JPH1050890A - Wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make wiring fine, and provide a high density wiring board by coating an insulating board, which is formed by bonding specific inorganic insulating powder by specific thermosetting resin, with a wiring conductor, which is formed by boding metal powder by thermosetting resin and thermoplastic resin. SOLUTION: An insulating base 1 is formed by laminating three insulating boards 1a, 1b and 1c, a recessed part 1d is provided at the center of the top plane, and a semiconductor element 3 is bonded and fixed with adhesive such as resin. The insulating boards 1a, 1b and 1c which form the insulating base 1 contain inorganic insulating powder at 60-95wt.%, and thermosetting resin at 5-40wt.%, and the area from the periphery of the recessed part 1d to the bottom plane is coated with wiring conductor 2, which is formed by bonding metal powder by thermosetting resin such as epoxy resin and thermoplastic resin such as acrylic resin. Thus, high density wiring board with fine wiring is obtained.

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 housed in a central portion of an upper surface thereof. An insulating base having a concave portion to be formed, and a wiring conductor made of a metal having a high melting point metal such as tungsten and molybdenum led out from the periphery of the concave portion to the lower surface of the insulating base,
Glass, resin, a semiconductor element on the bottom of the concave portion of the insulating base,
The electrodes of the semiconductor element are electrically connected to the wiring conductors through electrical connection means such as a bonding wire, and then are fixed to the upper surface of the insulating base by using an adhesive such as a brazing material. A lid made of metal, ceramics, or the like is bonded via a sealing material such as glass, resin, or brazing material so as to cover the concave portion of the insulating base, and the semiconductor element is hermetically accommodated in the concave portion of the insulating base. A semiconductor device as a product, and each electrode of the semiconductor element is electrically connected to the external electric circuit board by connecting a portion of the wiring conductor protruding to the bottom surface of the concave portion of the insulating base to the wiring conductor of the external electric circuit board. Becomes

This conventional wiring board is manufactured by a ceramic green sheet laminating method. Specifically, an organic binder suitable for a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc.
A plurality of ceramic green sheets are obtained by adding a solvent or the like to form a slurry and forming the sheet into a sheet shape by employing a conventionally known doctor blade method. Thereafter, a suitable punching process is performed on the ceramic green sheet. And a metal paste serving as a wiring conductor is printed and applied in a predetermined pattern. Finally, the ceramic green sheets are laminated vertically in a predetermined order to form a green ceramic molded body. It is manufactured by firing at a high temperature of ° C.

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 a disadvantage that it is difficult to accurately and reliably electrically connect the conductor or the wiring conductor and 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 metal powder is replaced with the conventional metal powder of the high melting point, and the metal powder is heated in the same manner. 2. Description of the Related Art A wiring board formed of a material bonded with a curable resin has been proposed.

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 comprises a thermosetting resin and an inorganic insulating material. Prepare a precursor sheet in a semi-cured state by mixing powder and a suitable punching process on the precursor sheet, and then apply a metal paste formed by mixing a thermosetting resin and metal powder to this. Print and apply in a predetermined pattern,
Finally, a precursor sheet on which the metal paste is printed and applied is laminated as necessary, and the precursor sheet is laminated for about 100 to 30.
It is manufactured by thermosetting at a temperature of 0 ° C.

[0008]

However, a wiring board comprising an insulating base 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, The viscosity of the thermosetting resin contained in the metal paste serving as the wiring conductor is poor, so that the printability of the metal paste is poor, and a predetermined pattern is formed when the metal paste is printed and applied to a precursor sheet serving as an insulating base. However, it is difficult to print and apply the wiring accurately and it is difficult to obtain a wiring board with fine wiring and high density.

[0009] When the content of the thermosetting resin contained in the metal paste as the wiring conductor is set to a large amount exceeding, for example, about 30% by weight, the printability of the metal paste can be improved. The resistance becomes large, and it is impossible to obtain a wiring board with fine wiring and high density.

[0010]

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 formed by bonding a metal powder with a thermosetting resin and a thermoplastic resin to an insulating substrate formed by bonding the inorganic insulating powder with the thermosetting resin. It is characterized in that the insulating substrate is formed by bonding inorganic insulating powder with a thermosetting resin having excellent toughness, so that the wiring substrates are connected to each other or to the wiring substrate and a part of a semiconductor device manufacturing automatic line. Even if a strong collision occurs, the insulating substrate will not be chipped, cracked, cracked, etc., and it is not necessary to include a large amount of resin in the wiring conductor, and the electric resistance of the wiring conductor can be extremely small. it can.

Further, the method for manufacturing a wiring board according to the present invention comprises the steps of preparing a precursor sheet formed by mixing a thermosetting resin and an inorganic insulating powder; and semi-curing the precursor sheet. A step of printing a metal paste formed by mixing a thermosetting resin, a thermoplastic resin, and a metal powder on the precursor sheet in a predetermined pattern, and a step of completely thermosetting the precursor sheet and the metal paste. A precursor sheet formed by mixing a thermosetting resin and an inorganic insulating powder; and a metal paste formed by mixing a thermosetting resin, a thermoplastic resin, and a metal powder. It is manufactured by curing, and since there is no firing step, there is no deformation or dimensional variation due to uneven firing shrinkage, and the metal paste printed and applied to the precursor sheet is heatable. It has an appropriate viscosity because it contains sexual resin, which can be accurately printed coating when printing applied to the precursor sheet.

[0012]

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 is a wiring conductor.

The insulating base 1 comprises three insulating substrates 1a,
The semiconductor device 3 is formed by laminating 1b and 1c, and has a concave portion 1d for accommodating a semiconductor element in the center of the upper surface thereof. Fixed.

An 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. Since the three insulating substrates 1a, 1b, and 1c constituting the first substrate 1 are each formed by bonding an inorganic insulating powder with a thermosetting resin such as an epoxy resin having excellent toughness, an external force is applied to the insulating substrate 1. Chipping or cracking of the insulating substrate 1 due to the external force even when
There is no crack or the like.

Incidentally, three insulating substrates 1 constituting an insulating base 1 formed by bonding the inorganic insulating powder with a thermosetting resin.
a, 1b, and 1c are such that when the content of the inorganic insulating powder contained therein is less than 60% by weight, the coefficient of thermal expansion of the insulating base 1 greatly differs from the coefficient of thermal expansion of the semiconductor element 3,
When the semiconductor element 3 generates heat, the heat is generated by the semiconductor element 3
When the semiconductor element 3 is applied to both the insulating substrate 1 and the insulating substrate 1, a large thermal stress is generated between the two due to a difference in thermal expansion coefficient between the two. The element 3 is cracked or chipped. Therefore, the insulating substrate 1a constituting the insulating base 1
1b and 1c are each specified so that the amount of the inorganic insulating powder contained therein is in the range of 60 to 95% by weight.

The insulating substrate 1 has a wiring conductor 2 formed by bonding metal powders of, for example, copper, silver, gold or the like from the periphery to the lower surface of the recess 1d with a thermosetting resin such as an epoxy resin or a thermoplastic resin such as an acrylic resin. Are formed.

The wiring conductor 2 functions to electrically connect each electrode of the semiconductor element 3 to an external electric circuit. Each electrode of the semiconductor element 3 is located at a portion of the insulating base 1 located around the concave portion 1d. Electrical connection is made via a bonding wire 4, and a portion led out to the lower surface of the insulating base 1 is electrically connected to an external electric circuit.

The metal powder contained in the wiring conductor 2 is as follows:
The wiring conductor 2 acts to impart conductivity to the wiring conductor 2.
If the content is less than 70% by weight, the electrical resistance of the wiring conductor 2 becomes high, and if it exceeds 95% by weight, the metal powder is firmly bound with a thermosetting resin and a thermoplastic resin to form a predetermined wiring conductor 2. It tends to be difficult to form. Therefore, it is preferable that the amount of the metal powder contained in the wiring conductor 2 be in the range of 70 to 95% by weight.

The thermosetting resin and the thermoplastic resin contained in the wiring conductor 2 serve to bind the metal powder contained in the wiring conductor 2 and to adhere the wiring conductor 2 to the insulating base 1. If the content in the wiring conductor 2 is less than 5% by weight, it tends to be difficult to form the wiring conductor 2 by firmly bonding the metal powders to each other. Electric resistance tends to be large. Therefore, the content of the thermosetting resin and the thermoplastic resin contained in the wiring conductor 2 is preferably in the range of 5 to 30% by weight.

Further, the thermosetting resin and the thermoplastic resin contained in the wiring conductor 2 may be a thermosetting resin or a thermoplastic resin.
In addition to providing heat resistance to the resin, the thermoplastic resin acts to impart good printability to the metal paste that will be the wiring conductor 2 described below, and the thermoplastic resin with respect to the total amount of the thermosetting resin and the thermoplastic resin Is less than 5% by weight, the printability of the metal paste that becomes the wiring conductor 2 becomes poor, and the metal paste is printed and applied in a predetermined pattern on the precursor sheets that become the insulating bases 1a, 1b, and 1c. When the amount is more than 90% by weight, the heat resistance of the wiring conductor 2 becomes low, and when the heat is applied to the wiring board, the wiring conductor 2 is hardly printed.
This easily causes deformation and disconnection. Therefore,
The thermosetting resin and the thermoplastic resin contained in the wiring conductor 2 preferably have a blending amount of the thermoplastic resin of 5 to 90% by weight based on the total amount of the thermosetting resin and the thermoplastic resin.

The wiring conductor 2 is preferably provided with a metal having excellent corrosion resistance, such as nickel or gold, and a good conductivity, having a thickness of 1.0 to 20.0 μm by a plating method. Oxidation and corrosion of the wiring conductor 2 can be effectively prevented, and the wiring conductor 2 and the bonding wire 4
Can be firmly and electrically connected. Therefore, it is preferable that the wiring conductor 2 is coated with a metal having excellent corrosion resistance, such as nickel or gold, and a good conductivity by a plating method to a thickness of 1.0 to 20.0 μm on the exposed surface.

Thus, according to the wiring board of the present invention, the semiconductor element 3 is bonded and fixed to the bottom surface of the concave portion 1d of the insulating base 1 with an adhesive such as a resin, and each electrode of the semiconductor element 3 is bonded via the bonding wire 4. It is electrically connected to the wiring conductor 2, and finally, the lid 5 is joined to the upper surface of the insulating base 1 via a sealing material made of resin or the like, and the semiconductor is placed inside the container formed of the insulating base 1 and the lid 5. The semiconductor device as a product is completed by housing the element 3 in an airtight manner.

Next, a method of manufacturing a wiring board used in the package for housing a semiconductor element will be described.

First, as shown in FIG. 2 (a), three precursor sheets 1 formed by bonding inorganic insulating powder with a thermosetting resin
1a, 11b and 11c are prepared, and heat is applied to these to make them semi-cured.

The three precursor sheets 11a, 11b,
11c is formed by bonding an inorganic insulating powder with a thermosetting resin, and has a particle size of, for example, 0.1 to 10
A paste obtained by adding and mixing an epoxy resin and an imidazole-based curing agent to silicon oxide powder of about 0 μm is formed into a sheet by employing a sheet forming method such as a doctor blade method.

The semi-cured precursor sheet 11
a, 11b, and 11c have the hardness of JIS7215,6.
When semi-cured so as to have a prescribed hardness of 40 to 90 in the type A measurement of 301, the three precursor sheets 11a, 11b, and 11c are subjected to punching processing or the wiring conductor 2 as described later. It is possible to accurately and reliably perform punching and printing of the metal paste without causing deformation or cracks in the precursor sheets 11a, 11b, and 11c when printing and applying the metal paste to be formed. The substrate can be manufactured accurately and reliably. Accordingly, the semi-cured precursor sheets 11a, 1
It is preferable that the hardness of 1b and 11c is set in the range of 40 to 90 as the hardness specified in the type A measurement of JIS7215,6301.

Next, as shown in FIG. 2 (b), two precursor sheets 11a, 11b out of the three semi-cured precursor sheets 11a, 11b, 11c are provided with openings A, A which form recesses 1d. Are formed in the two precursor sheets 11b and 11c, respectively, to form through holes B and B 'for routing the wiring conductor 2.

The openings A and A 'and the through holes B and B'
The precursor sheets 11a, 11b, and 11c are subjected to a conventionally known punching method, and the precursor sheets 11a, 11b, and 1c are subjected to punching.
1c is formed by piercing a hole of a predetermined shape.

Next, as shown in FIG. 2 (c), a metal paste 12 serving as the wiring conductor 2 is formed on the upper and lower surfaces of the semi-cured precursor sheets 11b and 11c and in the through holes B and B 'by a known method. A predetermined pattern is printed and applied using a screen printing method and a filling method, and this is heated and semi-cured at a temperature of about 25 to 100 ° C. for 1 to 60 minutes.

The metal paste 12 serving as the wiring conductor 2 is, for example, a powder of copper having a particle size of about 0.1 to 20 μm or an epoxy resin such as a bisphenol A epoxy resin, a novolak epoxy resin, or a glycidyl ester epoxy resin. And amine-based curing agents, imidazole-based curing agents,
A paste formed by adding and mixing a thermoplastic resin such as an acrylic resin or a polyester resin to a thermosetting resin such as a curing agent such as an acid anhydride-based curing agent is used.

The metal paste 12 to be the wiring conductor 2
Has a suitable viscosity because it contains a thermoplastic resin, and when this is printed and applied in a predetermined pattern on the precursor sheets 11a, 11b, and 11c to be the insulating substrates 1a, 1b, and 1c, , So that a high-density wiring board with fine wiring can be manufactured.

The metal paste 1 to be the wiring conductor 2
2 when the content of the thermosetting resin and the thermoplastic resin contained therein exceeds 30% by weight,
Is cured to form the wiring conductor 2, the electric resistance of the wiring conductor 2 becomes high, and if it is less than 5% by weight, the metal paste 12 cannot sufficiently impart fluidity as a paste. The metal paste 12 is applied to the insulating substrates 1a, 1
It tends to be difficult to accurately print and apply the precursor sheets 11a, 11b, and 11c to be b and 1c. Therefore, the metal paste 12 preferably has a content of the thermosetting resin and the thermoplastic resin in the range of 5 to 30% by weight.

Further, the metal paste 12 serving as the wiring conductor 2 is made of a metal if the blending amount of the thermoplastic resin is less than 5% by weight based on the total amount of the thermosetting resin and the thermoplastic resin contained therein. The viscosity of the paste 12 becomes small, and it tends to be difficult to accurately print and apply the metal paste 12 to the precursor sheets 11a, 11b, 11c to be the insulating substrates 1a, 1b, 1c. If it exceeds, the metal paste 12 is hardened and the wiring conductor 2
When this is done, the heat resistance of the wiring conductor 2 becomes low,
When heat is applied to the wiring board, the wiring conductor 2 is likely to be disconnected or deformed. Therefore, in the metal paste 12, the blending amount of the thermoplastic resin with respect to the total amount of the thermosetting resin and the thermoplastic resin contained therein is 5 to 90.
A range of weight% is preferred.

Finally, the three semi-cured precursor sheets 11a, 11b, and 11c are vertically stacked and heated at a temperature of about 80 to 300 ° C. for about 10 seconds to 24 hours. Wiring in which a metal conductor 12 printed and applied in a predetermined pattern on 11a, 11b, 11c and precursor sheets 11b, 11c is completely cured by heat so that a wiring conductor 2 is applied to an insulating substrate 1 as shown in FIG. The substrate is completed. In this case, the precursor sheets 11a, 11b, 11c and the metal paste 12 hardly shrink during thermosetting, so that the resulting wiring board does not undergo any deformation or variation in dimensions. The element and the wiring conductor can be accurately connected.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Although 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, the present invention may be applied to a wiring board used for other purposes such as a hybrid integrated circuit.

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

Further, in the above-described embodiment, the insulating base was made of the inorganic insulating powder and the thermosetting resin. However, the insulating base was further made of glass fiber, carbon fiber, aramid fiber, alumina fiber, potassium titanate whisker. And short fibers such as aluminum borate whiskers.

Further, in the above embodiment, the wiring conductor is
Although the metal powder was formed by bonding with a thermosetting resin and a thermoplastic resin, the metal powder may be further formed by combining the metal powder with the low melting point metal by further mixing a low melting point metal in the wiring conductor. In this case, a low-melting-point metal powder made of, for example, tin-lead solder or the like is mixed as a low-melting-point metal into a metal paste to be a wiring conductor, and the paste is printed and applied to a precursor sheet to be an insulating base. Is applied to melt the low melting point metal powder, and the metal powder is bound by the melted low melting point metal.

[0039]

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. No chipping, cracking, cracks, etc. occur in the insulating base even if the part of the wire collides violently, and the wiring conductor contains a highly viscous thermoplastic resin. And the electric resistance of the wiring conductor can be made extremely small.

According to the method of manufacturing a wiring board of the present invention, a precursor sheet formed by mixing a thermosetting resin and an inorganic metal powder and a metal paste formed by mixing a thermosetting resin and a metal powder are used. Since the precursor sheet and the metal paste hardly shrink, they are manufactured by thermosetting, so that deformation and dimensional variation due to shrinkage do not occur, and it is possible to accurately electrically connect the semiconductor element to the wiring conductor. it can.

Further, according to the method for manufacturing a wiring board of the present invention, since the metal paste printed and applied to the precursor sheet contains a thermoplastic resin, the metal paste has an appropriate viscosity, and is printed and applied to the precursor sheet. In this case, printing and coating can be performed accurately, and a wiring board with fine wiring and high density can be provided.

[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.

FIG. 2 is a cross-sectional view of each process for explaining the method for manufacturing a wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 2 ... Wiring conductor 11 ... Precursor sheet 12 ... Metal paste

Claims (4)

[Claims] An inorganic insulating powder of 60 to 95% by weight and 5
To 40% by weight of a thermosetting resin, and a wiring conductor formed by bonding the metal powder with a thermosetting resin and a thermoplastic resin to an insulating substrate formed by bonding the inorganic insulating powder with the thermosetting resin. A wiring board characterized by being attached. 2. The wiring according to claim 1, wherein the total amount of the thermosetting resin and the thermoplastic resin contained in the wiring conductor is 5 to 30% by weight based on the total amount of the wiring conductor. substrate. 3. The composition according to claim 2, wherein the amount of the thermoplastic resin is in the range of 5 to 90% by weight based on the total amount of the thermosetting resin and the thermoplastic resin contained in the wiring conductor. Wiring board. 4. A step of preparing a precursor sheet comprising a mixture of a thermosetting resin and an inorganic insulating powder; a step of semi-curing the precursor sheet; A method of printing a metal paste formed by mixing a plastic resin and a metal powder in a predetermined pattern; and a step of completely thermosetting the precursor sheet and the metal paste. .