JP3329756B2 - Multilayer wiring board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board having excellent moisture resistance and a method for manufacturing the multilayer wiring board.

[0002]

2. Description of the Related Art Along with miniaturization of electronic equipment and the like, wiring boards for forming circuits are required to be compact or have high-density wiring. In response to such demands, various multilayer wiring boards have been developed. For example,
A wiring pattern is formed on the main surface of a polyimide resin film (insulating support) with a thickness of about 65 μm, and the polyimide resin film with the wiring pattern formed on these main surfaces is positioned, laminated, and integrated via an adhesive layer. Multilayer wiring boards are generally known.

[0003] The multilayer wiring board having the above-described structure is manufactured as follows. That is, a copper foil-bonded sheet is prepared by bonding a copper foil having a thickness of about 12 to 18 μm to a main surface of a polyimide resin film having a thickness of about 65 μm via an adhesive layer. Next, a predetermined area of the copper foil-bonded sheet is perforated to provide a through hole for interlayer connection, and then a conductor layer is formed on the inner wall surface of the perforated copper foil. After that, a photo-etching process is performed to form a wiring pattern,
A polyimide resin film with a wiring pattern in which the wiring patterns on both sides are connected.

[0004] On the other hand, a required area is subjected to punching and press working, while a required area is perforated to prepare a polyimide resin film having a thickness of about 65 µm with an adhesive layer having a conductive area in the perforated area. Thereafter, a multilayer wiring board is manufactured by aligning, laminating, and arranging one of the wiring patterning surfaces of the polyimide resin film on both main surfaces of the polyimide resin film, followed by crimping and integrating. In other words, a polyimide resin film provided with a through-hole connection portion is used as a core substrate, and on both main surfaces of the core substrate,
A multilayer wiring board is obtained by positioning, laminating and integrating the polyimide resin films of the double-sided wiring pattern.

[0005]

However, in the case of the above-mentioned multilayer wiring board, there is an inconvenience that the stability of characteristics and the like are lacking. That is, an adhesive layer is interposed in order to join and integrate the polyimide resin film (insulating support) and the wiring pattern (such as copper foil). By the way, the adhesive layer is generally added and blended with a flame retardant such as a halogen compound or a phosphorus compound in response to a demand for flame retardancy. Here, the insertion / presence of the adhesive layer containing the flame retardant not only adversely affects the electrical characteristics of the multilayer wiring board itself, but also affects the manufacturing process of the multilayer wiring board or the multilayer wiring board. In the disposal of wiring boards, etc.
The flame retardant may raise environmental issues.

Further, a multilayer wiring board using a polyimide resin film as an insulator may be affected by external humidity due to the water absorption or moisture absorption of the polyimide resin film itself. For example, electric signals in a high frequency region are handled. In such a case, the reliability is easily impaired. That is, in general, the moisture resistance is poor, so that the performance (for example, impedance) as an insulator fluctuates, and as a result, stable high-frequency signal transmission and conductivity are reduced. As a remedy, a configuration of a multilayer wiring board using a liquid crystal polymer as an insulator can be considered. That is, since the liquid crystal polymer has almost no hygroscopicity, has a dielectric constant of about 3.0 (1 MHz), and is stable in a wide frequency range, it is considered that the disadvantage caused by the hygroscopic action of the insulator can be solved. It is.

[0007] However, on the other hand, there is a problem that heat deformation is liable to occur and mechanical strength is also poor. Here, the fact that thermal deformation easily occurs has an adverse effect on the stability of the shape in the multilayering process and the like, while the mechanical strength is inferior in the handling process such as the attaching and detaching operation of the multilayer wiring board. There is a problem that damage to the device or damage in the manufacturing process is caused. The liquid crystal polymer is
For example, it is a multiaxially oriented thermoplastic polymer represented by Xidal (trade name, manufactured by Dartco) and Vectra (trade name, manufactured by Clanese).

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has high practicability in which the structure of joining and integrating with an adhesive is omitted. It is an object of the present invention to provide a multilayer wiring board capable of transmitting electrical characteristics, particularly, high-speed signals without deteriorating, and a method for manufacturing the same.

[0009]

According to the present invention, there is provided a bismaleimide triazine resin-based insulating layer containing reinforcing fibers, and a liquid crystal laminated and integrated on both main surfaces of the insulating layer. A wiring board using a polymer as an interlayer insulating layer;
A multilayer wiring board, comprising: an interlayer connection portion that penetrates at least one of the insulator layers in a thickness direction and connects between wiring patterns of the wiring board.

According to a second aspect of the present invention, in the wiring board according to the first aspect, an interlayer connecting portion for connecting the wiring patterns is formed of a conductive bump penetrating an insulator layer.

According to a third aspect of the present invention, a wiring board having a wiring pattern formed on a surface of an insulating substrate made of a liquid crystal polymer is positioned and laminated on both principal surfaces of a bismaleimide triazine resin-based insulating substrate containing reinforcing fibers. A step of forming a connection between wiring patterns in which at least one layer of the insulating base is penetrated in a thickness direction. This is a method for manufacturing a wiring board. According to a fourth aspect of the present invention, a conductive metal foil provided with conductive bumps at at least one predetermined position is placed on both main surfaces of an insulator layer made of a liquid crystal polymer, and pressurized and heated to be integrated. Forming a double-sided conductive metal foil-clad board in which both conductive metal foils are electrically joined by conductive bumps penetrating the body layer; and A step of forming a wiring board by patterning the wiring, and a bismaleimide triazine resin containing reinforcing fibers between the two main faces of the two wiring boards facing each other, and in a thickness direction at a required location. A step of positioning and arranging and stacking an insulating substrate provided with an electrical interlayer connecting portion to be inserted, and a step of integrating the laminated body under pressure and heat, and a wiring pattern of both wiring boards via the insulating substrate. And a step of connecting between A method for manufacturing a multilayer wiring board to.

According to a fifth aspect of the present invention, a conductive metal foil provided with conductive bumps on at least one of predetermined positions is placed on both main surfaces of an insulator layer made of a liquid crystal polymer, and pressurized and heated integrally. Forming a double-sided conductive metal foil-clad board in which both conductive metal foils are electrically joined by conductive bumps penetrating the insulator layer; A step of forming a wiring board by patterning a metal foil, and positioning and arranging a bismaleimide triazine resin-based insulating substrate containing a reinforcing fiber between the main faces of the two wiring boards so as to face each other. A step of laminating, and a step of pressurizing and heating and integrating the laminate, and at the time of pressurizing and heating integration of the laminate, applying a conductive pump to the wiring pattern surface of at least one wiring board. Set it up,
A method for manufacturing a multilayer wiring board, characterized in that connection between opposed wiring patterns is performed by inserting the conductive pump through an insulating substrate.

In each of the above inventions, the liquid crystal polymer forming the outer insulating layer (insulating support) is represented by, for example, Xidal (trade name, manufactured by Dartco) and Vectra (trade name, manufactured by Clanese). A multiaxially oriented thermoplastic polymer having a thickness of about 25 to 100 μm. Here, the melting point of the liquid crystal polymer differs depending on the molecular structure, and the melting point varies depending on the crystal structure and the additive even with the same molecular structure. For example, Vectran A type (melting point, 285 ° C.), Vectran C type (melting point, 325 ° C.), BIAC film (melting point, 335 ° C.) and the like are exemplified.

[0014] The inner insulating layer may be a film-like material in which a reinforcing agent such as glass fiber or liquid crystal polymer fiber is impregnated and supported with bismaleimide triazine resin (BT) or a mixed resin mainly composed of BT. It is a sheet. And the film thickness is generally 25-100
It is about μm.

[0015] Each of the above-mentioned insulator layers may be formed by laminating a plurality of layers. That is, the outer insulating layer may be formed by combining the same or different liquid crystal polymer layers, and the inner insulating layer may be formed by combining the same or different insulating sheets.

In general, liquid crystal polymers have almost no hygroscopicity, a dielectric constant of about 3.0 (1 MHz), and are stable over a wide frequency range. Further, it is thermally deformed by a hot press at a high temperature of, for example, about 300 ° C., and is easily joined and integrated with a wiring pattern facing the liquid crystal layer. In this case, in the case of the roughened surface of the wiring pattern surface and the liquid crystal polymer surface, the fixation / integration becomes stronger.

In each of the above-mentioned inventions, the electrical connection between the wiring pattern layers is made by so-called perforation processing and making the inside of the perforations conductive (for example, formation of a plating layer, filling of a conductor).
For example, the following means may be used, but the following means are preferable. That is, a conductive bump is formed at a predetermined position on the wiring pattern surface (or a surface on which a wiring pattern is to be formed), and the other side of the wiring pattern that is insulated and separated by inserting an insulator layer at the tip of the conductive bump. By adopting a structure in which the wiring patterns are brought into contact with each other, the manufacturing process can be simplified, and furthermore, a fine and highly reliable connection between wiring pattern layers can be obtained.

The conductive bumps recommended for the connection between the wiring pattern layers can be arranged and formed by printing a conductive paste or the like. Here, examples of the conductive paste include pastes prepared by mixing a conductive powder such as silver, gold, copper, and solder powder, or an alloy powder or a composite (mixed) metal powder thereof with a resin binder component. No. Examples of the resin binder component include thermoplastic resins such as polycarbonate resin, polysulfone resin, polyester resin, and phenoxy resin, and thermosetting resins such as phenol resin, polyimide resin, melamine resin, and epoxy resin.

In each of the above inventions, the wiring pattern of the multilayer wiring board is generally formed by photo-etching a conductive metal foil of, for example, copper or aluminum having a thickness of about 5 to 35 μm. That is, a wiring pattern is formed by selective etching of the conductive metal foil adhered to the liquid crystal polymer film surface. Therefore, in general, the wiring pattern protrudes from the liquid crystal polymer film by the thickness thereof, but if this is pressed into the liquid crystal polymer film surface to make the liquid crystal polymer film flat with the flat surface, Not only is it easy to arrange and cover the film, but also because it forms a dense coating layer such as a pattern with no irregularities, it reduces the entrapment of voids and improves the reliability of the cover coat. The adhesion strength with respect to is improved. According to the first and second aspects of the present invention, the insulator layer supporting the outer wiring pattern is formed of a liquid crystal polymer, and no interposition of an adhesive layer is required. There will be no environmental issues. In other words, it is possible to provide a highly reliable wiring circuit having moisture resistance, high electrical insulation, and high-speed signal transmission stability, which are inherent features of the liquid crystal polymer.

According to the third to fifth aspects of the present invention, it is possible to provide a highly functionalized wiring circuit with high yield by utilizing the inherent characteristics of the liquid crystal polymer such as moisture resistance, high electrical insulation and high-speed signal transmission stability.

[0021]

1 and 2 (a), 2 (b) and 2 (c).
An example will be described with reference to FIG.

FIG. 1 is a sectional view showing the structure of a main part of a wiring board according to an embodiment. In FIG. 1, reference numeral 1 denotes a bismaleimide triazine film (BT film) having a thickness of about 60 μm.
... an insulator layer ... 2 is a wiring board having a liquid crystal polymer as an interlayer insulator layer 2a integrally disposed on one main surface side of the BT film 1, and 3 is also integrated on the other main surface side of the BT film Wiring board 4 in which a liquid crystal polymer arranged in an interposed manner is an interlayer insulating layer 3a, penetrates in the thickness direction of the insulating layers 1, 2a, 3a,
This is an interlayer connecting portion for connecting the wiring patterns 2b, 2c, 3b, 3c of the wiring board.

Here, the BT film 1 is a system in which bismaleimide triazine is impregnated and supported on glass fiber and has a thickness of
The interlayer insulating layers 2a and 3a are liquid crystal polymer films (insulating layers) having a melting point of 285 ° C. (or 325 ° C.) and a thickness of about 50 μm. Further, the wiring patterns 2b, 2c, 3b, 3c provided on both sides of the liquid crystal polymer films 2a, 3a have a thickness of 12 μm.
It is a wiring pattern made of electrolytic copper foil. The wiring boards 2 and 3 having these wiring patterns 2b and 2c or 3b and 3c are connected to the BT film (inner insulator ... support layer) 1
It is configured to be bonded and integrated with the surface by thermocompression bonding.
On the other hand, between the wiring patterns 2b and 2c, between 2c and 3c, or
The electrical connection part 4 between 3b and 3c is connected to each of the insulator layers 1 and 2
It is formed by conductive bumps penetrating a and 3a.

Next, FIG. 2 schematically shows the embodiment.
With reference to (a) to (C), a method for manufacturing the multilayer wiring board will be described.

First, an electrolytic copper foil 2c '(3b') having a thickness of 12 μm
Position and arrange the metal mask on one main surface, print the conductive paste, dry it, print the conductive paste at the same position using the same metal mask, repeat the drying, and repeat the cone to a height of about 200 μm. The mold conductive bump 4a was formed.
The metal mask is a stainless steel plate having a thickness of about 250 μm and a hole having a diameter of 250 μm is formed at a required position. The conductive paste is a conductive composition made of silver powder and epoxy resin.

Electrodeposited copper foil 2c '(3b') having conductive bumps 4a provided at required positions is provided with a thickness of 50 μm prepared in advance.
m on one side of the liquid crystal polymer film 2a (3a), the front end of the conductive bump is opposed to the other side, and the copper foil 2b '
(3c ') is arranged. In this state, a vacuum hot press is performed, and electrolytic copper foil 2c '(3b') or 2b '(3c') is crimped on both sides of the liquid crystal polymer film 2a (3a), and the conductive bumps 4a A double-sided copper foil-bonded sheet in which the electrolytic copper foils 2c 'and 2b' or 3c 'and 3b' were electrically connected was produced (see FIG. 2A).

Thereafter, the copper foil 2 of the double-sided copper foil-bonded sheet 2
A dry film type photosensitive resist is bonded to each of the c 'and 2b' (or 3c 'and 3b') surfaces, a wiring pattern film mask is positioned, an exposure process is performed, and then an etching process is performed to perform wiring patterning. Thus, a double-sided wiring type wiring board 2 (3) is manufactured (FIG. 2B).
reference). Here, a conductive bump 4a is formed on a surface of a required position of the wiring pattern 3c of one double-sided wiring type wiring board 3 in accordance with the formation of the conductive bump 4a.

Next, the BT prepared in advance is placed on the wiring board 3 on which the conductive bumps 4a are formed on the surface of the wiring pattern 3c.
The wiring board 2 is positioned, laminated and arranged via the film 1 and subjected to vacuum hot press processing (pressure bonding processing) to attach (join) and integrate the two wiring boards 2 and 3 to the BT film 1. The BT film 1 is inserted through and connected to the tip of the conductive bump 4a on the wiring pattern 3c side to the facing wiring pattern 2c side, thereby producing a multilayer wiring board as shown in FIG.

Incidentally, between the wiring patterns 2b and 2c, 2c and 3c
Instead of forming the electrical connection portion 4 between the conductive bumps 4a or 3b and 3c by penetrating the insulator layers 1, 2a and 3a at the tip of the conductive bump 4a, for example, an excimer laser is used and a selective laser is used. The hole may be formed by forming a through hole by light irradiation and growing a copper plating layer or the like on the inner wall surface of the through hole and the adjacent wiring pattern surface, or by filling a conductor.

In the method of manufacturing the multilayer wiring board, the copper foils 2c ', 2b', 3c ', 3 for the liquid crystal polymer layers 2a, 3a are formed.
b 'lamination, wiring board 2, 3 for BT film 1
In the bonding (joining / integration), heat bonding is performed using the properties of the liquid crystal polymer, so that a bonding adhesive is not required and the manufacturing process is greatly simplified. In addition, in the disposal of multilayer wiring boards, there is no generation of harmful substances including halogens and phosphorus by combustion, which is advantageous in terms of environmental hygiene and has a simple structure consisting of a combination of thermoplastic resin and metal. Another advantage is that resin and metal can be easily separated by heat melting, and the resin and metal can be separated and recycled.

The present invention is not limited to the above examples, and various changes can be made without departing from the gist of the invention. For example, the thickness of the inner insulating layer (insulating support), the thickness of the outer insulating layer (liquid crystal polymer layer), the material of the wiring pattern, the number of wiring pattern layers, the material for forming the conductive bumps, etc. It can be appropriately selected and used depending on the use and purpose.

[0032]

According to the first and second aspects of the present invention, since there is no need to interpose an adhesive layer, environmental problems caused by the flame retardant due to the inclusion of the adhesive layer can be solved. In addition, a highly reliable wiring board utilizing the inherent characteristics of the liquid crystal polymer such as moisture resistance and excellent high frequency characteristics is provided.

According to the third to fifth aspects of the present invention, a highly functional wiring board is provided while taking advantage of the inherent characteristics of a liquid crystal polymer such as moisture resistance and excellent high-frequency characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a main part of a multilayer wiring board according to an embodiment.

FIGS. 2A, 2B, and 2C are cross-sectional views illustrating an embodiment of a manufacturing process of a multilayer wiring board according to an example.

[Explanation of symbols]

 1 BT insulating layer 2, 3 Wiring board 2a, 3a Insulating layer 2b, 2c, 3b, 3c made of liquid crystal polymer Wiring pattern 4 Interlayer connection

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/46 H05K 1/11 H05K 3/40

Claims (5)

(57) [Claims] 1. A bismaleimide triazine resin-based insulating layer containing a reinforcing fiber, and a wiring board having a liquid crystal polymer laminated and integrated on both main surfaces of the insulating layer as an interlayer insulating layer. A multi-layer wiring board, comprising: an interlayer connecting portion that penetrates at least one of the insulator layers in a thickness direction and connects between wiring patterns of the wiring board. 2. The wiring board according to claim 1, wherein the interlayer connection for connecting the wiring patterns is formed of a conductive bump penetrating the insulator layer. 3. A step of positioning and laminating a wiring board having a wiring pattern formed on a surface of an insulating substrate made of a liquid crystal polymer on both principal surfaces of a bismaleimide triazine resin-based insulating substrate containing reinforcing fibers; A process for forming a connection between wiring patterns in which at least one layer of the insulating base is penetrated in a thickness direction, the method comprising the steps of: . 4. An insulating layer comprising a liquid crystal polymer, a conductive metal foil having conductive bumps provided on at least one predetermined position is placed on both main surfaces of the insulating layer, and pressurized and heated to be integrated. Forming a double-sided conductive metal foil-clad board in which both conductive metal foils are electrically joined by conductive bumps penetrating the wiring, and wiring patterning the conductive metal foil of the double-sided conductive metal-foiled board Forming a wiring board, and inserting a bismaleimide triazine resin containing reinforcing fibers between the two main faces of the two wiring boards in a thickness direction at a required position. Positioning and arranging and laminating an insulating substrate provided with an electrical interlayer connecting portion to be formed, and pressing and heating the laminated body, and connecting the wiring patterns of both wiring boards via the insulating substrate. And a step of connecting Of manufacturing a multilayer wiring board. 5. A conductive metal foil having conductive bumps provided on at least one predetermined position is placed on both main surfaces of an insulator layer made of a liquid crystal polymer, and pressurized and heated to be integrated. Forming a double-sided conductive metal foil-clad board in which both conductive metal foils are electrically joined by conductive bumps penetrating the wiring, and wiring patterning the conductive metal foil of the double-sided conductive metal-foiled board Forming a wiring board; and positioning and laminating a bismaleimide triazine resin-based insulating substrate containing reinforcing fibers between the two main faces of the two wiring boards. A step of pressurizing and heating the laminate, and at the time of pressurizing and heating the laminate, providing a conductive pump on the wiring pattern surface of at least one of the wiring boards. Insertion of conductive pump into insulating substrate Method for manufacturing a multilayer wiring board and performing more connections between the opposed wiring patterns.