JPS63293899A - Multi-layered circuit board - Google Patents

Abstract

PURPOSE:To obtain a multi-layered circuit board having a conductor with lower seat resistance by a method wherein a specific conductive paste is used as the conductive paste for an inside layer circuit and the conductive paste for the most outside layer land section to improve the matching between the circuit conductor and board. CONSTITUTION:A conductive paste A for outside layer is printed as an outside layer land section 1 and an outside layer circuit section 2. The conductive paste A for the inside layer is printed as an inside layer land section 3 and an inside layer circuit section 4. The paste A is made with the mixing ratio of low resistance conductive powder 100 weight section, glass frit 0.5-10 weight section, organic binder 10-50 weight section, and suitable amount of solvent, and the softening temperature of the glass frit is lower than that of ceramic board material. The paste B is made with the mixing ratio of low resistance conductive powder 100 weight section, glass frit 0.5-10 weight section, organic binder 10-50 weight section and suitable amount of solvent, and the softening temperature of the glass frit is higher than that of ceramic board material.

Description

[Detailed Description of the Invention] [Technical Field] The present invention provides a ceramic multilayer wiring board that can be co-fired with low resistance metals such as silver, silver-palladium, gold, and copper, and is capable of mounting a large number of highly integrated LS. belongs to the technical field of

[Background technology]

In recent years, as demands for miniaturization and high reliability have increased in multilayer wiring boards for mounting highly integrated LSIs and large numbers of various elements, the use of ceramic materials has been expanding. Multilayer wiring board using ceramics
The main material is alumina, and a high melting point metal (
Conductive wiring (Mo, W, etc.) is printed using thick film technology. Thereafter, several layers of the green sheets are stacked one on top of the other and fired in a high temperature non-oxidizing atmosphere at about 1500 to 1600°C.

However, in wiring boards mainly made of alumina as described above, the transmission time of signals propagating through the wiring of the wiring board is long due to the high dielectric constant of alumina and the ultra-fine refractory metal wiring with high resistance. (As a result, it was difficult to meet the demand for higher speeds.Of course, instead of using high-resistance, high-melting-point metal materials,
It is also conceivable to form wiring using low resistance metal materials (Au, Ag, Ag-Pd, Cu, etc.). However, each of the above-mentioned low-resistance metal materials has a melting point of around 1000° C., which is much lower than the sintering temperature of alumina. Therefore, even if it were used, there was a problem that the wiring pattern would melt before sintering, shrink due to surface tension, and break.

In order to solve this problem, attempts have been made to manufacture wiring boards using glass or glass powder sintered bodies (glass-ceramic bodies), as disclosed in Japanese Patent Application No. 61-057341 and Japanese Patent Application No. 61-013357. has been disclosed.

When applying such a glass powder sintered body (glass-ceramic body) to a wiring board, a conductor is printed on a green sheet made of glass powder, laminated, and fired to obtain the desired multilayer wiring board. However, in this case, the conductor paste used for the inner layer of a multilayer board does not require much adhesion to the board, but if the shrinkage characteristics during firing are not matched properly, the fired board may warp. ,
This may cause cracks and result in defective products. In addition to matching, for the outer layer of multilayer wiring boards,
High adhesion is required.

Furthermore, a low sheet resistance is required as an inherent characteristic of the conductor.

Conventionally, in alumina wiring boards, a glass material with the same composition as the insulating substrate material has been added to the conductor metal as a conductive paste, but in glass-based multilayer wiring boards, if the amount of glass added is small, The shrinkage characteristics of the insulating layer and the conductor did not match, causing warping and cracking. Furthermore, there was a problem in that sheet resistance increased when the amount of glass added increased.

[Purpose of the invention]

It is an object of the present invention to provide a glass-based multilayer wiring board in which circuit conductors and substrates are well matched and wiring with low sheet resistance is formed.

[Disclosure of the invention]

In the present invention, the weight percent composition is as follows: 48≦SiO□≦63 10≦Al2O,≦25 105MgO≦25 4≦B2O3≦10, and O to 20% of the MgO is BaO
At least one selected from the group consisting of 1SrO, CaO
and optionally T 10 !
,Z r 02 ,,S n Oz XP 205,
MQO3, Taz Os% Nbz Os, AS20
, a multilayer wiring board made of a ceramic substrate material selected from a glass composition in which at least one nucleating agent selected from the group consisting of is added in a proportion of 3% by weight or less to the main component. The present invention provides a multilayer wiring board characterized in that a specific conductor paste is used as a conductor paste for an inner layer circuit (including an inner layer land portion) and a conductor paste for an outermost layer land portion.

100 parts by weight of low-resistance conductor powder as a conductor paste with excellent matching for the above-mentioned glass-based multilayer wiring board;
Glass frit 0.5-10 parts by weight, organic binder 1
A conductive paste consisting of 0 to 50 parts by weight and an appropriate amount of solvent is used, but as the conductive paste for the inner layer circuit or inner layer land portion of the multilayer wiring board, a glass whose softening temperature is higher than that of the substrate glass material is mixed. Use the one you made.

The reason for increasing the softening temperature is as follows.

That is, as shown in FIG. 2, the shrinkage curve of the substrate material during firing and the shrinkage curve of the conductor are quite different. In this figure, curves (a) and (b) represent the contraction curves of the conductor, and (
c) represents the shrinkage curve of the substrate. However, (a)
The conductor in (b) is gold (Au), and the conductor in (b) is gold-palladium (
Ag/pd=80/20). Low resistance conductor (metal)
Gold, silver, copper, etc. are well known as materials, but their melting points are around 1000° C., and they start shrinking much earlier than the shrinkage start temperature of the substrate.

Therefore, by bringing the shrinkage curve of the conductor composition closer to that of the substrate, it is possible to reduce warping and cracking defects during simultaneous firing of the substrate and the conductor. Therefore, it is possible to add the same glass frit as the substrate material, but if a considerable amount is added, matching can be achieved, but the sheet resistance of the conductor will increase considerably. Therefore, the softening temperature is higher than that of the substrate material glass frit (preferably 30 to 50°C).
) When glass frit is added, matching can be achieved with a small amount, and the sheet resistance of the conductor does not increase significantly.

However, when a multilayer board is manufactured using this conductive paste, the conductor in the outermost layer of the multilayer wiring board does not have sufficient adhesion to the board. Therefore, the outermost layer conductor of the multilayer board is not fired at the same time, but after the inner layer circuit is formed (substrate sintered state B).
), print and fire the outer layer conductor. However, in this case, unless the land portion of the outer layer is formed at the time of forming the inner layer circuit, the connection reliability between the inner layer circuit and the outer layer circuit will deteriorate.

Therefore, it is necessary to form a conductor with good adhesion by co-firing only the land portion. This can be solved by adding a glass frit whose softening temperature is lower than the softening temperature of the substrate material (preferably 30 to 50° C.). However, if the temperature difference is too large, even a small land will warp.
Cracks are more likely to occur. Furthermore, it is advantageous for the glass frit to have a composition similar to that of the substrate material glass, as it is more compatible with the glass frit. .

FIG. 1 shows an example of a multilayer wiring board manufactured using the conductor paste described above.

That is, FIG. 1 is a schematic diagram showing a layer structure for explaining the structure of a multilayer wiring board. In this diagram, (a) is
This is a diagram showing a state in which four layers are prepared by printing conductor paste on a green sheet. 5a is a green sheet for the outer layer, and the conductor paste for the outer layer is applied to the outer layer land portion l, the outer layer circuit portion 2. is printed as. However, the conductor paste for the outer layer land portion l is formed from the conductor base I, which contains glass with a lower softening temperature than the substrate material, and is fired at the same time, but the conductor paste for the outer layer circuit portion 2 is Not necessarily fired at the same time. Rather, it is preferable to print and fire only the outer layer circuit portion 2 after firing the inner layer circuit and the outer layer land portion. On the other hand, 5b is an inner layer green sheet, on which conductor paste for the inner layer is printed as inner layer land portions 3 and inner layer circuit portions 4. This part is always fired at the same time.

When the above Green Sea) 5a and 5b are stacked and fired,
As shown in FIG. 1(b), the conductor for the outer layer land portion and the conductor for the inner layer are fused in the through-hole portion, resulting in a multilayer wiring board with excellent connection reliability.

Note that it is desirable that the glass frit for the conductor paste has a composition similar to the glass composition for the substrate described above, and that the softening temperature is changed by changing the blending amount.

Hereinafter, it will be explained in more detail based on examples.

(Example) (1) Melting of Glass Raw materials were mixed in the proportions shown in Table 1, glass was melted at 1450°C, and the glass was quenched by pouring into water to obtain a glass frit.

Table 1 shows the softening temperature of the glass.

(2) Preparation of Green Sheet The above frit was ground in an alumina ball mill to form a powder with an average particle size of 1 to 10 μm.

Next, add acrylic resin, dispersant, plasticizer,
A solvent was added and kneaded, followed by defoaming treatment under reduced pressure, and a 0.2 dragon green sheet was prepared using a conventional doctor blade method.

■ Preparation of conductor paste Add conductor metal powder,
Glass powder and an organic binder prepared by dissolving ethyl cellulose in butyl carpitol acetate in advance were added to a viscosity suitable for printing, and thoroughly kneaded to obtain a conductive paste.

(2) Preparation of multilayer substrate After printing a conductive paste on a green sheet and drying it, a plurality of sheets were laminated to form a molded body under press molding conditions of 70° C. and 100 kg/cd.

This molded body was fired in the firing mode shown in FIG. 3, and the sheet resistance, adhesion of the conductor to the substrate, warping, interlayer peeling, and conductor peeling (outermost layer land portion) were evaluated.

The results are shown in Table 2.

[Hereinafter, blank spaces] [Effects of the Invention] In the present invention, the composition expressed in weight percent is as follows: 48≦Sing≦63 10≦A1zCh≦25 10≦MgO≦25 4≦B20. ≦10 and 0 to 20% by weight of the MgO is Ba5
s Substituted with at least one selected from the group consisting of SrO and CaO, and if necessary, T i O
z, Z r O2, S n O2, P z Os, M
oO3, TaxOs, Nbz05, As2O,
At least one nucleating agent selected from the group consisting of
A multilayer wiring board made of a ceramic substrate material selected from among glass compositions in which 3% by weight or less is added to the main components, and which is used as a conductive paste for inner layer circuits rather than ceramic substrate materials. A conductor paste containing glass frit with a high softening temperature is used, and the conductor paste for the outermost land portion is a conductor paste containing glass frit with a lower softening temperature than the ceramic substrate material. Therefore, it was possible to provide a multilayer wiring board having a conductor that matches well with the substrate and has a low sheet resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of a multilayer wiring board according to the present invention, FIG. 2 is a graph illustrating the relationship between firing temperature and shrinkage rate in a conductor, and FIG. 3 is an example of a firing mode. This is a graph showing. l is the outer layer land portion 2 is the outer layer circuit portion 3 is the inner layer land portion 4 is the inner layer circuit portion 5a, 5b is the green sheet Patent applicant Toshimaru Takemoto (and 2 other people, patent attorney representing Matsushita Electric Works Co., Ltd.) Figure 1 ( b) (b)

Claims (1)

[Claims] (1) The composition expressed in weight% is 48≦SiO_2≦63 10≦Al_2O_3≦25 10≦MgO≦25 4≦B_2O_3≦10, and 0 to 20% by weight of the MgO is BaO
, SrO, and CaO.
and optionally, TiO_2,
ZrO_2, SnO_2, P_2O_5, MoO_3,
A multilayer made of a ceramic substrate material selected from a glass composition in which at least one nucleating agent selected from the group consisting of Ta_2O_5, Nb_2O_5, and As_2O_3 is added at a ratio of 3% by weight or less to the main component. For wiring boards, the following (
A multilayer wiring board characterized in that the conductor paste of A) is used, and the conductor paste of the following (B) is used as the conductor paste for the outermost land portion. (A) The formulation consists of 100 parts by weight of low resistance conductor powder, 0.5 to 10 parts by weight of glass frit, 10 to 50 parts by weight of organic binder, and an appropriate amount of solvent, and the glass frit has a softening temperature lower than that of the ceramic substrate material. Conductor paste with high quality. (B) The composition consists of 100 parts by weight of low resistance conductor powder, 0.5 to 10 parts by weight of glass frit, 10 to 50 parts by weight of organic binder, and an appropriate amount of solvent, and the glass frit has a softening temperature lower than that of the ceramic substrate material. conductor paste, which has a low