JP2001102756A - Multilayer wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer wiring board which attains a fine wiring structure and the dimension stability of a glass ceramic wiring board, can be stably manufactured by simultaneously baking metal foils and glass ceramic moldings, and has superior mounting reliability also for external circuit boards such as printed wiring boards. SOLUTION: This wiring board comprises a glass ceramic insulation board 2 and wiring circuit layers 3 formed in the insulation board 2. The insulation board comprises, at least in the interior, inner wiring layers composed of high- purity metal conductors having a metal content of 99.5 wt.% or more which are composed of foils, of at least one metal selected from among Cu, Ag, Al, Au, Ni, Pt and Pd. The insulation board 1 is made of glass ceramics, having a Young's modulus of 120 GPa or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board suitable for a multilayer wiring board and a package for accommodating a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, a multilayer ceramic wiring board capable of relatively high-density wiring has been frequently used as a wiring board, for example, a multilayer wiring board used for a package for housing a semiconductor element. This multilayer ceramic wiring board is composed of an insulating substrate such as alumina or glass ceramic, and a wiring conductor formed on the surface thereof and made of a metal such as W, Mo, Cu, or Ag. A cavity is formed in the portion, the semiconductor element is accommodated in the cavity, and the cavity is hermetically sealed by the lid.

In recent years, high-density packaging has been required for semiconductor element storage packages for mounting semiconductor elements such as ICs and LSIs, and for hybrid integrated circuit devices on which various electronic components are mounted. Glass ceramic wiring boards, which are required to have a lower dielectric constant, a lower dielectric constant, and a lower resistance of the wiring layer than alumina-based ceramic materials, are attracting more attention.

However, in such a glass-ceramic wiring board, a technique for forming a wiring conductor layer is as follows.
A metallized paste mainly composed of a wiring conductor made of a metal such as Cu or Ag is printed on an insulating substrate by a screen printing method or the like. However, when such a method is used, it is difficult to form a wiring width of 100 μm or less,
This was a factor that hindered the achievement of higher density, smaller size and lighter weight, which are required in the future. Regarding the electric resistance, there are many voids because the wiring conductor layer is formed by the paste, and there is a problem that it is difficult to reduce the resistance.

As a method for solving this problem, a method is known in which a wiring circuit layer in a glass ceramic green sheet is formed by etching a metal foil (Japanese Patent Laid-Open No. 63-14493). However, when the metal foil and the glass ceramic are co-fired, the metal foil itself is substantially dense and hardly shrinks, so that there is a problem that the substrate is warped and cracks occur, which makes practical use difficult.

Therefore, a layer of an inorganic composition that does not sinter at the firing temperature of the wiring board is formed on both sides of the glass ceramic wiring board, and then fired at the same time to suppress shrinkage of the wiring board in the planar direction. There is known a technique which enables simultaneous firing of a metal foil and a glass ceramic (Japanese Patent Laid-Open No. 7-86743).

[0007]

In the case of simultaneous sintering of the glass ceramic molded body and the wiring circuit layer made of copper paste, it is absorbed in the sintering process of both, but the wiring circuit layer made of metal foil is not absorbed. When used, the wiring circuit layer itself is made of a dense body having high rigidity, and most of its thermal stress is applied to the glass ceramic side. There has been a problem that cracks are generated on the circuit layer formation surface, and in some cases, the substrate is broken.

In addition, when an inorganic composition that is not sintered at the firing temperature is laminated with respect to the firing, and then the composition is removed, there is another problem that cracks are easily generated in the glass ceramic.

Conventional glass ceramic wiring boards
The thermal expansion coefficient at around 400 ° C. is 4 to 7 ppm / ° C., whereas the printed circuit in which a Cu wiring layer is formed on a glass-epoxy insulating layer most frequently used as an external circuit board on which a wiring board is mounted. The coefficient of thermal expansion of the substrate is 12 to 1
Very large at 8 ppm / ° C. Therefore, when a semiconductor element is housed in a wiring board or a package for housing a semiconductor element and then mounted on a printed board or the like, heat generated when the semiconductor element is operated is repeatedly applied to both the insulating board and the printed board. Then, a large thermal stress is generated due to a difference in thermal expansion between the insulating substrate and the printed board.

[0010] For this purpose, thermal stress acts on the outer peripheral portion of the connection pad on the lower surface of the insulating substrate and the joint interface between the wiring conductor and the terminal of the external electric circuit board due to the repetition of the operation and stop of the semiconductor element. There is a drawback that the wiring substrate and the package cannot be stably electrically connected to the printed circuit board for a long period of time, because the wiring substrate and the package are separated from the insulating substrate and the terminals are separated from the wiring conductor.

Accordingly, an object of the present invention is to provide a glass-ceramic wiring board that can achieve fine wiring and dimensional stability, and can stably produce a metal foil and a glass-ceramic molded body by simultaneous firing. Another object of the present invention is to provide a multilayer wiring board having excellent mounting reliability even for an external circuit board such as a printed wiring board, and a method for manufacturing the same.

[0012]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have achieved the above object by using a glass ceramic having a low Young's modulus as a glass ceramic used as an insulating substrate. They found what they could do and led to the present invention.

That is, the multilayer wiring board of the present invention comprises an insulating substrate made of glass ceramic, a surface of the insulating substrate and / or
Or a wiring circuit layer including a wiring circuit layer formed therein, wherein at least the inside of the insulating substrate is made of a high-purity metal conductor having a metal component content of 99.5% by weight or more. And wherein the Young's modulus of the insulating substrate is 120 GPa or less, and in particular, the internal wiring circuit layer is made of metal foil, and the inside of the insulating substrate has metal powder. And a via-hole conductor filled with a conductor paste containing the same, and at least one end of the via-hole conductor is connected to an internal wiring circuit layer made of the high-purity metal conductor. It is.

Further, as a method of manufacturing a multilayer wiring board,
(A) a step of producing a green sheet made of a glass ceramic composition having a Young's modulus of 120 GPa or less after firing; and (b) a high purity of 99.5% by weight or more of a metal component on a predetermined transfer film surface. Forming a wiring circuit layer made of a metal conductor, (c) transferring the wiring circuit layer on the transfer film surface to the green sheet surface, and (d) steps (a) to (c). (E) laminating an inorganic composition that does not sinter at the firing temperature of the laminate on both surfaces or one surface of the laminate, and (f) laminating the laminated green sheets. Baking at a temperature lower than the melting point of the high-purity metal conductor,
(G) a step of removing the unsintered inorganic composition on the surface of the sintered body, wherein the unsintered inorganic composition is formed of Al ₂ O ₃ , SiO ₂ , Mg
It is preferable that at least one selected from the group consisting of O, ZrO ₂ , BN, and TiO ₂ is mainly used.

In the above structure, the high-purity metal conductor having a content of the metal component of 99.5% by weight or more includes:
It is desirable to be made of at least one or more metal foils selected from Cu, Ag, Al, Au, Ni, Pt, and Pd.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multilayer wiring board according to the present invention will be described with reference to the drawings. In the description, according to the multilayer wiring board 1 of the present invention, the insulating substrate 2 is composed of a laminated body formed by laminating a plurality of glass ceramic insulating layers 2a to 2d. And a wiring circuit layer 3 made of a high-purity metal foil having a thickness of about 10 to 15 μm. Further, via-hole conductors 4 having a diameter of 80 to 200 μm are formed so as to penetrate through the thickness direction of each of the glass ceramic insulating layers 2 a to 2 d, thereby forming a circuit network for achieving a predetermined circuit. You.

In the present invention, the insulating substrate 2 is formed from glass ceramics, and the Young's modulus of the glass ceramics is 120 GPa or less, especially 110 GPa.
It is a great feature that it is made of a material having a low Young's modulus of not more than a and not more than 100 GPa.

If the Young's modulus is greater than 120 GPa, cracks and cracks are likely to occur in the insulating substrate 2 made of glass ceramic in the cooling process after the simultaneous firing with the wiring circuit layer 3 made of a high-purity metal conductor. It is.

Further, as the above glass ceramics,
10 to 70% by weight of glass component and 30 of filler component
It is desirable to contain it in a proportion of up to 90% by weight.

The glass constituting the glass ceramic contains at least SiO ₂ and Al ₂ O
₃ , containing at least one of B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxides and alkali metal oxides, and being an amorphous glass by firing, and firing Lithium silicate, cordierite, mullite, anorthite, Celsian,
It is known to precipitate at least one crystal of spinel, ganite, willemite, dolomite, petalite or a substituted derivative thereof.

Inorganic fillers such as quartz, quartz glass, quartz, cristobalite, etc.
O ₂ , Al ₂ O ₃ , ZrO ₂ , mullite, forsterite, enstatite and the like are known.

The Young's modulus of the glass ceramic varies depending on the material and the mixing ratio of the glass and the inorganic filler. For example, as an inorganic filler, Al ₂ O ₃ has a high Young's modulus, so that if it is added in an amount of 50% by weight or more, the Young's modulus becomes larger than 120 GPa.
In particular, in order to achieve a high thermal expansion and a low Young's modulus, it is desirable to contain at least one of the above-mentioned SiO ₂ , forsterite, and enstatite as a filler.

The wiring circuit layer 3 is made of a high-purity metal conductor of 99.5% by weight or more, and includes Cu, Ag, Al, A
It is desirable to be made of at least one or more metal foils selected from u, Ni, Pt, and Pd. It is desirable that the via hole conductor 4 is filled with a conductor having the same components as those of the above-described wiring circuit layer 3.

The wiring circuit layer on the surface of the multilayer wiring board serves as a pad for mounting various electronic components 5 such as an IC chip, a shielding conductor film, and a terminal electrode for connecting to an external circuit. And various electronic components 5 are joined to the wiring circuit layer 3 via solder, a conductive adhesive, or the like. Although not shown, a thick-film resistor film such as tantalum silicide or molybdenum silicide, a wiring protection film, or the like may be further formed on the surface of the wiring substrate as necessary.

Next, a method for manufacturing the multilayer wiring board of the present invention will be described. First, a glass-ceramic composition is prepared by mixing the above-mentioned inorganic filler component with the above-mentioned crystallized glass or amorphous glass, and after adding an organic binder or the like to the mixture, doctor blade method, rolling method, pressing It is formed into a sheet by a method or the like to produce a green sheet.

Next, a diameter of 80 to 20 is applied to the green sheet by laser, micro drill, punching or the like.
A through hole of 0 μm is formed, and the inside thereof is filled with a conductive paste. The conductive paste is formed by homogeneously mixing an organic binder such as an acrylic resin and an organic solvent such as toluene, isopropyl alcohol, and acetone, in addition to the metal powder containing Cu or Ag as a main component. The organic binder is used in an amount of 0.5 to 100 parts by weight of the metal component.
Preferably, the organic solvent is mixed at a ratio of 5 to 100 parts by weight with respect to 100 parts by weight of the solid component and the organic binder. Note that a slight glass component or the like may be added to the conductor paste.

Next, a wiring circuit layer made of a high-purity metal conductor is transferred onto the surface of the green sheet. As a method of transfer, first, a high-purity metal conductor, particularly a metal foil, is bonded onto a transfer film made of a polymer material or the like, and then a mirror image resist is applied in a circuit pattern on the surface of the metal conductor, and then etched. Processing and resist removal are performed to form a mirror image of the wiring circuit layer.

After the transfer film having the mirror image wiring circuit layer formed thereon is positioned on the surface of the green sheet on which the via hole conductor is formed and pressure-bonded by lamination, the transfer film is peeled off to form a wiring circuit layer connected to the via hole conductor. Can be formed as one unit of green sheet. Thereafter, a plurality of green sheets obtained in the same manner are laminated and pressed to form a laminate 1.

Next, in order to suppress shrinkage in the plane direction, an inorganic composition that does not sinter at the firing temperature of the laminate 1 is A
l ₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , BN, TiO
_An organic binder is added to a ceramic powder mainly composed of at least one selected from the group ₂ and formed into a sheet by a doctor blade method or the like to produce a green sheet. Then, the green sheet is pressure-laminated on both sides or one side of the laminate to produce a laminate.

Next, the laminate is heated in a nitrogen atmosphere at 400 to 750 ° C. to decompose and remove the organic components in the green sheet and the via-hole conductor paste.
Co-firing in a nitrogen atmosphere at ~ 1000 ° C. When an Ag conductor is used as the wiring circuit layer, the firing can be performed in the air. If the cooling rate after the firing is too fast, cracks occur due to the difference in thermal expansion between the insulating substrate and the wiring circuit layer.
/ Hr or less.

Thereafter, the non-sintered inorganic composition is removed by ultrasonic cleaning or blasting, whereby a multilayer wiring board having a wiring circuit layer and a via-hole conductor can be manufactured.

[0032]

EXAMPLE 1 The glass ceramic wiring board of the present invention is evaluated based on one example.

First, as shown in Table 1, in order to adjust the Young's modulus, several kinds of glass and ceramic components
l ₂ O ₃ , forsterite, and SiO ₂ were weighed to produce glass ceramics A to G. Using a slurry prepared by adding an acrylic resin as a binder, DBP (dibutyl phthalate) as a plasticizer, and toluene and isopropyl alcohol as a solvent, a green sheet having a thickness of 500 μm was prepared by a doctor blade method.

First, in order to measure the Young's modulus, each green sheet is laminated and fired at 900 ° C., and 3 × 4 × 40 m
m JIS bending test pieces were prepared. The specific gravity of the obtained test piece was measured by the Archimedes method. Next, the surface of the test piece is mirror-polished and subjected to an ultrasonic pulse method (JISR).
1602-1995), and each Young's modulus was measured from the result of the specific gravity. Table 1 shows the measurement results.

[0035]

[Table 1]

Next, Cu alone having an average particle size of 5 μm, an acrylic resin as an organic binder, and DB as a solvent
P was added and kneaded to prepare a paste-like paste sample for via-hole conductor. The organic binder in the via hole paste sample was added in an amount of 2.0 parts by weight based on 100 parts by weight of Cu alone, and a solvent was added in an amount of 75 parts by weight based on 100 parts by weight of Cu alone and the organic binder.

A via hole was formed at a predetermined portion of the green sheet, and the via hole was filled with the Cu paste.

Next, a 15 μm-thick Cu foil having a purity of 99.9% or more is adhered to a transfer film made of PET, and a mirror image resist of a wiring pattern is applied.
The resist was removed to form a mirror image wiring circuit layer. Although the wiring width was 0.05 mm, an extremely fine wiring circuit layer could be formed as compared with the conventional screen printing method due to the formation by etching.

Then, a transfer film was laminated on the green sheet having the via hole formed therein while the via hole was being positioned, and was thermocompression-bonded at 60 ° C. and 150 kgf / cm ² . By peeling off the transfer film, one unit of a green sheet having a wiring circuit layer connected to the via-hole conductor was formed.

[0040] Five green sheets produced in the same manner were laminated and pressed together. Next, a green sheet was produced in the same specification as the glass ceramic green sheet using Al ₂ O ₃ having a purity of 92% by weight or more as an inorganic composition not to be sintered. A green sheet of the obtained inorganic composition was applied on both sides of the glass ceramic laminate at 60 ° C. and 200 kgf.
/ Cm ² to produce a laminate.

Next, the unfired laminate is fired at 700 ° C. in a nitrogen atmosphere in order to decompose and remove organic components such as an organic binder.
Firing was performed at ℃. Thereafter, the inorganic composition that did not sinter was removed by blasting to produce a wiring substrate.

The surface of the obtained wiring board was checked for cracks using a scanning electron microscope (SEM). No crack was defined as a good product.

Next, the conduction resistance of the wiring circuit layer was evaluated using the obtained wiring board. For the evaluation, a width of 0.
A copper wiring circuit layer having a length of 05 mm and a length of 20 mm is formed in advance,
The wiring resistance was measured using a tester, the cross section of the copper wiring circuit layer was measured using a scanning electron microscope (SEM), and the length of the copper wiring circuit layer was measured using a 40 × microscope. The resistivity was calculated. In addition, as a judgment of good or bad, a product having a resistivity of 2.5 μΩ · cm or less was defined as a good product.

In connection reliability evaluation, connection terminals made of solder (10 to 60% of tin, 40 to 90% of lead) were attached to connection pads. The connection terminals were formed on the entire lower surface of the wiring board at a density of 30 terminals per 1 cm ² . On the other hand, a printed circuit board on which a wiring conductor made of a glass-epoxy substrate is formed is prepared, and the above-mentioned wiring board is aligned with the wiring conductor on the printed board and each connection terminal is connected. Heat treatment was performed at 260 ° C. for 3 minutes in an N ₂ atmosphere, and the glass ceramic wiring board was mounted on the surface of the printed board. By this heat treatment, it was confirmed that the connection terminal made of solder on the wiring board was melted and electrically connected to the wiring conductor on the printed board.

As described above, the glass-ceramic wiring board mounted on the surface of the printed circuit board was subjected to -4 in air.
The test sample is held in a thermostat controlled at a temperature of 0 and 125 ° C. for 15 minutes / 15 minutes as one cycle.
Repeated 0 cycles. Then, the electrical resistance between the wiring conductor of the printed circuit board and the glass ceramic wiring substrate was measured for each cycle, and the number of cycles until the electrical resistance changed was shown in Table 2. Those that exceeded 500 cycles were regarded as good products.

Examples 2, 3, and 4 As the high-purity metal conductor forming the wiring circuit layer, the purity was 9%.
Using a metal foil of 9.9% or more of Ag, Ag-Pd, and Ag-Pt, a multilayer wiring board was manufactured in the same specifications as in Example 1. The firing was performed at 900 ° C. in the air. Table 2 shows the evaluation results.

Examples 5, 6, 7 A multilayer wiring board was produced in the same manner as in Example 1 except that green sheets of SiO ₂ , ZrO ₂ , and MgO were used as the non-sintered inorganic composition. Table 2 shows the evaluation results.

Comparative Example 1 The same specifications as in Example 1 were used, and the wiring circuit layer was formed by screen printing using a conventional copper paste instead of transferring a metal foil. Table 2 shows the evaluation results.

[0049]

[Table 2]

According to Table 2, the Young's modulus of the insulating substrate material is 12
Sample No. exceeding 0 GPa In Nos. 1 and 2, a large number of cracks were observed on the surface of the wiring board after removing the non-sintered inorganic composition. Moreover, in the temperature cycle test, a resistance change appeared in less than 500 cycles. In Sample No. 14 in which the wiring circuit layer was formed by the screen printing method, disconnection occurred, and fine wiring having a wiring width of 0.05 mm could not be formed.

In contrast to these comparative examples, according to the multilayer wiring board of the present invention, even when a metal foil is used, the occurrence of cracks after firing can be reduced, and in particular, the Young's modulus is set to 100 GPa or less. As a result, the generation of cracks was completely eliminated. Moreover, the connection reliability with the printed circuit board was excellent.

[0052]

As described in detail above, according to the present invention,
When a high-purity metal conductor having a metal component content of 99.5% by weight or more is formed as a wiring circuit layer, the insulating substrate is made to have a low Young's modulus, thereby enabling fine wiring and reducing the resistance of the conductor. It is possible to provide a multilayer wiring board which satisfies no cracks or the like and has excellent connection reliability when mounted on a printed wiring board.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a multilayer wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer wiring board 2 Insulating board 3 Wiring circuit layer 4 Via hole conductor 5 Electronic component

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/09 H05K 1/09 A 1/11 1/11 NF term (Reference) 4E351 AA07 AA12 AA13 BB01 BB30 BB49 CC12 CC17 CC31 DD01 DD04 DD05 DD06 DD19 DD20 DD42 DD45 DD47 DD52 EE08 GG09 GG11 5E317 AA24 BB04 BB12 BB13 BB14 BB15 BB19 BB24 CC13 CC22 CC25 GG11 GG14 GG17 5E346 AA12 AA15 CCA31 CC32 CC01 DDCC EE25 EE27 EE29 FF18 GG03 GG08 GG09 HH11

Claims (6)

[Claims] An insulating substrate made of glass ceramics,
A wiring board comprising a wiring circuit layer formed on the surface and / or inside of the insulating substrate, wherein at least the inside of the insulating substrate has a metal component content of 99.5% by weight or more. A multilayer wiring board comprising an internal wiring circuit layer made of a conductor, wherein the Young's modulus of the insulating substrate is 120 GPa or less. 2. The semiconductor device according to claim 1, wherein said internal wiring circuit layer comprises Cu, Ag, A
2. The multilayer wiring board according to claim 1, comprising at least one or more metal foils selected from the group consisting of 1, Au, Ni, Pt, and Pd. 3. An internal wiring comprising a via-hole conductor filled with a conductive paste containing metal powder inside said insulating substrate, wherein at least one end of said via-hole conductor is made of said high-purity metal conductor. 2. The multilayer wiring board according to claim 1, wherein the multilayer wiring board is connected to a circuit layer. 4. A process for producing a green sheet comprising a glass-ceramic composition having a Young's modulus of 120 GPa or less after firing, and (b) a content of a metal component on a predetermined transfer film surface of 99.5% by weight. % Of a high-purity metal conductor, and (c) transferring the wiring circuit layer on the transfer film surface to the green sheet surface; and (d) (a) to (c). )) Laminating the green sheets produced through the step to produce a laminate; and (e) laminating an inorganic composition that does not sinter at the firing temperature of the laminate on both surfaces or one surface of the laminate. f)
A step of firing the laminate at a temperature lower than the melting point of the high-purity metal conductor; and (g) a step of removing the unsintered inorganic composition on the surface of the sintered body. Manufacturing method. 5. The high-purity metal conductor having a metal component content of 99.5% by weight or more is made of Cu, Ag, Al, Au, N
5. The method for manufacturing a multilayer wiring board according to claim 4, comprising at least one kind of metal foil selected from i, Pt, and Pd. 6. The non-sintered inorganic composition comprises Al
₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , BN, TiO ₂
5. The method according to claim 4, wherein at least one member selected from the group consisting of: