JPH09181419A - Manufacture of wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent chipping, crazing, cracks, etc., from being developed on an insulating base even when wiring boards strongly collide with one another or when a wiring board strongly collide with a part of the semiconductor device manufacturing automation line. SOLUTION: Precursor sheets 11a, 11b and 11c to be the insulating base mixed of thermosetting resin precursor and inorganic insulating powder are prepared. On the precursor sheets 11a, 11b and 11c, metal paste 12, which is to be the wiring conductor formed by mixing the thermosetting resin precursor and the metal powder and low melting point metal powder whose melting point is 300 deg.C or lower, is printed in a prescribed pattern. The precursor sheets 11a, 11b and 11c whereupon the metal paste 12 is printed are put in the inactive atmosphere at a prescribed temperature, the metal powder in the metal paste 12 is bonded with the low melting point metal powder, and the thermosetting resin precursor of the precursor sheets 1, 11b and 11c and the thermosetting resin precursor of the metal paste 12 are cured with heat.

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 the semiconductor element is housed in the center of its upper surface. And a wiring conductor made of a refractory metal powder such as tungsten or molybdenum, which is led out from the periphery of the recess of the insulating base to the lower surface, and a semiconductor element is formed on the bottom of the recess of the insulating base. The electrodes are bonded and fixed through an adhesive such as glass, resin, or a brazing material, and each electrode of the semiconductor element is electrically connected to a wiring conductor through an electrical connecting means such as a bonding wire. A lid made of metal, ceramics, or the like is placed on the upper surface of the so as to cover the concave portion of the insulating base with a sealing material such as glass, resin, or brazing material. A semiconductor device as a product is obtained by bonding and hermetically housing the semiconductor element in the recess of the insulating base. By connecting the portion of the wiring conductor led to the bottom of the insulating base recess to the wiring conductor of the external electric circuit board, the semiconductor Each electrode of the element is electrically connected to the external electric circuit board.

The wiring board is generally manufactured by a ceramic green sheet laminating method. Specifically, aluminum oxide, silicon oxide, magnesium oxide,
A plurality of ceramic green sheets are obtained by adding a suitable organic binder, solvent, etc. to a ceramic raw material powder such as calcium oxide and mixing it to form a slurry and forming it into a sheet shape by adopting the conventionally known doctor blade method. After that, a suitable punching process is applied to the ceramic green sheet and a metal paste to be a wiring conductor is printed and applied in a predetermined pattern, and finally the ceramic green sheet is laminated in a predetermined order on top and bottom to obtain a green ceramic molded body. It is produced by firing the ceramic green body at a high temperature of about 1600 ° C. in a reducing atmosphere.

[0004]

However, in this conventional wiring board, when the ceramic green body is fired, uneven firing shrinkage occurs in the ceramic green body, and the resulting wiring board is deformed such as warped or the like. Variations in dimensions occur, and as a result, it is difficult to electrically connect each electrode of the semiconductor element and the wiring conductor, or the wiring conductor and the wiring conductor of the external electric circuit board, accurately and reliably. It had drawbacks.

Further, in the obtained wiring board, since the ceramics such as aluminum oxide sintered body which constitutes the insulating substrate has the property of being hard and brittle, the wiring boards may not be connected to each other in a carrying process or an automatic line for manufacturing a semiconductor device, or When the wiring board and a part of the semiconductor device manufacturing automatic line violently collide with each other, the insulating substrate is chipped, cracked, or cracked, and as a result, the semiconductor element cannot be housed in an airtight manner and the semiconductor element cannot be stored for a long time. It also has a drawback that it cannot operate normally and stably.

[0006]

A method for manufacturing a wiring board in which a wiring conductor having a predetermined pattern is adhered to an insulating base according to the present invention is an insulating base in which a thermosetting resin precursor and an inorganic insulating powder are mixed. And a metal paste to be a wiring conductor in which a thermosetting resin precursor, a metal powder, and a low melting point metal powder having a melting point of 300 ° C. or less are mixed in a predetermined pattern on the precursor sheet. The step of printing, and the precursor sheet on which the metal paste is printed and applied is placed in an inert atmosphere at a predetermined temperature, and the metal powder in the metal paste is bonded with a low melting point metal powder and the thermosetting property of the precursor sheet And a step of thermally curing the resin precursor and the thermosetting resin precursor of the metal paste.

Further, in the method of manufacturing a wiring board in which a wiring conductor having a predetermined pattern is adhered to the insulating base of the present invention, a precursor sheet which becomes an insulating base is prepared by mixing a thermosetting resin precursor and an inorganic insulating powder. In the step of preparing and the precursor sheet,
A step of printing a metal paste, which is a wiring conductor, in which a thermosetting resin precursor and a low melting point metal powder having a melting point of 300 ° C. or less are mixed, in a predetermined pattern, and a precursor sheet on which the metal paste is printed and applied is heated to a predetermined temperature. Of the thermosetting resin precursor of the precursor sheet and the thermosetting resin precursor of the metal paste together with the low melting point metal powder in the metal paste are bonded together in an inert atmosphere, It is characterized by consisting of.

Further, the present invention is characterized in that the thermosetting resin precursor of the metal paste has conductivity.

According to the method for manufacturing a wiring board of the present invention, a precursor sheet formed by mixing a thermosetting resin precursor and an inorganic insulating powder on an insulating substrate on which a wiring conductor is adhered is thermally cured. Since there is no firing step when obtaining the insulating substrate, deformation and dimensional variation due to uneven shrinkage due to firing do not occur.

Further, according to the method for manufacturing a wiring board of the present invention, the precursor sheet on which the metal paste is printed and applied is placed in an inert atmosphere at a predetermined temperature, and the metal powder in the metal paste has a low melting point depending on the ambient temperature. Since they are joined by metal or the low melting point metal powders are joined together, electrical connection between the metal powders or between the low melting point metal powders is ensured, whereby the electrical resistance of the wiring conductor can be made low.

Further, according to the method of manufacturing a wiring board of the present invention, if the thermosetting resin precursor of the metal paste to be the wiring conductor is used as the conductive thermosetting precursor having conductivity, it may be reduced between metal powders or low. The electrical connection between the melting point metal powders becomes more reliable, so that the electrical resistance of the wiring conductor can be made lower.

Further, since the insulating substrate is formed by bonding the inorganic insulating powder with the thermosetting resin having excellent toughness, the wiring substrate obtained by the manufacturing method of the present invention can be connected to the wiring substrates or to each other. Even if a part of the automatic semiconductor device manufacturing line collides violently, the insulating substrate will not be chipped, cracked, or cracked.

[0013]

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

FIG. 1 shows an embodiment in which a wiring substrate manufactured by the manufacturing method of the present invention is applied to a semiconductor element housing package for housing a semiconductor element, 1 is an insulating substrate, and 2 is a wiring conductor. is there.

The insulating substrate 1 comprises three insulating substrates 1a,
It is formed by laminating 1b and 1c, and has a recess 1d for accommodating a semiconductor element in the center of the upper surface thereof, and the semiconductor element 3 is provided on the bottom surface of the recess 1d via an adhesive such as resin. Adhesively fixed.

An insulating substrate 1a constituting the insulating base 1;
1b and 1c are obtained by bonding inorganic insulating powders such as silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, and zeolite with a thermosetting resin such as epoxy resin, polyimide resin, polyphenylene ether resin. The three insulating substrates 1a, 1b, and 1c that form the insulating substrate 1 are formed by bonding the inorganic insulating powders with a thermosetting resin having excellent toughness. Even if an external force is applied to the insulating substrate 1, the insulating substrate 1 will not be chipped, cracked, or cracked.

In addition, three insulating substrates 1 constituting an insulating substrate 1 formed by bonding the inorganic insulating powders with a thermosetting resin.
When the content of the inorganic insulating powder is less than 60% by weight, the thermal expansion coefficient of the insulating substrate 1 is a, 1b, 1c.
When the semiconductor element 3 emits heat during operation, and the heat is applied to both the semiconductor element 3 and the insulating substrate 1, the difference in the thermal expansion coefficient between the two is caused. A large thermal stress is generated due to this, and there is a risk that the semiconductor element 3 may be separated from the insulating substrate 1 or the semiconductor element 3 may be cracked or chipped due to the large thermal stress. Also 95
If it exceeds 5% by weight, the inorganic insulating powder cannot be completely bonded with the thermosetting resin, and the predetermined insulating substrates 1a, 1
It is difficult to obtain b and 1c. Therefore, the insulating substrates 1a, 1b, 1c constituting the insulating base 1 have the amount of the inorganic insulating powder contained in each of 60 to 95.
It is preferable to set it in the range of weight%.

A wiring conductor 2 is formed on the insulating substrate 1 from the periphery of the recess 1d to the lower surface thereof. The wiring conductor 2 is made of metal powder such as copper, silver and gold and has a melting point of 300.degree.
The following low-melting point metals, specifically those which are joined via solder, or those where low-melting point metals such as solder having a melting point of 300 ° C. or less are joined, are attached to the insulating substrate 1 via a thermosetting resin. Is formed.

The wiring conductor 2 has the function of electrically connecting the electrodes of the semiconductor element 3 housed therein to an external electric circuit, and the semiconductor element 3 is provided at a portion located around the recess 1d of the insulating substrate 1. Are electrically connected to each other via the bonding wire 4, and the portion led out to the lower surface of the insulating substrate 1 is electrically connected to an external electric circuit.

The wiring conductor 2 is also formed by joining metal powders such as copper, silver and gold with a low melting point metal having a melting point of 300 ° C. or less, or joining low melting point metals such as solder having a melting point of 300 ° C. or less. Since the wiring conductor 2 is formed by the above, the electric resistance of the wiring conductor 2 can be made low by ensuring the electrical connection between the metal powders or between the low melting point metals.

Further, if the wiring conductor 2 is made of a conductive resin such as a conductive polypyrrole resin, a polyparaphenylene resin, or a polyaniline resin, a thermosetting resin for attaching the metal powder or the like to the insulating substrate 1 is formed. The electrical connection between the metal powders of the above and the low melting point metals becomes more reliable and the wiring conductor 2
The electric resistance of can be made lower.

When the wiring conductor 2 is composed of a metal powder, a low melting point metal having a melting point of 300 ° C. or lower, and a thermosetting resin, the total weight of the metal powder and the low melting point metal having a melting point of 300 ° C. or lower is When the amount is less than 70% by weight based on the total weight of the wiring conductor 2, the bonding between the metal powder and the low melting point metal is incomplete, and when it exceeds 95% by weight, the wiring conductor 2 is firmly bonded to the insulating substrate 1 by the thermosetting resin. The wiring conductor 2 tends to be weakened. Therefore, it is preferable that the total weight of the metal powder contained in the wiring conductor 2 and the low melting point metal having a melting point of 300 ° C. or less is set in the range of 70% by weight to 95% by weight with respect to the total weight of the wiring conductor 2. .

When the wiring conductor 2 is made of a low melting point metal having a melting point of 300 ° C. or lower and a thermosetting resin, the weight of the low melting point metal having a melting point of 300 ° C. or lower is relative to the total weight of the wiring conductor 2. If it is less than 70% by weight, the joining of the low melting point metals becomes incomplete, and if it exceeds 95% by weight, it becomes difficult to firmly adhere the wiring conductor 2 to the insulating substrate 1 with a thermosetting resin, and the wiring conductor becomes difficult. 2 tends to be fragile. Therefore, the melting point contained in the wiring conductor 2 is 300.
It is preferable that the weight of the low-melting-point metal having a temperature of not more than 0 ° C. be 70% to 95% by weight based on the total weight of the wiring conductor 2.

Further, when the wiring conductor 2 is composed of a metal powder, a low melting point metal having a melting point of 300 ° C. or lower and a thermosetting resin, the amount of the metal powder is low and the melting point of the melting point is 300 ° C. or lower. If it is less than 20% by weight with respect to the total weight of the metals, the amount of the low melting point metal becomes large with respect to the metal powder, and the low melting point metals are melted to each other, making it difficult to integrate the metal powders into the wiring conductor 2 The electric resistance of the wiring conductor 2 tends to increase, and when it exceeds 80% by weight, the amount of the low melting point metal for joining the metal powder is relatively small, and the metal powder cannot be completely joined. Electric resistance tends to increase. Therefore, when the wiring conductor 2 is composed of a metal powder, a low melting point metal having a melting point of 300 ° C. or lower, and a thermosetting resin, the amount of the metal powder is set to the metal powder and the low melting point metal having a melting point of 300 ° C. or lower. 20 for total weight
It is preferable to set it in the range of 80 to 80% by weight.

Further, the metal powder and the low melting point metal having a melting point of 300 ° C. or less contained in the wiring conductor 2 have a metal powder and a melting point of 300 ° C. when the average particle diameter is less than 0.1 μm.
The following low-melting-point metals agglomerate and a uniform dispersion cannot be obtained, and when it exceeds 50 μm, it tends to be difficult to print and form the width of the wiring conductor 2 in a range of 50 μm to 200 μm which is generally required. is there. Therefore, it is preferable that the metal powder contained in the wiring conductor 2 and the low melting point metal having a melting point of 300 ° C. or less have an average particle size of 0.1 μm to 50 μm.

Thus, according to the above-described wiring board manufactured by the manufacturing method of the present invention, the semiconductor element 3 is adhered and fixed to the bottom surface of the recess 1d of the insulating substrate 1 via an adhesive such as a resin, and each of the semiconductor elements 3 is formed. The electrodes are electrically connected to the wiring conductors 2 via the bonding wires 4, 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 to form the insulating base 1 and the lid. A semiconductor device as a product is completed by hermetically accommodating the semiconductor element 3 in a container composed of 5 and 5.

Next, a method of manufacturing the wiring board used for the semiconductor element housing package will be described with reference to FIG.

First, as shown in FIG. 2A, three precursor sheets 11a, 11b and 11c are prepared.

The three precursor sheets 11a, 11b,
11c is formed by binding an inorganic insulating powder with a thermosetting resin precursor, and has a particle size of, for example, 0.
Silicon oxide powder of about 1 μm to 100 μm and epoxy resin such as bisphenol A type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin, etc. and curing agent such as amine type curing agent, imidazole type curing agent, acid anhydride type curing agent, etc. Is added and mixed to form a paste, and then the paste is formed into a sheet.

Next, as shown in FIG. 2B, the recess 1 for accommodating the semiconductor element 3 in the two precursor sheets 11a, 11b among the three precursor sheets 11a, 11b, 11c.
The openings A and A ′ to be d are formed by the two precursor sheets 11b,
Through holes B and B'for routing the wiring conductor 2 are formed in 11c.

The openings A and A'and the through holes B and B'are
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), the metal paste 12 to be the wiring conductor 2 is formed on the upper and lower surfaces of the precursor sheets 11b and 11c and in the through holes B and B'by the conventionally known screen printing method and A filling method is adopted to print and apply a predetermined pattern.

The metal paste 12 to be the wiring conductor 2 is, for example, a metal powder such as copper having a particle size of about 0.1 to 20 μm, a low melting point metal powder made of solder having a melting point of 300 ° C. or less, and bisphenol. Epoxy resin such as A type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin and the like, and amine type curing agent, imidazole type curing agent, curing agent such as acid anhydride type curing agent are added and mixed to form a paste. Stuff used.

Further, a metal paste 1 to be the wiring conductor 2
When a conductive resin such as a conductive polypyrrole resin, a polyparaphenylene resin, or a polyaniline resin is used instead of the bisphenol A type epoxy resin or the like 2, three precursor sheets 11a are formed by printing and applying a metal paste 12 described later in a predetermined pattern. , 11b, 11c are thermally cured to form the wiring conductor 2
When the insulating base 1 having the above is formed, the electrical connection between the metal powders of the wiring conductor 2 or between the low melting point metals becomes more reliable, and the electric resistance of the wiring conductor 2 can be made lower. Therefore, it is preferable to use a conductive resin such as conductive polypyrrole resin, polyparaphenylene resin, or polyaniline resin as the thermosetting resin used for the metal paste 12 that becomes the wiring conductor 2.

And finally, the three precursor sheets 11
a, 11b, 11c are stacked on top of each other and
It is put into an inert atmosphere of 0 to 300 ° C., and the metal powder in the metal paste is joined with the low melting point metal powder at the ambient temperature, or the low melting point metals are joined together, and at the same time, three precursor sheets 11a, 11b are joined. , 11c and the thermosetting resin precursor of the metal paste 12 are heat-cured to complete the wiring substrate in which the wiring conductor 2 is adhered to the insulating substrate 1 as shown in FIG. . In this case, the precursor sheets 11a, 11b, 11c and the metal paste 12 hardly shrink during thermosetting, so that the obtained wiring board does not deform or vary in size, and the wiring conductor is not broken. In this case, the electrodes of the semiconductor element or the like can be surely electrically connected to the external electric circuit through the wiring conductor.

Further, the three precursor sheets 11a, 11b, 1 on which the metal paste 12 is applied by printing in a predetermined pattern.
An inert atmosphere in which 1c is charged at a temperature of 80 to 300 ° C. is, for example, Galden (trade name of Ausimont Co., Ltd., Italy).
It is formed by heating an inert solution called a heater with a heater and using its vapor phase. The inert atmosphere using the vapor phase of the inert solution is easy to control the temperature, so Thermosetting of the three precursor sheets 11a, 11b, 11c while surely joining the metal powders of the metal paste 12 with a low melting point metal or securely joining the low melting point metals to each other at a predetermined temperature. The resin precursor and the thermosetting resin precursor of the metal paste 12 can be thermoset.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-mentioned embodiments, the present invention is possible. The case of applying the wiring board of 1 to a semiconductor element housing package for housing a semiconductor element has been described as an example, but the wiring board may be applied to a wiring board used for other purposes such as a hybrid integrated circuit.

In the above-mentioned embodiment, the wiring board is manufactured by laminating the three precursor sheets. However, the wiring board is manufactured by using one, two, or four or more precursor sheets. May be made.

[0039]

According to the method of manufacturing a wiring board of the present invention,
The insulating substrate on which the wiring conductor is adhered is formed by heat-curing a precursor sheet formed by mixing a thermosetting resin precursor and an inorganic insulating powder, and the firing step is performed when obtaining the insulating substrate. Since it does not exist, deformation or dimensional variation due to uneven shrinkage due to firing does not occur.

According to the method for manufacturing a wiring board of the present invention, the precursor sheet on which the metal paste is printed and applied is placed in an inert atmosphere at a predetermined temperature, and the metal powder in the metal paste has a low melting point depending on the ambient temperature. Since they are joined by metal or the low melting point metal powders are joined together, electrical connection between the metal powders or between the low melting point metal powders is ensured, whereby the electrical resistance of the wiring conductor can be made low.

Further, according to the method for manufacturing a wiring board of the present invention, if the thermosetting resin precursor of the metal paste to be the wiring conductor is used as the conductive thermosetting precursor having conductivity, it may be reduced between metal powders or low. The electrical connection between the melting point metal powders becomes more reliable, so that the electrical resistance of the wiring conductor can be made lower.

Furthermore, since the wiring substrate obtained by the manufacturing method of the present invention is formed by bonding the inorganic insulating powder with the thermosetting resin having excellent toughness, the wiring substrates are connected with each other or with the wiring substrate. Even if a part of the automatic semiconductor device manufacturing line collides violently, the insulating substrate will not be chipped, cracked, or cracked.

[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 (3)

[Claims] 1. A step of preparing a precursor sheet to be an insulating substrate in which a thermosetting resin precursor and an inorganic insulating powder are mixed, and the thermosetting resin precursor, metal powder, and melting point in the precursor sheet. A step of printing a metal paste, which is a wiring conductor mixed with a low-melting-point metal powder having a temperature of 300 ° C. or less, in a predetermined pattern, and the precursor sheet on which the metal paste is printed and applied is placed in an inert atmosphere at a predetermined temperature. A step of bonding the metal powder in the metal paste with a low melting point metal powder and thermosetting the thermosetting resin precursor of the precursor sheet and the thermosetting resin precursor of the metal paste to a predetermined insulating substrate. A method for manufacturing a wiring board on which a wiring conductor having a pattern is applied. 2. A step of preparing a precursor sheet to be an insulating substrate in which a thermosetting resin precursor and an inorganic insulating powder are mixed, and the thermosetting resin precursor and a melting point of 300 ° C. in the precursor sheet. A step of printing a metal paste to be a wiring conductor mixed with the following low melting point metal powder in a predetermined pattern, and the precursor sheet on which the metal paste is printed and applied is placed in an inert atmosphere at a predetermined temperature, and the metal paste is added. A step of bonding the low-melting-point metal powders to each other and thermosetting the thermosetting resin precursor of the precursor sheet and the thermosetting resin precursor of the metal paste, and forming a wiring conductor of a predetermined pattern on the insulating substrate. A method of manufacturing a deposited wiring board. 3. The method for manufacturing a wiring board according to claim 1, wherein the thermosetting resin precursor of the metal paste has conductivity.