JPH05275861A - Multilayer circuit board - Google Patents

Abstract

PURPOSE:To obtain a multilayer circuit board such that its excellent printability is maintained, delamination does not occur, the density, speed, and reliability are enhanced and the cost can be reduced by forming inner interconnections of Ag paste capable of minimizing the sheet resistance. CONSTITUTION:A multilayer circuit board is formed of a board body 1 containing ceramic and glass, and inner interconnections 2 arranged in the body 1. The interconnection 2 is formed of Ag paste which contains Ag conductor powder, fritted glass, 8-10 of an HLB value, 0.15-0.3wt.% of dispersant, and organic vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer circuit board having a low resistance and no peeling between the boards.

[0002]

2. Description of the Related Art Generally, multi-layer circuit boards used in electronic equipment include high density, high speed, high reliability,
There is a strong demand for lower prices.

In order to meet these requirements, the internal wiring has a relatively low melting point of Ag, Cu, Au or the like instead of a high melting point metal material such as molybdenum or tungsten.
And low resistance materials are being used. Further, as the substrate material, a low temperature firing substrate material containing ceramic and glass frit is used instead of alumina ceramic or the like.

As a conductive paste used for forming the internal wiring of such a low-temperature fired substrate, Ag powder is mainly used, and a glass frit and an organic vehicle are homogeneously kneaded.
Examples of the paste include a paste that controls the grain size of Ag powder in order to approximate the sintering behavior of a glass-ceramic substrate material and prevent warping of the substrate, and also to be used with both substrate materials that sandwich internal wiring. In order to prevent peeling (delamination) at the contact portion, the lamination conditions are controlled, and the printing conditions are controlled to control the thickness of the coating film to be the internal wiring.

A suitable for glass-ceramic substrate materials
In the g paste, for example, the thickness of the coating film is made thin in order to prevent the above-mentioned delamination, but with this, the sheet resistance of the internal wiring increases. Therefore, it is possible to increase the content of the Ag powder. However, if the content of the Ag powder is increased, the printability of the coating film forming the internal wiring, that is, the linearity and the smoothness of the surface are impaired. A sufficient amount of Ag powder cannot pass through the eyes of the screen, resulting in increased resistance. Considering the above points, the content of Ag powder in the conventional Ag paste is limited to 70% by weight.

However, an Ag paste having an Ag powder content of 70% by weight is used as a low temperature firing multilayer circuit board.
It was not possible to obtain a more preferable sheet resistance value, for example, 4.5 mΩ / □ or less.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to maintain good printability, to prevent delamination, and to minimize sheet resistance Ag. It is intended to provide a multilayer circuit board which can form high density, high speed, high reliability and low cost by forming internal wiring with paste.

[0008]

According to the present invention, there is provided a multilayer circuit board comprising a substrate body containing ceramic and glass, and internal wiring arranged inside the substrate body. The wiring contains an Ag conductor powder, a glass frit, and an HLB value of 8 to 10 and a dispersant of which the content is 0.15 to 0.3% by weight in the entire paste.
The multilayer circuit board is characterized by being formed by a g paste, and the content of the Ag powder is preferably 71 to 76% by weight in the total paste.

[0009]

In the present invention, the HLB value showing the ratio of the molecular weight of the hydrophilic group to the molecular weight of the lipophilic group is 8 to 10, and the weight thereof is 0.
Since it is an Ag paste containing 15 to 0.3% by weight of a dispersant, even if the content of Ag powder is added up to 76% by weight,
In the paste state, the printability can be maintained without agglomeration / sedimentation, and a coating film can be formed with a thickness that can prevent delamination, and the sheet resistance of the internal wiring formed by this can be less than a predetermined value. Can be

Therefore, in a multilayer circuit board having such internal wiring, it is possible to achieve high density due to printability, high speed due to low resistance, and reliability is improved by preventing delamination. , Ag, a low melting point material can be used to obtain a multi-layer circuit board at low cost.

The HLB value is derived by the following equation. H
LB value = 7 + 11.7 log M _w / M _o , where M _w is the molecular weight of the hydrophilic group and M _o is the molecular weight of the lipophilic group.

When the above HLB value is less than 8, the agglomeration of the Ag powder cannot be avoided regardless of the content of the dispersant, the content of the Ag powder cannot be increased, and the internal resistance is low. Wiring cannot be obtained.

On the other hand, when the HLB value exceeds 10, it reacts with the organic vehicle in the paste, such as ethyl cellulose, the dispersion effect is reduced, the Ag powder is agglomerated, the sedimentation phenomenon occurs, and the printability is deteriorated. It will deteriorate.

If the content of the dispersant is less than 0.15% by weight, the dispersing effect cannot be sufficiently obtained, and the amount of Ag powder cannot be increased, so that the internal wiring of the low resistance material can be obtained. I can't.

On the other hand, if it exceeds 0.31% by weight, the dispersing effect becomes too strong and a large amount of the dispersant intervenes between the Ag powders, and due to the excessive dispersion action, the Ag powders conversely agglomerate. The printability is deteriorated, or the Ag powder cannot sufficiently pass through the screen, resulting in a large resistance value.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multilayer circuit board of the present invention will be described below with reference to the drawings.

In the figure, 1 is a substrate body, 2 is internal wiring, and 3 is surface wiring.

The substrate body 1 is formed by stacking a plurality of green sheets 1a, 1b ...
It is configured by being integrally sintered.

The internal wiring 2 is made of a conductive material whose main component is Ag and is formed according to a predetermined circuit. The internal wiring 2 is connected between the layers via a via hole 2a.

The surface wiring 3 is made of a low resistance material such as Cu having excellent migration property, and if necessary, various electronic components 4, such as a chip resistor, a chip capacitor, and a semiconductor element, are soldered. Mounted by.

In the concrete manufacturing method, first, the green sheets 1a, 1b, ... Mg
A ceramic material such as O—Al ₂ O ₃ —SiO ₂ , a glass frit, and an organic vehicle are homogeneously kneaded to prepare a slurry material.

At this time, the ceramic material and the glass frit are mixed in the proportions of 10 to 45% by weight and 90 to 55% by weight, respectively, with respect to the solid components of the ceramic material and the glass frit. Acrylic resin, toluene, dibutyl phthalate, etc. are used as the organic vehicle. Alumina, mullite, cordierite or the like may be used as the ceramic material.

Next, a sheet of 150 μm in thickness is prepared from the above-mentioned slurry material by a doctor blade method or the like, and cut into a predetermined size. It should be noted that this dimension allows a plurality of multilayer circuit boards to be extracted.

The sheets 1a, 1b formed as described above
..- Punching through holes to be the via holes 2a according to the circuit pattern.

Each sheet 1a having through holes formed therein,
1b ... Ag on top of a predetermined circuit pattern
The paste is screen-printed to form a coating film to be the internal wiring 2. At this time, the Ag paste is also filled in the through holes.

Next, the sheets 1a, 1b, ... Are laminated by thermocompression bonding. Then, break lines are formed according to the shapes of the plurality of multilayer circuit boards.

Next, the laminated body was subjected to a peak temperature of 900 ° C.
Bake in air atmosphere for 30 minutes.

At this time, at the same time that the ceramic-glass material is sintered, the coating film of the internal wiring is also sintered, and a sintered multilayer substrate having the internal wiring 2 and the via hole 2a can be prepared.

A coating film to be the surface wiring 3 is formed on this sintered multilayer substrate by a screen printing method and baked. For example, if the coating film is formed of a conductive paste containing Cu as a main component, the coating is fired in a reducing or neutral atmosphere. If the conductive paste is, for example, an oxidation-resistant conductive component, it can be fired in the air atmosphere.

After that, a predetermined electronic component 4 is soldered onto the surface wiring 3 and divided along break lines to obtain a multilayer circuit board.

If Ag or Ag-Pd is used for the surface wiring, the surface wiring 3 can be baked simultaneously with the sintering of the substrate and the internal wiring 2. Further, the step of dividing along the break line may be performed before mounting the electronic component 4.

As the Ag paste for forming the above-mentioned internal wiring 2, as the conductive powder, Ag powder having an average particle diameter of 3 to 8 μm is contained in the total paste in an amount of 71 to 76% by weight, and further, barium borosilicate. 1. The glass frit of the system is contained in an amount of 5 to 20% by weight in the solid component added together with the Ag powder, and about 5% by weight of ethylcellulose, which is a binder of the organic vehicle, is contained in the organic vehicle to be a solvent.
2.4-trimethyl-1.3-pentanediol monoisobutyrate is contained in the organic vehicle in an amount of about 95% by weight,
Furthermore, the phosphoric acid ester of polyoxyethylene alkyl ether serving as a dispersant is 0.15 to 0.
30 wt% is contained, and these are uniformly kneaded and formed.

Here, the important thing is that the HL of the dispersant is
The B value is 8 to 10.

The HLB value is a parameter indicating the ratio of hydrophilic groups and lipophilic groups in the molecular structure of the dispersant, and A
In the g paste, it has a great effect on the dispersion of Ag powder, and HLB value = 7 + 11.7log M _w / M _o , where M _w is the molecular weight of the hydrophilic group and M _o is the molecular weight of the lipophilic group. It is represented by.

The average particle size of the Ag powder is 3 to 8 μm.
This is set larger than the normal particle size,
This is to approximate the sintering behavior of the substrate material. It is difficult to grow the average grain size of more than 8 μm, and if the average grain size is less than 3 μm, the substrate material starts the sintering reaction at the starting temperature during the temperature rising process during sintering. Therefore, there is a great possibility that the warp of the substrate may occur.

The addition of 71 to 76% by weight of Ag powder achieves a low resistance of the internal wiring.
If it is less than 71% by weight, the sheet resistance of the internal wiring 2 will be 4.5 mΩ / □ or more even if the coating film is thick enough not to cause delamination at the contact portion between the internal wiring 2 and the substrate 1. On the other hand, if it exceeds 76% by weight, the content of Ag powder is relatively large, and when the paste is formed,
The agglomeration of the powder causes a sedimentation phenomenon. When the sedimentation phenomenon occurs, screen printing is practically impossible, linearity is significantly impaired, and the surface becomes uneven, so that stable printability cannot be obtained.

The glass frit improves the adhesion to the substrate material, and the binder, after printing and coating, contains the conductive powder and the glass frit in the green sheets 1a, 1b.
.. Above, it is to maintain the printing state, and the solvent is to adjust the viscosity to be suitable for screen printing.

The dispersant uniformly disperses the Ag powder in the Ag paste and prevents the aggregation and sedimentation of the Ag powder. Here, it is important that the HLB value is 8 to 10 and the content rate is 0.15 to 0.3% by weight.

When the above HLB value is less than 8, the dispersing effect of the Ag powder does not work sufficiently regardless of the content of the dispersant, and the content ratio of the Ag powder cannot be 71 weight or more. , The low resistance internal wiring 2 cannot be obtained.

On the other hand, when the HLB value exceeds 10, it reacts with the binder component in the paste, for example, ethyl cellulose, the dispersion effect is reduced, the Ag powder is agglomerated, the sedimentation phenomenon occurs, and the printability is deteriorated. It will deteriorate.

If the content of the dispersant is less than 0.15% by weight, the dispersing effect cannot be sufficiently obtained, and the amount of Ag powder cannot be increased, so that the internal wiring of the low resistance material can be obtained. I can't.

On the other hand, if it exceeds 0.31% by weight, the dispersing effect becomes too strong, and a large amount of the dispersant intervenes between the Ag powders, and the excessive dispersing action causes the Ag powders to conversely agglomerate. The printability is deteriorated, and the Ag powder cannot pass through the screen sufficiently.

The inventors of the present invention, in the Ag paste to be the internal wiring 2 of the multilayer circuit board produced in the above process,
By changing the Ag powder content, the HLB value of the dispersant, and the dispersant content, respectively, the conductor resistance of the internal wiring, the adhesion between the sheets of the circuit board 1, that is, the occurrence of delamination, printing on the sheet The printability, that is, the linearity and the unevenness of the surface, were examined. The results are shown in Table 1.

[0044]

[Table 1]

In the sample No. 1, when the Ag powder content is less than 71% by weight, the sheet resistance value desirable for the internal wiring 2 of the low temperature firing multilayer circuit board becomes, for example, 4.5 mΩ / □ or more, and the low resistance is achieved. This is not possible, and high speed cannot be obtained in the multilayer circuit board.

Further, in the sample No. 4, the Ag powder was 7
When it exceeds 6% by weight and the dispersant is 0.32% by weight, low resistance is achieved, but the solid component becomes relatively large, the thickness of the coating film becomes thick, and delamination occurs. However, the multilayer circuit board becomes unreliable.

Further, in Sample No. 5, H of the dispersant was used.
If the LB value is less than 8, aggregation of Ag powder in the paste will occur, and Ag powder printed on the sheet through the screen will decrease, and as a result, low sheet resistance cannot be achieved, resulting in a multilayer structure. High speed cannot be obtained in the circuit board.

Further, in Sample No. 7, H of the dispersant was used.
If the LB value exceeds 12, it will react with the resin component,
Printability deteriorates.

On the other hand, in Sample Nos. 2, 3, and 6, the Ag powder content was 71 to 76% by weight and the dispersant H was H.
LB value 8-10, dispersant content 0.15-0.3
Since it is set to 0% by weight, the conductor resistance of the internal wiring 2 can be 4.5 mΩ / □ or less, the adhesion between the sheets of the substrate body 1 can be improved, and the printability, that is, the linearity and the surface The unevenness becomes good.

By forming the internal wiring 2 of the multilayer circuit board by the above-mentioned Ag paste, the low-resistance internal wiring 2 can speed up the signal propagation, and the reliability that delamination does not occur between the sheets. In addition, the multilayer circuit board can achieve internal wiring with high density and high density pattern.

In the above-mentioned Ag paste, the conductive powder was explained only with Ag, but conductive powder other than Ag, such as Pd, may be contained to the extent that the resistance value does not deteriorate significantly. Further, the resin, the solvent, the dispersant, etc. are not limited to the above-mentioned materials, and can be replaced as long as the same effects can be obtained.

[0052]

As described above, in the present invention, since the HLB value is 8 to 10 and the content of the dispersant is 0.15 to 0.3% by weight, 71% by weight or more of Ag powder is added. And a multilayer circuit board having low resistance internal wiring.

At this time, even if 71 wt% or more of Ag powder is added, delamination does not occur and printability does not deteriorate, so that a highly reliable, high-density wiring multilayer circuit board is achieved. It

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a multilayer circuit board of the present invention.

[Explanation of symbols]

 1 ... Circuit board 2 ... Internal wiring 2a ... Via hole 3 ... Surface wiring 4 ... Electronic component element

Claims (2)

[Claims] 1. A multi-layer circuit board comprising a substrate body in which a plurality of sheets containing ceramics and glass are sintered and integrated, and internal wiring arranged inside the substrate body,
The internal wiring includes Ag powder, glass frit, and HL.
B value is 8 to 10, and the content rate is 0.
A multi-layer circuit board formed by an Ag paste containing a dispersant of 15 to 0.3% by weight. 2. The multilayer circuit board according to claim 1, wherein the content of the Ag powder is 71 to 76% by weight in the total paste.