JPH09289380A - Multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin the line width of wiring conductors and besides, make the diameter of through holes small, and wiring conductors above and below in high density, by forming organic resin insulating layers out of acid catalyst type photosensitive epoxy resin. SOLUTION: For an insulating substrate 1, a multilayer wiring consisting of an organic resin insulating layer 2 and a film wiring conductor 3 is arranged on the topside, and it works as a support member to support the multilayer wiring 4. Then, the organic resin insulating layer 2 of the multilayer wiring 4 consists of acid catalyst type of photosensitive epoxy resin, and paste-form acid catalyst type of photosensitive epoxy resin precursor is obtained by adding and mixing, for example, phenol novolak resin, etc., and also the acid catalyst type of photosensitive resin precursor is stuck in specified thickness to the top of the insulating substrate 1 by spin coating method or the like, and next this is exposed and developed to form a hole to serve as a through hole 5, and then, this is heated for 30-60min. at a temperature of 180 deg.C, and it is hardened completely, thus this is made.

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, and more particularly to a multilayer wiring board used for a hybrid integrated circuit device, a semiconductor element housing package for housing a semiconductor element, and the like.

[0002]

2. Description of the Related Art Conventionally, in a multilayer wiring board used for a hybrid integrated circuit device, a package for housing a semiconductor element, etc., its wiring conductor is formed by a thick film forming technique such as Mo--Mn method.

The Mo-M method is usually a screen-printing method in which a high-melting metal powder of tungsten, molybdenum, manganese or the like is mixed with an organic solvent and a solvent to form a paste-like metal paste on the outer surface of the green ceramic body. Is applied in a predetermined pattern by printing, and then a plurality of these are laminated and fired in a reducing atmosphere to sinter and integrate the high melting point metal powder and the green ceramic body.

Incidentally, the ceramic body on which the wiring conductor is formed is usually an oxide ceramic such as an aluminum oxide sintered body or a mullite sintered body, or an aluminum nitride having an oxide film adhered on the surface. Non-oxide ceramics such as a sintered compact or a silicon carbide sintered compact are used.

However, when the wiring conductor is formed by using this Mo-Mn method, the wiring conductor is formed by screen-printing a metal paste. Therefore, it is difficult to miniaturize the wiring conductor and the wiring conductor can be formed at a high density. It had the drawback of not being able to.

In order to solve the above-mentioned drawbacks, therefore, a multilayer wiring board is used which is formed at a high density by using a thin film forming technique capable of miniaturization instead of forming the wiring conductor by a conventional thick film forming technique. It's starting to happen.

A multilayer wiring board in which such a wiring conductor is formed by a thin film forming technique is generally a glass epoxy formed by impregnating a glass cloth woven with ceramics or glass fibers made of an aluminum oxide sintered body or the like into an epoxy resin. An insulating layer made of organic resin such as epoxy resin formed on the upper surface of an insulating substrate made of, for example, by spin coating and thermosetting, and a thin film forming technique such as electroless plating or vapor deposition of metal such as copper or aluminum And a thin film wiring conductor formed by adopting a photolithography technique are alternately laminated.

In this multilayer wiring board, the thin film wiring conductors arranged between the laminated organic resin insulating layers are electrically connected to each other through the through holes formed in the organic resin insulating layer. The through holes are formed in the organic resin insulating layer by first applying a resist material on each organic resin insulating layer and exposing and developing the resist material to form a window portion of a predetermined shape at a predetermined position, and then the resist is formed. Disposing the etching solution in the window of the resist material, removing the organic resin insulating layer located in the window of the resist material, forming a hole (through hole) in the organic resin insulating layer, and finally applying the resist material to the organic resin. It is carried out by peeling and removing from the insulating layer.

[0009]

However, in this multilayer wiring board, the organic resin insulating layer is formed of a thermosetting epoxy resin, and when a through hole is formed in the organic resin insulating layer, the final result is Requires a separate resist material to be peeled off and must be applied on the organic resin insulation layer, and the resist material to be finally removed is required for forming the through holes, and many operations are required. This requires a process, which causes a drawback that the multilayer wiring board as a product becomes expensive.

In view of the above drawbacks, an epoxy resin to be an organic resin insulating layer is made photosensitive, and the photosensitive epoxy resin is exposed and developed to form a through hole directly in the organic resin insulating layer. It is also possible.

However, the generally used photosensitive epoxy resin is an epoxy acrylic or acrylic resin, and has functional groups such as acryloyl group and acrylic group inside thereof, and these functional groups are ultraviolet rays. It cures by radical polymerization reaction by the energy of the ultraviolet ray, and in the curing by the radical polymerization reaction of the functional group such as acryloyl group and acryl group by the energy of the ultraviolet ray, the epoxy resin precursor is cured from the surface side irradiated with the ultraviolet ray. As a result, a difference in refractive index occurs at the boundary between the cured epoxy resin and the uncured epoxy resin, and as a result, ultraviolet ray diffraction, refraction, and reflection occur largely in the epoxy resin during curing, resulting in good pattern contrast. Therefore, the photosensitive epoxy resin precursor should be applied on the insulating substrate and When exposed, to form a through hole by performing development processing, the limit of the exposure resolution is about 10
The diameter is 0 μm, which causes a drawback that a through hole having a small diameter cannot be formed.

[0012]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and its object is to reduce the line width of the wiring conductor and to make the diameter of the through hole as small as about 30 μm. An object of the present invention is to provide an inexpensive multilayer wiring board that can be vertically wired with high density.

According to the present invention, the organic resin insulating layers and the thin film wiring conductors are alternately laminated on the substrate and the thin film wiring conductors located above and below are electrically connected through the through holes provided in the organic resin insulating layer. A multilayer wiring board obtained by the above, wherein the organic resin insulating layer is formed of an acid catalyst type photosensitive epoxy resin.

Further, the present invention is characterized in that each of the laminated organic resin insulating layers has a thickness of 5 μm to 100 μm.

Further, according to the present invention, the upper surface of each of the laminated organic resin insulating layers has a center line average roughness (Ra) of 0.05 μm.
m ≦ Ra ≦ 5 μm.

According to the multilayer wiring board of the present invention, since the wiring conductor is formed by the thin film forming technique, the wiring can be miniaturized, and the thin film wiring conductor can be formed with extremely high density. According to the multilayer wiring board of the present invention,
Since the organic resin insulating layer is formed of an acid catalyst type photosensitive epoxy resin, and the acid catalyst type photosensitive epoxy resin has a resolution of about 30 μm during exposure, the organic resin insulating layer has a fine diameter of about 30 μm. Through holes can be formed, which makes it possible to reliably electrically connect fine thin film wiring conductors arranged above and below.

Further, according to the multilayer wiring board of the present invention, since the organic resin insulating layer is formed of the acid catalyst type photosensitive epoxy resin, each organic resin insulating layer is exposed to the precursor thereof and developed to form a resist material. Directly without using
The through hole can be formed, the resist material is not required, and the through hole can be easily formed in the organic resin insulating layer, and the multilayer wiring board as a product can be made inexpensive.

Furthermore, according to the multilayer wiring board of the present invention,
When the upper surface of each of the laminated organic resin insulating layers is set to have a center line average roughness (Ra) of 0.05 μm ≦ Ra ≦ 5 μm, the upper and lower organic resin insulating layers to be laminated can be bonded very strongly, As a result, the function of the multilayer wiring board can be maintained for a long period of time.

[0019]

Next, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the multilayer wiring board of the present invention, in which 1 is an insulating substrate, 2 is an organic resin insulating layer, and 3 is a thin film wiring conductor.

On the upper surface of the insulating substrate 1, a multilayer wiring 4 composed of an organic resin insulating layer 2 and a thin film wiring conductor 3 is arranged, and it functions as a supporting member for supporting the multilayer wiring 4.

The insulating substrate 1 is an oxide ceramic such as an aluminum oxide sintered body or a mullite sintered body, or an aluminum nitride sintered body having an oxide film on its surface.
It is made of a non-oxide ceramic such as a silicon carbide sintered body, and an electrically insulating material such as a glass epoxy resin obtained by impregnating a cloth woven with glass fiber with an epoxy resin. For example, an aluminum oxide sintered body. In the case of being formed of, alumina (Al ₂ O ₃ ) and silica (Si
O ₂ ), calcia (CaO), magnesia (MgO), and other raw material powders are mixed with an appropriate organic solvent and solvent to form a slurry, which is then applied by the well-known doctor blade method or calendar roll method. To form a ceramic green sheet (ceramic green sheet), and then subject the ceramic green sheet to an appropriate punching process to form a predetermined shape and a high temperature (about 160).
(0 ° C.) or by mixing a raw material powder such as alumina with an appropriate organic solvent and solvent to prepare the raw material powder, and molding the raw material powder into a predetermined shape by a press molding machine, and finally It is manufactured by firing the molded body at a temperature of about 1600 ° C.

On the upper surface of the insulating substrate 1, the organic resin insulating layers 2 and the thin-film wiring conductors 3 are alternately arranged in multiple layers and the multilayer wiring 4 is applied. The resin insulation layer 2 serves to electrically insulate the thin film wiring conductors 3 located above and below, and the thin film wiring conductor 3 also serves as a transmission path for transmitting an electric signal.

The organic resin insulation layer 2 of the multi-layer wiring 4 is made of an acid-catalyzed photosensitive epoxy resin. For example, phenol novolac resin, methylol melamine, diallyl diazonium salt is added and mixed with propylene glycol monomethyl ether acetate to form a paste. A photosensitive acid-catalyst-type photosensitive epoxy resin precursor is obtained, and the acid-catalyst-type photosensitive epoxy resin precursor is applied to the upper portion of the insulating substrate 1 by a spin coating method or a doctor blade method to a predetermined thickness. Then, this is subjected to predetermined exposure with an energy of 1 to ³ J / cm ³ by an exposing machine using a high-pressure mercury lamp and is developed with a spray developing machine to form a hole to be a through hole 5 which will be described later. It is formed by heating it at a temperature of 180 ° C. for 30 to 60 minutes to completely cure it.

Further, the organic resin insulating layer 2 of the multi-layered wiring 4 has through holes 5 formed at respective predetermined positions, and the through holes 5 are thin film wiring conductors which are vertically arranged with the organic resin insulating layer 5 interposed therebetween. , And each of them acts as a connection path for electrically connecting them.

Since the organic insulating resin layer 2 is formed of an acid catalyst type photosensitive epoxy resin, the through hole 5 is applied to the upper part of the insulating substrate 1 when the organic resin insulating layer 2 is formed. The resist material for directly forming the through hole 5 in the organic resin insulating layer 2 by exposing and developing the acid-catalyzed photosensitive epoxy resin precursor is prepared separately. There is no need at all, which makes it possible to easily form the through holes 5 in the organic resin insulating layer 2 and to make the multilayer wiring board as a product inexpensive.

Further, a thin film wiring conductor 3 having a predetermined pattern is provided on the upper surface of each organic resin insulating layer 2, and each thin film wiring conductor 3 located above and below with the organic resin insulating layer 2 interposed therebetween. Each is electrically connected through a thin film wiring conductor 3 arranged in a through hole 5 formed in the organic resin insulating layer 2.

The thin film wiring conductors 3 disposed on the upper surface of each organic resin insulating layer 2 and the through holes 5 are made of a metal material such as copper, nickel, gold, aluminum, etc. by electroless plating, vapor deposition, sputtering or the like. Is formed by adopting the thin film forming technology and the etching processing technology, and when it is made of copper, 0.06 mol / liter of copper sulfate is formed on the upper surface of the organic resin insulating layer 2 and the inner surface of the through hole 5. , Formalin 0.3 mol / l, sodium hydroxide 0.35 mol / l, ethylenediaminetetraacetic acid 0.35 mol / l, using an electroless copper plating bath to deposit a copper layer having a thickness of 1 μm to 40 μm. Thereafter, the copper layer is processed into a predetermined pattern by an etching processing method so as to be disposed between the organic resin insulating layers 2. In this case, since the thin-film wiring conductor 3 is formed by a thin-film forming technique, the wiring can be miniaturized, whereby the thin-film wiring conductor 3 can be formed at an extremely high density.

The thin film wiring conductors 3 disposed between the organic resin insulating layers are electrically connected to each other through the through holes 5 provided in the organic resin insulating layer 2. The organic insulating resin layer 2 is formed of an acid catalyst type photosensitive epoxy resin, and when the acid catalyst type photosensitive epoxy resin is first irradiated with ultraviolet rays to the acid catalyst type epoxy resin precursor, the precursor becomes Although it does not cure, a catalytic substance such as Lewis acid having a catalytic action for promoting the polymerization reaction of the epoxy resin precursor by heat is formed in the epoxy resin precursor by the energy of ultraviolet rays, and when heat is applied to the catalyst substance, The epoxy resin precursor, on which the catalyst substance is formed by heat energy, undergoes a polymerization reaction due to the catalytic action of the catalyst substance and is thermally cured. Since the curing does not occur when the catalyst substance is formed on the body, the diffraction, refraction and reflection of ultraviolet rays do not occur largely in the acid catalyst type epoxy resin precursor, and therefore the catalyst substance is sharp in the epoxy resin precursor. When a catalyst is formed with a high contrast pattern and is hardened by heat, only the portion where the catalyst substance is formed with the sharp contrast pattern is polymerized and hardened by heat under the catalytic action of the catalyst substance. When the mold-type photosensitive epoxy resin precursor is subjected to exposure heating treatment, the resolution is set to about 30 μm and the diameter of the through hole 5 is set to about 30
As a result, the fine thin film wiring conductors 3 vertically arranged with the organic resin insulating layer 2 interposed therebetween are surely electrically connected through the through holes 5 which are also finely formed. It becomes possible to make a physical connection.

The multilayer wiring 4 formed by alternately arranging the organic resin insulating layers 2 and the thin film wiring conductors 3 in multiple layers has the center line average roughness (Ra) on the upper surface of each organic resin insulating layer 2. With a rough surface of 0.05 μm ≦ Ra ≦ 5 μm, the organic resin insulating layer 2 and the thin film wiring conductor 3 can be joined firmly and the organic resin insulating layers 2 located above and below can be firmly joined. Therefore, each organic resin insulating layer 2 of the multi-layer wiring 4 is roughened by spraying a gas such as CHF ₃ , CF ₄ , Ar or the like on its upper surface to perform a reactive ion etching process to obtain the center line average roughness (Ra). ) Is 0.05 μm ≦ Ra ≦
It is preferable to have a rough surface of 5 μm.

When the organic resin insulating layer 2 has a thickness of more than 100 μm, the photosensitive epoxy resin precursor is exposed and developed to form through-holes, and the holes are made clear. There is a risk that it becomes difficult to form the predetermined through holes 5 in the organic resin insulating layer 2, and if it is less than 5 μm, it will be positioned above and below the upper surface of the organic resin insulating layer 2. When roughening the organic resin insulating layer 2 to increase the bonding strength, unnecessary holes are formed in the organic resin insulating layer 2 and an unnecessary electrical short circuit is caused in the upper and lower thin film wiring conductors 3. There is a risk. Therefore, it is preferable that the thickness of each of the organic resin insulating layers 2 is in the range of 5 μm to 100 μm.

Further, when the thickness of each thin film wiring conductor 2 of the multilayer wiring 4 is less than 1 μm, the electric resistance of each thin film wiring conductor 3 becomes large and a predetermined electric signal is transmitted to each thin film wiring conductor 3. If the thickness exceeds 40 μm, the thin-film wiring conductors 3 are connected to the organic resin insulation layer 2
When adhered to, the large stress is internally present in the thin film wiring conductor 3, and the thin film wiring conductor 3 is easily separated from the organic resin insulating layer 2 due to the inherent stress. Therefore, it is preferable that the thickness of each thin-film wiring conductor 2 of the multilayer wiring 4 be in the range of 1 μm to 40 μm.

[0033]

According to the multilayer wiring board of the present invention, since the wiring conductor is formed by the thin film forming technique, the wiring can be miniaturized, and the thin film wiring conductor can be formed with extremely high density. Further, according to the multilayer wiring board of the present invention, the organic resin insulating layer is formed of an acid catalyst type photosensitive epoxy resin, and the acid catalyst type photosensitive epoxy resin has a resolution at the time of exposure of about 30 μm. It is possible to form fine through holes having a diameter of about 30 μm in the organic resin insulating layer, which makes it possible to reliably electrically connect fine thin film wiring conductors arranged above and below.

Further, according to the multilayer wiring board of the present invention, since the organic resin insulating layer is formed of the acid catalyst type photosensitive epoxy resin, each organic resin insulating layer is subjected to exposure and development of its precursor to form a resist material. Directly without using
The through hole can be formed, the resist material is not required, and the through hole can be easily formed in the organic resin insulating layer, and the multilayer wiring board as a product can be made inexpensive.

Furthermore, according to the multilayer wiring board of the present invention,
When the upper surface of each of the laminated organic resin insulating layers is set to have a center line average roughness (Ra) of 0.05 μm ≦ Ra ≦ 5 μm, the upper and lower organic resin insulating layers to be laminated can be bonded very strongly, As a result, the function of the multilayer wiring board can be maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view showing one embodiment of a multilayer wiring board of the present invention.

[Explanation of symbols]

 1 ... Insulating substrate 2 ... Organic resin insulating layer 3 ... Thin film wiring conductor 4 ... Multilayer wiring 5 ... Through hole 6 ... Groove

Claims (3)

[Claims] 1. An organic resin insulating layer and a thin film wiring conductor are alternately laminated on a substrate, and the upper and lower thin film wiring conductors are electrically connected through through holes provided in the organic resin insulating layer. A multilayer wiring board comprising the organic resin insulation layer formed of an acid catalyst type photosensitive epoxy resin. 2. The multilayer wiring board according to claim 1, wherein the thickness of each of the stacked organic resin insulating layers is 5 μm to 100 μm. 3. An upper surface of each of the laminated organic resin insulating layers has a center line average roughness (Ra) of 0.05 μm ≦ Ra ≦ 5.
The multilayer wiring board according to claim 1, wherein the thickness is μm.