JP3292645B2 - Wiring board and method of manufacturing the same - Google Patents

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. 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 to the lower surface of the insulating base, and a semiconductor element is formed on the bottom of the recess of the insulating base. The electrodes of the semiconductor element are electrically connected to wiring conductors via electrical connection means such as a bonding wire, and then the insulating base is adhered and fixed by an adhesive such as glass, resin, or brazing material. A lid made of metal, ceramics, or the like is placed on the top surface of the insulating base with a sealing material such as glass, resin, brazing material, etc. A semiconductor device as a product is obtained by joining the semiconductor elements in a concave portion of the insulating base in an airtight manner, and a portion of the wiring conductor led out to the bottom of the concave portion of the insulating base is connected to the wiring conductor of the external electric circuit board. Each electrode of the element is electrically connected to the external electric circuit board.

Incidentally, the wiring board is generally manufactured by a ceramic green sheet laminating method, and specifically, aluminum oxide, silicon oxide, magnesium oxide,
A ceramic raw material powder such as calcium oxide is mixed with an appropriate organic binder, a solvent, and the like to form a slurry, which is formed into a sheet by employing a conventionally known doctor blade method, thereby obtaining a plurality of ceramic green sheets. Thereafter, the ceramic green sheet is subjected to a suitable punching process and 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 sintering and firing the ceramic forming body at a high temperature of about 1600 ° C. in a reducing atmosphere.

[0004]

However, in this conventional wiring board, since the ceramics such as the aluminum oxide sintered body constituting the insulating base have a hard and brittle property, the automatic wiring of the transfer process and the semiconductor device manufacturing is difficult. When the wiring boards collide with each other or the wiring board and a part of the semiconductor device manufacturing automatic line violently collide with each other, chips, cracks, cracks, etc. occur in the insulating base, and as a result, the semiconductor element can be housed in an airtight manner. In addition, the semiconductor device cannot operate normally and stably for a long period of time.

According to the method of manufacturing a wiring board,
When firing the ceramic forming body, uneven firing shrinkage occurs in the ceramic forming 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 conductor Or the wiring conductor and the wiring conductor of the external electric circuit board are difficult to accurately and reliably electrically connect.

[0006]

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
Comprising a thermosetting resin, wherein the inorganic insulating powder is
Precursor sheet composed of thermosetting resin precursor
Thereof a plurality are stacked and thermally cured by curing, multi comprising the inorganic insulator powder bonded by the thermosetting resin
The insulating substrate <br/> insulating substrate formed by laminating several sheets of the insulating substrate, and together with the precursor sheet in a semi-cured and thermally cured,
The copper powder is characterized in that the composed by depositing a wiring conductor bound by a phenolic resin.

The wiring board of the present invention is characterized in that the copper powder of the wiring conductor is joined by solder.

Further, in the method for manufacturing a wiring board according to the present invention, there is provided a step of preparing a precursor sheet formed by mixing a thermosetting resin precursor and an inorganic insulating powder, and heating the precursor sheet.
A step of semi-curing, and printing a metal paste obtained by mixing a phenol resin precursor and copper powder on the semi-cured precursor sheet in a predetermined pattern and heating and semi-curing
A step of causing, semi cured the metal paste is printed
When a plurality of semi-cured precursor sheets are vertically stacked
Both are characterized in that consisting of the step of thermally curing the phenolic resin precursor of a thermosetting resin precursor and the metal paste is heated to the precursor sheet this.

Still further, the method for manufacturing a wiring board according to the present invention comprises:
Preparing a precursor sheet comprising a mixture of a thermosetting resin precursor and an inorganic insulating powder, and heating the precursor sheet;
A step of semi-curing by the steps of printing a semi-cured the precursor sheet to the phenolic resin precursor and the copper powder and the solder powder and the formed by mixing the metal paste in a predetermined pattern,
A step of heat-treating the metal paste and joining copper powder with solder; and a step of attaching the heat-treated metal paste to the metal paste.
A plurality of the precursor sheets for curing are laminated one above the other.
Is characterized in that consists of the steps of thermally curing the phenolic resin precursor of a thermosetting resin precursor and the metal paste of the precursor sheet by heating it to.

Further, the method for manufacturing a wiring board according to the present invention comprises:
The metal paste further contains a solder wetting accelerator.

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 mutually connected or the wiring board and the semiconductor device manufacturing automatic line. 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 phenol resin binding the copper powder of the wiring conductor effectively prevents the surface oxidation of the copper powder, thereby improving the electrical connection between the copper powders. The migration resistance and high frequency characteristics are improved.

Further, according to the wiring board of the present invention, when the copper powders of the wiring conductors are bonded together via solder, the electrical connection between the copper powders becomes better, and as a result, the migration resistance of the wiring conductors is improved. Properties and high frequency characteristics are further improved.

Further, according to the method of manufacturing a wiring board of the present invention, since there is no baking step for obtaining an insulating substrate, there is no deformation or dimensional variation due to uneven shrinkage due to baking.

Further, according to the method of manufacturing a wiring board of the present invention, when solder and a solder wetting accelerator are contained in a metal paste, bonding between copper powders via solder can be performed in a short time. As a result, the electrical resistance of the wiring conductor can be reduced, and the migration resistance, high-frequency characteristics, and the like can be improved.

[0016]

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 package for housing a semiconductor element for housing a semiconductor element, wherein 1 is an insulating base, and 2 is a wiring conductor.

The insulating substrate 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, and the semiconductor element 3 is provided on the bottom surface of the concave portion 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 an inorganic insulating powder such as silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, and zeolite with a thermosetting resin such as an epoxy resin, a polyimide resin, and a polyphenylene ether resin. The three insulating substrates 1a, 1b, and 1c constituting the insulating substrate 1 are formed by bonding inorganic insulating powder with a thermosetting resin having excellent toughness. Even when an external force is applied to the insulating substrate 1, the external force does not cause chipping, cracking, cracking or the like in the insulating substrate 1.

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 show that when the content of the inorganic insulating powder is less than 60% by weight, the thermal expansion coefficient of the insulating base 1 is lower than that of the semiconductor element 3.
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 is caused by the difference in the thermal expansion coefficient between the two. A large thermal stress is generated, and the large thermal stress causes the semiconductor element 3 to be separated from the insulating base 1 or the semiconductor element 3 to be cracked or chipped. 95% by weight
The ultra El and the inorganic insulating powder can not be completely bound with a thermosetting resin, a predetermined insulating substrate 1a, 1b, 1c
Can not be obtained. Therefore, the insulating substrates 1a, 1b, and 1c constituting the insulating base 1 have an inorganic insulating powder content of 60 to 95% by weight contained therein.
Specified in the range.

The insulating base 1 has a wiring conductor 2 formed by bonding copper powder with a phenol resin from the periphery of the concave portion 1d to the lower surface.

The wiring conductor 2 serves to electrically connect each electrode of the semiconductor element 3 housed therein to an external electric circuit. Are electrically connected via bonding wires 4, and a portion led out to the lower surface of the insulating base 1 is electrically connected to an external electric circuit.

The wiring conductor 2 is formed by bonding copper powder through a phenol resin. Since the phenol resin has an effect of preventing surface oxidation of the copper powder, an oxide is formed on the surface of the copper powder. As a result, the electrical connection between the copper powders becomes good, and the migration resistance and high frequency characteristics of the wiring conductor 2 are greatly improved.

[0024] Incidentally, copper powder contained in the wiring conductor 2 will tend the content of the electric resistance value of the wiring conductor 2 is high is less than 70 wt%, also the ultra-El and copper powder 95 wt% It tends to be difficult to bond firmly with a phenolic resin. Therefore, the content of the copper powder contained in the wiring conductor 2 is preferably in the range of 70 % by weight to 95% by weight.

Further, the wiring conductor 2 contains solder such as lead solder or lead-less solder in the inside thereof, and the copper powder is connected between the copper powders by the solder so that the electrical connection between the copper powders can be obtained. And the migration resistance and high frequency characteristics of the wiring conductor 2 are further improved.

When the wiring conductor 2 contains solder such as lead solder or lead-less solder, the total weight of the copper powder and the solder is 60 to 95% by weight based on the total weight of the wiring conductor 2. It is necessary to keep the range, and further, copper powder and solder,
When the amount of the copper powder is less than 20% by weight based on the total weight of the copper powder and the solder, the amount of the solder increases with respect to the copper powder, and the solders are melted with each other to make it difficult to integrate the copper powder. tends to electric resistance of the wiring conductor 2 is high, and the amount of 80% by weight solder for bonding is exceeded and copper powder is relatively small, the wiring conductor can not be completely bonded copper powder 2 tends to have a high electric resistance. Therefore, when the wiring conductor 2 contains solder such as lead solder or lead-less solder, it is preferable that the copper powder be in the range of 20% by weight to 80% by weight based on the total weight of the copper powder and the solder. .

Further copper powder and the solder contained in the wiring conductor 2 has an average particle size of no longer copper powder and the solder are aggregated uniform dispersion is obtained when less than 0.1 [mu] m, also a 50μm is exceeded In addition, it tends to be difficult to print and form the width of the wiring conductor 2 in a generally required range of 50 μm to 200 μm. Accordingly, the copper powder and the solder contained in the wiring conductor 2 have an average particle size of 0.1 μm to 50 μm.
It is preferable to set the range of m.

Further, the wiring conductor 2 is preferably provided with a metal having excellent corrosion resistance and good conductivity, such as nickel or gold, having a thickness of 1.0 to 20.0 μm by plating on the exposed surface. 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 to a thickness of 1.0 to 20.0 μm by a plating method 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 1 d of the insulating base 1 with an adhesive such as a resin, and each electrode of the semiconductor element 3 is bonded with 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 for the semiconductor element storage 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 bonding an inorganic insulating powder with a thermosetting resin precursor, and for example, has a particle size of 0.1.
Epoxy resin such as bisphenol A type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin and amine type curing agent, imidazole type curing agent, acid anhydride type curing agent etc. to silicon oxide powder of about 1 μm to 100 μm. Is added and mixed to form a paste. Thereafter, the paste is formed into a sheet and about 25 to
It is manufactured by heating at a temperature of 100 ° C. for 1 to 60 minutes and semi-curing.

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

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. 2C, a 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 a screen printing method known in the art. A predetermined pattern is printed and applied by using a filling method, and this is heat-treated at a predetermined temperature to be semi-cured.

As the metal paste 12 to be the wiring conductor 2, for example, a mixture of a copper powder having a particle size of about 0.1 to 20 μm and a phenol resin precursor added and used is used.

The metal paste 1 to be the wiring conductor 2
No. 2 is a mixture of copper powder and a phenolic resin precursor added and mixed, and since phenolic resin acts to effectively prevent surface oxidation of copper powder, an oxide film is formed on the surface of copper powder. As a result, the electrical connection between the copper powders is improved, and the migration resistance, the high-frequency characteristics, and the like are improved.

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. The thermosetting resin precursors of the sheets 11a, 11b and 11c and the phenolic resin precursor of the metal paste 12 printed and applied in a predetermined pattern on the precursor sheets 11b and 11c are completely thermoset as shown in FIG. A wiring board in which the wiring conductor 2 is applied to the insulating base 1 is completed. In this case, the precursor sheet 11
The a, 11b, 11c and the metal paste 12 hardly shrink during thermosetting, and therefore, the resulting wiring board does not undergo deformation or dimensional variation, and the wiring conductor 2 does not break. Semiconductor element via wiring conductor 2
It is possible to reliably electrically connect the third and other electrodes to an external electric circuit.

Further, in the manufacturing method of the present invention, the metal paste 12 composed of the above-mentioned copper powder and the phenol resin precursor further improves the wettability between the solder such as lead solder and lead-less solder and the solder and the copper powder. Solder wetting accelerator for, specifically, a rosin flux or a fatty acid or a metal salt thereof, a metal chelating agent, oxydylcarboxylic acid or a metal salt thereof, aminodicarboxylic acid or a metal salt thereof, etc. The metal paste is applied to the precursor sheet 11b, 1
1c is printed and applied on the upper and lower surfaces, etc., and then heated at a temperature of about 200 ° C. to melt the solder and bond the copper powder with the melted solder. fully and become to become a better electrical connection of the wiring conductor 2, as a result, it becomes possible to Ru further improve the migration resistance and high frequency characteristics of the wiring conductor 2 and the like. Therefore, according to the present invention, in the method of manufacturing a wiring board, solder such as lead solder or lead-less solder and solder wettability for improving the wettability between solder and copper powder in the metal paste to be the wiring conductor 2 are provided . It is preferable to contain an accelerator.

Further, the metal paste 12 to be the wiring conductor 2
When further containing a solder such as lead solder or lead-less solder and a solder wetting accelerator for improving the wettability between the solder and the copper powder, the amount of the solder wetting accelerator consisting of a rosin flux, a fatty acid, etc. Is 0.1% with respect to the weight of the total metal paste.
If less than wt%, there is a tendency that wettability between the solder and the copper powder is lowered, there is a 20% by weight tends to Exceeding the electric resistance of the wiring conductor 2 becomes large. Therefore, when the solder wetting accelerator is contained in the metal paste 12, the amount thereof is 0.1% by weight based on the total weight of the metal paste 12.
It is preferable to set it in the range of 20 to 20% by weight.

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 description has been given by taking as an example the case where the wiring board is applied to a semiconductor element housing package for housing a semiconductor element, the wiring board 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, the wiring board is formed by using one, two, or four or more precursor sheets. May be manufactured.

[0043]

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

Further, according to the wiring board of the present invention, the phenol resin binding the copper powder of the wiring conductor effectively prevents the surface oxidation of the copper powder, thereby improving the electrical connection between the copper powders. The migration resistance and high frequency characteristics are improved.

Further, according to the wiring board of the present invention, when the copper powders of the wiring conductors are bonded to each other via solder, the electrical connection between the copper powders becomes better, and as a result, the migration resistance of the wiring conductors is improved. Properties and high frequency characteristics are further improved.

Further, according to the method of manufacturing a wiring board of the present invention, since there is no baking step for obtaining an insulating base, there is no occurrence of deformation or dimensional variation due to uneven shrinkage due to baking.

Furthermore, according to the method of manufacturing a wiring board of the present invention, when solder and a solder wetting promoter are contained in a metal paste, bonding between copper powders via solder can be performed in a short time and As a result, the electrical resistance of the wiring conductor can be reduced, and the migration resistance, high-frequency characteristics, and the like can be improved.

[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

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 1 / 02,1 / 03,1 / 09 H05K 3 / 12,3 / 46 H01L 23 / 12,23 / 14 H01B 1/00-1/24

Claims (5)

(57) [Claims] An inorganic insulating powder of 60 to 95% by weight and 5
Or consists of a 40 wt% of a thermosetting resin, wherein the inorganic insulation
Before bonding the edge powder with the thermosetting resin precursor
Semi-cured precursor sheets, laminating multiple sheets and heat curing
An insulating base formed by laminating a plurality of insulating substrates each formed by bonding the inorganic insulating powder with the thermosetting resin.
On the insulating substrate , together with the semi-cured precursor sheet
A wiring board, comprising a wiring conductor formed by bonding a heat-cured copper powder with a phenol resin to a wiring conductor. 2. The wiring board according to claim 1, wherein the copper powder of the wiring conductor is joined by solder. 3. A process for preparing a precursor sheet formed by mixing a thermosetting resin precursor and the inorganic insulating powder, said precursor
A step of semi-cured by heating the sheet, printing a semi-cured the precursor sheet to the phenolic resin precursor and the copper powder formed by mixing a metal paste in a predetermined pattern together
A step of semi-cured by heating the said metal Bae was semi-cured
A plurality of semi-cured precursor sheets on which paste is printed
Method for manufacturing a wiring substrate, characterized in that it consists a step of thermally curing the phenolic resin precursor is heated to the thermal curing of the precursor sheet resin precursor and the metal paste which, as well as vertically stacked. 4. A process for preparing a precursor sheet formed by mixing a thermosetting resin precursor and the inorganic insulating powder, said precursor
A step of semi-cured by heating the sheet, a step of printing a semi-cured the precursor sheet to the phenolic resin precursor and the copper powder and the solder powder formed by mixing a metal paste in a predetermined pattern, the metal paste Heat-treating, bonding the copper powder with solder, and the heat-treated metal paste
A plurality of the applied semi-cured precursor sheets are stacked vertically.
Method for manufacturing a wiring substrate, characterized in that it consists a step of thermally curing the phenolic resin precursor is heated to the thermal curing of the precursor sheet resin precursor and the metal paste which, together with the layers. 5. The method according to claim 4, wherein the metal paste further contains a solder wetting accelerator.