JPH0794989A - Ceramic sheet and production of ceramic package - Google Patents

Abstract

PURPOSE:To provide a ceramic package manufacturing method capable of simultaneously forming projections on the bottom of a ceramic package by the thermal press-contacting process of plural thick film sheets. CONSTITUTION:Plural square-like ceramic-made thick film sheets 14, 14', 14'' are laminated on a metallic back plate 42 through a resin sheet 44 forming through holes 43 on prescribed positions, these sheets are thermally pressed by thermal pressing from the upper part of the sheets and electrode forming parts on the bottom of the lowermost layer sheet 14 are extruded into the through holes 43 of the resin sheet 44 to form projections 32.

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 sheet and a ceramic package made of a ceramic material.

[0002]

2. Description of the Related Art For example, as an accommodating container for elements such as a crystal oscillator and a SAW filter, as shown in FIG. 8, a ceramic package (3) having a base (1) which is a ceramic sheet and a cap (2) is used. ).

When manufacturing the base (1),
As shown in FIG. 9, a doctor blade method is used. First, a long carrier tape (7) made of a plastic material wound around a supply drum (6) is sequentially fed in the direction of the arrow while its surface (8) is being fed. , A slurry-like material (11) made of a ceramic material or a mixed material of ceramic and glass is supplied from the blade-like opening (10) of the cylindrical body (9) and applied in a form of a final impression, and is fixed on the carrier tape (7). After the material (11) is deposited to a thickness, it is passed through a drying oven (12) to dry the solvent by semi-drying, and the thick ceramic raw sheet (1
3), and then, as shown in FIG. 10 (a), three thick film sheets (14) (14 ') (14'') formed by cutting the raw sheet (13) into a rectangular shape. ) As a set, two central thick film sheets (14 ') and (14'') are punched out in small and large sizes to form a rectangular frame body having different small and large openings. . Then, as shown in FIG. 10 (b), they are sequentially laminated on the other thick film sheet (14) in three layers, and then pressed by a hot press from above to be thermocompression bonded, followed by firing, A two-step recess (16) for storing a rectangular cross section of a staircase wall having a step (15) on the intermediate inner wall surface is provided. The cap (2) is formed in the same manner.

Then, as shown in FIG. 8, the periphery of the element (21) such as a crystal unit is attached to the step (15) of the base (1) through a conductive adhesive, for example, a silver paste (20). The ends are fixed and stored and held so that they can vibrate freely, and the terminal leads (22) are formed on the surface of the base (1), and externally formed on the electrode forming parts (24) (25) of the bottom surface (23). Electrode (26) (2
7) is formed, and the external electrodes (26) and (27) are connected to the element lead (22) and the silver paste (20) through the element (21).
After connecting to the pair of electrodes (28) and (29) respectively, the cap (2) is sealed on the upper surface of the base (1) via the sealant (30).

Ceramic package (3) having the above structure
Are so-called surface-mounted by soldering or the like directly on the surface of a printed circuit board or the like. However, when the ceramic package (3) is placed on the printed circuit board, a space between the bottom surface of the ceramic package (3) and the upper surface of the printed circuit board is
A small gap is formed that is approximately the same size as the protruding size (about 20 μm thickness) of the external electrodes (26) (27). Therefore, the conductive flux contained in the solder penetrates deeply into the gap due to the capillary phenomenon. May cause a short circuit.

Therefore, in order to prevent the capillary phenomenon from occurring during surface mounting, the bottom surface of the ceramic package (1) should be widened so that the gap between the bottom surface (23) of the ceramic package (3) and the printed circuit board becomes wide. A protrusion having a predetermined protrusion size (thickness of about 300 μm) is formed on (23). Conventionally, a protrusion forming step is provided after the manufacturing process of the ceramic package (3), and gold or the like is bumped to the external electrodes (26) (27) or the external electrode (26) is formed in the protrusion forming step. Apply multiple layers of conductive material to (27),
Alternatively, the bottom surface of the ceramic package (3) is partially thick-film printed with a ceramic material or the like to form protrusions on the bottom surface of the ceramic package (3).

[0007]

According to the conventional method for manufacturing a ceramic package (3), in order to prevent the capillary phenomenon from occurring during surface mounting of the ceramic package, it is necessary to perform a subsequent step of the manufacturing process of the ceramic package. Since the projection forming step is provided and the projection is formed in this projection forming step, a special step and apparatus for forming the projection are separately required, and it takes much time to manufacture and workability deteriorates. However, there was a problem that the manufacturing cost was high.

The present invention has been proposed in view of the above problems, and it is an object of the present invention to provide a method for manufacturing a ceramic sheet and a ceramic package, which can simultaneously form protrusions in a thermocompression bonding process of a plurality of thick film sheets. Has an aim.

[0009]

In order to achieve the above object, the present invention provides a plurality of rectangular ceramic thick film sheets made of metal through a resin sheet having through holes formed at predetermined positions. Laminate it on the plate, press this thick film sheet from above with a hot press to perform thermocompression bonding, and at the same time,
A portion of the bottom thick film sheet is extruded into the through holes of the resin sheet to form protrusions on the bottom surface of the ceramic sheet.

Further, in the same manner, a protrusion may be formed on the electrode forming portion of the lowermost thick film sheet of the ceramic package, or a protrusion may be formed substantially at the center of the lowermost thick film sheet. Good.

[0011]

Function: At the same time as thermocompression bonding of a plurality of thick film sheets, a projection can be formed on the bottom surface of the lowermost thick film sheet.

[0012]

Embodiments of the manufacturing method according to the present invention will be described below with reference to FIGS. The same parts as those shown in FIGS. 8 to 10 are designated by the same reference numerals, and the description thereof will be omitted.

[Embodiment 1] As shown in FIG. 2, external electrodes (26) and (27) are formed on both sides of the bottom surface (23) of the ceramic package (31) in the longitudinal direction.
4) The projection (32) is integrally formed on the (25). The protrusion size of the protrusion (32) is a size capable of preventing the occurrence of a capillary phenomenon during surface mounting on the printed circuit board (33), that is,
The conductive flux contained in the solder has a dimension such that it may not enter between the surface (34) of the printed board (33) and the bottom surface (23) of the ceramic package (31) due to the capillary phenomenon, for example, about 300 μm. It is set to thick.

The protrusions (32) of the ceramic package (31) are formed in the following manner. First, as shown in FIG. 1, a metal back plate (4
2) On top of this, install a resin sheet (44) of approximately the same thickness as the height of the protrusions in which the through holes (43) are formed in correspondence with the electrode forming portions (24) (25) of the ceramic package (31). , Three thick film sheets (1
4) Lay down (14 ') and (14''). Then 80-1
The thick film sheets (14), (14 ') and (14'') are pressed from above by a press (not shown) in a heating atmosphere of 20 ° C. By this pressing, the thick film sheet (14) (14 ') (1
4 '') is thermocompression bonded and at the same time the bottom thick film sheet (1
The portion of the bottom surface (23) of the (4) facing the through hole is the resin sheet (4
4) Extruded into each through hole (43) of 4) to form the electrode forming part (24)
Protrusions (32) are formed on (25), respectively. Thick film sheet (1
4) When the protrusions (32) are formed on the bottom surface (23) of the bottom thick film sheet (14) by thermocompression bonding of (14 ') and (14''), 10
The base (1), which is a ceramic sheet, is formed by firing at about 00 ° C, as shown in FIGS. 3 and 4. On the stepped portion (15) of the base (1) thus formed, the peripheral end portion of the element (22) such as a crystal resonator is attached via a conductive adhesive, for example, a silver paste (20) as in the conventional case. The base (1) is firmly fixed and vibratably accommodated and held, and terminal lead portions (22) are formed on the upper and side surfaces of the base (1), and the electrode forming portion (24) of the bottom surface (23) of the base (1) is formed. ) (25), the external electrodes (26) (27) are formed so as to surround the projection (32), and these external electrodes (26) (27) are connected to the terminal lead portion (2).
2) and a pair of electrodes (28) (29) of the element (22) via silver paste (20) respectively, and then cap (2) on the upper surface of the base (1) via a sealant (30). ) Is sealed.

When the ceramic package (31) having the above structure is surface-mounted, the ceramic package (31) is placed on the surface (34) of the printed circuit board (33) as shown in FIG. The external electrodes (26) (27) are soldered to the surface of the printed board (33) with solder (45). At this time, the bottom surface (23) of the ceramic package (31)
Between the surface of the printed circuit board (33) and the surface (34) of the printed board (33), the projection (32) forms a gap (46) having a space dimension that does not cause capillary action, and thus is included in the solder (45). The melted flux does not penetrate deeply into the gap (46) and a short circuit is prevented.

[Embodiment 2] By the method of the present invention described in Embodiment 1, as shown in FIGS. 6 and 7, substantially the center of the bottom surface (23) of the base (1) constituting the ceramic package (31). You may form a protrusion (51) in a part. In this case, a through hole is formed in the resin sheet (44) at a substantially central portion.

[0017]

According to the present invention, it is possible to form a protrusion on the bottom surface of the lowermost thick film sheet of the stacked thick film sheets at the same time as the thermocompression bonding of the plurality of thick film sheets by pressing. Unlike the conventional case, it is not necessary to specially provide a protrusion forming step and a device for forming a protrusion, and thus it is possible to shorten the manufacturing time of the ceramic package accordingly.
Workability is improved and manufacturing cost is reduced.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of a manufacturing method according to the present invention.

FIG. 2 is a vertical cross-sectional view of a ceramic package manufactured by the method of the present invention.

FIG. 3 is a bottom view of a base having a projection formed on an electrode forming portion.

FIG. 4 is a side view of FIG.

FIG. 5 is a front view showing a surface mounting procedure of a ceramic package.

FIG. 6 is a bottom view showing another specific example of the base manufactured by the method of the present invention.

FIG. 7 is a side view of FIG.

FIG. 8 is a schematic side sectional view showing an example of a conventional ceramic package.

FIG. 9 is a schematic side view of a doctor blade method showing an example of a method for manufacturing a ceramic package.

10A and 10B are perspective views showing steps of forming a ceramic package from a thick film sheet formed by the doctor blade method shown in FIG. 9.

[Explanation of symbols]

 14, 14 ', 14' 'Thick film sheet 24, 25 Electrode forming part 32 Protrusion 42 Back plate 43 Through hole 44 Resin sheet

Claims (3)

[Claims] 1. A plurality of square-shaped ceramic thick film sheets are stacked and mounted on a metal back plate through a resin sheet having through holes formed at predetermined portions, and the thick film sheets are placed from above. A method for producing a ceramic sheet, comprising pressing by a hot press to perform thermocompression bonding, and at the same time, a part of the bottom thick film sheet is extruded into the through holes of the resin sheet to form protrusions. 2. A plurality of rectangular ceramic thick film sheets are stacked and mounted on a metal back plate through a resin sheet having through holes formed at predetermined portions, and the thick film sheets are placed from above. A method of manufacturing a ceramic package, comprising pressing by a hot press to perform thermocompression bonding, and at the same time, forming an protrusion by extruding an electrode forming portion on a bottom surface of a lowermost thick film sheet into a through hole of a resin sheet. 3. A plurality of square-shaped ceramic thick film sheets are stacked and mounted on a metal back plate via a resin sheet having a through hole formed at a substantially central portion thereof, and the thick film sheets are placed upward. A method for manufacturing a ceramic package, characterized in that the central portion of the thick film sheet of the lowermost layer is extruded and formed into the through hole of the resin sheet to form a protrusion while being pressed by a heat press from the above to perform thermocompression bonding.