JPH09307230A - Printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the positional accuracy facilitate forming conductive bumps of very small sizes by forming the bumps by the photographic method. SOLUTION: An electrolytic Cu foil is used for a support base 1. A photosensitive resin component-contained Ag paste is applied to a rough surface of the Cu foil to form a bump-forming compd. layer 11, and it is dried until tack disappears. A film 12 impermeable to light, except a bump forming area, is laid on the Ag paste being tack-free, exposed and developed to remove undesired Ag paste to form conductive bumps on a board. A synthetic resin sheet 3 is prepared, faced at the bumps 2 and primarily pressed to pierce the bumps 2 through the sheet, and the electrolytic Cu foil 4 is laid on the pierced surface and secondarily pressed through press plates 5. Since the bumps are formed by the photographic method, their positional accuracy is very high. Thus it is possible to improve the positional accuracy and facilitates forming the very small size bumps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a method for manufacturing the same, and in particular, it has a structure in which wiring layers are connected by a penetrating conductor wiring portion and enables high-density wiring and mounting. A highly reliable printed wiring board is provided, and the manufacturing method thereof is a method which can be manufactured reasonably with a good yield.

[0002]

2. Description of the Related Art In a two-layer or multi-layer printed wiring board, electrical connection between wiring layers such as double-sided conductive patterns is required.
It is done as follows. That is, in a two-layer printed wiring board, perforation processing is performed at a predetermined position of a double-sided copper clad laminate, and electroless and electrolytic plating processes are performed on the entire surface including the inside of the hole to thicken the metal layer on the inner wall surface of the hole. The electrical connection is made between wiring layers with improved reliability of conduction. In the case of a multilayer printed wiring board, after patterning the copper foils stretched on both sides of the substrate, copper foils are laminated and arranged on the patterned surfaces via an insulating sheet and integrated by heating and pressing. After that, similarly to the above-mentioned two-layer printed wiring board, electrical connection between wiring layers by drilling and plating, and patterning of the surface copper foil are performed to obtain a multilayer printed wiring board. In manufacturing the printed wiring board,
As a means for electrically connecting the wiring layers without using a plating method, holes are formed at predetermined positions on the double-sided copper-clad laminate, and a conductive paste or the like is poured into the holes and cured to electrically connect the wiring layers. The method is also done.

[0003]

As described above, in a method of manufacturing a printed wiring board using a plating method for electrical connection between wiring layers, a copper clad laminate is punched for electrical connection between wiring layers. However, there is a drawback in that a plating process including the inner wall of the hole is required and the manufacturing process of the printed wiring board is complicated. On the other hand, a method of embedding a conductive paste in a hole for electrical connection between wiring layers by printing or the like also requires a hole forming step as in the case of the plating method. Moreover, it is particularly difficult to pour the conductive paste or the like into the holes even if the hole diameter is small, and there is a problem in reliability. In any case, the necessity of the perforating step is reflected in the cost, yield, etc. of the printed wiring board, and there is a drawback that the demand for cost reduction cannot be met.

Further, according to the above-mentioned conventional method, since conductor holes for connecting wiring layers are provided on the front and back surfaces of the printed wiring board, wiring cannot be formed and components cannot be mounted in that area. There is a problem that the improvement of the density is restricted and the improvement of the mounting density of components is also hindered. With the miniaturization and weight reduction of electronic devices, high density wiring of printed wiring boards by the conventional method,
It cannot be said that high-density mounting is sufficient, and a more effective printed wiring board and its manufacturing method are desired. The present invention has been made to address these situations,
It is a reliable printed wiring board capable of high-density wiring and mounting by a simple process, and is a method of manufacturing this with a high yield.

[0005]

According to the present invention, there is provided a step of placing a synthetic resin sheet on a main surface of a supporting substrate having a group of conductor bumps formed at predetermined positions so as to be in contact with each other, and laminating the synthetic resin sheet. Primary heating and pressurizing of the stacked sheets arranged to penetrate and expose the tip of the bump group in the thickness direction of the synthetic resin sheet, and a conductive metal foil is laminated on the penetrated and exposed surface of the tip of the conductor bump group. A step of arranging, and a step of secondarily pressing the laminated body in which the conductive metal foils are laminated and connecting the tip of the bump group to the surface of the conductive metal foil by plastic deformation to form a through conductor wiring portion. In the method for manufacturing a printed wiring board, including the step of forming a pattern for connecting to the through-type conductor wiring portion by etching on the conductive metal foil of the laminated body on which the through-type conductor wiring portion is formed, Copy the bump A method for manufacturing a printed wiring board, which comprises forming at law. Further, the present invention is a conductor bump group formed on a supporting substrate, wherein the conductor bump group is formed on the supporting substrate by a photographic method. Further, the present invention uses a conductor bump group formed on a supporting substrate, characterized in that the conductor bump group is formed on the supporting substrate by a photographic method. It is a printed wiring board.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the supporting substrate forming the conductor bump group is, for example, a synthetic resin sheet or a conductive sheet (foil) having good peelability, a synthetic resin sheet to which a conductive sheet is attached, or the like. There is. The support substrate may be a single sheet or a patterned one, and is not particularly limited.

In the present invention, the conductor bump group may be formed not only on one main surface of the supporting substrate but also on both main surfaces. In the present invention, the conductor bumps are hard enough to be penetrated through the synthetic resin sheet or the like in the heating and pressing in the state where the resin content of the synthetic resin sheet is in the plastic state or the glass transition temperature or more, that is, in the primary pressing step. In the second pressurizing step, the tip end is plastically deformed and the joined state with the conductive metal foil which is in contact is completed.

In the present invention, the conductor bump is formed on the supporting substrate by a photographic method. That is, the bump-forming composition is applied to the surface (one surface or both surfaces) of the supporting substrate on which the conductor bumps are formed, and the composition is dried to obtain a tack-free state. The method of applying the liquid bump-forming composition onto the supporting substrate is not particularly limited, and examples thereof include a roll coater, a dip coater, a curtain coater, and screen printing. There is also a method in which the bump-forming composition is formed into a sheet shape in advance like a dry film which is usually used for an etching resist or the like and is laminated. The composition for bump formation on the supporting substrate formed by such a method is exposed by irradiating ultraviolet rays or the like only to the portion where the conductive bump is formed. Next, development work is carried out with an alkaline aqueous solution such as sodium carbonate or a solvent such as chlorine to remove the unirradiated portion of the unnecessary bump-forming composition. Then, if necessary,
In some cases, heating is performed to cure the thermosetting component.

The conductor bump group consisting of the conductor bumps formed by such a method has extremely good positional accuracy and is easy to form a conductor bump group having a minute diameter by using a photographic method. It is effective for forming a high-density wiring board. In addition, since it is easy to secure the positional accuracy as described above, it is possible to increase the plate size for the working work, which also contributes to the improvement of working efficiency.

In the present invention, the conductor bumps are silver, gold,
It is composed of a conductive composition such as copper, solder or the like, an alloy or a mixed powder thereof, and a binder composition such as a polyimide resin, a phenol resin or a polyester resin, or a conductive metal.

In the present invention, the resin component as a constituent component of the conductor bump contains one having a functional group capable of being exposed to light and developed by a photographic method. Although not particularly limited, for example, a half-esterified compound obtained by esterifying a styrene-maleic anhydride copolymer with a monomer having at least one hydroxyl group and at least one (meth) acroyl group in one molecule. A resin composition or the like composed of a saturated polymer having a carboxyl group is preferable. In the present invention, the height of the conductive bump is not particularly limited, but is generally about 0.1 to 0.4 mm.

In the present invention, the synthetic resin sheet that penetrates the conductor bump group and forms the through-type conductor wiring portion is, for example, a thermoplastic sheet and has a thickness of 0.05 to 0.
8 mm is common. Here, examples of the thermoplastic sheet include polycarbonate resin, thermoplastic polyimide resin, and polyether ether ketone resin. The B-stage thermosetting resin sheet includes epoxy resin, polyimide resin, phenol resin, bismaleimide triazine resin and the like. These synthetic resins may be used alone or may contain an insulating inorganic material or an organic filler, and are a prepreg-based sheet formed by combining with a reinforcing material such as glass cloth, mat, organic synthetic fiber cloth or mat, or paper. May be.

In the present invention, the shape of the conductor bump group formed on the supporting substrate is not particularly limited.

In the present invention, in the primary pressing step, a roller of heatable metal, heat resistant resin, ceramic or the like, and a roller which elastically deforms when pressed, for example, rubber of butadiene or neoprene, A method of passing between rollers made of polytetrafluoroethylene resin or the like is preferable.

In the present invention, when the pressed body is arranged on the synthetic resin sheet side (the side opposite to the supporting substrate on which the conductor bump group is formed) in the primary pressurizing step, the tip of the conductor bump group can be more easily and securely formed. It is possible to penetrate the synthetic resin sheet. The material is not particularly limited, but for example, a silicon film or the like is used.

In the present invention, it is general to use a hydraulic type multi-stage vacuum press or an autoclave type fresh air press in the secondary pressurizing step.

According to the method of manufacturing a printed wiring board of the present invention, the conductive bumps are formed on the supporting substrate while ensuring excellent positional accuracy by the photographic method, and the wiring bumps are electrically connected to each other. In the conductor wiring portion, the tip of the conductor bump firstly and accurately penetrates a predetermined position of the synthetic resin sheet forming the interlayer insulating layer with high accuracy by the primary pressure in the so-called laminated integration process, and the secondary addition is performed. Under pressure, plastic deformation easily occurs due to plasticization of the synthetic resin sheet and pressure contact of the tip of the conductor bump to the surface of the conductive metal foil, and reliable lamination integration and reliable electrical connection between wiring layers The connection is achieved. That is, by simplifying the process, it is possible to form a highly accurate and reliable electrical connection between fine wiring layers at any position, and it is possible to manufacture a high-density printed wiring board at low cost. Become. Further, it is not necessary to form a connection hole for electrical connection between the wiring layers, and accordingly, high-density wiring and high-density mounting can be realized.

[0018]

EXAMPLES Examples will be described below with reference to the drawings. 0.
A photosensitive resin component such as a compound obtained by esterifying a styrene-maleic acid copolymer with polyimide as a binder using a compound having a hydroxyl group and an acroyl group and a compound having a carboxyl group, using an electrolytic copper foil of 018 mm as the supporting substrate 1. The silver paste was used as a layer 11 of the bump-forming composition applied to the roughened surface of the copper foil with a roll coater and dried to a tack-free state (FIG. 1). A film (exposure film for forming bumps) 12 formed so that only the bump forming portion transmits light is placed on the tack-free silver paste (Fig. 2), exposed, and developed with sodium carbonate. Unnecessary silver paste was removed, conductor bumps 2 were formed on the substrate, and then heat-cured (FIG. 3).

The diameter of the conductor bump 2 formed here is 0.
3 mm (15), 0.2 mm (14), 0.1 mm (1
There are three types, 3), but all could be formed without any problem (FIG. 7).

On the other hand, a polyetherimide resin sheet having a thickness of 0.15 mm is prepared as the synthetic resin sheet 3,
The conductor bump was passed through a roller composed of a metal roller and a flexible rubber roller heated to 250 ° C. so as to face the formed conductor bump, and the conductor bump was penetrated (FIG. 4). Next, a 0.018 mm electrolytic copper foil (conductive metal foil) 4 is placed on the surface through which the conductor bumps penetrate, a contact plate 5 is placed (Fig. 5), and a hydraulic die press is used at 270 ° C and 50 kg / cm ² for 6 times.
Secondary pressure was applied for 0 min. As a result, a double-sided copper clad laminate for a printed wiring board having a conductor wiring portion 6 penetrating was obtained (FIG. 6). A conductor circuit was formed on the surface of these also by an etching method to obtain a two-layer printed wiring board. An electrical inspection, which is usually performed by inspecting a printed wiring board, was applied to this, but there was no problem in electrical connection, and there was no problem in reliability in a solder heat resistance test at 288 ° C. for 60 seconds.

[0021]

According to the present invention, it is possible to provide a two-layer printed wiring board or a multilayer printed wiring board having a high connection reliability and high density, and a manufacturing method thereof, while simplifying the manufacturing process of the printed wiring board. . Particularly in the case of a multilayer printed wiring board having a long process, the process is greatly simplified and the productivity is greatly improved. Further, the hole-drilling plating step in the conventional method is not necessary, and defects occurring in the manufacturing process can be reduced.
Further, since the printed wiring board of the present invention has no interlayer connection hole,
The wiring density can be significantly improved, and the component mounting density can also be expected to be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a stage in which a bump-forming composition is applied to a supporting substrate and dried to make it tack-free.

FIG. 2 is a view showing a state where a bump forming composition is applied to a supporting substrate, dried and tack-free, and a film formed so that light is transmitted only through a bump forming portion is applied with the bump forming composition. Sectional view of the stage

FIG. 3 is a sectional view showing a stage in which a conductor bump group is formed on a support base.

4] A synthetic resin sheet is passed through a roller made of a metallic and flexible material so as to face the conductor bump group side of the supporting substrate having the conductor bump group formed in FIG. Sectional view showing steps

5 is a plan view of the synthetic resin sheet formed in FIG. 4 and a support substrate having a conductor bump group, which is first pressed, and a conductive metal foil is arranged on a surface through which the bumps penetrate, a contact plate is arranged, and a secondary application is performed. Cross section of the stage of applying pressure

FIG. 6 is a cross-sectional view of a laminated plate having a through conductor wiring portion formed by secondarily pressing the one in the stage of FIG. 4;

FIG. 7 is a cross-sectional view showing bumps having different diameters formed on a support base.

[Explanation of symbols]

 1 Support Substrate 2 Conductor Bump 3 Synthetic Resin Sheet 4 Conductive Metal Foil 5 Touch Plate 6 Penetrating Conductor Wiring Part 11 Bump Forming Composition (Applicable to Photographic Method) 12 Bump Forming Exposure Film 13 Conductor Bump ( Diameter 0.1mm) 14〃 (〃 0.2mm) 15〃 (〃 0.3mm)

Claims (3)

[Claims] 1. A step of laminating and placing a synthetic resin sheet on a main surface of a supporting substrate on which a group of conductor bumps are formed at predetermined positions, and a step of laminating a synthetic resin sheet on the laminated body. Next, heating and pressurizing to penetrate and expose the tip of the bump group in the thickness direction of the synthetic resin sheet; piercing the tip of the conductor bump group and placing a conductive metal foil on the exposed surface; 2 layers of laminated metal foil
Next, a step of applying pressure to connect the tip of the bump group to the surface of the conductive metal foil by plastic deformation to form a through-type conductor wiring portion; and a conductive metal foil of a laminated body on which the through-type conductor wiring portion is formed. In a method of manufacturing a printed wiring board, which comprises a step of forming a pattern for connecting to the through-type conductor wiring portion by etching, a method of manufacturing the printed wiring board, wherein the conductor bump is formed by a photographic method. Method. 2. A conductor bump group formed on a supporting substrate, wherein the conductor bump group is formed on the supporting substrate by a photographic method. 3. A conductor bump group formed on a supporting substrate, wherein the conductor bump group is formed on the supporting substrate by a photographic method. Printing using the conductor bump group formed on the supporting substrate. Wiring board.