JPS6024095A - Method of producing glass ceramic multilayer circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing a glass-ceramic multilayer wiring board, and in particular, in the sintering process for manufacturing the same, deformation of the board due to recoil, disconnection of wiring conductors, etc. The present invention relates to a method for manufacturing a glass-ceramic multilayer wiring board suitable for preventing the occurrence of defective products.

[Background of the invention]

The substrate material is a so-called glass ceramic made by adding a crystalline substance such as SiC to low melting point glass.

A glass-ceramic multilayer wiring board in which a low melting point metal conductor such as Ag, Au, or Cu is applied and laminated in multiple layers is attracting attention as a future six-dimensional hybrid technology or a mounting technology for LSI elements for electronic computers. The reason for this is that compared to conventional and currently under development technologies, especially multilayer wiring boards that use alumina (A, I, Ofi) ceramics as the substrate material and W or Mo as the conductors, the following characteristics are different. It's for a reason.

1. 800-900 compared to AI, α-W or Mo system
Can be sintered at a low temperature of 'G (1600'C for A1.α-W system).

2. In air as the firing atmosphere (AI, 0.-W is N!
(medium) can be sintered.

5. Low wiring resistance due to the use of highly conductive metals such as Ag, Au, and Cu.

4. Glass ceramics are AI, 0. Compared to ceramics, it has a lower dielectric constant, so there is less electrical parasitic capacitance at the interface with wiring conductors, and there is less reduction in the propagation speed of electrical signals.

For these reasons, for example, LSI for electronic computers
If this technology is applied to assemble a group of wiring circuits (hereinafter referred to as a module) for mounting elements such as, it is possible to manufacture high-speed arithmetic circuits at low cost and with high-density packaging.

However, conventionally, during the manufacturing process of t glass ceramics,
In particular, during the firing process, the multilayer board being manufactured may be warped or otherwise deformed, or wired conductors may be disconnected, resulting in many defective boards. The reason for this is that there is a large difference in shrinkage rate during the sintering process between the glass ceramic substrate material and the wiring conductor, such as the frame.

In order to explain these matters in more detail, the manufacturing process of a conventional glass-ceramic multilayer wiring board will be described below.

FIG. 1 shows the main manufacturing process of a glass-ceramic multilayer wiring board. Moreover, FIG. 2 is a partially enlarged conceptual diagram of the glass chiramix multilayer wiring board.

In FIG. 2, 1 indicates an element to be mounted, such as an LSI, 2 indicates solder connecting this, and 3 indicates a pad for receiving this solder.

6 is a vertically filled through-hole conductor made of Au, Cu, etc., which filled the through-hole holes, and 5 is a cross section of a wiring conductor similarly laid in the horizontal direction.

Reference numeral 4 denotes a glass ceramic substrate material that supports these conductors, and although only 5 layers are shown in this figure, in an actual module, there will be as many as 20 to 30 layers.

8 indicates a pin for transmitting the signal from the through-hole filled conductor to the outside of the module, and 7 indicates a pad for connecting this knob.

In this way, this multilayer wiring board is constructed by applying thick film technology and stacking and bonding a large number of single sheets with countless printed wirings, and connecting the top and bottom of these sheets with through-hole conductors.

This configuration involves applying the necessary wiring to each green sheet, crimping them all together, and then simultaneously sintering the conductor paste and glass-ceramic material in the firing process shown in (8) in Figure 1. make.

For this reason, it is necessary to sinter the conductive materials such as Au, Cu, etc. and the glass ceramic material at the same temperature at the same time.

However, what was very inconvenient here was ~, Au
The contraction rate due to sintering of the Cu fz paste and the contraction rate of the glass ceramics are significantly different at each temperature and even at the final maximum temperature. for example,
The glass-ceramic compositions that have been commonly used so far are low melting point glasses (composition = Sin, , B,
α, BaO, A1*α, Pb0) with 50 wt 0% silica glass (Sin, ) added has a shrinkage rate of about 10 to 15%. In contrast, conductors of, for example, M paste shrink by about 20-25%. For this reason, for example, shrinkage of the fine conductor wiring paste causes the glass ceramic of the substrate to be stretched. As a result, the glass ceramic substrate being sintered is warped in a concave manner on the side where the Ag paste is printed.

Further, a disconnection may occur at the connection point between the vertical direction and the horizontal direction of the conductor shown in FIG.

The reason for this is that while horizontal conductors contract significantly,
This is because the vertical conductor is blocked by the glass-ceramic wall and is difficult to move together with the horizontal conductor.

Furthermore, a cavity may be created between the conductor and the through hole. The reason for this is, for example, that paste through-hole-filled conductors shrink significantly, whereas glass-ceramic conductors have small through-holes.
This is because the diameter of the conductor did not shrink in the same way as the Ag conductor, and a gap was created.

[Object of the Invention] The object of the present invention is to provide a method for manufacturing a glass-ceramic multilayer wiring board and a composition of materials used, which can eliminate the above-mentioned drawbacks and prevent the occurrence of defective products due to deformation due to board warpage, disconnection of wiring conductors, etc. The goal is to provide technology.

[Summary of the invention]

The principle of the present invention is to match the shrinkage rates of the glass-ceramic substrate material and the conductor material as much as possible. This eliminates the difference in shrinkage rate during the sintering process and eliminates defects such as warping of the substrate, disconnection, and cavities around the through-hole conductor.

There are two main methods to eliminate this difference in shrinkage rate. One method is to match the shrinkage ratio by adding about % or less (Wt, %) of powder of a glass ceramic substrate material to a conductor material such as a paste. However, in this method, it is important to match the shrinkage rate, and the original properties, such as the excellent conductivity, are lost.
In addition, the optimum sintering temperature for glass ceramics (800 to 9
00°) may have to be changed. Therefore, in this method, it is necessary to improve these disadvantages within an acceptable range.

Another method is to change the particle size of the raw material powder to match the shrinkage rate during sintering without changing the composition so as not to impair the original material properties. The principles of these methods will be explained in more detail below. Figure 1 shows the shrinkage rate accompanying the sintering of the glass-ceramic substrate material and the conductive paste. Here, ■ is the shrinkage rate curve when the ~particles in the conductor paste are changed from 0.5 to 3.0μ, and ■ is the shrinkage rate curve of low melting point glass (Sin,
, B, Os, BaO, AI, 0. , Pb0)
This is the shrinkage rate curve when the amount of Sin added as aggregate is changed.■ is the shrinkage rate of an Ag conductor made into a paste by adding glass (■) to 2.0μ Ag to 20Wt%. It is a curve.

As shown in this figure, the shrinkage rate of conductive paste made of Ag alone is approximately 26 μm even when the particle size used is varied from 0.5 to 30 μm.
% to 18%, that of glass ceramics is the amount of 8jα added (30 to 50wt0%) that is usually used.
It is in the range of 15 to 10%. For this reason, when M single conductor paste is used, there will be a difference in shrinkage rate of 4% at the minimum and 16 inches at the maximum.

On the other hand, the curve ■ in the same figure means that the raw material powder for glass ceramics used at the same time as the 2.0μ Ag powder is 20W.
When adding up to t0%, the value of the shrinkage rate increases from 20 inches to 12 inches.
%. For this reason, S in glass ceramics
The amount of iα added can be matched to the shrinkage rate up to a range of 20-50%.

Next, FIG. 4 shows the sintering shrinkage rates of conductor pastes using two raw material powders with different Ag (individual) particle sizes and varying the mixing ratio. Here, the curve ■ shows the shrinkage rate when 0.5μ fine particles are mixed with 6.0μ coarse particles of M, and the curve ■ is 0.1μ fine particles of M mixed with 3.0μ fine particles.
The figure shows the shrinkage rate when M coarse particles are mixed.

By mixing two conductor powders having different particle sizes in this way, the sintering shrinkage rate of the conductor paste can be greatly changed.

In other words, the shrinkage rate of the curve (■) in Figure 4 is approximately 10 cm to 2 cm.
You can get up to 8%. This coincides with the shrinkage rate over almost the entire Siα mixing ratio of Siα used in the glass ceramics shown in FIG.

Furthermore, when these two conductor powders with different particle sizes are used,
We investigated why the sintering shrinkage rate changes. As a result, it was found that by mixing and using powders* with different particle sizes, the packing density of conductor particles in the paste was improved and the volume could be changed during sintering.

As described above, the present invention provides S in glass ceramics.
Addition composition ratio of iα, or by mixing glass to be used at the same time in a conductor such as Ag, or by using a conductor paste of two or more mixed powders with different particle sizes of conductor raw material powders such as M. The shrinkage rates due to sintering of the ceramic substrate material and the conductive paste used for wiring thereon are made to match as much as possible. This provides a method for manufacturing a glass-ceramic multilayer wiring board that is free from defects such as deformation due to warping, disconnection of conductor parts, and cavities around through holes during the firing process.

[Embodiments of the invention]

Examples of the present invention will be described below.0 Example 1゜(1) Preparation of green sheet Low melting point film; yx (Siα44.52, Btα33.
03, BaO11,55.

AItos 10.84, KtO+Na! O O,
Siα (crystalline) was added to each powder of 0.06wt, %).
0, 20, 30, 40'; 5 types of raw material powders were prepared by adding 5 Dwt% each and mixing in a ball mill for about 8 hours.

Each of these five types of raw material powders was separately prepared at 50 OI, and each was coated with polyvinyl butyral (
Add 38.15,9' of solid form) and mix by 3μ in a dry ball mill.

Next, 149.97 J of trichlorethylene was used as a solvent for the organic binder and as a flexible agent for the sheet.

42.4 ml of tetrachlorethylene, 56.6 ml of n-butyl alcohol, and 11.75 g of butylphthalyl butyl glycoate were added at the same time, and mixed by 4 μm using a wet ball mill.

The sample mixed in this way produces a viscous fluid called slip.

Next, these five types of slips were formed into sheets using a casting machine using a conventional green sheet manufacturing method, that is, a doctor blade method. The manufacturing conditions at this time were a drying temperature of 120°C, a casting belt speed of approximately 1 ocm AI, and a long green sheet with a width of approximately 20 cm and a thickness of approximately 0.5 cm. be.

These five types of long sheets are rolled and cut separately.
I stored it, cut it to the required size, and used it when I needed it.

(2) Preparation of conductor paste 5% of coarse powder with a particle size of 01μ to 2.0μ.

An M conductor paste was prepared by mixing 10%, 20%, 50%, and 40% (wt), respectively, and using these to make a normal thick film printing paste. That is, ethyl cellulose and α-terpineol were mixed with the above mixed powder in a mortar, and this was further kneaded well using six rolls.

Table 1 shows the types of diagonal members obtained as described above.

Table 1 Tested Green Sea), Ag conductor paste Table 2 Result of the condition of the prepared board Using the materials shown in Table 1, first, to check the warping condition of the board, we used the materials shown in Table 2. A single layer sheet (
The conductor was printed on a single sheet (only one sheet) and fired.

The printing and firing conditions are as follows.

Substrate size: 70 mm x 70 mm Wiring printing = 50 μm Line width: 70 μm pitch Wiring pattern: Single wire in one direction, 60 mm length Firing temperature = 850° C., in air The results are shown in Table 2 under 1-1 current conduction. In other words, there is no warpage in combinations where the shrinkage rates of the Gasis ceramic material and the paste conductor are almost the same, and the sheet A65 and the Ag conductor paste AI, situation 2. In the combination of 60 and 60, oxidation occurred.

Example 2゜Example 1. Green sheets prepared by /I63 and /I6
4 are used, and each conductor base/I66 is used.
Two types of 20-layer modules with through-hole filling and wiring as shown in Fig. 2 are applied and /164 is applied, and three types of modules are combined with Sea 1-A5 and Paste /162 as reference comparison products. was created.

Substrate size - 100mm x 100n square printed pattern with 50μ line width 150μ pitch Through hole filling = 200 holes filled Horizontal wiring and connection layer Number = 20 layers stacked per sheet Layering method = 125℃ x 15 minutes Pressure bonding firing temperature - 850℃ The results were as follows.

In both of the above-mentioned types of Example 2, no warping of the substrate and no disconnection in the through-hole filling conductor and horizontal wiring were observed.

However, for the type 1 manufactured as a reference comparison product, there were approximately 38 electrically disconnected locations that appeared to be disconnected.Example 3 20Wt0% of the glass ceramic raw material powder (A2) used in Example 1 was mixed with 25μ M powder. Then, a conductive paste was produced by the method of Example 1.

Using Green Shinito/162 prepared in Example 1, a module consisting of 20 layers was produced by the method of Example 2.

As a result, it was confirmed that there was no disconnection in the sintered glass-ceramic multilayer substrate through a conduction test.

[Brief explanation of the drawing]

Fig. 1 is a manufacturing process diagram of a glass-ceramic multilayer wiring board, Fig. 2 is a partially enlarged conceptual diagram of a glass-ceramic multilayer wiring board, and Fig. 3 is a glass-ceramic board material and Ag.
FIG. 4 is a sintering shrinkage diagram of the M conductor paste material according to the present invention. 1... LSI, 2-Solder, 6... Pad, 4... Board material. 1st ugliness 20 (%) + Hiro γA ci > red syh thing - 452 =

Claims (1)

[Claims] A method for manufacturing a glass-ceramic multilayer wiring board, characterized in that a material having a small difference in shrinkage rate due to sintering between the glass-ceramic board material and the metal conductor wired thereon is used.