG. 3D, the release sheet 106 is peeled off and removed.
(E) Next, as shown in FIG. 3E, for example, a metal layer 114 made of copper is pressed onto the surface of the resin 104 and the metal bump 112, and the metal layer 114 and the metal bump 112 are pressed strongly. (The applied pressure is, for example, 5.0 to 10.0 MPa) to make the connection strong and favorable. As a result, the metal bump 112 shrinks, for example, by about 30%. Then, while maintaining the pressed state, the resin 104 is heated to 170 to 220 ° C. to change the resin 104 to a C-stage state to form an interlayer insulating film.
Thereafter, although not shown, the metal layers 108 and 114 are patterned by selective etching to form a wiring film.
JP 2002-43506 A (Japanese Patent Application No. 2000-230142) JP 2002-141629 A (Japanese Patent Application No. 2000-334332) JP 2002-43506 A (Japanese Patent Application No. 2002-66410)

By the way, according to the above-described conventional technology, first, there is a problem that the pressing process is required twice until the state shown in FIG. .
That is, according to the above-described conventional technique, the first press is performed when the B-stage resin 104 and the release sheet 106 made of an epoxy resin serving as an interlayer insulating film are laminated on the metal plate 102.
Further, the resin 104 and the release sheet 106 are polished until the top surface of the metal bump 112 is exposed, and the remaining portion of the release sheet 106 is removed, and then a metal made of, for example, copper for forming a wiring film is used. A second press is performed when laminating the layers.

  The press needs to be performed by stacking a large number of various members for forming a wiring board in a predetermined combination and adjusting the pressure, temperature, etc. very accurately and uniformly. Since skill is required, it is preferable to reduce the number of pressing steps as much as possible. However, according to the prior art, since two presses were necessary, it was difficult to achieve a significant improvement in production efficiency.

According to the above-described prior art, secondly, there is a problem that the peeling strength between the interlayer insulating film and the wiring film forming metal layer laminated thereon is not sufficiently strong.
Specifically, in the past, the peel strength was only about 500 to 600 g / cm ² .
However, in order to obtain sufficient reliability as a wiring board, it is preferable to set the peel strength to about 1000 g / cm ^2. However, in the conventional technique, a metal layer such as copper by pressurizing or laminating a resin interlayer insulating film There is a limit to increasing the adhesive strength of the film, and it was difficult to increase the peel strength as such.

  The present invention has been made in order to solve such problems. One object of the present invention is to increase the production efficiency by reducing the number of pressing steps necessary for the production of the wiring board, and to improve the productivity. Another object is to increase the peeling strength of the wiring film forming metal layer or the wiring film on the interlayer insulating film with respect to the insulating film.

  In the wiring board according to claim 1, an interlayer insulating film is penetrated by the metal bump on the one surface of the metal plate for wiring film formation having a metal bump for interlayer connection formed on one surface of the metal bump. A top surface is formed so as to be exposed, and a metal layer is formed on the surface of the interlayer insulating film so as to be spaced apart from the metal bumps so that the surface and the surface of the interlayer insulating film are substantially flush with each other. A metal layer by plating connected to the top surface of the metal bump is formed on the surface of the interlayer insulating film.

According to a second aspect of the present invention, there is provided a wiring board having an interlayer connection metal bump projecting to one side from at least a part of a plurality of wiring films of the same layer, on the surface of the one side of the wiring film. The interlayer insulating film is formed so as to penetrate through the metal bump and the top surface of the metal bump is exposed, and the metal layer is separated from the metal bump on the surface of the interlayer insulating film so that the surface of the interlayer insulating film and the interlayer insulating film The wiring layer is formed so as to be substantially flush with the surface, and a plating wiring layer having at least a portion connected to the top surface of the metal bump is formed on the surface of the interlayer insulating film. To do.
The wiring board according to claim 3 is the wiring board according to claim 1 or 2, wherein the surface of the portion of the interlayer insulating film on which the embedded metal layer is formed and the side of the embedded metal layer on the side of the interlayer insulating film Both or any one of these surfaces is roughened.

The method for manufacturing a wiring board according to claim 4 includes: preparing a wiring film forming metal plate having metal bumps for interlayer connection formed on one surface; and on the one surface of the wiring film forming metal plate. In addition, the step of laminating a metal layer for embedding through an interlayer insulating film by pressing, and polishing the surface portion of the metal layer for embedding and the interlayer insulating film until the top surface of the metal bump is exposed, Separating the metal bumps on the surface of the interlayer insulating film and forming the embedded metal layer in a state of being embedded so that the surface and the surface of the interlayer insulating film are substantially flush with each other; And forming a wiring film forming metal layer having at least a portion connected to the top surface of the metal bump by plating on the surface of the interlayer insulating film.
In the present specification and claims, the polishing includes mechanical polishing, mechanical chemical polishing, and chemical polishing (etching).

The wiring board manufacturing method according to claim 5 is the wiring board according to claim 4, wherein the embedding metal layer is pressed on the one surface of the wiring film forming metal plate via the interlayer insulating film. In the stacking step, one or both of the upper surface of the interlayer insulating film and the lower surface of the embedding metal layer is roughened in advance.
The method for manufacturing a wiring board according to claim 6 is the method for manufacturing a wiring board according to claim 5, wherein the formation of the metal layer for forming the wiring film by plating is first performed by electroless plating and then by electrolytic plating. It is characterized by performing by.

According to the wiring substrate of the first and second aspects, the wiring film forming metal layer formed on the interlayer insulating film is formed by plating, so that the press can be reduced by the amount of forming the wiring film forming metal layer.
Therefore, by reducing the number of presses, it is possible to increase manufacturing efficiency and improve productivity.
Then, the metal layer for forming the wiring film by plating can be formed with the embedded metal layer having a higher adhesion strength embedded in the surface portion of the interlayer insulating film, so it is integrated with the embedded metal layer. The peel strength from the interlayer insulating film can be increased.
According to the wiring substrate of claim 3, in the wiring substrate of claims 1 and 2, the surface of the portion of the interlayer insulating film where the embedded metal layer is formed, and the interlayer insulating film of the embedded metal layer Since either or both of the side surfaces are roughened, the adhesion strength between the interlayer insulating film and the embedding metal layer can be further increased. The adhesion strength with the formed metal layer for forming a wiring film can be further increased.

According to the method for manufacturing a wiring board of claim 4, the metal layer for embedding is laminated via the interlayer insulating film, and the metal layer for forming the wiring film is formed by plating on the interlayer insulating film in which the metal layer is embedded in the surface portion. Since it is formed, the pressing process is only required once.
Then, the metal layer for forming the wiring film by plating is formed as a base with a metal layer that is embedded and has higher adhesion strength with respect to the surface portion of the interlayer insulating film, so that it can be integrated with the embedded metal layer. As a result, the peel strength from the interlayer insulating film can be increased.

According to the method for manufacturing a wiring board according to claim 5, in the method for manufacturing a wiring board according to claim 4, prior to the step of laminating the metal layer for embedding through the interlayer insulating film by pressing, the interlayer insulating film Since either one or both of the upper surface and the lower surface of the embedding metal layer is roughened in advance, the adhesion strength between the interlayer insulating film and the embedding metal layer can be further increased. The adhesion strength between the metal layer and the metal layer for forming a wiring film formed thereon can be further increased.
According to the method for manufacturing a wiring board according to claim 6, since the formation of the metal layer for forming a wiring film by plating is performed by first performing an electroless plating process and then performing an electrolytic plating process. A metal layer is formed on the entire surface by plating, and a high-quality metal layer for forming a wiring film can be formed by electroless plating using the metal layer as a base.

In the present invention, an epoxy resin containing glass cloth or an epoxy resin containing glass mat is suitable for forming the interlayer insulating film, and copper is suitable for various metal layers.
Further, for example, a pressure of about 3 to 10 MPa is suitable for laminating an interlayer insulating film made of, for example, an epoxy resin through an embedding metal layer.
Also, prior to the step of laminating the burying metal layer by pressing through the interlayer insulating film, either one or both of the upper surface of the interlayer insulating film and the lower surface of the burying metal layer is roughened in advance. good.

For example, when the interlayer insulation film is made of a resin such as an epoxy resin, roughening the surface is to immerse the resin in a treatment solution such as potassium permanganate solution, sodium dichromate solution or concentrated alkaline solution. Can be performed.
Moreover, the roughening of the surface of a metal layer, for example, a copper layer, can be performed by the roughening process by blackening reduction.
Further, the formation of the metal layer for forming the wiring film on the interlayer insulating film by plating can be performed by first performing an electroless plating process and then performing an electrolytic plating process.

Hereinafter, the present invention will be described in detail according to illustrated embodiments.
FIGS. 1A to 1D and FIGS. 2E and 2F are sectional views showing a first embodiment of a method for manufacturing a wiring board according to the present invention in order of steps (A) to (F).
(A) As shown in FIG. 1A, a metal plate 6 having a metal bump 4 formed on one surface of a wiring film forming metal layer 2 is prepared.

  For example, the metal plate 6 is formed by, for example, electroless plating an etching barrier layer (eg, 1 μm thick) 8 made of, for example, nickel on one main surface of a metal layer (eg, 60 μm thick) 4 made of, for example, bumps. Further, a metal plate having a three-layer structure in which a metal layer (for example, 18 μm in thickness) 2 made of, for example, copper for forming a wiring film is formed on the main surface of the etching barrier layer is used as a wiring board forming member. The metal layer (4) for bump formation is selectively etched to form the metal bump 4, and then the etching barrier layer 8 made of nickel, which functions as an etching stopper during the etching, is formed on the metal bump 4 It is manufactured by the method of removing it by etching using as a mask.

(B) Next, as shown in FIG. 1 (B), for example, an epoxy resin (thickness, for example, 60 in a B-stage state) that becomes an interlayer insulating film on the side on which the metal bumps 4 of the metal plate 6 are formed. ˜110 μm) 10 and a buried metal layer (thickness, eg, 35 μm) 12 made of copper. In addition, as this epoxy resin, the epoxy resin containing glass cloth or the epoxy resin containing glass mat is suitable.
In the next step, the embedding metal layer 12 is laminated on the metal plate 6 through the epoxy resin 10 by pressing and heating, but a direct die (not shown) is directly attached to the embedding metal layer. Since the press die is applied through the release sheet 14a, 14b and further through a cushion material (not shown), the release sheet 14a, 14b faces the embedding metal layer 12. Incidentally, the release sheets 14a and 14b are made of foamed polyethylene, for example. For example, two aflexes (thickness, for example, 50 μm) are stacked, and an aluminum foil is placed thereon and pressed.
Further, pyrene (trade name) may be used. In this case, the thickness of the release sheet 14a is preferably 35 μm, for example, and the thickness of the release sheet 14b is preferably 110 μm, for example.
Further, in order to further enhance the adhesion between the embedding metal layer 12 and the epoxy resin 10, one or both of the lower surface of the embedding metal layer 12 and the upper surface of the epoxy resin 10 is roughened in advance. And good.

(C) Next, the embedding metal layer 12 and the epoxy resin 10 are laminated via the release sheets 14b and 14a by heating and pressurization, and then the release sheets 14a and 14b are peeled and removed. FIG. 1C shows a state after the release sheets 14a and 14b are removed.
In this case, the pressurizing pressure for lamination is, for example, about 3 to 10 MPa, the heating temperature is, for example, 160 to 250 ° C., and the epoxy resin 4 is changed from the B stage to the C stage state. In this way, the epoxy resin 10 is changed from the B stage to the C stage state before polishing. 10c is an epoxy resin in a C-stage state, and can function as an interlayer insulating film. The thickness of the epoxy resin 10 c in the C stage state needs to be formed so as to be much thinner than the height of the metal bump 4. Otherwise, the embedded metal layer (12a), which will be described later, formed after polishing cannot remain sufficiently thick.

(D) Next, the exposed metal layer 12 and the epoxy resin 10c are exposed so that the top surfaces 4a of the metal bumps 4 are exposed, and the upper surfaces of the epoxy resin 10c, the metal bumps 4 and the embedded metal layer 12 are exposed. Mechanical polishing, mechanical chemical polishing, or chemical polishing (half-etching) is performed so that the surfaces are substantially flush (located on the same plane). By this polishing, not only the top surface 4a of the metal bump 4 is exposed, but also the embedding metal layer 12 is formed so as to remain embedded on the surface in the portion where the metal bump 4 of the epoxy resin 10c is not formed. It becomes a state. Reference numeral 12a denotes a metal layer that remains embedded in the surface of the epoxy resin 10c.
The polishing of the embedding metal layer 12 and the epoxy resin 10c may be performed by mechanical polishing or mechanical chemical polishing from the beginning to the end, or first, chemical polishing (half etching) treatment is performed. Thereafter, the top surface 4a of the metal bump 4 may be exposed by polishing by mechanical polishing or mechanical chemical polishing.

(E) Next, as shown in FIG. 2 (E), the wiring film forming metal layer 16 made of, for example, copper is formed on the epoxy resin 10c, the embedded metal layer 12a, and the top surface 4a of the metal bump 4 without electrolysis. It is formed by plating and subsequent electrolytic plating. 16a shows a metal layer formed by electroless plating, 16b shows a metal layer formed by electrolytic plating, and a broken line shows the boundary between them. In practice, there is no such clear boundary.
The wiring board shown in FIG. 2 (E) corresponds to the wiring board according to claim 1 of the claims.
(F) Next, as shown in FIG. 2F, a wiring film is formed by selectively etching the wiring film forming metal layer 2 and the wiring film forming metal layer 16 simultaneously or differently. .
Note that the selective etching of the wiring film forming metal layer 16 needs to be performed to such a depth that the underlying embedded metal layer 12a is also etched.
The wiring board shown in FIG. 2 (F) corresponds to the wiring board according to claim 2 of the claims.

According to this embodiment, the embedded metal layer 12 is laminated via the epoxy resin 10 serving as an interlayer insulating film, and the wiring film forming metal layer 16 forms an interlayer insulating film in which the metal layer 12a is embedded in the surface portion. Since it is formed on the epoxy resin 10c by plating, the pressing process is only required once.
Then, the metal layer 16 for forming the wiring film by plating is formed by using the metal layer 12a which is embedded in the surface portion of the epoxy resin 10c forming the interlayer insulating film and has higher adhesion strength as a base, so that the embedded metal layer 12a can be integrated, and as a result, the peeling strength with the epoxy resin 10c forming the interlayer insulating film can be increased. Specifically, it could be 1000 g / cm ² or more.

Note that the wiring board shown in FIG. 2 (F) is used as a core board, and the wiring board as shown in FIG. 2 (F) is provided on both sides or one side thereof, or a type different from the wiring board shown in FIG. 2 (F). It is also possible to obtain a multilayered wiring board by laminating these wiring boards.
In addition, a wiring board different from the wiring board shown in FIG. 2F is used as a core board, and the wiring board as shown in FIG. May be obtained.
As described above, the wiring board of the present invention can be used alone as a wiring board, but can be used as a wiring board in which a plurality of wiring boards are stacked and combined with different types of wiring boards. It can be used as an integrated wiring board.

  The present invention is widely applicable to a wiring board using a metal bump made of, for example, copper as an interlayer connection means, and using, for example, a resin such as an epoxy resin as an interlayer insulating film, and a manufacturing method thereof.

(A)-(D) are sectional drawings which show process (A)-(D) of the 1st Example of the manufacturing method of this invention wiring board in order. (E), (F) is sectional drawing which shows process (E), (F) of the said 1st Example of the manufacturing method of this invention wiring board in order. (A)-(E) is sectional drawing which shows one prior art example of the manufacturing method of a wiring board in process order (A)-(E).

Explanation of symbols

2 ... Metal layer for wiring film formation, 4 ... Metal bump, 4a ... Metal bump top surface,
10: B-stage epoxy resin to be an interlayer insulating film,
10c: Epoxy resin (interlayer insulating film) in the C stage state,
12 ... Metal layer for embedding, 12a ... Metal layer of embedding shape,
16 ... Metal layer for forming a wiring film,
16a: electroless plating layer, 16b: electrolytic plating layer.

Claims (6)

An interlayer insulating film is formed on one surface of the wiring film forming metal plate having a metal bump for interlayer connection formed on one surface so that the top surface of the metal bump is exposed through the metal bump. And
A metal layer is formed on the surface of the interlayer insulating film so as to be spaced apart from the metal bumps and embedded so that the surface thereof and the surface of the interlayer insulating film are substantially flush with each other,
A wiring board, wherein a metal layer by plating connected to the top surface of the metal bump is formed on the surface of the interlayer insulating film. A metal bump for interlayer connection is formed on at least a part of a plurality of wiring films in the same layer and protrudes on one side therefrom,
On the surface of the one side of the wiring film, an interlayer insulating film is formed so as to be penetrated by the metal bump and the top surface of the metal bump is exposed,
A metal layer is formed on the surface of the interlayer insulating film so as to be spaced apart from the metal bumps and embedded so that the surface thereof and the surface of the interlayer insulating film are substantially flush with each other,
A wiring board formed by plating having at least a portion connected to the top surface of the metal bump is formed on the surface of the interlayer insulating film. The surface of the portion of the interlayer insulating film on which the embedded metal layer is formed and the surface of the embedded metal layer on the side of the interlayer insulating film or both of them are roughened. The wiring board according to claim 1 or 2. A step of preparing a metal plate for forming a wiring film in which metal bumps for interlayer connection are formed on one surface;
A step of laminating a metal layer for embedding by pressing on the one surface of the metal plate for wiring film formation via an interlayer insulating film;
The surface of the metal layer for embedding and the interlayer insulating film is polished until the top surface of the metal bump is exposed, whereby the metal layer for embedding is separated from the metal bump on the surface of the interlayer insulating film. A step of forming a buried surface so that the surface thereof and the surface of the interlayer insulating film are substantially flush with each other;
Forming a metal layer for forming a wiring film having at least a portion connected to the top surface of the metal bump on the surface of the interlayer insulating film by plating;
A method of manufacturing a wiring board having at least In the step of laminating the burying metal layer on the one surface of the wiring film forming metal plate via the interlayer insulating film, the upper surface of the interlayer insulating film and the lower surface of the burying metal layer are The wiring board according to claim 4, wherein either or both of them are roughened in advance. 6. The method of manufacturing a wiring board according to claim 4, wherein the formation of the metal layer for forming a wiring film by plating is performed by first performing an electroless plating process and then performing an electrolytic plating process.

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