JPH04206401A - Inner layer silver paste composite material for low temperature baked multiple layer board - Google Patents

Abstract

PURPOSE:To prevent delamination or blistering of a board by using both low softening point glass frit and high softening point glass frit, and also using filler components including alimina powders, zirconia powder or magnesia powders. CONSTITUTION:Low softening point glass frit of a softening point of 300 deg.C-450 deg.C by 3-8 pts.wt., high softening point glass frint of a softening point of 580 deg.C-850 deg.C by 5-20 pts.wt., and more than one sort of alumina powders, zirconia powders, and magnesia powders by 1-5 pts.wt. are included in silver powders by 100 pts.wt. Composition of the low softening point glass frit and high softening point glass frit are not especially specified, but they may be any material of borosilicate, borosilicate lead, borosilicate zinc, borosilicate lead zinc, etc., and they may be either noncrystalline or crystalline. Peeling phenomena between layers, that is no so-called delamination, or warping or blistering of a board can thus be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inner layer silver paste composition for low temperature fired multilayer substrates.

Conventional technology Conventionally, a conductive paste is printed on a green sheet, dried, and then laminated, pressed, and fired to form a multilayer substrate.M is printed on an alumina green sheet.

A typical example was a multilayer board using a paste of or W. However, green sheets that can be fired at temperatures of 800° C. to 1000° C., which are lower than those of alumina green sheets, are now being manufactured, and a conductive paste that is compatible with the green sheets is being sought.

Problems to be Solved by the Invention Green sheets that can be fired at 800 to 1000 degrees Celsius are generally made into a slurry by mixing alumina powder with glass powder, binder resin, plasticizer, solvent, etc., and then used as green sheets. A conductive paste is printed and dried on this green sheet, and these are laminated and bonded under heat and pressure, and then fired.

However, in the case of such low-temperature fired multilayer substrates, existing Ag, Ag/Pd, Ag/Pt, Au, and Cu materials used in hybrid ICs using conventional alumina substrates cannot be used.
When paste is used as a wiring material, various problems occur. The main problems are (1) occurrence of delamination phenomenon, so-called delamination, and (2) warping and blistering of the substrate. The main cause of these problems is considered to be a mismatch in the timing of sintering the substrate material and the conductor material. SUMMARY OF THE INVENTION An object of the present invention is to provide an inner layer conductor paste that prevents the sintering timings of the substrate material and the conductor material from mismatching, thereby solving the above-mentioned problems.

Means for Solving the Problems The present invention provides that (1) 3 parts of low softening point glass frit with a softening point of 300°C to 450°C is added to 100 parts by weight of silver powder.
~8 parts by weight, (2) 5 to 20 parts by weight of high softening point glass frit with a softening point of 580°C to 850°C, (3) 1 to 5 parts by weight of one or more of alumina powder, zirconia powder, or magnesia powder. This is an inner layer silver paste composition for a low-temperature fired multilayer board, comprising:

Function The present invention is characterized by having different softening points, that is, low softening points (
300 to 450°C) and a glass frit with a high softening point of 580 to 850°C), and at least one of alumina powder, zirconia powder, or magnesia powder is added.

It is thought that the glass frit with a low softening point functions to cause the inner layer silver paste to bond with the green sheet at the initial stage of sintering at around 500°C. Therefore, the softening point is 3
The reason for limiting the temperature range to 00 to 450°C is that it is difficult to produce glass with fluidity below 300°C.
On the other hand, if the temperature exceeds 450°C, the fluidity of the glass is insufficient at the initial stage of sintering the inner layer silver paste at around 500°C, so that the bonding with the green sheet cannot be achieved sufficiently.

However, if glass frit with only a low softening point is used as the inner layer paste, it will contribute to bonding in the initial stage of sintering, but as the temperature increases, the inner layer silver paste will sinter faster than the green sheet, resulting in sintering shrinkage. As a result, a gap is created between the inner silver layer and the green sheet, resulting in the occurrence of so-called delamination.

Glass frit, which has a high softening point, does not react with the green sheets in the early stages of sintering and is considered a kind of filler component, but at high temperatures it reacts with the green sheets and increases the bonding strength. The reason why the softening point range was limited to 580 to 850°C is that if it is below 580°C, it cannot play the role as a filler component in the early stage of sintering, and the inner layer silver paste sinters earlier than in the early stage of sintering. This is because delamination is more likely to occur due to the formation of knots. On the other hand, the softening point is 85
This is because if the temperature is higher than 0°C, bonding with the green sheet as glass becomes difficult to occur during the firing process in the high temperature range.

In this way, it was found that the occurrence of delamination can be significantly suppressed by blending glasses with low softening points and glasses with high softening points in a well-balanced manner. However, as we proceeded with various studies, we found that the printing area of the inner layer silver paste was small (for example, 1
Although no delamination was observed when the above-mentioned glasses were used in combination (such as lines of 00 μm to 1 day), delamination sometimes occurred when the area became larger than 51 Wl×51 m1. Alumina powder, zirconia powder, or magnesia powder is
This is added to prevent delamination from occurring even when the printing area of the inner layer silver paste on the green sheet is large. This is thought to be because these powders suppress sintering of the inner layer silver paste, and even if the printed area becomes large and sintering shrinkage increases, the shrinkage is suppressed. The amount of glass frit with a low softening point is 3~
The reason why the amount is 8 parts by weight is that if it is less than 3 parts by weight, the bonding with the green sheet will not be sufficient in the initial stage of sintering, and if it exceeds 8 parts by weight, sintering shrinkage will be significant and delamination will inevitably occur. It is from. The reason for setting the content of high softening point glass frit to 5 to 20 parts by weight is that if it is less than 5 parts by weight, the bonding strength with the green sheet at high temperatures will not be sufficient, and if it exceeds 20 parts by weight, the inner layer This is because the silver resistance layer is too thick (too thick).
The reason why it is expressed as parts by weight is that if it is less than 1 part by weight, the effect as a filler will not be sufficient, and if it exceeds 5 parts by weight,
This is because the resistance value of the inner layer silver becomes too large. The composition of the low softening point glass frit and the high softening point glass frit is not particularly limited, and may be any one of borosilicate type, lead borosilicate type, zinc borosilicate type, lead zinc borosilicate type, etc. It can be either crystalline or crystalline.

In addition, the particle size of these powders is about the same as that of thick film paste used for ordinary hybrid ICs, etc.
0 μm is used.

EXAMPLE An example of the present invention will be described below. silver powder 10
0 parts by weight, LS-0803 manufactured by Nippon Electric Glass Co., Ltd. (softening point 350°C) as a low softening point glass frit, GA-1 manufactured by Nippon Electric Glass Co., Ltd. (softening point 595°C) as a high softening point glass frit, and alumina. The powders were added in different amounts, and 20 parts by weight of an organic vehicle (ethyl cellulose dissolved in terpineol) was added to 100 parts by weight of these inorganic substances and mixed to create silver pastes of data formulas 1 to 16. The blended parts of low softening point glass frit, high softening point Karasufuri Soto, and alumina powder of these data formulas 1 to 16 are listed.

(Margins below) These pastes were screen printed onto ceramic crow green sheets and dried. Note that the printing pattern consists of lines with a width of 0.11 to 1 m and 1. mm
A pad of 1 mm to 20 + nm x 20 openings was used. Thereafter, the eight green sheets were heat-pressed and fired. Firing was carried out using a box-type furnace, and after removing the binder at 400°C for 2 hours, a belt-type firing furnace was used to reach a peak temperature of 900°C in 1 hour from input of the substrate to exit (in-out).
x It was done in 10 minutes.

In addition, ×, △, and ○ in the delamination column are respectively ×: After firing the board, the board swelled significantly and cannot be used as a product.) △: After firing the board, no bulge was observed on the board, but the cross section was examined using an electron microscope. Delamination is observed when observed (not acceptable as a product). ○: After the substrate is fired, neither swelling of the substrate nor delamination is observed when observed using an electron microscope (good as a product).

In the above-mentioned document NQI-16, studies were conducted by changing the softening points of glass frits with low softening points and high softening points, and using zirconia powder and magnesia powder instead of alumina powder. The results are shown in Table 2.

(Margin below) Note that 5 parts by weight of the low softening point glass frit, 10 parts by weight of the high softening point glass frit, and 3 parts by weight of the zirconia and magnesia powders were each used for 100 parts by weight of silver.

Effects of the Invention The inner layer silver paste composition for a low-temperature fired multilayer substrate of the present invention uses a low softening point glass frit and a high softening point glass frit in combination, and further contains alumina powder, zirconia powder, or magnesia powder as a filler component. By using this method, it becomes possible to manufacture a low-temperature fired multilayer substrate in which no delamination or bulging of the substrate occurs.

Claims (1)

[Claims] For 100 parts by weight of silver powder, (1) 3 to 8 parts by weight of a low softening point glass frit with a softening point of 300°C to 450°C, (2) a high softening point of 580°C to 850°C. An inner layer silver paste composition for a low-temperature fired multilayer substrate, comprising: 5 to 20 parts by weight of softening point glass frit; (3) 1 to 5 parts by weight of one or more of alumina powder, zirconia powder, or magnesia powder. .