JP4214068B2 - Multilayer glass substrate manufacturing method - Google Patents

Description

The present invention relates to a method for bonding glass substrates, and more particularly to a method for producing a multilayer glass substrate in which a conductor film for connecting both surfaces of a glass substrate requiring airtightness is formed.

Conventionally, a multilayer substrate in which a through hole is formed in a ceramic substrate is used as a multilayer substrate in which a through hole on which an electronic component is mounted is formed.

  In recent years, the number of fields in which multilayer boards mounted with electronic components also require airtightness has increased. For example, crystal resonators and the like are used in many electronic devices such as mobile phones because they have stable frequency characteristics due to oscillation of extremely stable vibrations, SAW filters (surface acoustic wave filters), automobile air For mounting electronic parts that require airtightness such as acceleration sensors for bags, various pressure sensors for automobiles, etc., multilayer boards are also required to be airtight.

  For example, taking the quartz crystal as an example, silver is used for the electrodes of the quartz crystal. However, the air resistance is insufficient, and if air (especially oxygen) enters, the internal resistance increases, causing oscillation. This causes a problem that the frequency to be changed changes and finally oscillation stops. Therefore, in mounting these electronic components requiring airtightness, not only the cover but also the substrate on which the electronic components are mounted requires many fields.

As described above, a multilayer substrate in which a through hole is formed in a ceramic substrate is conventionally used as a multilayer substrate in which a through hole for mounting an electronic component is formed.
Usually, a through hole of a ceramic substrate is filled with a paste made of a metal powder as a conductive material and a ceramic powder as a binder component that easily adheres to the ceramic substrate, and fired at a high temperature.

  By the way, in recent years, since electronic devices including circuit boards and circuit boards are required to be downsized, multilayer substrates are becoming thinner.

  However, in the case of a ceramic substrate, if a thin substrate is used, the ceramic substrate is a porous material. Therefore, there is a problem that the reliability is not sufficient in terms of airtightness for mounting electronic components that require airtightness. Will occur.

Therefore, the use of a dense glass substrate is considered. In the case of a glass substrate, the means for firing the conductive material in the through hole at a high temperature as in the case of a ceramic substrate cannot be adopted because the glass substrate melts and deforms.
Therefore, as a conductive material in the through hole of the glass substrate, a material filled with a conductive resin paste containing metal powder, solder coating, or the like can be considered.

  Further, as a conventional method for producing a glass substrate, there has been a method in which a foamable glass paste is filled in a through hole and fired (for example, see Patent Document 1 below).

  FIG. 3 is a cross-sectional view showing a manufacturing process flow of the conventional glass substrate described in Patent Document 1.

In FIG. 3, a step of forming a through-hole conductor 103 a and a through-hole land 103 b by a conductive film 103 around the peripheral wall and opening of the through-hole 102 provided in the glass insulating substrate 101, and foaming as a filler 104 in the through-hole 102. The glass paste is filled and fired to close the through hole 102. When the glass paste is fired, the glass paste is foamed in the through hole. Thus, the apparent volume of the glass component is increased by the amount of foaming, and as a result, the shrinkage of the filler formed by firing the glass paste can be prevented, and the through hole 102 is sealed with the filler 104 made of foamed glass. It stopped.
Japanese Patent Laid-Open No. 05-67868

  However, this technique does not take into consideration the problems associated with a laminated glass substrate in which a plurality of glass substrates are laminated, and is mainly a technique relating to a single-layer glass substrate. Since the glass paste is foamed, the apparent volume is increased after firing and the through hole is filled. As a result, as a matter of course, the glass after firing becomes very porous, and, like the ceramic substrate, there is a problem that it is difficult to ensure airtightness with the porous glass.

  Even when a conductive resin paste containing metal powder is filled as a conductive material in the through hole, glass is an inorganic material, and the resin is an organic material. In addition, in fields where airtightness is required, there is a problem that the reliability is not sufficient, and in the case of solder application, if the hole diameter for the through hole is small, there is a problem that a small amount of application is industrially difficult.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a method for producing a multilayer glass substrate that ensures airtightness even if there are through holes.

In order to solve the conventional problem, in the method for manufacturing a multilayer glass substrate of the present invention, a through hole for connecting the first main surface and the second main surface is formed, and the inner wall surface of the through hole, when sleeping heavy a plurality of glass substrates a conductive film on the surface of the vicinity is formed comprising a through hole opening periphery surface and the second major surface including and neighboring the through-hole opening periphery of the first main surface In the laminated surface, at least a part of the conductive films formed on the surface in the vicinity of the glass substrate including the periphery of the through-hole opening overlap, and at least the first main surface side of the through-hole opening or the second One of the two principal surface sides is blocked by the laminated glass substrate, and is heated and pressed to adhere to each other.

  A plurality of glass substrates in which a conductive film is formed on a surface near the through hole opening of the first main surface and a surface near the through hole opening of the second main surface by the method of the present invention. The conductive film formed on at least the surface including the periphery of the through-hole opening is hermetically bonded to the other glass substrate to be bonded. The multilayer glass substrate in which the opening of the through-hole portion of the glass substrate is hermetically bonded to the other glass substrate to be bonded and the through-hole portion hermeticity is secured can be manufactured.

  As described above, according to the method for manufacturing a glass substrate of the present invention, a through hole for connecting the first main surface and the second main surface is formed, the inner wall surface of the through hole, and the first main surface A plurality of glass substrates having conductive films formed on the surface near the through hole opening of the surface and the surface near the through hole opening of the second main surface are stacked and heated to press each other. By adhering to the glass substrate of the other side to which the conductive film on the surface including at least the periphery of the through-hole opening is adhered, the through-hole is not filled with a conductive material or insulator. A multi-layer glass substrate that secures hermeticity can be produced.

  In the present invention, the single-layer raw glass substrate before being laminated in a plurality of layers may be simply referred to as a glass substrate unless otherwise specified. A glass substrate in a state where a plurality of these layers are laminated is abbreviated as a multilayer glass substrate unless otherwise specified.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a multilayer glass substrate according to an embodiment of the present invention, FIG. 1 (a) is a perspective view of a state before two glass substrates are bonded, and FIG. 1 (b) is a state after bonding. It is a perspective view of a multilayer glass substrate.

  FIG. 2 is a cross-sectional view of the manufacturing process flow of the multilayer glass substrate in one embodiment of the present invention, showing the method for manufacturing the glass substrate shown in FIG. 1B in a cross-sectional view along the line XX ′. It is.

  In FIG. 1, 1a and 1b are glass plates for constituting a glass substrate, 2a and 2b are through holes formed in the glass substrates 1a and 1b, 3a and 3b are through holes 2a and 2b, and glass plates 1a and 1b. It is a conductor film formed on the first main surface 10 and the second main surface 11. Although the conductor film in the through holes 2a and 2b is shown as 3c in FIG. 2, the conductor film in the through holes 2a and 2b is not denoted by reference numeral 3c in FIG. Since the conductor films formed in the through holes 2a and 2b and on the first main surface 10 and the second main surface 11 of the glass plate are a series of continuous bodies, they may be collectively referred to as a conductor film 3 for convenience of explanation. However, reference numeral 3 is not attached in the drawing. As described above, the conductor film 3 is formed in the through hole, in the vicinity of the first main surface including the periphery of the through hole opening, and in the vicinity of the second main surface including the periphery of the through hole opening. .

  In FIG. 2 (c), reference numeral 4 denotes a crimping die used when the glass substrates 1a and 1b are heated and pressed to adhere to each other.

  The manufacturing process will be described below.

  Through holes 2 (2a, 2b) are formed on glass substrates 1a, 1b made of borosilicate glass or the like by dry blasting using fine granular media such as alumina or silicon carbide, or etching (FIG. 2A). reference).

  Vacuum is applied to the inner wall 5 of the through holes 2a and 2b of the glass substrates 1a and 1b and the surfaces of the first main surface 10 and the second main surface 11 of the glass substrates 1a and 1b in the vicinity of the through holes 2a and 2b around the openings 6b. A conductor film 3 made of 3a, 3b, 3c is formed by vapor deposition or sputtering (see FIG. 2B). The conductor films 3a and 3b are formed in a pattern corresponding to a required wiring pattern. For the formation of the wiring pattern, a photoresist method or other appropriate wiring pattern forming methods can be employed. Here, for convenience of explanation, a conductor film that is a series of conductor films 3a, 3b, and 3c is collectively expressed as 3, but the reference numeral 3 is omitted in FIG.

  At this time, the adhesiveness at the time of thermocompression bonding between the conductive films 3a, 3b and the glass substrates 1a, 1b formed on the second main surface 11 of each glass substrate 1a to be bonded and the first main surface 10 of the glass substrate 1b. Therefore, titanium or copper is desirable as a material for the conductor film.

  The glass substrates 1a and 1b thus obtained are pressed using a pressure die 4 while being heated to a temperature that is preferably higher than the annealing point of the glass and lower than the softening point (see FIG. 2C).

  In this case, normally, the conductor film 3a of the glass substrate 1b adheres to the second main surface 11 of the glass substrate 1a, and the conductor film 3b of the glass substrate 1a adheres to the first main surface 10 of the glass substrate 1b. In the portion where the conductor film 3b on the second main surface 11 of the glass substrate 1a and the conductor film 3a on the first main surface 10 of the glass substrate 1b overlap, the conductor film 3b and the conductor film 3a come into contact with each other and are conducted. The conductor films in which the conductor film 3b and the conductor film 3a are in contact with each other are collectively shown as a conductor film 3a + b. (See FIG. 2 (d)).

  This is because, as described above, the second main surface 11 of the glass substrate 1a and the conductor film 3a on the first main surface 10 of the glass substrate 1b are formed between the first main surface 10 of the glass substrate 1b and the glass substrate 1a. Since the conductor film 3b on the second main surface 11 is bonded by thermocompression bonding, the overlapping portion of the conductor film 3a and the conductor film 3b comes into contact with each other so that the conductor film 3a + b is conductive. Thus, the conductive connection between the glass substrates 1a and 1b is enabled.

  Mainly, the conductor film formed on one glass substrate and the surface of the other glass substrate facing each other are bonded by heating and pressing because the conductor film is more thermally conductive than the glass material. It is considered that the heat of the crimping die 4 is easily conducted through the conductor film. By this heat and pressure bonding, it adheres closely to the surface of the other glass substrate facing the conductor film on the surface near the through hole opening of one glass substrate, so it adheres from the through hole opening. The gas flow path to the surface is blocked, and the airtightness of the multilayer substrate is maintained.

Here, the airtightness means a state in which a leak rate of 1 × 10 ⁻⁹ Pa · m ³ / sec or less is maintained with an airtight leak measuring machine using helium as a tracer gas.

  The airtightness was measured using “Helium leak detector manufactured by ULVAC, Inc.” according to JISZ2331 “Helium leak test method (vacuum spraying method)”.

  According to the above method, the air-tightness between the through-holes 2a and 2b can be maintained by the heat and pressure adhesion, and at the same time, the conductor film 3a + b in which at least a part of the conductor films 3a and 3b are in contact with each other is configured to lead. Electrical continuity between the glass substrates can be secured at the same time without using a terminal or the like.

  Further, instead of using a glass plate of a predetermined individual size, a glass plate having a larger plane area is used, a number of through holes are formed in the glass plate, and a conductor film is formed and heated in the same manner as in the above embodiment. Then, it is possible to obtain a large number of multilayer glass substrates at a time by cutting into pieces of a predetermined size after clamping.

  Moreover, although the embodiment described with reference to FIGS. 1 and 2 has been described by showing an example in which two glass substrates are bonded, a multi-layer glass substrate composed of three or more glass substrates is made in the same manner. It can also be manufactured.

  The glass material used for the glass substrate is not particularly limited as long as it is an electrically insulating glass, but various glasses used for the glass substrate such as borosilicate glass and soda lime glass are preferably used. . Borosilicate glass is one of the particularly preferred glasses.

There is no particular limitation on the size of the glass substrate. Particularly in recent years, in fields where miniaturization is required, for example, a thickness of about 0.1 to 3 mm, more preferably about 0.1 to 0.3 mm is preferably used. Although the plane area of the glass substrate is not particularly limited, for example, a glass substrate having a size of 0.1 to 40 mm ² is used depending on the application. As described above, a conductive film is formed on a glass plate in which a large number of through-holes are formed as in the above-described embodiment, and after pressing while heating, it is cut into individual pieces, thereby producing a large amount at a time. It is also possible to obtain individual multilayer glass substrates.

  The diameter of the through-hole penetrating in the thickness direction of the glass substrate (meaning the smaller diameter of the through-hole diameter of the first main surface and the second main surface) is not particularly limited. Is preferably used in a range of preferably 0.01 to 1.5 mm, more preferably about 0.1 to 0.5 mm.

  As a method for forming the through hole, a dry blast method (sand blast method) or an etching method is suitable. In particular, dry blasting is preferable, and fine granular media used in the dry blasting method include fine granular media such as alumina and silicon carbide, but are not limited thereto. By performing dry blasting or etching from one main surface side of the glass substrate, for example, through holes are formed from the first main surface side toward the second main surface of the glass substrate by dry blasting or etching from the first main surface side. Assuming that it is formed, the opening of the through hole on the first main surface tends to be large, and the opening of the through hole on the second main surface tends to be smaller than the opening of the through hole on the first main surface. It is estimated that the contact time with the dry blast medium or the etching medium decreases from the first main surface toward the second main surface. In addition, it is estimated that the spraying power (polishing power) of the dry blast medium is stronger toward the first main surface side and decreases toward the second main surface side.

  Therefore, although it is not certain, in the above case, the diameter of the through hole tends to decrease toward the second main surface because the diameter increases toward the first main surface. It is presumed that the taper narrows from the side toward the second main surface side in a substantially tapered shape.

  The angle of the taper is not particularly limited, but is preferably about 5 to 20 degrees in terms of an angle with a perpendicular drawn in the thickness direction with respect to the glass substrate plane. The taper angle is a value estimated by calculation from the thickness of the glass substrate used, the diameter of the through hole opening on the first main surface side, and the diameter of the through hole opening on the second main surface side.

  From the above situation, when the conductor films 3a, 3b, and 3c are formed by vacuum deposition or sputtering, it is presumed that the conductor film 3c is likely to be formed on the inner wall of the through hole by vacuum deposition or sputtering.

  As described above, the conductor films 3a, 3b, 3c are formed by vacuum deposition or sputtering around the through-hole opening 6 around the inner wall of the through-hole and the first main surface and the second main surface of the glass substrate. As the material for the film, titanium or copper is preferably used because of its good adhesion to glass in the heating and pressing step of the present invention.

In particular, when a through-hole having a small diameter as described above is employed due to a demand for miniaturization, it is an industrially advantageous method to form a conductor film by vacuum deposition or sputtering. Although the film thickness of a conductor film is not specifically limited, About 0.05 micrometer-0.1 micrometer are preferable.
The atmosphere in the heating and pressurizing step is preferably an inert gas atmosphere such as a nitrogen gas atmosphere or a vacuum atmosphere.

  The heating temperature is preferably higher than the annealing point of the glass and lower than the softening point. If the heating temperature is too high, deformation tends to occur, and if the heating temperature is too low, the adhesiveness tends to decrease and the airtightness tends to decrease. As a more specific heating temperature, since it varies considerably depending on the type of glass used and the pressure in the heating and pressurizing step, it is difficult to define it generally, but a range of 300 to 700 ° C. is preferable.

  The annealing point of glass (also referred to as annealing temperature) is the temperature at which the internal strain of glass is substantially removed in 15 minutes (see JIS R 3103), and the softening point (also referred to as softening temperature) is also JIS. Softening point based on R 3103. In addition, the annealing point and softening point of the said glass mean the annealing point and softening point under a normal pressure.

The applied pressure in the heating and pressurizing step is difficult to specify because it varies depending on the type of glass to be used and the heating temperature, but a pressure that is 1 × 10 ⁶ Pa or higher and can be bonded by the heating temperature may be appropriately selected. More specifically, a range of 1 × 10 ⁷ Pa to 1 × 10 ⁹ Pa is preferable.

  Dry blasting using alumina particulate media on glass substrates 1a and 1b having a flat surface area of 1.6 mm × 10 mm and a thickness of 0.2 mm made of borosilicate glass having an annealing point of 557 ° C. and a softening point of 736 ° C. A through hole 2 having a diameter of 0.15 mm and a taper angle of the through hole of about 5 degrees was formed by the method with respect to a perpendicular line lowered in the thickness direction with respect to the glass substrate plane (see FIG. 2A).

The through-holes 2a and 2b inner walls 5 of the glass substrates 1a and 1b, and the openings around the through-holes 2a and 2b of the first main surface and the second main surface of the glass substrates 1a and 1b (here, the area is 0.1 mm ^2). 6) Titanium conductor films 3a and 3b having a thickness of about 0.1 μm (thickness on the main surface around the through-hole opening) were formed by sputtering (see FIG. 2B).
The glass substrates 1a and 1b were clamped at a pressure of 1 × 10 ⁸ Pa while being heated to about 610 ° C. in a nitrogen gas atmosphere using a crimping die (Sumitomo Heavy Industries, Ltd. glass mold molding machine) (FIG. 2). (See (c)).

  A multilayer glass substrate is formed by thermocompression bonding of the glass substrates 1a, 1b and the conductor films 3a, 3b on the bonding surfaces thereof, and the conductor films 3a + b are bonded together including the portion where the conductor films 3a, 3b overlap on the bonding surfaces. A multilayer glass substrate having a surface was formed (see FIG. 2D).

  The conductive film (3a, 3b, 3c, 3a + b) formed on the glass substrates 1a and 1b was confirmed to be conductive when the conductive connection between the glass substrates 1a and 1b was tested with a digital multimeter.

Further, according to JISZ2331, when the airtightness was tested with an airtight leak measuring machine using helium as a tracer gas (“Helium leak detector” manufactured by ULVAC, Inc.), the amount of leakage between the front and back of the obtained multilayer glass substrate was 1 ×. 10 ⁻⁹ Pa · m ³ / sec or less.

  The method for producing a multilayer glass substrate of the present invention is applied to electronic components that require airtightness, such as crystal components, SAW filters, acceleration sensors for automobile airbags, and various other pressure sensors for automobiles. It is suitable as a method for producing a multilayer glass substrate, and is useful for a substrate for mounting various electronic components. In particular, it is suitable as a method for producing a multilayer glass substrate for use in electronic components that require miniaturization and require airtightness.

The perspective view of the multilayer glass substrate in one embodiment of this invention Manufacturing process flow sectional view of a multilayer glass substrate in an embodiment of the present invention Sectional drawing which shows the manufacturing process flow of the conventional glass substrate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Glass substrate 1b Glass substrate 2a Through hole 2b Through hole 3a Conductor film 3b Conductor film 3c Conductor film 3a + b Conductor film having the overlapping part of the conductor films 3a and 3b 4 Crimping die 5 Inner wall 6 Opening periphery 101 Glass substrate 102 Through-hole 103 Conductor film 103a Through-hole conductor 103b Through-hole land 104 Filler

Claims (8)

A through hole for connecting the first main surface and the second main surface is formed, an inner wall surface of the through hole, a surface in the vicinity including the periphery of the through hole opening of the first main surface, and the second main surface a plurality of glass substrates conductive film formed on a surface including and neighboring the through-hole opening surrounding surface when sleeping heavy, in the lamination plane, formed on a surface including and neighboring the through-hole opening periphery of the glass substrate The conductive films formed are overlapped at least partially, and at least one of the first main surface side or the second main surface side of the through-hole opening is cut off by the glass substrate and heated and pressed. And a method for producing a multilayer glass substrate, wherein the substrates are bonded to each other. The method for producing a multilayer glass substrate according to claim 1, wherein the heating temperature of the glass substrate is higher than the annealing point of the glass and lower than the softening point. 3. The method for producing a multilayer glass substrate according to claim 1, wherein the pressure of the glass substrate is 1 × 10 ⁶ to 1 × 10 ⁹ Pa. 4. Conductive film, a method for manufacturing a multilayer glass substrate according to claim 1, characterized in that a conductive film selected from titanium or copper. The thickness of a glass substrate is 0.1-3 mm, The manufacturing method of the multilayer glass substrate in any one of Claims 1-4 characterized by the above-mentioned. The method for producing a multilayer glass substrate according to claim 1 , wherein the glass substrate has a plane area of 0.1 to 40 mm ² . Method for manufacturing a multilayer glass substrate according to any one of claims 1 to 6, the diameter of the through hole is characterized 0.01~1.5mm der Rukoto. Atmosphere pressure of the glass substrate, an inert gas atmosphere, or a method for manufacturing a multilayer glass substrate according to any one of claims 1 to 7, wherein the vacuum atmosphere der Rukoto.

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