JPH066015A - Manufacture of glass ceramic multilayer wiring substrate - Google Patents

Abstract

PURPOSE:To prevent the lowering of mechanical strength of a substrate by conducting a surface treatment on a substrate before a surface grinding operation is conducted. CONSTITUTION:A laminated body is obtained by laminating (S6) in a highly precise manner a plurality of green sheets obtained by conducting a thick film printing process, they are thermo-compression bonded (S7). Subsequently, the sintered body of glass ceramic multilayer wiring substrate, in which a three-dimensional wiring circuit is constituted on the inner layer by a low resistance conductor, is obtained by baking (S8) the above-mentioned laminated body. This sintered body is dipped into (S9) the container containing a hydrogen fluoride solution which is diluted to 20 to 40% by ammonium fluoride. Then, the hydrogen fluoride solution and the dissolved glass component adhering to the sintered body are washed away. Lastly, the dissolved layer is completely scraped off by conducting a plane grinding operation (S10), and an external-shape cutting operation is conducted. As a result, alumina grains only are left on the substrate surface which is brought into a very fragile state. Accordingly, the load of grinding in the initial stage of grinding, where the heaviest load is applied to the material to be ground, can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass ceramic multilayer wiring board.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and diversification of electronic equipment, further increase in speed and density are demanded for this type of ceramic multilayer wiring board. Under such circumstances, a low resistance metal can be used, a low relative dielectric constant is very advantageous for speeding up the signal propagation speed, and a glass ceramic material is selected because of a coefficient of expansion close to that of silicon. The ceramic multilayer wiring board used has received a great deal of attention.

Next, an example of a conventional method for manufacturing a glass-ceramic multilayer wiring board having such a background will be described. First, alumina powder and glass powder with controlled particle size are mixed and stirred with a butyral binder and an organic solvent to form a slurry. This is cast on a carrier film by a doctor blade method so as to have a predetermined film thickness and dried to obtain a green sheet. Via holes are formed at a predetermined pitch on the green sheet thus obtained using a punch and a die.

Next, a conductor paste made of a low melting point metal is embedded in the via ball portion by a screen printing method. In addition, at this time, the wiring pattern is similarly thick-film printed. Next, a predetermined number of these sheets are precisely laminated in accordance with a predetermined order, thermocompression-bonded, and fired at about 900 ° C. Finally, the ceramic substrate that has been fired is subjected to contour cutting and surface grinding while being cooled with water.

The conventional glass ceramic multilayer wiring board is
Since it contains more than 50% of glass component, it is very brittle, and it is about one half of the conventional alumina ceramic multilayer wiring board.
Only the strength of is obtained. In addition, as an internal conductor, A
Although low resistance metals such as u and Ag / Pd can be used, these metals have strong ductility and are likely to lead to clogging of ground low stones in the surface grinding process. In particular, the grinding load is the highest at the initial stage when the grinding stone starts contacting the ceramic substrate.

[0006]

In the conventional method for manufacturing a glass-ceramic multilayer wiring board, the grinding resistance during grinding tends to be relatively high. As a result, residual stress is left on the substrate after grinding or a work-affected layer having a thickness of 30 μm or more is formed, resulting in a drawback that the mechanical strength of the substrate is reduced.

[0007]

The present invention has a process of performing surface grinding after dissolving a glass component on the substrate surface of a glass ceramic multilayer wiring substrate which has been baked by a hydrofluoric acid solution. is doing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing an embodiment of the present invention.

The manufacturing method of the glass-ceramic multilayer wiring board shown in FIG. 1 includes a powder mixing step S ₁ , an agitation mixing step S ₂ ,
Film-forming step S _3, the through hole forming step S _4, a thick film printing process S _5, the lamination step S _6, the thermocompression bonding step S _7, the firing step S _8, the hydrofluoric acid treatment step S _9, the surface grinding step S _10, the outer shape It consists of a cutting step S ₁₁ .

In manufacturing this glass-ceramic multilayer wiring board, first, alumina powder and glass powder are mixed with each other.
The mixed powder of 5:45 w% was stirred and mixed with an organic solvent such as ethyl cellosolve and butoxyethanol together with a butyral-based binder to obtain S ₂ and a ceramic slurry. Next, this is deposited on a carrier film through a doctor blade whose gap is adjusted to a predetermined thickness (S
₃ ) Then, it was made into a green sheet, and this was subjected to through hole processing (S ₄ ) using a punch and a die. After that, a conductor paste was filled in the through holes, and a wiring pattern was thick-film printed (S ₅ ). The conductor paste contains
A silver-palladium paste having a composition of 85% by weight of silver powder and 15% by weight of palladium was used.

Next, a plurality of green sheets obtained by the thick film printing process are laminated with high precision (S ₆ ), and thermocompression bonding (S ₇ ).
A laminate was obtained. Then, the laminated body was fired (S ₈ ) in the atmosphere at about 900 ° C. to obtain a sintered body of a glass ceramic multilayer wiring board having a wiring circuit three-dimensionally composed of a low resistance conductor in the inner layer.

FIG. 3 is an enlarged partial cross-sectional view of the surface layer portion of the glass-ceramic multilayer wiring board before chemical treatment, which has a composite structure in which innumerable alumina particles 2 and glass component 1 are occupied. . Next, a chemical treatment for dissolving the glass component in the thus obtained sintering or the like will be described.

FIG. 2 is an enlarged partial sectional view of the surface layer portion of the glass-ceramic multilayer wiring board which has undergone the chemical treatment process of the present invention. In the chemical treatment, first, a container containing a hydrogen fluoride solution diluted to about 20% with ammonium fluoride was prepared, and the sintered body obtained by the above-mentioned method was immersed in this for about 10 minutes. As a result, the glass component 1 on the surface layer of the glass-ceramic multilayer wiring board was dissolved, and the alumina particles 2
It was confirmed that the dissolved layer 3 in which only the remaining portion was formed was formed with a thickness of about 50 μm.

After that, in order to remove the hydrogen fluoride solution and the dissolved glass component adhering to the fired body that had been treated, it was diluted with pure water and completely rinsed.

Finally, the melted layer 3 is completely scraped off by surface grinding and contour cutting is performed. However, since the glass component has been removed, only the alumina particles 1 remain on the substrate surface, resulting in a very brittle state. Has become. Therefore, it was possible to reduce the grinding load at the initial stage of grinding when the load on the object to be ground is the highest.

After the surface grinding is completed, the outer shape is cut,
It was completed as a glass-ceramic multilayer wiring board by adjusting the external dimensions.

Next, the concentration of the hydrofluoric acid solution used will be described.

FIG. 4 shows the relationship between the hydrogen fluoride solution concentration and the etching amount of the glass component in the glass-ceramic multilayer wiring board. Warpage occurs in the ceramic substrate that has been fired. In order to remove this warp and flatten the surface of the substrate, a grinding allowance of 100 to 200 μm is usually required on both front and back surfaces of the substrate. Further, the glass component melting layer for reducing the grinding load is required to have a thickness of about 50 μm that can be completely removed within the grinding allowance.

When the concentration of hydrogen fluoride is set to 20% to 40%, if the concentration is higher than this, the reaction rate is too fast, and it becomes difficult to control the depth of the molten layer of the glass component. This is because if the concentration is lower than this, the reaction rate is slow and it takes too long to form the dissolved layer.

However, the present invention is not limited to this when the glass-ceramic multilayer wiring board having different components is used, and the concentration of the hydrogen fluoride solution is set in accordance with various conditions such as the type of the glass-ceramic multilayer wiring board and the thickness of the grinding allowance.

[0022]

As described above, according to the present invention, the glass component on the surface of the glass-ceramic multilayer wiring board is melted, and when the surface of the melted layer is ground later, the grinding can be performed with a low load, so that the grinding resistance can be greatly reduced. The glass-ceramic multilayer wiring board can be surface-ground with almost no residual stress remaining, which is useful for preventing cracks and the like, and also has the effect of preventing a decrease in mechanical strength.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is an enlarged partial cross-sectional view of a substrate surface layer after chemical treatment.

FIG. 3 is an enlarged partial sectional view of a substrate surface layer before chemical treatment.

FIG. 4 is a graph showing an etching amount of a glass component by a hydrogen fluoride solution.

[Explanation of symbols]

 1 glass component 2 alumina particles 3 melted layer

Claims (2)

[Claims] 1. A method for producing a glass-ceramic multilayer wiring board, which comprises a step of surface-treating the surface of the glass-ceramic multilayer wiring board with a chemical that dissolves a glass component before the surface grinding of the glass-ceramic multilayer wiring board. 2. The chemical is ammonium fluoride, which is 20 to
The method for producing a glass-ceramic multilayer wiring board according to claim 1, which is a hydrogen fluoride solution diluted to 40%.