JPH0983141A - Method of manufacturing ceramic multi-layered substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply form a protruded electrode of a ceramic multi-layered substrate in which shorticircuiting is prevented even when terminals are narrowed in pitches thereof and which is unlikely to be affected by thermal distortion in a method of manufacturing the ceramic multi-layered substrate suitable for a CSP(chip size package). SOLUTION: Alumina sheets 1, 12 are disposed on the upper and lower surfaces of a laminated non-calcined glass ceramic sheet 2 for restricting contraction thereof upon calcination. An opening 13 is formed in the alumina sheet 12 at a position of a via conductor 3. With calcination in this state, the glass ceramic sheet 2 is contracted in the height direction while the via conductor 3 having the opening 13 is not contracted but protruded. Once the alumina sheet 12 is removed, a ceramic substrate 4 having a protruded electrode 14 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramic multilayer substrate used in electronic equipment.

[0002]

2. Description of the Related Art In recent years, submicron technology in Si chips has been rapidly advanced, and progress in higher integration and higher density of ICs has been remarkable. However, along with this, the size of the Si chip and the increase in the number of electrodes have advanced, and the size of the IC package has become unavoidable. Therefore, although the pitch of the terminal leads has been rapidly narrowed down, the mounting efficiency of the IC (IC chip area / IC package area) is 5
It is as low as 0% or less, which is one of the causes for lowering the mounting efficiency.

Therefore, a chip size package (hereinafter referred to as CS
A new semiconductor package called P) has been developed, and with the digitization of electronic circuits, attention has been paid to the use of ceramic multilayer substrates. The cross-sectional view of FIG. 3 shows a typical CSP structure using a ceramic multilayer substrate.

In the figure, numeral 5 is a semiconductor element, and a bump 10 is formed on an aluminum electrode 6 thereof. Reference numeral 4 denotes a ceramic multilayer substrate obtained by laminating and sintering glass ceramic sheets, and electrical conduction between layers is obtained by the via conductor 3 and the internal conductor 11. At the time of CSP, solder 10 for adhesion is applied on the substrate electrodes 9 of the ceramic multilayer substrate 4, the bumps 10 of the semiconductor element 5 are aligned and placed, and both are fixed, and then the gap is sealed with a resin 8. It has stopped.

[0005]

However, when the bump electrodes are formed and the semiconductor element is mounted as in the conventional case, it is difficult to form bumps having a smaller diameter because there is a limit. For this reason, it becomes impossible to reduce the diameter of the bumps to the narrow pitch of the terminals, and short-circuiting between terminals frequently occurs due to the spread of the adhesive such as solder.

Further, since it is difficult to form the bumps at a high height, the distance between the semiconductor element and the ceramic multilayer substrate cannot be increased, and there is a problem that the strain due to the difference in thermal expansion coefficient between the two cannot be fully absorbed.

In view of the above, the present invention utilizes a non-shrinkable substrate, and at the same time as firing the ceramic multi-layer substrate, it is possible to form a protruding electrode which can sufficiently cope with a narrow pitch of terminals and thermal strain. A method for manufacturing the same is provided.

[0008]

In order to solve the above-mentioned problems, a method for manufacturing a ceramic multilayer substrate according to the present invention comprises a via conductor penetrating between the laminated ceramic sheets on the upper surface of the laminated unfired ceramic sheets. An opening having a size for forming a protruding electrode is provided at a position, and a shrinkage suppression sheet having a thickness corresponding to the height of the protruding electrode is placed and then fired.

[0009]

According to the above method, the via conductor is baked without receiving the contraction stress generated during baking. Therefore, when the shrinkage suppression sheet is removed, a protruding electrode having a diameter and height corresponding to the opening of the sheet appears.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing each step in a method for manufacturing a ceramic multilayer substrate according to an embodiment. FIG.
In (a), 1 and 12 are alumina sheets, which are arranged on the upper surface and the lower surface of the laminated unfired glass ceramic sheets 2 to control the shrinkage of the glass ceramic sheets 2 during firing. Via conductors 3 are provided on the alumina sheet 12 to provide conduction between the laminated glass ceramic sheets 2.
An opening 13 having the same diameter as that of the via conductor 3 is formed at the position of with an NC punch.

When firing is performed in this state, as shown in FIG. 1B, the alumina sheet is not sintered, but the glass ceramic sheet 2 inside is sintered. At this time, the glass ceramic sheet 2 is X
The shrinkage in the Y direction, that is, the plane direction is suppressed, and the Z direction, that is, the height direction is not suppressed, and the shrinkage is about 55 to 60%.

Therefore, the opening 13 formed in the alumina sheet 12 is not restrained from shrinking, so that the via conductor 3 rises as a protruding electrode at the same time as firing. Then, by removing the alumina sheets 1 and 12, the ceramic multilayer substrate 4 having the protruding electrodes 14 is obtained as shown in FIG.

When performing CSP using the ceramic multi-layer substrate obtained as described above, as shown in FIG. 2, the solder 7 serving as an adhesive is attached to the aluminum electrode 6 of the semiconductor element 5.
After being applied, it is placed on the ceramic multilayer substrate 4 and then sealed with the resin 8.

Here, by adjusting the size of the opening 13 and the thickness of the alumina sheet 12, the diameter and height of the protruding electrode can be controlled. For example, if the diameter of the opening 13 is smaller than the diameter of the via conductor 3, it is possible to obtain the protruding electrode 14 having a smaller diameter, and it is possible to cope with a narrower pitch between terminals. When a plurality of alumina sheets 12 are stacked and used, the height of the bump electrode 13 can be increased and the distance between the semiconductor element 5 and the ceramic multilayer substrate 4 can be increased.
Therefore, it is difficult to be affected by the difference in the linear expansion coefficient, and it is possible to prevent the disconnection.

In the above embodiment, if the via conductor 3 projects from the upper surface of the alumina sheet 12 during firing, the projection electrode 14 having a desired shape cannot be obtained. Therefore, the thickness of the alumina sheet 12 must be higher than the height of the bump electrodes 14 formed during firing.
Further, as the size of the opening 13 becomes smaller, the formed protruding electrode 14 also becomes higher. Therefore, the thickness of the alumina sheet must be determined in consideration of this point as well.

[0016]

As described above, according to the present invention, it is possible to obtain a suitable ceramic multilayer substrate by applying it to CSP,
In particular, it is possible to easily form the protruding electrodes of the ceramic multi-layer substrate which are not short-circuited even if the pitch is narrowed and are not easily affected by thermal strain, simultaneously with firing.

[Brief description of drawings]

FIG. 1 is a sectional view showing each step in a method for manufacturing a ceramic multilayer substrate according to an embodiment of the present invention.

FIG. 2 is a sectional view of a CSP using a ceramic multilayer substrate obtained by the same method.

FIG. 3 is a sectional view showing a conventional CSP.

[Explanation of symbols]

 1, 12 Alumina Sheet 2 Glass Ceramic Sheet 3 Via Conductor 4 Ceramic Multilayer Substrate 5 Semiconductor Element 6 Aluminum Electrode 7 Solder 8 Resin 9 Board Electrode 10 Bump 11 Internal Conductor 13 Open Hole 14 Projection Electrode

Claims (1)

[Claims] 1. An upper surface of a laminated unfired ceramic sheet has an opening of a size for forming a protruding electrode at a position of a via conductor penetrating between the laminated ceramic sheets, and a height of the protruding electrode is increased. A method for manufacturing a ceramic multi-layer substrate in which a shrinkage suppression sheet having a thickness according to the thickness is placed and then fired.