JP2870351B2 - Manufacturing method of ceramic multilayer circuit board with cavity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of a ceramic multilayer circuit board with a cavity, in particular, cell
The present invention relates to an improvement in the shape of a cavity hole formed on a lamic green sheet .

[0002]

2. Description of the Related Art FIG. 3 is a perspective view showing a conventional ceramic multilayer circuit board 1 having a cavity. The multilayer circuit board 1 has a cavity 2 in which a chip component such as a semiconductor chip (not shown) is accommodated. The chip components and the electrode lands provided on the multilayer circuit board 1 are electrically connected directly or via wire bonding.

Usually, a chip component such as a semiconductor chip is manufactured through, for example, a dicing process. Therefore, the chip component has a right angle in a planar shape. Therefore, as a matter of course, the corner 3 of the cavity 2 is also made a right angle in a planar shape to enable an efficient accommodation state of chip components, and to avoid an increase in the size of the multilayer circuit board 1.

[0004] The ceramic multilayer circuit board 1 with a cavity as described above is basically manufactured using a laminating technique of a plurality of ceramic green sheets. That is, a plurality of ceramic green sheets are prepared, and a wiring pattern, a via hole, or the like for providing a conductive film or an internal wiring conductor is formed on a specific one of them by screen printing or the like. In addition, as shown in FIG. 4, a specific ceramic green sheet 4 among these ceramic green sheets is provided with a cavity hole 5 that provides a part of the cavity 2. The formation of this cavity hole 5
This is performed by punching using a punch and a die.

Next, a plurality of ceramic green sheets including the above-described ceramic green sheet 4 are laminated and pressed. That is, as shown in FIG. 5, a laminate 6 obtained by laminating a plurality of ceramic green sheets.
Is compressed via an elastic body 7 as shown by an arrow 8.
At this time, the elastic body 7 is deformed so as to conform to the shape of the cavity 2 and exerts a sufficient pressure-bonding action even in the cavity 2.

[0006] After the completion of the pressing step, the laminate 6
Is fired, whereby a ceramic multilayer circuit board 1 with a cavity is obtained. After firing, appropriate electrode lands and the like may be formed on the surface of the multilayer circuit board 1 as necessary.

[0007]

As described above, since the corners 3 of the cavities 2 provided in the multilayer circuit board 1 are at right angles, they are provided, for example, in the ceramic green sheet 4 shown in FIG. Corner 9 of cavity hole 5
Are also at right angles. Therefore, when the cavity hole 5 is formed by punching, as shown in FIG. 6, a crack 10 may be formed starting from the corner 9. Such cracks 10 remain as minute gaps even in the fired multilayer circuit board 1, and thereafter, for example, when subjected to a plating process, a plating solution permeates the cracks 10 and the electrical characteristics of the multilayer circuit board 1 Or moisture resistance is deteriorated.

The crack 10 as described above can be generated not only when the cavity 5 is formed by punching but also in the following situation. That is, since the ceramic green sheet 4 has a relatively small thickness and is mechanically weak, stress is concentrated on the corners 9 in handling until the ceramic green sheets 4 are laminated, and
Cracks 10 may occur. Further, as shown in FIG. 5, when the laminate 6 is press-bonded via the elastic body 7, the elastic body 7 that has entered the cavity 2 also acts in a direction in which the corner 3 of the cavity 2 is widened. Stress concentrates in the corner 3 or the corner 9, thereby causing the crack 10
May enter.

Further, as shown in FIG. 4, a cavity 5 having a corner 9 at a right angle is formed in a ceramic green sheet 4.
When attention is paid to the mold used to form the die, that is, the punch and the die, the punch must have a ridge line that gives a right-angled cross section, and the die must have a right-angled corner. Of these, it is difficult or complicated to machine the corners at right angles in the die. In other words, in order to make the corners square, a special post-polishing or
A split die must be used, which makes the die expensive.

[0010] An object of the present invention can solve the various problems as described above, and Rukoto Kyosu Hisage a method of manufacturing a ceramic multilayer circuit board with a cavity.

[0011]

Means for Solving the Problems A cabinet according to the present invention is provided.
Method of manufacturing a ceramic multilayer circuit board with tee is, ceramic
Preparing a green sheet;
Form a cavity with rounded corners in the lean sheet
Forming, and a ceramic in which the cavity is formed
A step of obtaining a laminate by laminating a plurality of green sheets;
Pressing the laminated body through an elastic body;
And firing the laminated body .

[0012]

According to the action this invention, it is possible to impart are shaped in the corner of the cavity bore provided in Rousset La Mick green sheet is prepared in order to obtain a ceramic multilayer circuit board with key Yabiti. Such rounded corners can alleviate stress concentration and are less likely to be cracks.

[0013]

Therefore, according to the present invention, when punching out a cavity hole in a ceramic green sheet, handling a ceramic green sheet, and pressing a laminate of ceramic green sheets together,
Since cracks are less likely to be formed in the cavities or the corners of the cavity holes, it is possible to prevent the electrical characteristics and moisture resistance of the ceramic multilayer circuit board with cavities caused by such cracks from deteriorating.

Further, in the pressure bonding step of the laminate composed of a plurality of ceramic green sheets, the elastic body enters the cavity based on its deformation. At this time, the shape of the elastic body is more easily conformed when the corners of the cavity are rounded than when the corners of the cavity are right angles as in the related art. Therefore, it is possible to prevent the laminate from being undesirably deformed in the crimping step, thereby preventing, for example, the position of the electrode land from shifting and causing a wire bonding error.

Further, if the radius is formed at the corner of the cavity, the radius is also formed at the corner of the cavity hole provided in the ceramic green sheet, and a punch for punching such a cavity hole is formed. In the die and the die, a radius is formed at a predetermined position. In particular, when a radius is formed at a corner of a die, a necessary shape of the die can be easily given by electric discharge machining or the like, so that the cost of a die used for punching can be reduced.

The size of the radius at the corner of the cavity provided in the present invention is arbitrary. For example, in a 3 mm square cavity, R = 0.2 m
In the case of m or more and 10 mm square, R = 1.0 mm or more is sufficient. Therefore, due to the presence of such a radius, the plane dimension of the cavity does not need to be so large as compared to the plane dimension of the chip component housed therein, and the dimensional relationship between the cavity and the chip component is: It can be substantially the same as the conventional case.

[0017]

FIG. 1 is a perspective view showing a ceramic multilayer circuit board 11 having a cavity according to an embodiment of the present invention.
The multilayer circuit board 11 includes a cavity 12 for receiving a chip component (not shown) such as a semiconductor chip. The corner 13 of the cavity 12 is rounded in a planar shape.

Such a multilayer circuit board 11 is manufactured by substantially the same method as the conventional multilayer circuit board 1 described above.

First, a ceramic green sheet is formed by, for example, a doctor blade method or the like. A specific one of the plurality of ceramic green sheets thus obtained is provided with a hole to be a via hole by a method such as a drill, a mold, or a laser. Next, a conductive paste is filled into the conductive film and the via holes described above and a wiring pattern is printed by screen printing or the like.

Next, as shown in FIG. 2, a specific ceramic green sheet 14 is provided with a cavity hole 15 for providing a part of the cavity 12, for example, by punching using a punch and a die. The corner 16 of the cavity hole 15 is rounded in a planar shape.

Next, a plurality of ceramic green sheets including the above-described ceramic green sheets 14 are laminated, and then, as shown in FIG. 5, pressed and fired.

Thus, a desired ceramic multilayer circuit board 11 with a cavity is obtained. The corners 13 of the cavities 12 provided in the multilayer circuit board 11 are rounded in plan view based on the shapes of the corners 16 of the cavity holes 15 of the used ceramic green sheet 14.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a ceramic multilayer circuit board with cavities 11 according to an embodiment of the present invention.

FIG. 2 is a plan view showing a ceramic green sheet 14 prepared to obtain the multilayer circuit board 11 shown in FIG.

FIG. 3 shows a conventional ceramic multilayer circuit board 1 with a cavity.
FIG.

FIG. 4 is a plan view showing a ceramic green sheet 4 prepared to obtain the multilayer circuit board 1 shown in FIG.

FIG. 5 is a cross-sectional view illustrating a pressure bonding step of the laminated body 6 performed to obtain the multilayer circuit board 1 illustrated in FIG.

6 is an enlarged plan view showing a part of the ceramic green sheet 4 shown in FIG. 4 for describing a problem encountered in the multilayer circuit board 1 shown in FIG.

[Explanation of symbols]

 11 Ceramic Multilayer Circuit Board with Cavity 12 Cavity 13 Corner

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 3/46 H01L 23/12-23/14

Claims (1)

(57) [Claims] 1. A process for preparing a ceramic green sheet.
And the ceramic green sheet has a rounded corner.
Forming a cavity hole; and forming a ceramic green sheet having the cavity hole formed therein.
A step of obtaining a laminate by laminating a plurality of layers, a step of press-bonding the laminate via an elastic body, and a step of firing the pressed laminate . Ceramic multilayer
A method for manufacturing a circuit board.