JP6575644B2 - Tablet-like sealing material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sealing material containing glass and an inorganic filler, and a method for producing the sealing material.

  Conventionally, sealing materials containing glass and inorganic fillers have been widely used for the purpose of sealing electronic components and the like.

  For example, Patent Document 1 below describes a sealing material for an airtight terminal containing glass and an inorganic filler such as alumina. Patent Document 1 describes that the sealing material is formed by stacking a plurality of layers having different glass and inorganic filler content ratios.

JP-A-6-20732

  As in Patent Document 1, in the sealing material in which a plurality of layers having different glass and inorganic filler content ratios are laminated, the inventor is able to increase the temperature of the adherend by increasing the temperature when sealing the adherend. It was found that the shrinkage of the layer with a high content is larger than the shrinkage of the other layers. For this reason, the present inventor has found that there is a problem that the sealing material warps due to the temperature rise when sealing the adherend, and the adherend cannot be sufficiently sealed.

  An object of the present invention is to provide a sealing material capable of suppressing warpage that occurs when sealing an adherend, and capable of reliably sealing the adherend, and manufacturing the sealing material. It is to provide a method.

  The sealing material according to the present invention is a sealing material in which a plurality of layers containing glass and an inorganic filler are laminated, and the plurality of layers are formed of the first layer and the glass from the first layer. And the second layer has a porosity smaller than that of the first layer.

  In the sealing material according to the present invention, the first layer may be an outermost layer on one side in the stacking direction, and the second layer may be the outermost layer on the other side in the stacking direction.

  In the sealing material according to the present invention, preferably, the thermal expansion coefficient of the second layer is larger than the thermal expansion coefficient of the first layer.

  In the sealing material according to the present invention, a third layer may be provided between the first layer and the second layer.

  In the sealing material according to the present invention, preferably, the glass content of the third layer is larger than the glass content of the first layer and is smaller than the glass content of the second layer.

  In the sealing material according to the present invention, the porosity of the third layer is preferably smaller than the porosity of the first layer and larger than the porosity of the second layer.

  In the sealing material according to the present invention, the thermal expansion coefficient of the third layer is preferably larger than the thermal expansion coefficient of the first layer and smaller than the thermal expansion coefficient of the second layer.

  The method for producing a sealing material according to the present invention includes a step of preparing a first green sheet for forming the first layer and a second green sheet for forming the second layer; And a step of treating the second green sheet so as to reduce the porosity of the second layer, and a step of producing a laminate including the first and second green sheets.

  In the method for manufacturing the sealing material according to the present invention, the step of treating the second green sheet may be a step of pressing the second green sheet by hot pressing.

  In the method for producing a sealing material according to the present invention, the step of producing a laminate including the first and second green sheets is produced by pressure bonding at a pressure lower than the pressure of the hot press. It may be a process to do.

  The sealing material according to the present invention is a sealing material in which a plurality of layers are laminated, and the plurality of layers includes a first layer and a second layer having a glass content higher than that of the first layer. With. The porosity of the second layer is smaller than the porosity of the first layer. Therefore, the second layer can reduce the amount of shrinkage despite the glass content being higher than that of the first layer. Accordingly, warpage that occurs when the adherend is sealed is suppressed, and the adherend can be reliably sealed.

It is a typical perspective view which shows the sealing material which concerns on one Embodiment of this invention. It is a typical perspective view which shows the structure which sealed the dissimilar material from which a thermal expansion coefficient mutually differs using the sealing material which concerns on one Embodiment of this invention.

  Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Moreover, in each drawing, the member which has the substantially the same function may be referred with the same code | symbol.

(Sealing material)
FIG. 1 is a schematic perspective view showing a sealing material according to an embodiment of the present invention. As shown in FIG. 1, the sealing material 1 has a tablet shape. More specifically, the sealing material 1 has a disk shape. The sealing material 1 may be a ring shape or a rectangular plate shape.

  The sealing material 1 includes a first layer 2, a second layer 3, and a third layer 4. A third layer 4 is stacked on the second layer 3. A first layer 2 is stacked on the third layer 4. Thus, the sealing material 1 has a three-layer laminated structure. In the present invention, the number of layers is not particularly limited as long as a plurality of layers are stacked.

  The first layer 2 is the outermost layer on one side in the stacking direction. The second layer 3 is the outermost layer on the other side in the stacking direction. A third layer 4 is provided between the first layer 2 and the second layer 3.

  The sealing material 1 contains glass and an inorganic filler. More specifically, each of the first to third layers 2 to 4 includes glass and an inorganic filler. Although it does not specifically limit as said glass, For example, the low melting glass etc. which contain many lead and bismuth etc. can be used.

  The inorganic filler is not particularly limited, and examples thereof include cordierite, mullite, silica, lead titanate, willemite, β-spodumene, zircon, zirconium phosphate, and alumina.

  The glass content of the second layer 3 is greater than the glass content of the first layer 2. The glass content of the third layer 4 is greater than the glass content of the first layer 2 and is less than the glass content of the second layer 3.

  In this embodiment, the thermal expansion coefficient of glass is larger than the thermal expansion coefficient of an inorganic filler. Therefore, the thermal expansion coefficient of the second layer 3 having a higher glass content is larger than the thermal expansion coefficient of the first layer 2. Further, the thermal expansion coefficient of the third layer 4 is larger than the thermal expansion coefficient of the first layer 2 and smaller than the thermal expansion coefficient of the second layer 3. But in this invention, the thermal expansion coefficient of an inorganic filler may be larger than the thermal expansion coefficient of glass.

  The porosity of the second layer 3 is smaller than the porosity of the first layer 2. When the porosity of the second layer 3 is smaller than the porosity of the first layer 2, the amount of shrinkage of the second layer 3 can be made smaller than when the porosity is the same. As a result, it is possible to suppress warping that occurs when the adherend is sealed. This will be described in more detail below.

  Compared with inorganic fillers, glass is easily melted by the temperature rise in the sealing process, and the molten glass flows so as to fill the gaps between the particles. For this reason, a layer having a high glass content tends to shrink due to an increase in temperature during the sealing process, which causes warping of the sealing material.

  In order to reduce the amount of shrinkage, in this embodiment, the porosity of the second layer 3 having a high glass content is set to be smaller than the porosity of the first layer 2 having a low glass content. When the porosity is reduced, the shrinkage amount of the second layer 3 is reduced, and the warpage caused by the temperature rise in the sealing process can be suppressed. Therefore, the sealing material 1 can reliably seal the adherend. The difference between the porosity of the first layer 2 and the porosity of the second layer 3 is preferably 1% by volume or more, more preferably 2% by volume or more, and 4% by volume or more. Particularly preferred. Thereby, a curvature can be suppressed further and a to-be-adhered body can be sealed more reliably.

  The porosity of the third layer 4 is smaller than the porosity of the first layer 2 and larger than the porosity of the second layer 3. When the porosity of the third layer 4 is smaller than the porosity of the first layer 2 as in this embodiment, the warp that occurs between the first layer 2 and the third layer 4 and the second Warpage that occurs between the layer 3 and the third layer 4 can be suppressed. Therefore, the warp of the sealing material 1 can be more effectively suppressed, and the adherend can be sealed more reliably.

  When providing the 3rd layer 4 between the 1st layer 2 and the 2nd layer 3 like this embodiment, the difference of the porosity of the 1st layer 2 and the porosity of the 3rd layer 4, The difference between the porosity of the third layer 4 and the porosity of the second layer 3 is preferably 1% by volume or more, and more preferably 2% by volume or more. Thereby, a curvature can be suppressed further and a to-be-adhered body can be sealed more reliably.

  The porosity of each of the first layer 2, the second layer 3, and the third layer 4 is preferably in the range of 25 to 50% by volume, and preferably in the range of 27 to 40% by volume. Further preferred. Within these ranges, by providing a difference in porosity between the layers as described above, warpage can be further suppressed, and the adherend can be more reliably sealed.

  Although it does not specifically limit as thickness of the sealing material 1, Preferably, it is 200 micrometers-1 mm or less. If the thickness of the sealing material 1 is smaller than 200 μm, it becomes difficult to absorb the difference in thermal expansion coefficient of the adherend, and peeling tends to occur at the interface with any of the adherends. If the thickness of the sealing material 1 is greater than 1 mm, cohesive failure tends to occur inside the sealing material, and it may be difficult to seal between different materials.

  FIG. 2 is a schematic perspective view showing a structure in which different kinds of materials having different thermal expansion coefficients are sealed using the sealing material according to the first embodiment of the present invention.

  As shown in FIG. 2, the sealing material 1 is provided between a material 10 having a small thermal expansion coefficient and a material 20 having a large thermal expansion coefficient. That is, the material 10 having a small thermal expansion coefficient and the material 20 having a large thermal expansion coefficient are sealed by the sealing material 1. More specifically, the material 10 having a small coefficient of thermal expansion is provided on the first layer 2 side of the sealing material 1, and the material 20 having a large coefficient of thermal expansion is the second layer 3 of the sealing material 1. On the side.

Here, for example, silicon (thermal expansion coefficient of about 40 × ^{10 -7} / ℃), alumina (thermal expansion coefficient of ^{70~80 × 10 -7 / ℃),} SUS ( thermal expansion coefficient of 110 to 150 × 10 ^{- 7} / ° C.), the thermal expansion coefficient differs greatly between the materials. Therefore, when sealing is performed using a sealing material in which glass and inorganic filler are uniformly dispersed, peeling occurs at the interface between the material 10 having a small thermal expansion coefficient and the material 20 having a large thermal expansion coefficient. It becomes.

  However, in this embodiment, the first layer 2 side of the sealing material 1 having a small thermal expansion coefficient is in contact with the material 10 having a small thermal expansion coefficient. Further, the second layer 3 of the sealing material 1 having a large thermal expansion coefficient is in contact with the material 20 having a large thermal expansion coefficient. That is, the sealing material 1 has a small difference in thermal expansion coefficient between the sealing material 1 and these materials 10 and 20 on the surface in contact with any of the different materials 10 and 20 having different thermal expansion coefficients. Therefore, the sealing material 1 is unlikely to peel off at the interface on the side in contact with any of the different materials 10 and 20 having different thermal expansion coefficients. Therefore, by using the sealing material 1, different materials having different thermal expansion coefficients can be sealed.

  As described above, the sealing material according to the present invention can seal different materials having different thermal expansion coefficients. Therefore, the sealing material which concerns on this invention can be used suitably for uses, such as a pressure sensor.

(Method for producing sealing material)
Although it does not specifically limit as a manufacturing method of the sealing material which concerns on this invention, For example, the 1st green sheet for forming a 1st layer, and the 2nd green sheet for forming a 2nd layer Including a step (step 1), a step of processing the second green sheet so as to reduce the porosity of the second layer (step 2), and the first and second green sheets. It can manufacture with a manufacturing method provided with the process (process 3) which produces a laminated body. Hereinafter, Step 1 to Step 3 will be described in more detail.

(Process 1)
First, a glass powder and an inorganic filler powder are dispersed in a solvent containing a binder resin to produce a slurry. Next, the obtained slurry is applied in a sheet shape and dried. Thereby, a plurality of green sheets including a first green sheet for forming the first layer and a second green sheet for forming the second layer are prepared.

  When the slurry is prepared, the glass content of the first green sheet is larger than that of the first green sheet so that the glass content of the second green sheet is larger than the glass content of the first green sheet. And slurry having different blending ratios of glass and inorganic filler (glass powder / inorganic filler powder). Thereby, when the first layer and the second layer are formed, the thermal expansion coefficient of the second layer can be made larger than the thermal expansion coefficient of the first layer.

  The mixing ratio (glass powder / inorganic filler powder) of the glass powder and the inorganic filler powder for producing the first green sheet is preferably in the range of 45/55 to 90/10 by mass ratio.

  On the other hand, the mixing ratio (glass powder / inorganic filler powder) of the glass powder and the inorganic filler powder for producing the second green sheet is preferably in the range of 47/53 to 95/5 in mass ratio. .

  When the blending ratio of the first green sheet (glass powder / inorganic filler powder) and the blending ratio of the second green sheet (glass powder / inorganic filler powder) are within the above ranges, the first and second Since the difference in the coefficient of thermal expansion of the layers can be set in a more appropriate range, different types of materials having different coefficients of thermal expansion can be more reliably sealed.

  Further, the number of prepared green sheets is not particularly limited. For example, when producing the sealing material 1 mentioned above, the 3rd green sheet for producing the 3rd layer 4 is prepared. In that case, when producing the slurry, the glass content of the third green sheet is greater than the glass content of the first green sheet and less than the content of the second green sheet. It is preferable to adjust the blending ratio of the third green sheet.

(Process 2)
Next, the prepared second green sheet is treated so as to reduce the porosity of the second layer formed by pre-baking the second green sheet. A method for performing the treatment on the second green sheet is not particularly limited. For example, the porosity of the second green sheet can be reduced by pressurizing the second green sheet by hot pressing.

  The hot pressing is desirably performed at a temperature of 80 to 100 ° C. and a pressure of 10 to 300 MPa for 60 to 300 seconds. When hot pressing is performed under the above conditions, the porosity can be further reduced.

  The treatment applied to the second green sheet may be applied to other green sheets other than the second green sheet which is the green sheet having the smallest glass content. For example, you may process a 3rd green sheet so that the porosity of the 3rd layer formed by pre-baking the 3rd green sheet mentioned above may be reduced.

(Process 3)
Next, a laminate of a plurality of green sheets including the first and second green sheets is produced. More specifically, a laminate of a plurality of green sheets including a first green sheet that has not been subjected to the treatment and a second green sheet that has been subjected to the treatment is produced.

  Thereafter, the obtained laminate is hot pressed. At this time, in order to reduce the porosity of the second layer, it is preferable to perform pressure bonding at a pressure lower than the pressure of the hot press applied to the second green sheet. Specifically, it is desirable to carry out at a temperature of 80 to 100 ° C. and a pressure of 5 to 200 MPa for 60 to 300 seconds.

  Next, the pressure-bonded laminate is punched out with a mold to obtain a desired shape. Finally, the punched laminate is temporarily fired at a temperature lower than the softening point of the glass powder to obtain a sealing material.

  In the manufacturing method according to the present invention, as described above, the treatment for reducing the porosity of the second green sheet for forming the second layer having a higher glass content than the first layer. Is given. Therefore, it is possible to obtain a sealing material in which the porosity of the second layer is smaller than the porosity of the first layer. Therefore, in the obtained sealing material, the shrinkage amount of the second layer is reduced, and the warpage that occurs when the adherend is sealed can be suppressed. Therefore, according to the manufacturing method according to the present invention, it is possible to obtain a sealing material that can reliably seal the adherend.

  Hereinafter, the present invention will be clarified by giving specific examples of the present invention. In addition, this invention is not limited to a following example.

Example 1
A first green sheet containing 70% by mass of Bi ₂ O ₃ —B ₂ O ₃ —ZnO-based glass as glass powder and 30% by mass of cordierite as inorganic filler powder, and Bi ₂ O ₃ —B ₂ O as glass powder _A second green sheet containing 80% by mass of _3- ZnO-based glass and 20% by mass of cordierite as an inorganic filler powder was prepared.

  Next, a first hot press was applied to the prepared second green sheet at a temperature of 90 ° C. and a pressure of 200 MPa for 120 seconds. Thereafter, the first and second green sheets were laminated to produce a laminate, and the obtained laminate was subjected to a second hot press at a temperature of 90 ° C. and a pressure of 70 MPa for 60 seconds. The pressure-bonded laminate was punched out with a mold to form a disk, and pre-baked at a temperature of 470 ° C. to obtain a disk-shaped sealing material having a diameter of 10 mm.

(Example 2)
Disc-shaped sealing with a diameter of 10 mm in the same manner as in Example 1 except that the contents of the glass powder and inorganic filler powder in the first and second green sheets were set as shown in Table 1 below. The material was obtained.

(Example 3)
A first green sheet containing 15 wt% amorphous silica as _PbO-SiO 2 _-B 2 _{O 3} based glass 85% by weight and an inorganic filler powder as a glass powder, _PbO-SiO 2 _-B 2 _{O 3} as a glass powder A second green sheet containing 93% by mass of a glass and 7% by mass of amorphous silica as an inorganic filler powder, 89% by mass of a PbO—SiO ₂ —B ₂ O ₃ glass as a glass powder and amorphous as an inorganic filler powder A third green sheet containing 11% by mass of porous silica was prepared.

  Next, a first hot press was applied to the prepared second green sheet at a temperature of 100 ° C. and a pressure of 120 MPa for 180 seconds, and a third green sheet was applied at a temperature of 100 ° C. and a pressure of 90 MPa for 180 seconds. Thereafter, the third green sheet and the first green sheet are laminated in this order on the second green sheet to produce a laminate, and the resulting laminate is heated at 85 ° C. and a pressure of 50 MPa for 90 seconds. A second hot press was applied. The pressure-bonded laminate was punched out with a mold to form a disk, and was calcined at a temperature of 420 ° C. to obtain a disk-shaped sealing material having a diameter of 10 mm.

Example 4
Disc-shaped sealing with a diameter of 10 mm, as in Example 3, except that the glass powder and inorganic filler powder contents of the first to third green sheets were set as shown in Table 1 below. The material was obtained.

(Comparative Example 1)
A disc-shaped sealing material having a diameter of 10 mm was obtained in the same manner as in Example 1 except that the first green sheet was not subjected to the first hot press.

(Comparative Example 2)
A disc-shaped sealing material having a diameter of 10 mm was obtained in the same manner as in Example 3 except that the first and second green sheets were not subjected to the first hot press.

(Evaluation)
Porosity and coefficient of thermal expansion;
First, the first, second and third green sheets before the second hot press are prepared and cut into 50 cm ² , respectively. By pre-baking each cut green sheet, a pre-fired body (first, second, and third layers) is produced at the pre-baking temperature. The thickness and mass of each prepared calcined body are measured to determine the volume V and mass M. Next, the composite density ρ of the mixed powder matched to the mixing ratio of the glass and the inorganic filler was determined by calculation, and the porosity ε was determined from ε = 1−M / (V · ρ). Similarly, pre-fired bodies (first, second, and third layers) of the first, second, and third green sheets were prepared, and the thermal expansion coefficients were measured.

Evaluation of warpage amount;
The sealing materials obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were baked for 10 minutes at a temporary baking temperature + 20 ° C. After firing, the sealing material was sandwiched between two flat plates, and the distance between the two flat plates sandwiched with the sealing material was measured. The difference between the measured distance between the two flat plates and the thickness of the sealing material itself was defined as the amount of warpage.

  From Table 1, the sealing obtained in Examples 1 to 4 in which the first hot press was performed on the green sheet having a large glass powder content (the porosity of the green sheet having a large glass powder content is small). It was confirmed that the warpage amount of the material was smaller than the warpage amount of the sealing materials of Comparative Examples 1 and 2.

DESCRIPTION OF SYMBOLS 1 ... Sealing material 2 ... 1st layer 3 ... 2nd layer 4 ... 3rd layer 10 ... Material with a small thermal expansion coefficient 20 ... Material with a large thermal expansion coefficient

Claims (5)

A plurality of layers containing glass and an inorganic filler are laminated, and are tablet-like sealing materials used for sealing materials having different coefficients of thermal expansion,
The plurality of layers include a first layer and a second layer having a lower porosity than the first layer,
A tablet-like sealing material in which the first layer and the second layer are bonded to materials having different thermal expansion coefficients.   The tablet-like sealing material according to claim 1, wherein a thermal expansion coefficient of the second layer is larger than a thermal expansion coefficient of the first layer.   The tablet-like sealing material according to claim 1 or 2, wherein the glass content of the second layer is larger than the glass content of the first layer. A plurality of layers containing glass and an inorganic filler are laminated, and are tablet-like sealing materials used for sealing materials having different thermal expansion coefficients, wherein the plurality of layers include the first layer and the first layer. A method for producing a tablet-like sealing material, comprising a second layer having a porosity smaller than that of the first layer,
Preparing a first green sheet for forming the first layer and a second green sheet for forming the second layer;
Treating the second green sheet so as to reduce the porosity of the second layer;
Producing a laminate including the first and second green sheets;
Punching the laminate with a mold to form a tablet;
A method for producing a tablet-like sealing material.   The manufacturing method of the tablet-shaped sealing material of Claim 4 further equipped with the process of pre-baking the said tablet-shaped laminated body after the process which makes the said laminated body the said tablet shape.

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