JPH0464281A - Manufacture of ceramic multilayer board - Google Patents

Abstract

PURPOSE:To reduce and compensate for the deviation and failure of shrink produced by deformation behavior or difference in shrink in a conductor section and an insulation section by carrying out design and execution in preconsideration for difference in shrink in the conductor section and the insulation section and deformation behavior during laminating. CONSTITUTION:Difference in shrink in a conductor section and an insulation section and deformation behavior during laminating with regards to horizontal direction is estimated and confirmed experimentally. When the information thus obtained is reflected on through hole working position or the design and execution of wiring patterns, it will be possible to reduce and compensate for the deviation and failure of shrink after lamination and firing and produce a ceramic multilayer substrate having high dimensional accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a ceramic multilayer substrate in which a plurality of green sheets each having a conductor portion formed thereon are laminated and fired.
In particular, the present invention relates to a manufacturing method for obtaining a ceramic multilayer substrate with excellent one-dimensional accuracy.

[Conventional technology]

In recent years, with the increase in speed and density of integrated circuits such as LSI,
Attempts have been made to increase the speed of the mounting portion by mounting these semiconductor elements on a ceramic substrate directly or via a chip carrier. However, as the integration of LSIs and other devices progresses, these semiconductor elements become larger and ceramic substrates also become finer in their wiring.

Multi-layered and larger devices have become more common. Such ceramic multilayer substrates are generally made by a green sheet lamination method. The manufacturing method is as follows. First, a slurry is prepared by adding and mixing ceramic raw material powder, a binder (thermoplastic resin) that makes them adhere to each other, a plasticizer, etc. in a suitable solvent that dissolves the binder. Next, a defoaming process is performed to remove trapped air bubbles and to adjust the viscosity, and then it is formed into a sheet by a doctor blade method or the like. Finally, the solvent is scattered by drying to obtain a green sheet. After the green sheet is processed with predetermined through holes using a punch or the like, the through holes are filled with conductors, and predetermined conductor wiring is formed on the surface of the sheet. A predetermined number of sheets obtained in this manner are stacked one on top of the other, taking care not to cause any positional shift, and are heat-pressed and bonded using a hot press to produce a laminate. Finally, the ceramic multilayer substrate is obtained by firing under an atmosphere with a firing profile that does not oxidize the conductor wiring.

Incidentally, when producing such a ceramic multilayer substrate, one of the requirements is dimensional accuracy. This has become an indispensable requirement due to the increased density of connection points on ceramic substrates of semiconductor devices and the increased size of the substrates as semiconductor devices become more integrated. In order to improve dimensional accuracy, it is necessary to control the firing storage rate. The firing shrinkage rate varies greatly depending on the accuracy distribution of raw materials, process conditions, etc.
It is widely known that their control and management are important. However, in actual ceramic multilayer substrates, there are differences in deformation characteristics during lamination and firing shrinkage between the conductor and insulating parts, resulting in problems such as abnormal shrinkage, warping, and unevenness during firing. Something happened.

Several attempts have been made to address these problems. JP 60-137884, JP 62-260777
No. 1, etc., the multilayer substrate is sandwiched from both sides and pressure is applied during firing, causing horizontal contraction and deformation.

Attempts to suppress warpage, etc. have been reported. Also, JP-A-6
1-90448, an attempt was made to fabricate a highly accurate, high-density ceramic multilayer substrate with small shrinkage rate deviation by screen printing conductor wiring on adjacent green sheets by moving a squeegee in the opposite direction. has been done. Furthermore, in Japanese Patent Application Laid-Open No. 62-35659, by sandwiching and laminating an appropriate amount of additional green sheets outside the conductor wiring area, --like shrinkage is applied to the entire substrate during sintering.

A method for manufacturing ceramic multilayer substrates that does not warp and preserves its original geometry has been reported.

[Problem to be solved by the invention]

However, the above-mentioned conventional technology is not necessarily sufficient to suppress the above-mentioned firing shrinkage rate abnormality. The method of sintering by applying pressure from above and below the substrate may not provide any improvement, and may not remove the binder smoothly. The method of adjusting the printing direction of conductor wiring is not a fishing boat. Inserting additional green sheets outside the conductor wiring area is also effective, but is often not sufficient, and it is difficult to determine the amount of additional green sheets.

An object of the present invention is to reduce or compensate for deviations and abnormalities in shrinkage rates caused by such deformation behavior during lamination of a conductor part and an insulating part, and differences in shrinkage rates.

[Means to solve the problem]

In order to achieve the above object, the present invention does not expect similar shrinkage or similar changes in patterns during firing, but rather predicts or experimentally confirms these deformation behaviors, and then determines the deformation behavior through the through-hole. By reflecting this in the processing position and the design of the wiring pattern, the dimensional accuracy of the conductor wiring within the substrate after firing is improved. This seems difficult to see.

Once the wiring pattern and manufacturing process are determined, the deformation behavior is relatively stable and can be realized. This method works without the material systems of the conductive layer and the insulating layer being close to each other, but in that case,
Naturally, the way this is reflected in the design differs depending on the case.

[Effect]

As mentioned above, the present invention enables dimensional accuracy after firing by predicting deformation behavior during lamination and firing in advance and incorporating it into design and construction when designing through-hole processing positions and wiring patterns. A ceramic multilayer substrate with good quality can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

<Example 1> First, an example of green sheet production and a flow of substrate production will be presented, and then an example of the present invention will be described.

70 parts by weight of mullite powder with an average particle size of 3.0 μm.

Glass powder mainly composed of silica (average particle size 1.2μm)
30 parts by weight were added to a ball mill, and 6.5 parts by weight of polyvinyl butyral with a degree of polymerization of 1000 was added as a binder, and 2.5 parts by weight of butyl phthalyl glycolate were added as a plasticizer.
1 part by weight was added, and as a solvent, trichlorethylene,
A slurry was prepared by adding a three-component solvent of tetrachloroethylene and n-butanol and performing wet mixing for 24 hours. This slurry is vacuumed to perform defoaming treatment and viscosity adjustment. This is applied to a uniform thickness on a polyester film treated with silicone using a doctor blade method, etc., and then the solvent is scattered through a drying oven to form a green sheet with a thickness of about 0.25 mm. Obtained.

This green sheet is set to a predetermined size, here 200.
After cutting to a size of 200 m x 200 m, through holes are punched at predetermined positions using the punch method. By printing a conductive paste prepared with W powder, a binder such as ethyl cellulose, and a small amount of organic solvent on the through holes and the surface of the sheet using a screen printing method, via holes for interlayer connection and a predetermined circuit are printed. A pattern can be formed.

Forty-four of these green sheets were stacked with the guide holes aligned, and then heated at 120°C using a hot press machine.
, 100 kgf/J for 15 minutes to produce a ceramic laminate.

This laminate is placed in a firing furnace and fired in a nitrogen atmosphere containing about 20% hydrogen by volume. At that time, in the temperature raising process, the binder was removed by further increasing the temperature by 80 to 80℃ in an atmosphere containing a small amount of water vapor, and the maximum temperature was 1640℃.
After reaching this temperature, the water vapor is removed and the temperature is maintained for 1.5 hours to obtain a sintered body. Firing in a reducing atmosphere is
This is to prevent the metal of the wiring conductor, here W, from being disposed.

Ceramic multilayer substrates are produced as described above, but many of them shrink in distorted shapes as shown in FIGS. 2 and 4, depending on the type of substrate, the type of conductive paste, etc.

It should be noted that in the drawings, the distortion is emphasized. Here, 1 represents the laminate before firing, and 2 represents the sintered body after firing. Also, 1
1 and 21 are chip areas (L) before and after firing, respectively.
A large number of via holes are formed in the area where the SI chip is mounted. On the other hand, 12 and 22 represent the white plate parts before and after firing, respectively, and these parts have no surface pads or via holes, and only have inner layer power wiring, signal wiring, and a few back pads. This distorted form of shrinkage is due to the deformation during lamination of the white plate part (ceramic insulating part) and the conductor part, the difference in the shrinkage rate and its anisotropy, or the difference in the shrinkage start temperature. There is a major reason for this. By the way, such distorted shrinkage behavior is almost impossible if the type, composition, raw material particle size, preparation method, etc. of the ceramic substrate and conductive paste are the same, and if the circuit configuration and dimensions of the multilayer substrate are constant. , exhibiting reproducible shrinkage behavior. Therefore, in the present invention, these deformation behaviors are predicted in advance or confirmed through experiments, and this is reflected in the through-hole processing position and wiring pattern design, thereby improving the dimensional accuracy of the conductor wiring in the board after firing. It becomes possible to do so.

Figure 1 shows that when the shrinkage occurs in a drum-like shape as shown in Figure 2, the degree of distortion is determined in advance so that the chip areas are regularly arranged after firing and each area is finished in a square shape with high dimensional accuracy. We demonstrated a method for forming circuit patterns. It takes some effort to form a pattern like the one shown in Figure 1, but since the holes are drilled and the pattern is designed under computer control, it is possible and very effective in improving dimensional accuracy.

Figure 3 shows that when the shrinkage is distorted into a drum shape as shown in Figure 4, the degree of distortion is determined in advance so that after firing, the chip areas are arranged regularly and each area is finished in a square shape with high dimensional accuracy. This method shows a method for forming a circuit pattern, which is also effective in improving dimensional accuracy.

In this example, the ceramic substrate material is mullite-glass, and the wiring conductor material is W.
It is not limited to this system.

For example, alumina is used as a ceramic substrate material.

Alumina glass type, mullite type, W as wiring conductor material
Alternatively, when MO is used, it is possible to fabricate a multilayer substrate through the same manufacturing and firing process, and this method can be applied to the problem of shrinkage in a distorted form similar to the above. be.

Furthermore, when using a highly thermally conductive aluminum nitride-based ceramic substrate material, it is possible to create a multilayer substrate by using W or MO for the wiring conductor and by setting the firing temperature to 1800 to 2000'C. However, this method can still be applied.

Furthermore, we use low dielectric constant glass as a ceramic substrate material, low resistance Cu, or Ag-Pd that can be fired in air.
The present method can also be applied to low-temperature fired substrates using Ag-Pt as a conductive material.

〈Example 2〉 When manufacturing a ceramic multilayer board using the material system described above, if the circuit pattern has conductor wiring or via holes densely concentrated in some parts, only those parts will shrink significantly. As a result, the entire structure may shrink in a distorted manner. In such a case, as in Example 1, by confirming the deformation behavior in advance through prediction or experiment, and reflecting it in the design of the through-hole processing position and wiring pattern, the conductor inside the board after firing can be adjusted. The dimensional accuracy of wiring can be improved.

FIG. 6 shows the dimensional changes before and after firing without such improvement measures, and FIG. 5 shows an example of the case with improvement measures. As in the previous example, 1 in the figure represents the laminate before firing, and 2 represents the sintered body after firing. 12 and 22 represent the white plate portions before and after firing, respectively. Also, 11
and 21 represent normal chip areas before and after firing, respectively. In this example, there are further areas (13 and 23 in the figure) that have a large area and are densely arranged. As expected, due to the difference in shrinkage rate between the white plate part and the conductor part, there were many cases where the shrinkage occurred in a distorted manner as shown in FIG. 6.

In this example as well, by predicting or experimentally confirming such deformation behavior in advance and reflecting it in the design of through-hole processing positions and wiring patterns, the chip area can be changed after firing as shown in Figure 5. It is possible to arrange them regularly and finish each area in a square shape with high dimensional accuracy.

This embodiment is also effective for various material systems as shown in the previous example.

<Example 3> In the firing of the substrate as described in Example 1, even if no large irregularities appear on the entire substrate, the shrinkage rate of the chip area where the via holes are densely formed is 0 compared to the shrinkage rate of the white plate part. In some cases, it was as high as .2 to 0.5%. Such dimensions may be compensated for in advance during design. Such compensation is often required even when large irregularities are observed in the wiring pattern.

〔Effect of the invention〕

According to the present invention, there is a method for manufacturing a ceramic multilayer board in which a plurality of green sheets on which via holes and conductor wiring layers are formed are laminated and fired, and the difference in deformation characteristics and firing shrinkage rate during lamination of conductor parts and ceramic insulating parts is achieved. In order to suppress or compensate for the effects of distortions and irregularities caused by such factors, we can create ceramic multilayer boards with good dimensional accuracy by assuming these distortions and irregularities in advance or confirming them through experiments and reflecting them in wiring patterns, etc. can be obtained. As a result, it becomes possible to manufacture a highly reliable ceramic multilayer substrate with high wiring density. Furthermore, this method is effective for various material systems.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the wiring pattern before and after firing according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the wiring pattern in the case where the present invention is not applied to FIG. 1, and FIGS. 3 and 5. 3 and 4, and FIG. 5 and FIG. 6 respectively correspond to the relationship in FIG. 1 and FIG. 2, respectively. DESCRIPTION OF SYMBOLS 1... Laminate before firing, 2... Sintered body, 11... Chip area of laminate, 12... White plate part of laminate, 13
...Large area connection area of the laminate, 21...Chip area of the sintered body, 22...White plate part of the sintered body, 23...Sintered body box diagram

Claims (4)

[Claims] 1. In a method for manufacturing a ceramic multilayer board, in which a plurality of sheets obtained by processing through-holes in a green sheet and embedding a conductive material therein, and/or a step of creating conductor wiring on the surface of the sheet are laminated and fired. , The through-hole processing position and/or the surface conductor wiring pattern should be designed by considering in advance the difference in shrinkage rate between the conductor part and the insulating part in the horizontal direction, as well as the deformation behavior during lamination. 1. A method for manufacturing a ceramic multilayer substrate, characterized by: 2. 2. The method of manufacturing a ceramic multilayer board according to claim 1, wherein the design and construction are performed by setting the assumed shrinkage rate of the semiconductor mounting portion in which the via holes are densely formed to a value different from the assumed shrinkage rate of the entire board. 3. 3. The method of manufacturing a ceramic multilayer substrate according to claim 1, wherein the insulating layer is made of alumina, alumina glass, mullite, mullite-glass, or aluminum nitride, and the conductor layer is made of W or Mo. 4. In claim 1 or 2, the insulating layer is made of low dielectric constant glass or a composite of low dielectric constant glass and ceramics, and the conductive layer is made of Cu, Ag-Pd, or Ag-Pt.
A method for manufacturing a ceramic multilayer substrate using