JPH1174649A - Wiring board and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: A surface wiring conductor made of a metal foil is peeled off from an insulating base, and moisture penetrates between the two to make electrical connection uncertain, so that a semiconductor element to be mounted can be normally used for a long time. Cannot operate stably. SOLUTION: An internal wiring conductor is formed on a surface of an insulating substrate 1 in which an inorganic insulating powder is bonded with a bismaleimide triazine resin and an internal wiring conductor 2 formed by bonding a metal powder with a thermosetting resin is embedded therein. 2 is a wiring board in which surface wiring conductors 3a and 3b made of metal foil electrically connected to 2 are fixed via epoxy resin adhesive layers 6a and 6b. The bonding between the insulating base 1 and the surface wiring conductors 3a and 3b is strengthened, and the infiltration of moisture from between them is effectively prevented, and the electrical connection between the surface wiring conductors 3a and 3b and the internal wiring conductor 2 is made. Will not be uncertain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board used for a package for housing a semiconductor element for housing a semiconductor element or a hybrid integrated circuit board.

[0002]

2. Description of the Related Art Conventionally, a wiring board, for example, a wiring board used for a semiconductor element housing package for housing a semiconductor element is made of ceramics such as an aluminum oxide sintered body, and a mounting portion for mounting the semiconductor element on an upper surface thereof. And a wiring conductor made of a refractory metal metallization such as tungsten or molybdenum led out from the mounting portion or the vicinity of the mounting portion to the lower surface of the insulating substrate on the upper surface of the insulating substrate. The semiconductor element is mounted on the substrate and each electrode of the semiconductor element is electrically connected to a wiring conductor led out on the upper surface of the insulating base via an electrical connection means such as a solder bump or a bonding wire.
A lid made of metal, ceramics, etc. is bonded to the upper surface of the insulating base via a sealing material such as glass, resin, brazing material, etc. so as to cover the semiconductor element, and the semiconductor element is housed in a gas-tight manner as a product. It becomes a semiconductor device. And
Each electrode of the semiconductor element is electrically connected to the external electric circuit board by connecting a portion of the wiring conductor extending to the lower surface of the insulating base to the wiring conductor of the external electric circuit board.

[0003] This conventional wiring board is manufactured by a ceramic green sheet laminating method. Specifically, an appropriate organic binder or solvent is added to a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide or calcium oxide. A plurality of ceramic green sheets are obtained by mixing and forming a slurry into a sheet shape by employing a well-known doctor blade method, and thereafter, these ceramic green sheets are subjected to an appropriate punching process. A metal paste to be a wiring conductor is printed and applied in a predetermined pattern, and finally, these ceramic green sheets are stacked up and down in a predetermined order to form a green ceramic molded body and fired at a high temperature of about 1600 ° C. in a reducing atmosphere. Produced by

However, in the conventional wiring board, since ceramics such as an aluminum oxide sintered body constituting the insulating base have a hard and brittle property, the wiring boards are not connected to each other in a transfer process or an automatic line for manufacturing semiconductor devices. If the wiring board and a part of the automatic semiconductor device manufacturing line collide violently, the insulating substrate may be chipped, cracked, cracked, etc., and as a result, the semiconductor element cannot be housed in a gas-tight manner, and the length of the semiconductor element cannot be increased. There was a disadvantage that normal and stable operation could not be achieved over a period of time.

Further, according to this conventional method for manufacturing a wiring board, when the green ceramic molded body is fired, uneven firing shrinkage occurs in the green ceramic molded body, and the resulting wiring board has deformation such as warpage. Dimensional variations occur, and as a result,
There is a disadvantage that it is difficult to electrically and accurately connect the semiconductor element and the wiring conductor with each other.

Therefore, the insulating substrate of the wiring substrate is formed by laminating an insulating substrate made of a material obtained by bonding inorganic insulating powder with a thermosetting resin in place of conventional ceramics, and the wiring conductor is made of conventional tungsten or tungsten. There has been proposed a wiring board formed of a material obtained by bonding a metal powder such as copper with a thermosetting resin in place of a metal having a high melting point such as molybdenum.

A wiring board composed of an insulating base obtained by laminating an insulating substrate formed by bonding the inorganic insulating powder with a thermosetting resin and a wiring conductor formed by bonding a metal powder with a thermosetting resin is a thermosetting resin. A plurality of semi-cured precursor sheets prepared by mixing a resin precursor and an inorganic insulating powder are prepared and subjected to an appropriate punching process, and then these precursor sheets are mixed with a thermosetting resin precursor. A metal paste mixed with a metal powder is printed and applied in a predetermined pattern. Finally, a precursor sheet on which the metal paste is printed and applied is laminated, and a temperature of about 150 to 300 ° C. and about 4 to 100 kgf /
It is manufactured by hot pressing at a pressure of cm ² and heat curing.

According to this wiring board, the inorganic insulating powder serving as the insulating substrate and the metal powder serving as the wiring conductor are bonded by a thermosetting resin having excellent toughness. Even if a part of the automatic line collides violently, the insulating substrate will never be chipped, cracked or cracked.

According to this method of manufacturing a wiring board, the wiring board is manufactured by thermosetting a precursor of a thermosetting resin contained in the insulating base and the wiring conductor. No deformation or dimensional variation occurs.

[0010]

However, a wiring board composed of an insulating substrate obtained by bonding the inorganic insulating powder with a thermosetting resin and a wiring conductor obtained by bonding the metal powder with a thermosetting resin, The bonding strength between the metal powder constituting the wiring conductor and the thermosetting resin is slightly weak, and when a large external force is applied to the wiring conductor when connecting the electrodes of the semiconductor element to the wiring board, the external force causes the thermosetting resin to be hardened. The problem that the reliability of the electrical connection between the electrode of a semiconductor element and the wiring conductor is slightly inferior because the connection between the metal powders due to the metal powder is disconnected and a part of the wiring conductor may be separated from the wiring conductor. Had.

Accordingly, the applicant of the present application has proposed a material formed by bonding a metal powder with a thermosetting resin to a wiring conductor inside an insulating substrate formed by laminating an insulating substrate formed by bonding an inorganic insulating powder with a thermosetting resin. And a wiring board in which the wiring conductor on the surface of the insulating base is formed of metal foil.

This wiring board is embedded such that an internal wiring conductor made of a metal powder and a thermosetting resin is led out from the inside to the surface of the insulating base, and is electrically connected to the internal wiring conductor on the surface of the insulating base. A through-hole is formed in the precursor sheet in a semi-cured state, which is an insulating substrate exposed on the surface of the insulating substrate, and is fixed in the through-hole. Fill the metal paste which becomes the internal wiring conductor by curing, and further, on the surface of this precursor sheet, paste the metal foil which becomes the surface wiring conductor so as to cover the metal paste filled in the through hole, and finally After laminating this precursor sheet with a precursor sheet to be another insulating substrate constituting the insulating base,
By heating at a temperature of 0 to 300 ° C. and thermosetting the thermosetting resin, the inorganic insulating powder is bonded with the thermosetting resin to form an insulating base on which each insulating substrate is laminated, and the metal powder is heated. It is manufactured by embedding an internal wiring conductor formed of a hardening resin inside an insulating substrate and fixing a metal foil to the insulating substrate exposed on the surface of the insulating substrate with a thermosetting resin of the insulating substrate.

According to this wiring board, since the wiring conductor fixed to the surface of the insulating base is made of metal foil, even when a large external force is applied to the wiring conductor when an electrode of a semiconductor element is connected to the wiring conductor or the like. Part of the wiring conductor does not separate from the wiring conductor, and the electrodes of the semiconductor element and the like can be securely and firmly electrically connected to the wiring conductor.

However, a wiring board on which a wiring conductor on the surface of an insulating substrate formed of a metal foil is formed by laminating an insulating substrate formed by bonding the inorganic insulating powder with a thermosetting resin is formed by adding a metal to a semi-cured precursor sheet. Before attaching the foil, since the curing reaction of the thermosetting resin precursor contained in the semi-cured precursor sheet has already progressed and the reactive groups in the thermosetting resin precursor have been reduced, When the precursor sheet on which the metal foil is adhered is heated at a temperature of 150 to 300 ° C. to thermally cure the thermosetting resin precursor, the metal foil and the insulating substrate are not tightly bonded, and thus the The surface wiring conductor is slightly weakened and the external wiring conductor is peeled off from the insulating base when an external force is applied when connecting the electrode of the semiconductor element to the surface wiring conductor. Provoked.

Further, according to this wiring board, since the surface wiring conductor and the insulating base are not tightly coupled, the moisture resistance of this portion is slightly inferior, and the wiring board is exposed to a high temperature and high humidity outside atmosphere for a long period of time. When left undisturbed, moisture in the external atmosphere gradually enters between the insulating substrate and the surface wiring conductor made of metal foil, and the infiltrated water causes corrosion of the internal wiring conductor connected to the surface wiring conductor, As a result, the semiconductor element to be mounted cannot operate normally and stably for a long period of time.

The present invention has been made in view of the above circumstances, and has as its object to fix a surface wiring conductor made of a metal foil to the surface of an insulating substrate formed by bonding an inorganic insulating powder with a thermosetting resin. With respect to the wiring board made of, the surface wiring conductor made of a metal foil can be firmly joined to the insulating base, and infiltration of moisture from between the insulating base and the surface wiring conductor made of the metal foil can be effectively prevented, It is an object of the present invention to provide a wiring board capable of securing a reliable electric connection between an internal wiring conductor and a surface wiring conductor and allowing a mounted semiconductor element to operate normally and stably for a long period of time.

Another object of the present invention is to provide a method for manufacturing a wiring board comprising a surface wiring conductor made of a metal foil fixed to the surface of an insulating substrate formed by bonding an inorganic insulating powder with a thermosetting resin. Can be firmly bonded to the insulating base, the infiltration of moisture from between the insulating base and the surface wiring conductor made of metal foil can be effectively prevented, and the internal wiring conductor and the surface wiring conductor can be securely connected. An object of the present invention is to provide a manufacturing method capable of obtaining a wiring board capable of ensuring normal electrical connection and operating a mounted semiconductor element normally and stably for a long period of time.

[0018]

The wiring board of the present invention comprises an inorganic insulating powder bonded with a bismaleimide triazine resin, and an internal wiring conductor formed by bonding a metal powder with a thermosetting resin is embedded therein. A surface wiring conductor made of a metal foil electrically connected to the internal wiring conductor is fixed to a surface of the insulated base via an epoxy resin adhesive layer.

Further, in the method for producing a wiring board according to the present invention, a precursor sheet is prepared by adding an epoxy resin base material and an inorganic insulating powder which react with a curing agent by heating and cure to a precursor of a bismaleimide triazine resin. And a step of perforating a through hole in the precursor sheet and filling the through hole with a metal paste which is thermoset to become an internal wiring conductor, and a step of forming a metal to become a surface wiring conductor on the surface of the precursor sheet. A step of attaching the foil with a curing agent that reacts with the epoxy resin base agent therebetween, and heating the precursor sheet to which the metal foil is attached, and thermally curing the inorganic insulating powder to form a bismaleimide Forming an insulating substrate by bonding with a triazine resin, embedding an internal wiring conductor inside the insulating substrate, and forming an epoxy resin main agent and a curing agent inside the precursor sheet. It is characterized in that it comprises through an epoxy resin adhesive layer cured formed by the reaction and a step of fixing a metal foil on the surface of the insulating substrate.

According to the wiring board of the present invention, the surface wiring conductor made of a metal foil is fixed to the surface of the insulating base formed by bonding the inorganic insulating powder with the bismaleimide triazine resin via the epoxy resin adhesive layer. The insulating base and the surface wiring conductor made of a metal foil are firmly joined via the epoxy resin adhesive layer, and the epoxy resin adhesive layer effectively prevents moisture from entering between the insulating base and the surface wiring conductor.

Further, according to the method for manufacturing a wiring board of the present invention, the epoxy resin main agent inside the precursor sheet reacts with the curing agent interposed between the precursor sheet and the metal foil, thereby forming the insulating substrate. A cured epoxy resin adhesive layer is formed between the surface wiring conductor made of metal foil, and the cured epoxy resin adhesive layer firmly joins the insulating base and the surface wiring conductor, and forms the insulating base and the surface wiring conductor with each other. It is possible to provide a wiring board that can effectively prevent intrusion of moisture into the space.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of an embodiment in which the wiring board of the present invention is applied to a semiconductor element housing package for housing a semiconductor element, 1 is an insulating base, 2 is an internal wiring conductor, and 3a and 3b are surface wiring conductors. It is.

The insulating substrate 1 is made of a material obtained by binding an inorganic insulating powder such as silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, zeolite, etc. with a bismaleimide triazine resin. 4b on which two insulating substrates 1a are formed
1b, the upper surface of which is a mounting portion for mounting the semiconductor element 5, on which the semiconductor element 5 is mounted.

The inorganic insulating powder contained in the insulating substrates 1a and 1b has a particle size of about 0.1 to 100 μm, and the coefficient of thermal expansion of the insulating substrates 1a and 1b is close to that of the semiconductor element 5. And the insulating substrate 1a.
1b has an effect of imparting good thermal conductivity and water resistance, or a predetermined relative dielectric constant. On the other hand, the insulating substrates 1a and 1b
The bismaleimide triazine resin contained in the base material serves to bind the inorganic insulating powders together and hold the insulating base 1 in a predetermined shape.

Since the insulating substrates 1a and 1b are formed by bonding inorganic insulating powder with a bismaleimide triazine resin having excellent toughness, chipping, cracking, cracking, etc., of the insulating substrate 1 when the wiring substrates collide with each other are considered. It does not occur.

When the content of the inorganic insulating powder contained in the insulating substrates 1a and 1b is less than 60% by weight, the thermal expansion coefficient of the insulating base 1 is compared with that of the semiconductor element 5. When heat generated during the operation of the semiconductor element 5 is applied to the semiconductor element 5 and the insulating base 1, a large thermal stress is generated due to a difference in the coefficient of thermal expansion between the two. No. 5 tends to easily cause peeling or cracking from the insulating substrate 1. On the other hand, if the content of the inorganic insulating powder exceeds 95% by weight, it tends to be difficult to firmly bond the inorganic insulating powder with the bismaleimide triazine resin. Therefore, the content of the inorganic insulating powder contained in the insulating substrates 1a and 1b is preferably in the range of 60 to 95% by weight.

Each of the insulating substrates 1a and 1
The internal wiring conductor 2 formed by bonding a metal powder with a thermosetting resin is buried between b and the through holes 4a and 4b.

The internal wiring conductor 2 formed by bonding metal powder embedded in the insulating base 1 with a thermosetting resin is used to electrically connect the surface wiring conductors 3a and 3b attached to the upper and lower surfaces of the insulating base 1 to each other. For example, a metal powder such as copper, silver, or copper whose surface is coated with silver is bonded by a thermosetting resin such as an epoxy resin.

The metal powder contained in the internal wiring conductor 2 formed by bonding the metal powder with a thermosetting resin is
When the content in the internal wiring conductor 2 is less than 70% by weight, the conductivity of the internal wiring conductor 2 tends to deteriorate, and when the content in the internal wiring conductor 2 is 95% by weight. If it exceeds 300, it tends to be difficult to firmly bond the metal powder with a thermosetting resin. Therefore, the metal powder contained in the internal wiring conductor 2 formed by bonding the metal powder with the thermosetting resin has a content in the internal wiring conductor 2.
A range of 70-95% by weight is preferred.

If the average particle size of the metal powder contained in the internal wiring conductor 2 formed by bonding the metal powder with a thermosetting resin is less than 0.5 μm, the contact resistance between the metal powders increases. The electrical resistance of the internal wiring conductor 2 tends to be high. On the other hand, when the thickness exceeds 50 μm, the internal wiring conductor 2 having a predetermined pattern is formed on the insulating base 1 in a range of 50 to 200 μm which is generally required.
It tends to be difficult to form a line width of m. Therefore, it is preferable that the average particle diameter of the metal powder contained in the internal wiring conductor 2 formed by bonding the metal powder with a thermosetting resin is 0.5 to 50 μm.

The thermosetting resin contained in the internal wiring conductor 2 formed by bonding the metal powder with the thermosetting resin is combined with the metal powder in a state where the metal powders are in contact with each other, and the internal wiring conductor 2 is bonded. It acts to adhere to the insulating substrate 1, and is made of epoxy resin such as bisphenol A type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin, phenol resin, polyimide resin, bismaleimide triazine resin, thermosetting polyphenylene ether. It is made of a thermosetting resin such as a resin.

If the content of the thermosetting resin contained in the internal wiring conductor 2 formed by bonding the metal powder with the thermosetting resin in the internal wiring conductor 2 is less than 5% by weight, the metal powders cannot be firmly bonded to each other. At the same time, it tends to be difficult to firmly adhere the internal wiring conductor 2 to the insulating base 1. On the other hand, when the content in the internal wiring conductor 2 exceeds 30% by weight, it is difficult to bring the metal powders into sufficient contact with each other, and the electric resistance of the internal wiring conductor 2 tends to be large. Therefore, the content of the thermosetting resin contained in the internal wiring conductor 2 formed by bonding the metal powder with the thermosetting resin is preferably in the range of 5 to 30% by weight.

The upper surface of the insulating substrate 1a and the insulating substrate 1b
On the lower surface, surface wiring conductors 3a and 3b made of metal foil such as copper foil are attached so as to cover the internal wiring conductor 2 filled in the through holes 4a and 4b.

The surface wiring conductor 3a attached to the upper surface of the insulating substrate 1a serves as a connection pad for electrically connecting each electrode of the semiconductor element 5 to the internal wiring conductor 2 provided inside the insulating base 1. It functions, and each electrode of the semiconductor element 5 is connected thereto via the solder bump 7. On the other hand, the insulating substrate 1
b is attached to the lower surface of the insulating base 1
Functions as connection pads for electrically connecting the internal wiring conductor 2 provided inside the device to an external electric circuit board, and is connected to the wiring conductor of the external electric circuit board via solder.

The surface wiring conductors 3a and 3b adhered to the upper surface of the insulating substrate 1a and the lower surface of the insulating substrate 1b are made of metal foil such as copper foil, and the metal foil forming the surface wiring conductors 3a and 3b is Are extremely strongly bonded to each other by metal bonding, so that the electrode of the semiconductor element 5 is connected to the surface wiring conductor 3a or the surface wiring conductor 3b is connected to the wiring conductor of the external electric circuit board. When a large external force is applied to the surface wiring conductors 3a and 3b, for example, when the surface wiring conductors 3a and 3b
a and 3b, so that the semiconductor element 5
Of the electrodes and the wiring conductor of the external electric circuit board to the surface wiring conductor 3
a. 3b can be reliably and firmly connected.

It should be noted that the surface wiring conductors 3a.
The surface wiring conductors 3a and 3b are formed by plating a metal having excellent corrosion resistance such as nickel and gold and having excellent bondability with solder to a thickness of 1 to 20 μm on the exposed surface by plating. Can be effectively prevented from being oxidized and corroded, and the connection between the surface wiring conductor 3a and the electrode of the semiconductor element 5 and the surface wiring conductor 3b and the wiring conductor of the external electric circuit board can be easily and firmly performed. Therefore,
The surface wiring conductors 3a and 3b made of metal foil are formed by applying a metal having excellent corrosion resistance such as nickel or gold and having excellent connectivity with solder to a thickness of 1 to 20 μm by plating on the exposed surface. Preferably.

Surface wiring conductors 3a and 3 made of metal foil
b is fixed to the insulating substrates 1a and 1b via the cured epoxy resin adhesive layers 6a and 6b.

The epoxy resin adhesive layers 6a and 6b are made of a cured product of an epoxy resin such as a bisphenol A type epoxy resin or a novolak type epoxy resin or a glycidyl ester type epoxy resin, and the surface wirings made of metal foil are formed on the insulating substrates 1a and 1b. The conductors 3a and 3b are firmly joined and adhered, and also function to prevent moisture from entering between the insulating substrates 1a and 1b and the surface wiring conductors 3a and 3b made of metal foil.

The insulating substrate 1 has the surface wiring conductors 3a and 3b made of metal foil adhered to the insulating substrates 1a and 1b via the epoxy resin adhesive layers 6a and 6b. 6b, the insulating substrates 1a and 1b
And the surface wiring conductors 3a and 3b are firmly joined and fixed,
As a result, even when an external force is applied to the surface wiring conductors 3a and 3b when the electrode of the semiconductor element 5 is connected to the surface wiring conductor 3a or when the surface wiring conductor 3b is connected to the external electrode circuit board, the surface wiring conductor 3a 3b does not separate from the insulating substrates 1a and 1b.

The presence of the epoxy resin adhesive layers 6a and 6b in the insulating base 1 effectively prevents moisture from entering between the insulating substrates 1a and 1b and the surface wiring conductors 3a and 3b. The electrical connection between the surface wiring conductors 3a and 3b and the internal wiring conductor 2 does not become uncertain, and the semiconductor element 5 to be mounted can operate normally and stably for a long period of time.

The epoxy resin adhesive layers 6a and 6b are
If the thickness is less than 0.5 μm, it tends to be difficult to firmly join the insulating substrates 1 a and 1 b to the surface wiring conductors 3 a and 3 b made of metal foil, and if it exceeds 10 μm, the internal wiring conductor 2 and the surface wiring conductor There is a risk that the wires 3a and 3b may be electrically disconnected. Therefore, the thickness of the epoxy resin adhesive layers 6a and 6b is preferably in the range of 0.5 to 10 μm.

Thus, according to the wiring board of the present invention, the semiconductor element 5 is mounted on the mounting portion of the insulating base 1 and each electrode of the semiconductor element 5 is electrically connected to the surface wiring conductor 3a made of metal foil via the solder bump 7. And finally, a bowl-shaped lid (not shown) is joined to the upper surface of the insulating base 1 via a sealing material made of resin or the like, and the semiconductor element 5 is placed inside the container formed of the insulating base 1 and the lid. Is sealed to form a semiconductor device as a product.

Next, a method for manufacturing the above-described wiring board will be described.

First, as shown in FIG. 2A, a precursor of a bismaleimide triazine resin is added to an epoxy resin base material which reacts with a curing agent by heating and cured by adding an inorganic insulating powder to each of the precursors. Through holes 4a and 4b
Two precursor sheets 11a and 11b having through holes 14a and 14b formed therein are prepared.

The precursor sheets 11a and 11b are made of a precursor of a bismaleimide triazine resin such as a bisphenol A type epoxy resin, a novolak type epoxy resin, a glycidyl ester type epoxy resin or the like, and a silicon oxide, aluminum oxide, aluminum nitride, A paste obtained by adding and mixing an inorganic insulating powder such as silicon carbide, barium titanate or zeolite and a solvent such as methylcellosolve is formed into a sheet by employing a conventionally known doctor blade method, and is formed at about 25 to 100 ° C. The bismaleimide triazine resin contained therein is semi-cured by heating at a temperature of 1 to 60 minutes, and is subjected to a conventionally known punching process.

The epoxy resin base contained in the precursor sheets 11a and 11b is, as described later, the precursor sheet 11a and 11b.
A metal foil to be the surface wiring conductors 3a and 3b was adhered to 11b with a curing agent that reacts with the epoxy resin base agent interposed therebetween, and this was heated to fix the surface wiring conductors 3a and 3b made of the metal foil. When forming the insulating substrates 1a and 1b, the precursor sheet
By leaching and hardening between the metal foils 11a and 11b, the epoxy resin adhesive layers 6a and 6b for fixing the surface wiring conductors 3a and 3b to the insulating substrates 1a and 1b are formed.

If the content of the epoxy resin main ingredient contained in the precursor sheets 11a and 11b is less than 1% by weight based on the total amount of the bismaleimide triazine resin precursor and the epoxy resin main ingredient, as described later, Cured sheet 11a
A metal foil is adhered to the base material 11b with a curing agent that reacts with the main component of the epoxy resin interposed therebetween, and heated to heat the insulating substrate 1a / 1 on which the surface wiring conductors 3a / 3b made of the metal foil are fixed.
b, the surface wiring conductors 3a.
The epoxy resin adhesive layers 6a and 6b for fixing the 3b are not sufficiently formed, and it is difficult to firmly fix the surface wiring conductors 3a and 3b to the insulating substrates 1a and 1b via the epoxy resin adhesive layers 6a and 6b. It tends to be. On the other hand, if it exceeds 10% by weight, a large amount of the uncured epoxy resin remains in the insulating substrates 1a and 1b, and the strength of the insulating substrates 1a and 1b tends to be low.

Therefore, the content of the epoxy resin main component contained in the precursor sheets 11a and 11b is preferably in the range of 1 to 10% by weight based on the total amount of the bismaleimide triazine resin precursor and the epoxy resin main component.

Next, as shown in FIG. 2 (b), the internal internal wiring conductor 2 is thermally cured into the upper surface of the precursor sheet 11b and the through holes 14a and 14b formed in the precursor sheets 11a and 11b. The metal paste 12 is printed and applied in a predetermined pattern by using a conventionally known screen printing method and filling method.

The metal paste which becomes the internal wiring conductor 2
For example, epoxy resin such as bisphenol A type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin and amine curing agent, imidazole curing agent, metal powder such as copper having a particle size of about 0.1 to 20 μm A paste obtained by adding and mixing a curing agent such as an acid anhydride-based curing agent is used.

Next, as shown in FIG. 2 (c), curing agents 16a and 16b which react with the epoxy resin base material by heating are applied to the upper surface of the precursor sheet 11a and the lower surface of the precursor sheet 11b.

The curing agents 16a and 16b applied to the lower surfaces of the precursor sheets 11a and 11b
When a metal foil to be the surface wiring conductors 3a and 3b is adhered to 11a and 11b and heated to form the insulating substrates 1a and 1b, the epoxy resin base contained in the precursor sheets 11a and 11b is induced. The epoxy resin adhesive layers 6a and 6b which are exuded between the precursor sheets 11a and 11b and the metal foil and which have been cured by reacting with the epoxy resin base material between the insulating substrates 1a and 1b and the surface wiring conductors 3a and 3b are formed. It acts to form.

As the curing agents 16a and 16b applied to the lower surfaces of the precursor sheets 11a and 11b, curing agents such as amine curing agents, acid anhydride curing agents, and imidazole curing agents are used. If the amount of application per 1 cm ^{2 of the} upper surface or the lower surface of the precursor sheet 11a is less than 0.1 mg, the precursor sheets 11a
b, a metal foil to be the surface wiring conductors 3a and 3b is adhered to the substrate and heated to form the insulating substrates 1a and 1b. It tends to be difficult to form a sufficient amount of the epoxy resin adhesive layers 6a and 6b on the other hand, while if it exceeds 5 mg, the internal wiring conductor 2 and the surface wiring conductor 3a in the insulating base 1
-The reliability of the electrical connection with 3b tends to be low. Therefore, the precursor sheet 11a
The curing agents 16a and 16b applied to the precursor sheet 11b
0.1 to 5 mg of coating amount per 1 cm ^{2 of} a top surface or 11 b bottom surface
It is preferable to keep

Further, when the curing agents 16a and 16b applied to the precursor sheets 11a and 11b are amine-based curing agents, the amine-based curing agent removes an oxide film on the surface of the metal foil to be the surface wiring conductors 3a and 3b. As a result, the electrical connection resistance between the surface wiring conductors 3a and 3b made of metal foil and the internal wiring conductor 2 inside the insulating base 1 can be reduced. Therefore, the curing agent 16a applied to the precursors 11a and 11b
16b is preferably used as an amine-based curing agent.

Next, as shown in FIG. 2D, the surface wiring conductors 3a and 3b are provided on the upper surface and the lower surface of the precursor sheet 11a.
The metal foils 13a and 13b to be used are adhered in a predetermined pattern via the curing agents 16a and 16b.

Metal foil 13a to be surface wiring conductors 3a and 3b
13b is made of a highly conductive metal such as copper. For example, in the case of copper, a copper foil is stuck on a transfer sheet made of polyethylene terephthalate (PET) and the copper foil is applied to a conventionally known photolithography technique. The copper foil on the transfer sheet is then applied to the upper surface of the precursor sheet 11a and the precursor sheet 11b.
By pressing and adhering to the lower surface of the sheet and removing the transfer sheet therefrom, the sheet is adhered to the precursor sheets 11a and 11c in a predetermined pattern.

Finally, the precursor sheets 11a and 11b are laminated one on top of the other, and the temperature is about 150 to 300 ° C. and about 4 to 100 kgf.
/ Cm ² and further heated at a temperature of 150 to 300 ° C., if necessary, to obtain a precursor sheet 11.
a. Insulating substrate 1a in which the precursor of bismaleimide triazine resin contained in 11b is completely cured and the inorganic insulating powder is bonded with bismaleimide triazine resin thermally cured.
1b and by thermosetting the thermosetting resin in the metal paste 12, the internal wiring conductor 2 formed by bonding the metal powder with the thermosetting resin is adhered to the insulating substrates 1a and 1b. The epoxy resin base and the curing agents 16a and 16 in the precursor sheets 11a and 11b are provided on the upper and lower surfaces of the insulating substrate 1a.
By fixing the surface wiring conductors 3a and 3b composed of the metal foils 13a and 13b with the cured epoxy resin adhesive layers 6a and 6b formed by the reaction with the wiring board b, the wiring board of the present invention as shown in FIG. 1 is completed. I do.

In this case, the epoxy resin base material contained in the precursor sheets 11a and 11b before hot pressing and the curing agents 16a and 16b applied to the precursor sheets 11a and 11b do not react with each other, and a reactive group is formed. When the precursor sheets 11a and 11b are heated to form the insulating substrates 1a and 1b, the epoxy resin main agent contained in the precursor sheets 11a and 11b is applied to the precursor sheets 11a and 11b because the precursor sheets 11a and 11b are cured. The insulating layer 1 is guided by the agents 16a and 16b and exudes between the semi-cured sheets 11a and 11b and the metal foils 13a and 13b serving as the surface wiring conductors 3a and 3b, and reacts with the curing agents 16a and 16b.
A strong and tightly cured epoxy resin adhesive layer 6a, 6b is formed between the a.1b and the surface wiring conductors 3a, 3b. As a result, the epoxy resin adhesive layer 6a, 6b allows the insulating substrate 1a, 1b to be in contact with the surface. The wiring conductors 3a and 3b are firmly joined, and each of the insulating substrates 1a and 1b is
It is possible to provide a wiring board excellent in moisture resistance, which can effectively prevent intrusion of moisture from between the a and 3b.

In this case, the precursor sheets 11a and 11b and the metal paste 12 hardly shrink during thermosetting, so that the resulting wiring board does not undergo any deformation or dimensional variation. The element and the wiring conductor can be accurately connected.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the case where the wiring board of the present invention is applied to a semiconductor element housing package for housing a semiconductor element has been described as an example, but this is applied to a wiring board used for a hybrid integrated circuit board or the like. You may.

In the above embodiment, the wiring substrate is formed by laminating two insulating substrates. However, the wiring substrate is formed by laminating one or three or more insulating substrates. May be formed.

Further, in the above embodiment, the surface wiring conductors 3a and 3b made of metal foil are used as the precursor sheet 11a.
Metal foil 13a etched in a predetermined pattern on 11b
13b, which was formed by transferring, a large area metal foil was adhered to almost the entire upper surface of the precursor sheet 11a and the lower surface of the precursor sheet 11b.
It may be formed by heating b to form a predetermined pattern before forming the insulating substrates 1a and 1b or after forming the insulating substrates 1a and 1b.

[0063]

According to the wiring board of the present invention, a surface wiring conductor made of a metal foil is fixed to an insulating base formed by bonding an inorganic insulating powder with a bismaleimide triazine resin via an epoxy resin adhesive layer. The insulating base and the surface wiring conductor are firmly joined via the epoxy resin adhesive layer. As a result, even when an external force is applied to the surface wiring conductor, the surface wiring conductor does not separate from the insulating base.

Further, according to the wiring board of the present invention, the epoxy resin adhesive layer effectively prevents moisture from intruding between the wiring conductor on the insulating substrate and the surface, and as a result, the surface wiring conductor and the internal wiring conductor can be prevented. Does not become uncertain due to the infiltrated moisture, and the semiconductor element to be mounted can operate normally and stably for a long period of time.

Further, according to the method of manufacturing a wiring board of the present invention, a plurality of precursors obtained by adding and mixing an epoxy resin base material and an inorganic insulating powder which are cured by reacting with a curing agent by heating to a precursor of a bismaleimide triazine resin. Prepare a sheet and attach a metal foil to be a surface wiring conductor to this precursor sheet with a curing agent that reacts with the epoxy resin base material interposed between them, and then heat this to heat-cured insulator powder to cure the insulating powder. Since a wiring board having a surface wiring conductor made of metal foil fixed to an insulating base bonded with a maleimide triazine resin is obtained, the epoxy resin main agent and the curing agent in the precursor sheet are interposed between the insulating base and the surface wiring conductor. A cured epoxy resin adhesive layer formed by the reaction is formed, and the insulating base and the surface wiring conductor are firmly joined via the epoxy resin adhesive layer. And, it is possible to provide a wiring board having excellent moisture resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an embodiment of a wiring board of the present invention.

2 (a) to 2 (d) are cross-sectional views for respective steps for explaining a method of manufacturing the wiring board shown in FIG. 1;

[Explanation of symbols]

 1 ... Insulating base 1a, 1b ... Insulating substrate 2 ... Internal wiring conductors 3a, 3b ... Surface wiring conductors 4a, 4b ... Through hole 5 ... ··· Semiconductor element 6a, 6b ··· Epoxy resin adhesive layer 11a, 11b ··· Precursor sheet 12 ··· Metal paste 13a and 13b ··· Metal foil 14a and 14b ··· Holes 16a, 16b: Hardener

Claims (2)

[Claims] An internal wiring conductor is formed by bonding an inorganic insulating powder with a bismaleimide triazine resin and an internal wiring conductor formed by bonding a metal powder with a thermosetting resin. A wiring board comprising a surface wiring conductor made of a metal foil electrically connected to a conductor and fixed through an epoxy resin adhesive layer. 2. A step of adding and mixing an epoxy resin base material and an inorganic insulating powder which react with a curing agent by heating to a precursor of a bismaleimide triazine resin to prepare a precursor sheet; A step of forming a through-hole and filling the through-hole with a metal paste that is heat-cured to become an internal wiring conductor, and a metal foil that becomes a surface wiring conductor on the surface of the precursor sheet, and the epoxy resin base agent is interposed therebetween. Bonding the metal foil with the precursor sheet to which the metal foil is bonded, bonding the inorganic insulating powder with a thermoset bismaleimide triazine resin to form an insulating substrate. Forming and embedding an internal wiring conductor inside the insulating base; and a cured epoxy resin contact formed by a reaction between the epoxy resin main agent and the curing agent inside the precursor sheet. Fixing the metal foil to the surface of the insulating base via a deposition layer.