JPH10209324A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid breaking or cracking even due to application of an external force, by depositing wiring conductors made from a metal foil on the surface of an insulation board made by bonding an inorg. insulator powder of specified wt.% with a thermosetting resin and burying conductors bonded with a metal powder inside. SOLUTION: An insulation board 1 is composed of three insulation sheets 1a-1c, each composed of an inorg. insulator powder 60-95wt.% and thermosetting resin 5-40wt.% bonding the powder. Wiring conductors 2 composed of metal foils e.g. Cu foils are overlaid on the upper and lower surfaces of the board 1, and wiring conductors 3 composed of a Cu or other metal powder bonded with a thermosetting resin are buried therein. This avoids causing breaking or cracking the insulation board 1 even if the wiring boards collide each other or with part of a semiconductor device.

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 semiconductor element is mounted on an upper surface thereof. An insulating base having a portion, and tungsten led out from the mounting portion or the vicinity of the mounting portion on the upper surface of the insulating base to the lower surface of the insulating base,
And a wiring conductor made of a high melting point metal material such as molybdenum. The semiconductor element is mounted on the mounting portion of the insulating base, and each electrode of the semiconductor element is connected to a wiring conductor led out to the upper surface of the insulating base by a solder bump. And electrical connection means such as a bonding wire or the like, and thereafter, a glass, resin, brazing material is formed on the upper surface of the insulating base by covering a semiconductor element with a cover made of metal, ceramics or the like. A semiconductor device as a product is obtained by joining the semiconductor elements in a hermetically sealed manner through a sealing material such as a sealing material, and by connecting a portion of the wiring conductor led out to the lower surface of the insulating base to the electric wiring of the external electric circuit board. Each electrode of the semiconductor element is electrically connected to the external electric circuit board.

[0003] This conventional wiring board is generally manufactured by a ceramic green sheet laminating method. Specifically, an organic binder and a solvent suitable for ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide and calcium oxide are used. Are mixed and formed into a slurry, and this is formed into a sheet by employing a conventionally known doctor blade method to obtain a plurality of ceramic green sheets, and then the ceramic green sheets are subjected to an appropriate punching process. At the same time, a metal paste to be a wiring conductor is printed and applied in a predetermined pattern, and finally, the ceramic green sheets are stacked up and down in a predetermined order to form a green ceramic molded body. It is manufactured by firing at high temperature.

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 an airtight manner, and the semiconductor element may not be long. There was a drawback that normal and stable operation could not be achieved over a period of time.

According to the method of manufacturing a wiring board,
When the green ceramic molded body is fired, uneven firing shrinkage occurs in the green ceramic molded body, resulting in deformation and dimensional variation such as warpage of the obtained wiring board, and as a result, each electrode of the semiconductor element and the wiring There is also a disadvantage that it is difficult to accurately and reliably electrically connect the conductor or the wiring conductor to the wiring conductor of the external electric circuit board.

Therefore, the insulating base of the wiring board is formed of a material obtained by bonding inorganic insulating powder with a thermosetting resin in place of the conventional ceramics, and the wiring conductor is formed of a metal such as copper instead of the conventional high melting point metal material. There has been proposed a wiring board formed of a material in which powder is bonded with a thermosetting resin.

A wiring board composed of an insulating base formed by bonding an inorganic insulating powder with a thermosetting resin and a wiring conductor formed by bonding a metal powder with a thermosetting resin is composed of a thermosetting resin precursor and an inorganic hardening resin. Prepare a precursor sheet in a semi-cured state by mixing with an insulating powder, perform appropriate punching on the precursor sheet, and then mix a thermosetting resin precursor and metal powder with this. The metal paste is printed and applied in a predetermined pattern, and finally, the precursor sheet on which the metal paste is printed and applied is laminated as necessary, and is thermally cured at a temperature of about 100 to 300 ° C. .

[0008]

However, a wiring composed of an insulating base formed by bonding the inorganic insulating powder with a thermosetting resin and a wiring conductor formed by bonding a metal powder such as copper with a thermosetting resin. The substrate has a slightly weaker bonding strength between the metal powder constituting the wiring conductor and the thermosetting resin, and when a large external force is applied to the wiring conductor when, for example, connecting an electrode of a semiconductor element to the wiring substrate, heat is generated by the external force. The bond between the metal powders by the curable resin is released, and a part of the wiring conductor is detached,
There has been a problem to be solved in that the reliability of electrical connection between an electrode of a semiconductor element or the like and a wiring conductor is slightly deteriorated by peeling off from an insulating base.

Therefore, it is conceivable that the wiring conductor of the wiring board is formed of a metal foil such as a copper foil instead of a material obtained by bonding metal powder with a thermosetting resin.

In this case, the wiring board is prepared by preparing a precursor sheet in a semi-cured state comprising a mixture of a thermosetting resin precursor and an inorganic insulating powder, bonding a copper foil thereto, The foil is etched to form a wiring conductor having a predetermined pattern. Thereafter, a plurality of the precursor sheets are laminated and pressure-bonded and thermally cured at a temperature of 100 to 300 ° C.

However, when the wiring conductor of the wiring board is formed of a metal foil such as a copper foil, the wiring conductor made of the metal foil such as the copper foil is difficult to be deformed in cross-sectional shape, and is formed in a pattern by etching. Therefore, since the side surfaces have a steep shape, the vicinity of the side surface of the wiring conductor does not sufficiently adhere between the precursor sheets stacked up and down when the precursor sheets serving as the insulating base are stacked and pressed. As a result, a void is easily formed near the side surface of the wiring conductor buried inside the insulating base. When a gap is formed in the vicinity of the side surface of the wiring conductor in this way, moisture or the like in the air enters into the gap, the electrical insulation between the wiring conductors is deteriorated, and a leakage or short circuit occurs in the wiring. Or the wiring conductor is corroded and disconnected.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a wiring board which is unlikely to be chipped or cracked even when an external force is applied.

Another object of the present invention is to reduce warpage and dimensional variation, and to easily and accurately apply a semiconductor element or the like to a wiring conductor.
Another object of the present invention is to provide a wiring board capable of reliably and electrically connecting.

Still another object of the present invention is to effectively prevent a void from being formed near the side surface of a wiring conductor buried in an insulating substrate and to firmly join the wiring conductor to the surface, thereby forming a semiconductor. It is an object of the present invention to provide a wiring board capable of reliably electrically connecting elements and the like to wiring conductors.

[0015]

According to the present invention, there is provided a wiring board comprising:
0 to 95% by weight of inorganic insulating powder and 5 to 40% by weight
A wiring conductor made of a metal foil is adhered to a surface of an insulating base formed by bonding the inorganic insulating powder with the thermosetting resin, and a metal is provided inside the insulating base. A wiring conductor in which the powder is bonded by a thermosetting resin is embedded.

According to the wiring board of the present invention, since the insulating base is formed by bonding the inorganic insulating powder with the thermosetting resin having excellent toughness, the wiring boards are connected to each other or the wiring board and the semiconductor device manufacturing line. Even if it violently collides with a part, the insulating substrate will not be chipped, cracked, cracked or the like.

According to the wiring board of the present invention, since the wiring conductor adhered to the surface of the insulating base is made of metal foil, a large external force is applied to the wiring conductor when connecting the electrode of the semiconductor element to the wiring conductor. Is applied, a part of the wiring conductor is detached and does not peel off from the insulating base, so that an electrode of a semiconductor element or the like can be securely and firmly electrically connected to the wiring conductor.

Further, according to the wiring board of the present invention, the wiring conductor embedded in the insulating base is formed by bonding a metal powder with a thermosetting resin, and mixing the thermosetting resin precursor with the metal powder. Is formed by printing and applying a metal paste consisting of: a precursor which becomes an insulating substrate due to its side surface being gently inclined due to the fluidity of the metal paste and the plasticity of the metal paste When laminating and crimping the sheet, its cross-sectional shape collapses and becomes flat,
As a result, the vicinity of the side surface of the wiring conductor is sufficiently adhered between the vertically stacked precursor sheets, and no void is formed near the side surface of the wiring conductor buried inside the insulating base.

[0019]

Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment in which the wiring board of the present invention is applied to a semiconductor element housing package for housing a semiconductor element, wherein 1 is an insulating base, and 2 and 3 are wiring conductors.

The insulating substrate 1 comprises three insulating substrates 1a,
The semiconductor element 4 is formed by laminating 1b and 1c, and the semiconductor element 4 is mounted on the upper surface thereof.

The insulating substrate 1a constituting the insulating base 1
1b and 1c are, for example, silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, strontium titanate, calcium titanate, titanium oxide,
It is formed by bonding an inorganic insulating powder such as zeolite with a thermosetting resin such as an epoxy resin, a polyimide resin, a phenol resin, a thermosetting polyphenylene ether resin, a polyimide amide resin, and a bismaleimide triazine resin. The three insulating substrates 1a, 1b, and 1c constituting the base 1 are formed by bonding inorganic insulating powder with a thermosetting resin such as an epoxy resin having excellent toughness. Even when an external force is applied, the external force does not cause chipping, cracking, cracking, or the like in the insulating base 1.

The three insulating substrates 1a, 1b and 1c formed by bonding the inorganic insulating powder with a thermosetting resin have an inorganic insulating powder content of less than 60% by weight and a thermosetting resin content of 40% by weight.
If the weight percent is exceeded, the thermal expansion coefficients of the insulating substrates 1a, 1b, and 1c greatly differ from the thermal expansion coefficient of the semiconductor element 4, and the semiconductor element 4 generates heat during operation, and the heat is insulated from the semiconductor element 4. When applied to the insulating substrate 1 composed of the substrates 1a, 1b, and 1c, a large thermal stress is generated between the two due to the difference in thermal expansion coefficient between the two, and the semiconductor element 4 is separated from the insulating substrate 1 by the large thermal stress. Peeling or cracking or chipping of the semiconductor element 4 occurs. The amount of the inorganic insulating powder exceeds 95% by weight, and the amount of the thermosetting resin is 5% by weight.
If it is less than 3, the inorganic insulating powder cannot be firmly bonded with the thermosetting resin. Accordingly, each of the insulating substrates 1a, 1b, and 1c constituting the insulating base 1 has an inorganic insulating powder content of 60 to 95% by weight and a thermosetting resin content of 5 to 5% by weight.
-40% by weight.

The insulating substrate 1 has, for example, a particle size of 0.1 to
Thermosetting resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin, etc., and amine based curing agent, imidazole based curing agent, acid anhydride The insulating paste obtained by adding and mixing a curing agent such as a system curing agent is formed into a sheet by adopting a sheet forming method such as a doctor blade method, and is formed into about 25 to
The insulating substrate 1 is semi-cured at a temperature of 100 ° C.
a, 1b, and 1c are obtained. Thereafter, the precursor sheet is subjected to an appropriate punching process, and these are laminated and pressed in a predetermined order. Manufactured by thermosetting at a temperature of ~ 150 ° C.

Further, the insulating substrate 1 has a wiring conductor 2 made of a metal foil such as a copper foil adhered to the upper and lower surfaces thereof, and a metal powder such as copper is bonded to the inside thereof with a thermosetting resin. The wiring conductor 3 is embedded.

The wiring conductor 2 made of a metal foil adhered on the upper surface of the insulating base 1 is used to electrically connect each electrode of the semiconductor element 4 to the wiring conductor 3 provided inside the insulating base 1. Each electrode of the semiconductor element 4 is connected via a solder bump 5 to a wiring conductor 2 acting as a pad and attached to the upper surface of the insulating base 1.

The wiring conductor 2 made of metal foil and adhered to the lower surface of the insulating base 1 has connection pads for electrically connecting the wiring conductor 3 provided inside the insulating base 1 to an external electric circuit board. The wiring conductor 2 attached to the lower surface of the insulating base 1 is connected to the electric wiring of the external electric circuit board via solder.

The wiring conductor 2 attached to the upper and lower surfaces of the insulating base 1 is made of a metal foil such as a copper foil. The metal foil forming the wiring conductor 2 is formed by bonding metal atoms of the metal foil to each other. Are very strongly coupled to each other, so that a large external force is applied to the wiring conductor 2 when the electrode of the semiconductor element 4 is connected to the wiring conductor 2 or when the wiring conductor 2 is connected to the electric wiring of the external electric circuit board. Even when the voltage is applied, a part of the wiring conductor 2 is detached and does not peel off from the insulating base 1, whereby the electrodes of the semiconductor element 4 and the electric wiring of the external electric circuit board are securely and firmly connected to the wiring conductor 2. can do.

The wiring conductor 2 made of a metal foil such as a copper foil adhered to the upper and lower surfaces of the insulating base 1 is attached with a metal foil such as a copper foil on a transfer sheet made of, for example, polyethylene terephthalate (PET). At the same time, the metal foil is etched into a predetermined pattern by employing a conventionally well-known photolithography technique. Thereafter, the metal foil on the transfer sheet becomes the upper surface of the precursor sheet serving as the insulating substrate 1a and the insulating substrate 1c. The transfer sheet is removed therefrom while being pressed against and adhered to the lower surface of the precursor sheet, and the metal foil is placed on the upper surface of the precursor sheet to be the insulating substrate 1a and the insulating substrate 1c.
Is transferred onto the lower surface of the precursor sheet to be attached to the upper and lower surfaces of the insulating substrate 1.

The wiring conductor 3 buried inside the insulating base 1 serves to electrically connect the wiring conductors 2 attached to the upper and lower surfaces of the insulating base 1 to each other. A metal powder such as copper, silver-copper alloy, or gold, the surface of which is coated with silver, is bonded with a thermosetting resin such as an epoxy resin. Epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, epoxy resin such as glycidyl ester type epoxy resin, and curing agent such as amine type curing agent, imidazole type curing agent, acid anhydride type curing agent etc. are added and mixed. The metal paste is applied to the insulating substrates 1a, 1b, 1
The precursor sheet to be c is buried inside the insulating substrate 1 by previously applying a conventionally known screen printing method and printing and applying it in a predetermined pattern. In this case, the wiring conductor 3 buried inside the insulating base 1 is made of a metal paste composed of a thermosetting resin precursor and a metal powder by using the insulating substrate 1a, 1
b, is formed by printing and applying a predetermined pattern on the precursor sheet to be 1c, and the printed and applied metal paste has a gently sloped side surface due to its fluidity and its plasticity. When the precursor sheets to become the insulating substrates 1a, 1b, and 1c are laminated and pressed by the pressure, the cross-sectional shape becomes flat due to the pressure of the laminated pressure,
As a result, the precursor sheets stacked one above the other are the wiring conductors 3
All the surfaces including the vicinity of the side surface are completely adhered, and the wiring conductor 3
No void is formed in the vicinity of the side surface.

The metal powder contained in the wiring conductor 3 acts to impart conductivity to the wiring conductor 3, and if the content is less than 70% by weight, the electric resistance of the wiring conductor 3 becomes high. If the content exceeds 95% by weight, it tends to be difficult to form a predetermined wiring conductor 3 by firmly bonding the metal powder with a thermosetting resin. Therefore, the wiring conductor 3
Means that the amount of metal powder contained therein is 70-95.
It is preferable to set it in the range of weight%.

Thus, according to the wiring board of the present invention, the semiconductor element 4 is mounted on the upper surface of the insulating base 1 and each electrode of the semiconductor element 4 is electrically connected to the wiring conductor 2 via the solder bump 5. 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 4 is hermetically accommodated inside a container formed of the insulating base 1 and the lid. Thus, a semiconductor device is obtained.

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. Although the description has been given by taking as an example the case where the wiring board of the present invention is applied to a package for housing a semiconductor element for housing a semiconductor element, the present invention may be applied to a wiring board used for other purposes such as a hybrid integrated circuit board.

In the above-described embodiment, the insulating substrate 1 is manufactured by laminating three precursor sheets. However, one, two, or four or more precursor sheets are used to form the insulating substrate 1. May be manufactured.

Further, in the above-described embodiment, the insulating base 1 is formed of the inorganic insulating powder and the thermosetting resin. However, glass fiber, carbon fiber, aramid fiber, alumina fiber, potassium titanate whisker, and Short fibers such as aluminum acid whiskers may be mixed.

Further, in the above-described embodiment, the wiring conductor 3 is formed by bonding metal powder with a thermosetting resin. The bonding between the metal powders may be promoted. In this case, a low-melting-point metal powder made of, for example, tin-lead solder or the like may be blended as the low-melting-point metal in the metal paste to be the wiring conductor 3.

[0036]

According to the wiring board of the present invention, since the insulating base is formed by bonding the inorganic insulating powder with the thermosetting resin having excellent toughness, the wiring boards or the wiring board and the semiconductor device are formed. Even if a portion of the insulating base material collides violently, the insulating substrate will not be chipped, cracked or cracked.

Further, according to the wiring board of the present invention, the wiring conductor attached to the surface of the insulating base is made of a metal foil such as a copper foil, and forms the wiring conductor attached to the surface of the insulating base. Since the metal atoms that make up the metal foil are extremely strongly bonded to each other by metal bonding, the wiring conductor attached to the surface of the insulating base is connected to the electrodes of the semiconductor element and the electric wiring of the external electric circuit board. Even when a large external force is applied to the wiring conductor attached to the insulating base surface when performing, for example, a part of the wiring conductor attached to the insulating base surface separates and does not peel off from the insulating base. Electrodes such as semiconductor elements and wiring conductors of an external electric circuit board can be reliably and firmly connected to wiring conductors attached to the surface of the insulating base.

Further, according to the wiring board of the present invention, the wiring conductor embedded in the insulating base is formed by bonding a metal powder with a thermosetting resin, and mixing the thermosetting resin precursor with the metal powder. Is formed by printing and applying a metal paste consisting of: a precursor which becomes an insulating substrate due to its side surface being gently inclined due to the fluidity of the metal paste and the plasticity of the metal paste When laminating and crimping the sheet, its cross-sectional shape collapses and becomes flat,
As a result, the vicinity of the side surface of the wiring conductor is also sufficiently adhered between the precursor sheets stacked vertically, and no void is formed near the side surface of the wiring conductor embedded inside the insulating base.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which a wiring board of the present invention is applied to a package for housing a semiconductor element.

[Explanation of symbols]

1 ... Insulating substrate 1a, 1b, 1c ... Insulating substrate 2 ... ... Wiring conductor adhered on the surface of insulating substrate 1 ························· Semiconductor element

Claims (1)

[Claims] An inorganic insulating powder of 60 to 95% by weight and 5
A wiring conductor made of a metal foil is adhered to a surface of an insulating base formed by bonding the inorganic insulating powder with the thermosetting resin, and the insulating base. A wiring substrate, wherein a wiring conductor formed by bonding a metal powder with a thermosetting resin is embedded inside the wiring board.