JPH109431A - Magnetically driven valve and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a microminiature magnetically driven valve manufactured by using silicon as a base material and by using chemical etching, and a method of manufacturing the same. SOLUTION: As a magnetically driven valve, an opening is formed in a silicon wafer, and a movable portion for closing the opening is formed integrally with the silicon wafer, and an intermediate bonding material is attached to the movable portion. A ferromagnetic wafer is fixed via the ferromagnetic wafer, and the ferromagnetic wafer is suctioned and released by application of a magnetic field to open and close the opening, and a method of manufacturing the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetically driven valve for controlling a flow rate of a gas or a liquid and a method for manufacturing the same, and more particularly, to a microminiaturely magnetically driven valve manufactured by using silicon as a base material and performing chemical etching. And its manufacturing method.

[0002]

2. Description of the Related Art As a conventional first magnetically driven microvalve, a magnetic thin film of nickel or the like is grown on a valve made of silicon crystal by sputtering or plating, and this magnetic thin film is driven by an external magnetic field. .

[0003] Specifically, for example, B. Lochel, A. Macioss
ek, HJQuenzer, B. Wagner, G. Engelmann "Magnetically
driven microstructurs fabricated with multilayer e
lectroplating "Sensors and Actuators A, 46-47 (1995)
It is disclosed in magazines such as pp. 98-103.

[0004] As a second conventional magnetically driven microvalve, there is a type in which a magnetic material cut into small pieces is individually bonded to a valve made of silicon crystal, and this magnetic material is driven by an external magnetic field.

Specifically, for example, B. Wagner, W. Beneck
e, G. Engelmann, J. Simon "Microstructurs with moving
magnets for linear, torsional or multiaxial motion "
Sensors and Actuators A, 32 (1992) pp.598-603.

[0006]

However, in the case of the above-mentioned first conventional magnetically driven microvalve,
Since there is no individual chip process and the manufacturing can be performed only by the process of a silicon wafer unit, there is an advantage that the number of steps can be reduced and the manufacturing can be performed at low cost. However, the thickness of the magnetic film can only be increased to about 0.1 mm at most.

[0007] The magnetic force is proportional to the volume of the magnetic substance in the magnetic field. However, since the volume of the magnetic substance cannot be increased, for example, when an external magnetic circuit is arranged to concentrate the magnetic flux on the thin film, the magnetic flux density is immediately increased. Is saturated, and it cannot be expected that a large magnetic force is eventually obtained.

Next, in the case of the conventional second magnetically driven microvalve, it is possible to increase the volume of the magnetic material, but it is necessary to bond extremely small parts one by one. There is a problem that it takes much time and costs.

[0009]

According to the present invention, as a main structure for solving the above problems, as a magnetically driven valve, an opening is formed in a silicon wafer and a movable valve for closing the opening is provided. The part is formed integrally with the silicon wafer, and the ferromagnetic wafer is fixed to the movable part via an intermediate bonding material. The ferromagnetic wafer is suctioned and released by applying a magnetic field to open the opening. The part is opened and closed.

A method of manufacturing a magnetically driven valve includes a first step of forming an opening in a silicon wafer and forming a plurality of movable parts for closing the opening integrally with the silicon wafer. A second step of bonding the first movable part to the entire ferromagnetic wafer via the intermediate bonding material, and a third step of integrally dicing each of the previously bonded wafers by using each of the movable parts as a unit. Thereafter, a fourth step of applying a magnetic force to the ferromagnetic wafer is provided.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a longitudinal section of one embodiment of the present invention. Reference numeral 10 denotes a non-magnetic case, in which a drive coil 11 is fixed.

The case 10 has a rectangular shape, and an inlet 10A through which fluid flows in the upper center and an outlet 10B through which the fluid flows out are formed in the lower center, so as to cover the outlet 10B. Is fixed to the valve element 12.

The valve element 12 is provided on the silicon wafer 1
3. Consisting of a glass member 14 made of Pyrex glass functioning as an intermediate bonding material, and a ferromagnetic wafer 15 made of a Kovar alloy, and a plane viewed from above the silicon wafer 13, that is, from the glass member 14 side. The figure is as shown in FIG.

First, the configuration of the silicon wafer 13 will be described. The outer diameter of the silicon wafer 13 is formed in a rectangular shape.
The opening is formed such that the opening area gradually decreases toward the upper end from 3A.

On the other hand, a rectangular slit-shaped space 13B is formed in the silicon wafer 13, and the upper portion of the space 13B is slightly protruded at the center as shown in FIG. The movable portion 13C is formed as

The beams 13D to 13G are extended in the form of a bridge around the movable portion 13C, and four open portions 13H to 13K communicating with the space 13B are formed on the upper surface.

Further, the space 1 extending from the opening 13A
The rectangular opening 13L of the portion communicating with 3B is selected to have a size that can be completely closed by pressing the rectangular movable portion 13C. The beams 13D to 13G have a spring property based on physical properties, and the opening 13L is normally closed by the movable portion 13C.

The above structure can be manufactured by using photolithography and chemical etching techniques, which are general semiconductor processes. The silicon wafer 13 thus produced is bonded to the ferromagnetic wafer 15 via the glass member 14 by anodic bonding,
It is formed as a valve element 12.

The valve element 12 has an opening 13A.
Is fixed so as to coincide with the outlet 10B, and the case 10 is inserted so that the ferromagnetic wafer 15 enters the drive coil 11.
, The magnetic drive valve 16 is configured.

Next, the operation of the magnetically driven valve 16 configured as described above will be described with reference to FIG. When no current flows through the drive coil 11, the movable portion 13C
Closes the opening 13L so that the fluid does not flow.

However, when a current flows through the drive coil 11, a magnetic field is generated, and the ferromagnetic wafer 15 is attracted by a magnetic force proportional to the gradient of the square of the magnetic field strength and pulled up in the direction of the arrow. The portion 13C is lifted upward, and the opening 13L is opened.

As a result, the fluid flows in from the inlet 10A, passes between the drive coil 11 and the ferromagnetic wafer 15, passes through the openings 13H to 13K as indicated by arrows, and flows to the outlet 10B. As can be seen from the above operation, the magnetically driven valve 16 operates as a normally closed valve.

Next, a method of manufacturing the above-described magnetically driven valve will be described with reference to FIGS. FIG. 4 shows a wafer state before the valve element 12 shown in FIG. 1 is cut out and manufactured.

A magnetic wafer 18 such as a Kovar alloy having components such as iron, nickel and cobalt is bonded on the silicon wafer 17. In the case of the anodic bonding method, the magnetic wafer 18 is directly bonded to the silicon wafer 17. The body wafer 18 cannot be joined.

Therefore, anodic bonding is performed between the silicon wafer 17 and the magnetic wafer 18 via glass having a linear expansion coefficient close to these, such as Pyrex glass 19.
In the anodic bonding, first, the silicon wafer 17 and the Pyrex glass 19 are anodically bonded, and then the Kovar alloy is anodically bonded to the Pyrex glass 19.

The anodic bonding is performed at a high temperature of about 400 ° C.
Although a voltage of about 600 V to 1000 V is applied to join the glass and the conductor, the silicon-pyrex glass-kovar alloy has almost the same coefficient of linear expansion as each other. Does not occur.

In this manner, a three-layer wafer in which the silicon wafer 17, the magnetic wafer 18, and the Pyrex glass 19 functioning as an intermediate bonding material are bonded in a three-layer state can be integrally formed. Are composed of a plurality of valve elements, which are connected to the lines X _{1 to} X ₂ and the line X _{1
3 to} X ₄ , lines Y _{1 to} Y ₂ , and lines Y _{3 to} Y ₄ are cut out.

These lines X ₁ -X ₂ , lines X ₃ -X ₄ , line Y ₁
To Y _2, excised one element only (A portion) dicing surrounded by a line Y ₃ to Y _4, that have been enlarged it is shown as a longitudinal sectional view in FIG.

In FIG. 5, openings 17A 'and 17L', spaces 17B 'and movable portions 17C' are previously formed on a silicon wafer 17 'cut out from the silicon wafer 17 by using photolithography and chemical etching techniques.
Are manufactured similarly to those shown in FIGS.

The size of the silicon wafer 17 'shown in FIG.
′ Has a thickness of 0.5 mm and the magnetic wafer 18 ′ has a thickness of 1 mm.
mm.

As described above, the valve element can be manufactured by adding a large magnetic material without cutting a plurality of valve elements from each part of the silicon wafer 17 and performing machining on a chip basis.

FIGS. 6 and 7 are longitudinal sectional views showing a modified embodiment of the magnetic circuit for driving the valve element shown in FIG. FIG. 6 is a longitudinal sectional view of a magnetically driven valve in which a magnetic wafer is incorporated as a part of an external magnetic circuit to improve the driving force.

The valve element in this case is the same as the valve element 12 shown in FIG.
Numeral 5 is inserted into a part of the open portion of the yoke 20 made of a 磁性 -shaped magnetic body, and is incorporated in the case 21 as a whole.

In this case, unlike the case 10 in FIG. 1, the fluid inlet 21A is formed on the same plane as the outlet 21B corresponding to the fluid outlet 10B.

By supplying a current to the drive coil 22 in this case, it is possible to obtain nearly 100 times the magnetic force with the same power consumption as compared with the case of driving with only the single drive coil 11 shown in FIG.

FIG. 7 is similar to FIG. 6 in that a magnetic wafer is incorporated as a part of an external magnetic circuit to improve the driving force, but the magnetically driven valve has a different configuration of the external magnetic circuit. FIG.

The external magnetic circuit in this case uses a C-shaped core as the magnetic yoke 23, and arranges the magnetic wafer 15 of the valve element 12 along the outside of the open surface of the C-shaped core. Configuration.

A drive coil 24 is wound on the opposite side of the open surface, and when a current flows through the drive coil 24, a magnetic field is generated at the open portion of the core. generate.

In the magnetically driven valve shown in FIG. 7, when the thickness of the magnetic wafer 15 is changed and calculated by magnetic simulation using the finite element method, when the thickness is 1 mm, the magnetic flux density of the magnetic body is about 0.6T. However, it was found that when the thickness was 0.1 mm, the thickness reached 5T.

In general metal magnetic materials, the saturation of magnetic flux density occurs at about 1T. Therefore, in a conventional magnetic thin film, even if the magnetic flux is concentrated by the magnetic yoke, it cannot be used effectively. When the magnetic flux is concentrated by such a configuration, the magnetic force can be effectively used. Note that a similar effect is obtained in the case of the configuration shown in FIG.

In the above description, the anodic bonding was used to bond the magnetic wafer 15 to the silicon wafer 17 constituting the valve element 12. However, for example, the magnetic wafer 15 'shown in FIG. It is also possible to perform dicing after directly bonding a magnetic wafer 18 ′ such as a metal or a magnetic ceramic using an adhesive functioning as an intermediate bonding material. In this case, the labor of bonding is 1
There is a merit to be able to turn around.

[0042]

As described above, according to the first aspect of the present invention, a ferromagnetic wafer can be joined with a thick magnetic material of about 1 mm as described above. Since it is possible, a large driving force can be obtained, and a fluid with a higher pressure and a large flow rate can be controlled at a higher speed as compared with a conventional case using a magnetic thin film that can realize only a thickness of about 0.1 mm at most. .

According to the second aspect of the present invention, since the ferromagnetic wafer having a large thickness is formed as a part of the external magnetic circuit, the magnetic flux can be concentrated, and the magnetic flux can be concentrated. However, there is an advantage that magnetic saturation can be easily avoided and a strong magnetic force can be obtained.

Further, according to the third aspect of the present invention, since the bonding of the magnetic material wafer is performed in units of a wafer including a plurality of valve elements, the conventional method of manufacturing a valve by individually bonding magnetic materials. As compared with the manufacturing method, there is an advantage that the number of steps and cost required for joining can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a plan view of the silicon wafer side from the glass member side shown in FIG.

FIG. 3 is an operation explanatory diagram for explaining the operation of the embodiment shown in FIG. 1;

FIG. 4 is a perspective view showing a configuration for manufacturing the valve element shown in FIG.

FIG. 5 is an enlarged view in which a part in FIG. 4 is enlarged.

FIG. 6 is a longitudinal sectional view showing a first modified embodiment different from the embodiment shown in FIG. 1;

FIG. 7 is a longitudinal sectional view showing a second modified embodiment different from the embodiment shown in FIG.

[Explanation of symbols]

 10, 21 Case 11, 22, 24 Drive coil 12 Valve element 13 Silicon wafer 14 Glass member 15 Ferromagnetic wafer 16 Magnetic drive valve 17 Silicon wafer 18 Magnetic wafer 19 Pyrex glass 20, 23 Yoke

Claims (3)

[Claims] An opening is formed in a silicon wafer, and a movable portion for closing the opening is formed integrally with the silicon wafer, and a ferromagnetic wafer is provided on the movable portion via an intermediate bonding material. A magnetically driven valve which is fixed and which opens and closes the opening by sucking and releasing the ferromagnetic wafer by applying a magnetic field. 2. The magnetically driven valve according to claim 1, wherein said ferromagnetic wafer is formed as a part of an external magnetic circuit. 3. A first step of forming an opening in a silicon wafer and integrally forming a plurality of movable parts for closing the opening with the silicon wafer, and connecting the plurality of movable parts with an intermediate bonding material. A second step of bonding the ferromagnetic wafers as a whole, a third step of integrally dicing each of the wafers bonded to each of the movable parts as a unit, and thereafter applying a magnetic force to the ferromagnetic wafer. A method for manufacturing a magnetically driven valve, comprising: a fourth step of applying.