JPH08330751A - Manufacture of ceramic package - Google Patents

Abstract

PURPOSE: To provide a ceramic package by a method wherein after external electrodes are formed, the electrodes are densified by thermocompression bonding in a press process without raising a firing temperature and the reliability of the soldering heat resistance of the electrode is improved. CONSTITUTION: A plurality of sheets of thick film sheets, which are cut into a square form, prepressed and are made of ceramic, are prepared, the sheet 3a is provided with external electrodes 5, a rectangular through-hole is formed in the second sheet 3b to arrange internal electrodes 4 on the sheet 3b, a rectangular through-hole is formed in the third sheet 3c, these sheets 3a, 3b and 3c are laminated in order, the laminated material is thermocompression bonded by a press from over the laminated material to form a ceramic base main body 3, side surface part electrodes 5a are arranged on this main body 3 and the electrodes 4 are connected with the electrodes 5.

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 package, and more particularly, to a method of manufacturing a ceramic package which is pressed after forming external electrodes.

[0002]

2. Description of the Related Art Crystal oscillators have been commercialized by hermetically sealing them using airtight terminals, but in recent years, surface mount type electronic parts using ceramic packages have been put into practical use. Figure 7
And FIG. 8 shows a conventional surface mount ceramic package that has been put to practical use as a crystal unit. As shown in the figure, in the surface mount ceramic package 21, thick film sheets 23a, 23b and 23c are sequentially laminated to form a ceramic base body 23, and an external electrode 25 and a side surface electrode 25a are provided on the ceramic base body 23. And the internal electrodes 24 are provided on the sheet 23b. A crystal oscillator 26 is placed on the pair of internal electrodes 24, 24, and after fixing with a conductive paste, the ceramic lid 28 is sealed with a sealant 27 such as low melting point glass or epoxy to maintain airtightness. Complete surface mounted electronic components.

Here, a method of manufacturing the ceramic base body 23 of the ceramic package will be described with reference to FIGS.
Description will be given with reference to 0. In the film-forming step a, in which a ceramic material or a slurry-like material composed of a ceramic and glass mixed material is applied to a constant thickness on a long carrier tape made of a plastic material to make a semi-dried state, a thick ceramic raw sheet is formed. Formed, in the sheet cutting step b,
This green sheet is cut into a rectangular shape having a predetermined size, and in the perforating step c, as shown in FIG. 9, a large number of prescribed shapes, for example, the central portion is punched out in small and large dimensions, into the cut ceramic green sheet. Sheets 23b and 23c having a rectangular frame body having different small and large openings and a rectangular flat sheet 2
3a is formed. In the next electrode forming step d, the sheet 23
The internal electrode 24 is formed on screen b by screen printing.

Then, in the laminating step e, the sheets 23a ...
Several sheets of 23c, for example, 3 to 6 sheets are stacked as one set and thermocompression-bonded in the pressing step f to form the box-shaped ceramic base body 23 having a recess. The number of laminated sheets is different depending on the type. In the electrode forming step g, the external electrodes 25 are formed on the ceramic base body 23 by screen printing using silver / palladium to form the ceramic base 22. Further, the side surface electrode 2 is provided on the ceramic base body 23.
5a is also formed. Then, in a cutting step h, the ceramic bases 22 formed in large numbers are individually cut, and a degreasing step i and a firing step j are performed. The ceramic lid 28 is formed in the same manner.

[0005]

Generally, silver / palladium is often used as an electrode material when an external electrode is formed on a ceramic as a non-plated product. When a surface mount type electronic component using the ceramic package 21 is mounted on a printed wiring board and immersed in a solder bath, silver /
The solder heat resistance of the external electrode 25 using palladium is sometimes pointed out in terms of quality such as solder strength, and the problem of reliability must be solved. As a means for solving the reliability problem, it is considered that the firing temperature is raised to make the silver / palladium electrode dense.

However, in the external electrode 25 made of silver / palladium formed on the ceramic substrate as described above, there is a limitation that the firing temperature cannot be raised above a certain temperature due to the temperature resistance of the ceramic substrate. Therefore, the present invention has been proposed in view of the above problems, and an object of the present invention is to provide a means for densifying an electrode using a silver / palladium material without increasing the firing temperature. Another object of the present invention is to provide a ceramic package having improved reliability such as solder heat resistance even if it is an external electrode using palladium.

[0007]

According to the present invention, there is provided a step of forming a plurality of ceramic thick film sheets which are cut into a rectangular shape and pre-pressed, and an external electrode is arranged on the ceramic thick film sheet. A step of forming one sheet, a second sheet in which a rectangular through hole and an internal electrode are arranged in a thick film sheet, and a third sheet in which a rectangular through hole is provided in the thick film sheet; A ceramic package including a step of sequentially stacking the second and third sheets and thermocompressing with a press to form a ceramic base body, and a step of arranging a side surface electrode on the ceramic base body and connecting an internal electrode and an external electrode. A manufacturing method is provided.

[0008] Further, a step of forming a plurality of ceramic thick film sheets which are cut into a rectangular shape and pre-pressed, a first sheet which is the ceramic thick film sheet as it is, and a rectangular shape on the thick film sheet. A second sheet having through holes and internal electrodes,
A step of forming a third sheet in which a rectangular through hole is formed in the thick film sheet, a step of sequentially stacking the sheets and thermocompressing with a press to form a ceramic base body, and a side surface portion of the ceramic base body. Disclosed is a method for manufacturing a ceramic package, which comprises the steps of disposing electrodes and external electrodes and connecting the electrodes to internal electrodes and external electrodes.

Also provided is a method of manufacturing a ceramic package in which a side surface electrode and an external electrode are arranged on the ceramic base body, and the internal electrode and the external electrode are connected to each other, and then the ceramic base body is pressed again. further,
Provided is a method of manufacturing a ceramic package in which an external electrode is silver / palladium.

[0010]

According to the above structure, the manufacturing process is such that the pressing process is arranged after the external electrodes are formed in the electrode forming process. Therefore, after forming the external electrodes on the first sheet,
By stacking and press-bonding in the pressing process, the external electrode layer is partially embedded in the first sheet, and the external electrode becomes dense, and reliability in solder heat resistance etc. is improved by baking in the subsequent process. To do.

[0011]

EXAMPLES Examples of the present invention will be described below with reference to FIGS.
Will be described with reference to. In the figure, 1 is a ceramic package, 2 is a ceramic base on which each electrode is formed, 3 is a ceramic base body on which thick film sheets are laminated and thermocompression-bonded, 4 is an internal electrode, 5 is an external electrode, and 5a is a side surface portion. Electrodes, 6 are crystal oscillators, 7 is a sealant, and 8 is a ceramic lid. Note that FIG. 1 will be described as a diagram common to the two embodiments.

A first embodiment will be described with reference to the manufacturing process diagrams of FIGS. 1, 3 and 5. The surface mount ceramic package 1 includes a first sheet 3a on which external electrodes 5 are arranged.
Then, the second sheet 3b having the rectangular through holes and the internal electrodes 4 arranged thereon and the third sheet 3c having only the rectangular through holes are sequentially laminated and thermocompression bonded to form the ceramic base body 3. Further, the side surface electrode 5a is formed on the ceramic base body 3 to form the ceramic base 2. next,
For example, a crystal oscillator 6 is placed on the pair of internal electrodes 4 and 4 formed on the ceramic base 2, fixed with a conductive paste (not shown), and then a ceramic lid 8 is placed on the ceramic base 2. As described above, sealing is performed with the sealing agent 7 such as low melting point glass or epoxy resin. By this sealing, a surface mount type electronic component maintaining airtightness is completed.

Now, a method of manufacturing a ceramic package, particularly a ceramic base will be described. Although the description of the previous step is omitted, a film-forming step A in which a slurry-like material made of a ceramic material or a mixed material of ceramic and glass is applied to a constant thickness on a long carrier tape made of a plastic material to make a semi-dried state Then, a thick green ceramic green sheet is formed (not shown). Next, in a sheet cutting step B, it is cut into a rectangular shape having a predetermined size. Next, in a prepress step C, the raw sheet cut into a rectangular shape having a predetermined size is prepressed.

Next, in the perforating step D, as shown in FIG. 3, three thick film sheets are set as one set by using the cut ceramic green sheet, and two thick film sheets out of the set are formed. The central portion of the sheet is punched out in small and large dimensions to form a rectangular frame body having different small and large openings. In the electrode forming step E, the first sheet 3a is formed by screen-printing the external electrodes 5 on the thick film sheet having the through holes in the previous step. The material of the external electrode 5 is, for example, silver / palladium. In addition, the second sheet 3b in which the internal electrodes 4 are formed by screen printing is formed on one of the two thick film sheets described above. The material of the internal electrodes 4 is silver, for example. The other thick film sheet becomes the third sheet 3c without any electrodes.

In the laminating step F, the first sheet 3a and the second sheet 3a
Several thick film sheets each including the sheet 3b and the third sheet 3c, for example, 3 to 6 thick film sheets are laminated as a set,
By thermocompression bonding in the pressing step G, the box-shaped ceramic base body 3 having a recess is formed. The number of stacked thick film sheets differs depending on the product such as shape and size.
In the electrode forming step H, the side surface electrode 5a is formed on the ceramic base body 3 by using, for example, silver / palladium. The side surface electrode 5a connects the internal electrode 4 and the external electrode 5 to form the ceramic base 2 which is electrically connected to each other.
A large number of ceramic bases 2 formed in the cutting step I
To cut individually. Then, the degreasing process J and the baking process K are performed. The description of the subsequent steps is omitted. The ceramic lid 8 is also formed in the same manner.

A second embodiment will be described with reference to the manufacturing process diagrams of FIGS. 1, 4 and 6. The surface mount type ceramic package 1 is similar to that of the first embodiment, but a part of the manufacturing process is different. The first sheet 3aa and the second sheet 3bb having a rectangular through hole and having the internal electrodes 4 arranged therein.
And the third sheet 3cc having only rectangular through holes are sequentially laminated and thermocompression bonded to form the ceramic base body 3. As shown in FIG. 6, in the electrode forming step, the side surface electrode is formed on the ceramic base body 3. 5a and the external electrode 5a are arranged to form the ceramic base 2. Next, for example, a crystal oscillator 6 is placed on the pair of internal electrodes 4 and 4 formed on the ceramic base 2 and fixed with a conductive paste (not shown), and then a ceramic lid is placed on the ceramic base 2. 8 is covered with a sealant 7 such as low melting glass or epoxy resin. By this sealing, a surface mount type electronic component maintaining airtightness is completed.

The method of manufacturing the ceramic base in this embodiment will be described below with reference to FIGS. 4 and 6 for the parts different from the first embodiment. Drilling process D
In the subsequent electrode forming step E1, the plate-shaped thick film sheet having through holes is used as the first sheet 3aa without forming electrodes. Also,
One of the two thick film sheets is made of silver and the internal electrode 4
To form a second sheet 3bb formed by screen printing. The other thick film sheet is the third sheet 3c without electrodes.
c. Next, in the laminating step F, the first sheet 3a is
a, the second sheet 3bb and the third sheet 3cc, several thick film sheets, for example, 3 to 6 thick film sheets are stacked as a set, and the first thermocompression bonding is performed in the pressing step G1 to form the concave portion. A box-shaped ceramic base body 3 having the same is formed. The number of stacked thick film sheets differs depending on the product such as shape and size.

Next, in the electrode forming step H1, the external electrodes 5 and the side surface electrodes 5a are formed on the ceramic base body 3 by screen printing. This side surface electrode 5a is the internal electrode 4
And the external electrode 5 are connected to each other to form a ceramic base 2 which is electrically connected to each other. The external electrode 5 and the side surface electrode 5a
The material is, for example, silver / palladium. Next, a press 2 step G2 for the second press pressing is added. After the cutting step, a large number of ceramic bases 2 are individually cut, and a degreasing step and a firing step are performed.

As described above, in the two embodiments, the manufacturing process in which the external electrode is formed in the electrode forming process and then the pressing is performed is changed. Therefore, by forming the external electrodes first, and then stacking them and thermocompression-bonding them in a pressing process, as shown in a partially enlarged view of the external electrodes of
When comparing before and after pressing, after pressing, the layer of the external electrode is partially embedded (t dimension) in the sheet, and the external electrode is dense.

[0020]

As described above, according to the method for manufacturing a ceramic package of the present invention, after the external electrodes are formed in the electrode forming step, the pressing step is arranged. Therefore, by forming the external electrode first, and then laminating and thermocompressing it in the pressing step, the external electrode layer is partially embedded in the sheet, and the external electrode becomes dense. That is, the external electrode can be densified without raising the firing temperature, and even with an external electrode using a silver / palladium material, the problem of solder strength due to solder heat resistance is solved and the reliability of the ceramic is improved. Can provide package.

[Brief description of drawings]

FIG. 1 is a front sectional view of a ceramic package according to the present invention.

FIG. 2 is a partially enlarged view showing a state before and after pressing an external electrode according to the present invention.

FIG. 3 is a perspective view showing a state of stacking each sheet of Example 1 according to the present invention.

FIG. 4 is a perspective view showing a state of stacking each sheet of Example 2 according to the present invention.

FIG. 5 is a schematic manufacturing process diagram of Example 1 according to the present invention.

FIG. 6 is a schematic manufacturing process diagram of a second embodiment according to the present invention.

FIG. 7 is a perspective view of a conventional ceramic package.

FIG. 8 is a front cross-sectional view of the ceramic package of FIG. 7 viewed from XX.

FIG. 9 is a perspective view showing a state of stacking with each conventional sheet.

FIG. 10 is a schematic view of a conventional manufacturing process.

[Explanation of symbols]

 1 Ceramic Package 2 Ceramic Base 3 Ceramic Base Main Body 3a, 3aa First Sheet 3b, 3bb Second Sheet 3c, 3cc Third Sheet 4 Internal Electrode 5 External Electrode 5a Side Electrode 6 Crystal Oscillator 7 Sealant 8 Ceramic Lid

Claims (4)

[Claims] 1. A step of forming a plurality of ceramic thick film sheets that are cut into a rectangular shape and pre-pressed, a first sheet in which external electrodes are arranged on the ceramic thick film sheet, and the thick film sheet. Forming a second sheet having a rectangular through hole and an internal electrode in the first and a third sheet having a rectangular through hole in the thick film sheet, and the first, second and third sheets And a method for forming a ceramic base body by thermocompression bonding by pressing, and a step of disposing a side surface electrode on the ceramic base body and connecting the internal electrode and the external electrode to each other. . 2. A step of forming a plurality of ceramic thick film sheets which are cut into a rectangular shape and pre-pressed, a first sheet which is the ceramic thick film sheet as it is, and a rectangular shape on the thick film sheet. Forming a second sheet having the through holes and the internal electrodes and a third sheet having the rectangular through holes formed in the thick film sheet, sequentially stacking the sheets, and thermocompression-bonding with a press. And forming a ceramic base body with the ceramic base body, and arranging a side surface electrode and an external electrode on the ceramic base body to connect the side surface electrode with the internal electrode and the external electrode. Ceramic package manufacturing method. 3. The ceramic base body is repressed again after the step of arranging side surface electrodes and external electrodes on the ceramic base body and connecting the internal electrodes to the external electrodes. 2. The method for manufacturing a ceramic package according to 2. 4. The method of manufacturing a ceramic package according to claim 1, wherein the external electrode is silver / palladium.