Load sensor and method of manufacturing the load sensor, paste used for the method, and method of manufacturing the paste

• US 20050085393A1
• Filed: 08/07/2003
• Published: 04/21/2005
• Est. Priority Date: 08/07/2002
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakao, Keiichi, Ishida, Hiroaki, Mizukami, Yukio, Katsumata, Masaaki
• Granted Patent: US 7,164,342 B2
• Time in Patent Office: Days
• US Class Current: 505/100
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015
• CPC Class Codes: G01L 1/2287 constructional details of the strain gauges adjustable resistors H01C10/00
• CPC Class Codes: H01C 17/06533 composed of oxides

Abstract

The present invention relates to a load sensor and provides a highly accurate load sensor with multi-layered wiring at low costs. It provides crystallized glass and non-crystalline glass which are best for a load sensor, and combines these to form multi-layered wiring, and further, makes a glass layer of composite type as needed, and reduces uneven printing in printing multiple layers with use of hardening type paste.

Claims

1. A load sensor wherein a crystalline glass layer is formed by 10 to 200 μ

m in thickness on an elastic metal body;

a non-crystalline glass layer is formed by 5 to 100 μ

m in thickness on said crystalline glass layer;

silver wiring and strain sensitive resistor are formed by 5 to 50 μ

m in thickness each on said non-crystalline glass layer in such manner as to partially overlap each other;

said elastic metal body is connected to a part of said silver wiring via holes formed in said crystalline glass layer and said non-crystalline glass layer; and

a protective layer of 200 μ

m or less in thickness is formed so as to cover at least said strain sensitive resistor.

3. The load sensor of any one of claims 1 and 2, wherein crystalline glass is composite glass prepared by simultaneous burning of crystallized glass powder and ceramic powder, and the ratio by weight of crystallized glass to ceramic powder ranges from 95:

5 to 60;

40.

4. The load sensor of any one of claims 1 and 2, wherein non-crystalline glass is composite glass prepared by simultaneous burning of non-crystalline glass powder and ceramic powder, and the ratio by weight of non-crystalline glass to ceramic powder ranges from 95:

5 to 60;

40.

5. The load sensor of any one of claims 1 and 2, wherein crystalline glass is composite glass prepared by simultaneous sintering of crystallized glass powder and non-crystalline glass, and the ratio by weight of crystallized glass to non-crystalline glass ranges from 95:

5 to 50;

50.

6. The load sensor of any one of claims 1 and 2, wherein non-crystalline glass is composite glass prepared by simultaneous sintering of crystallized glass powder, non-crystalline glass and ceramic powder, and the ratio by weight of non-crystalline glass to crystalline glass ranges from 95:

5 to 50;

50.

7. The load sensor of any one of claims 1 and 2, wherein non-crystalline glass contains 40 to 80 wt % of SiO₂, 5 to 15 wt % of CaO, 3 to 15 wt % of PbO, 1 to 10 wt % of alumina, and 2 to 10 wt % of ZrO₂.

8. The load sensor of any one of claims 1 and 2, wherein crystalline contains 30 to 55 wt % of MgO, 5 to 30 wt % of B₂O₃, 10 to 25 wt % of SiO₂, 5 to 25 wt % of BaO, 1 to 30 wt % of alumina, 0 to 6 wt % of CaO, and 0 to 5 wt % of ZrO₂, SnO₂.

9. The load sensor of any one of claims 1 and 2, wherein ceramic powder is at least one of alumina, magnesia, zirconia, silica, calcium oxide, titanium oxide, and spinel, and its average grain diameter is 0.01 to 5 μ

m.

10. The load sensor of any one of claims 1 and 2, wherein strain sensitive resistor contains at least 10 to 30 wt % of PbO, 10 to 60 wt % of SiO₂, and 0 to 30 wt % of ruthenium compound.

11. The load sensor of any one of claims 1 to 10, wherein three layers of at least elastic metal body, crystallized glass layer, and non-crystalline glass layer commonly contain 1 wt % or over of alumina.

12. The load sensor of any one of claims 1 to 10, wherein three layers of at least crystallized glass layer, non-crystalline glass layer, and strain sensitive resistor commonly contain 1 wt % or over of alumina.

13. The load sensor of any one of claims 1 to 10, wherein at least internal electrode is based on silver and contains 1 to 10 wt % of Bi₂O₃, and 0.5 to 5 wt % of SiO₂ or CaO.

14. The load sensor of any one of claims 1 to 10, wherein at least wiring is based on silver and contains 5 to 30 wt % of Pd, 1 to 20 wt % of Bi₂O₃, and 0.5 to 4 wt % of SiO₂ or CuO.

15. The load sensor of any one of claims 1 to 10, wherein a plurality of independent wiring patterns are partially electrically connected to each other via internal electrode through a plurality of via-holes formed in the crystallized glass layer and the non-crystalline glass layer.

16. The load sensor of any one of claims 1 to 10, wherein an overcoat glass layer containing 60 wt % to 95 wt % of lead oxide is formed 10 μ

m to 200 μ

m thick in one layer at least on the strain sensitive resistor.

17. The load sensor of any one of claims 1 to 10, wherein an overcoat resin layer containing 5 wt % to 50 wt % of ceramic powder is formed 10 μ

m to 200 μ

m thick in two layers at least on the strain sensitive resistor.

18. The load sensor of any one of claims 1 to 10, wherein a first overcoat layer formed from glass or ceramic which is 10 μ

m to 200 μ

m in thickness and a second overcoat layer based on resin which is 10 μ

m to 200 μ

m in thickness are formed in a plurality of layers on the strain sensitive resistor.

19. The load sensor of any one of claims 1 to 10, wherein the thermal expansion coefficient of crystallized glass is 8 ppm/°

C. to 14 ppm/°

C. or the difference in thermal expansion coefficient from elastic metal body is less than 3 ppm/°

C., and the crystallinity is 20% or over.

20. The load sensor of any one of claims 1 to 10, wherein crystallized glass and ceramic powder which form composite glass vary in composition ratio with the direction of thickness of the composite glass layer, and the composite glass layer varies in thermal expansion coefficient in a range up to 2 ppm/°

C. max in the direction of thickness.

21. The load sensor of any one of claims 1 to 10, wherein wiring at least partially connected to the strain sensitive resistor contains at least 60 wt % to 90 wt % of Ag, and 5 wt % to 30 wt % of Bi₂O₃.

22. The load sensor of any one of claims 1 to 10, wherein an electrode containing at least 60 wt % to 90 wt % of Ag and 5 wt % to 30 wt % of BiO₂ is built into the composite glass layer.

2. A load sensor wherein a crystalline glass layer is formed by 10 to 200 μ

m in thickness on each side of an elastic metal body while an internal electrode of less than 50 μ

m in thickness is buried therein;

a non-crystalline glass layer is formed by 5 to 100 μ

m in thickness on said crystalline glass layer;

silver wiring and strain sensitive resistor are formed by 5 to 50 μ

m in thickness each on said non-crystalline glass layer;

said internal electrode is connected to a part of said wiring via holes formed in said crystalline glass layer and said non-crystalline glass layer; and

a protective layer of 200 μ

m or less in thickness is formed so as to cover at least said strain sensitive resistor.

23. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste on an elastic metal body by 10 to 300 μ

m in is thickness;

burning together at 800 to 900°

C.;

printing non-crystalline glass paste by 10 to 300 μ

m in thickness and burning at 800 to 900°

C.;

printing wiring and strain sensitive resistor and individually burning at 800 to 900°

C.;

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

34. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein all burning at 400°

C. or over is executed in an oxidation atmosphere.

35. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein the softening point of at least non-crystalline glass is 50⁰°

C. or over, and the working temperature ranges from 700 to 900°

C.

36. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein at least one of glass paste and electrode paste is hardened or insolubilized by light, UV, EB or heat after printing.

37. The method of manufacturing a strain sensor of any one of claims 23 to 33, wherein the thickness of glass paste after hardening or in solubilizing is 12 to 300 μ

m, and the thickness of glass layer after burning is 10 to 200 μ

m.

38. The method of manufacturing a strain sensor of any one of claims 23 to 33, wherein glass paste is repeatedly hardened or insolubilized by a plurality of times to be formed in multiple layers.

39. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein a plurality of glass pastes different in blending ratio of glass powder and ceramic powder are formed in multiple layers, followed by simultaneous burning.

40. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein glass paste is formed from at least glass powder of 0.1 μ

m to 10 μ

m in average grain diameter and ceramic powder of 0.05 μ

m to 5 μ

m in average grain diameter, at the weight ratio of glass powder to ceramic powder is in a range from 95;

5 to 60;

40.

41. The method of manufacturing a load sensor of any one of claims 23 to 33, wherein the paste contains at least 1 wt % to 20 wt % of resin that is soluble in organic solvent.

42. The glass paste of any one of claims 23 to ˜

41, wherein the glass composition of non-crystalline glass paste includes 60 to 80 wt % of SiO₂, 5 to 5 wt % of CaO, 3 to 15 wt % of PbO, 1 to 10 wt % of alumina, and 2 to 10 wt % of ZrO₂, and its average grain diameter is 0.1 to 5 μ

m;

the concentration of glass in the paste is 60 to 80 wt %, which is dispersed in the vehicle of solvent and resin.

43. The glass paste of any one of claims 23 to 41, wherein the glass composition of crystalline glass paste includes 30 to 55 wt % of MgO, 5 to 30 wt % of B₂O₃, 10 to 25 wt % of SiO₂, 5 to 25 wt % of BaO, 1 to 30 wt % of alumina, 0 to 6 wt % of CaO, and 0 to 5 wt % of ZrO₂, SnO₂, and its average grain diameter is 0.1 to 5 μ

m;

the concentration of glass in the paste is 60 to 80 wt %, which is dispersed in the vehicle of solvent and resin.

44. The glass paste of any one of claims 23 to 41, wherein the paste includes 1 to 20 wt % of resin, 10 to 40 wt % of solvent, and its viscosity is 10 to 1000 poise;

and the concentration of glass in the paste is 60 to 80 wt %.

45. The paste of any one of claims 23 to 41, wherein the paste includes 60 to 80 wt % of glass powder whose average grain diameter is 0.1 to 5 μ

m, 1 to 20 wt % of resin with hardening property or insolubility, 10 to 40 wt % of solvent whose boiling point is 150°

C. or over; and

its viscosity is 10 to 1000 poise, and 5 to 100 wt % of the resin is hardening type resin.

46. The paste of any one of claims 23 to 41, wherein the paste includes 5 to 40 wt % of ceramic powder whose grain diameter is 0.01 to 5 μ

m, 40 to 80 wt % of glass powder whose average grain diameter is 0.1 to 5 μ

m, 1 to 20 wt % of resin with hardening property or insolubility, 10 to 40 wt % of solvent whose boiling point is 150°

C. or over; and

its viscosity is 10 to 1000 poise, and 5 to 100 wt % of the resin is hardening type resin.

47. The paste of any one of claims 23 to 41, wherein the paste includes 60 to 80 wt % of metallic powder whose grain diameter is 0.1 to 10 μ

m, 1 to 20 wt % of resin, 10 to 40 wt % of solvent whose boiling point is 150°

C. or over; and

its viscosity is 10 to 10000 poise, and 5 to 100 wt % of the resin is hardening type resin.

48. The paste of any one of claims 23 to 41, wherein the paste includes 60 to 80 wt % of metallic powder whose grain diameter is 0.1 to 10 μ

m, 1 to 10 wt % of glass powder or ceramic powder, 1 to 20 wt % of resin, 10 to 40 wt % of solvent whose boiling point is 150°

C. or over; and

its viscosity is 10 to 10000 poise, and 5 to 100 wt % of the resin is hardening type resin.

49. The paste of any one of claims 23 to 41, wherein the resin is at least one of phenol resin and epoxy resin.

50. The paste of any one of claims 23 to 41, wherein the resin is hardened or insolubilized at 100°

C. for 30 sec. or over or at 400°

C. for 30 min. or less.

51. The paste of any one of claims 23 to 41, wherein the resin is hardened or insolubilized by UV (ultraviolet ray), IR (infrared ray including far infrared ray) or electron beam.

52. The method of manufacturing paste of any one of claims 23 to 41, wherein the ceramic powder is dispersed at viscosity of 0.01 poise to 100 poise together with a solvent and some binder or dispersant, which is mixed with glass powder and a specified amount of binder, then dispersed, and adjusted to the viscosity of 100 poise to 10000 poise.

24. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste;

burning them together at 800 to 900°

C.;

further printing second crystallized glass paste by 10 to 300 μ

m in thickness thereon and burning at 800 to 900°

C.;

printing non-crystalline glass paste by 10 to 300 μ

m in thickness and at 800 to 900°

C.;

further printing wiring and strain sensitive resistor and individually burning at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

25. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste;

burning them together at 800 to 900°

C.;

further printing second crystallized glass paste and non-crystalline glass paste by 10 to 300 μ

m each in thickness thereon and burning them together at 800 to 900°

C.;

further printing wiring and strain sensitive resistor and individually burning at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

26. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste, and printing second crystallized glass paste thereon and burning at 800 to 900°

C.;

further printing non-crystalline glass paste by 10 to 300 μ

m in thickness and burning at 800 to 900°

C.;

further printing wiring and strain sensitive resistor and burning at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

27. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste, and printing thereon second crystallized glass paste and non-crystalline glass paste by 10 to 300 μ

m each in thickness, and after printing wiring, burning them together at 800 to 900°

C.;

further printing strain sensitive resistor thereon and burning at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

28. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness;

printing electrode paste, and printing thereon second crystallized glass paste and non-crystalline glass paste by 10 to 300 μ

m each in thickness, and after printing wiring, printing a plurality of strain sensitive resistors so as to be partially connected to the wiring at least and burning them together at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

29. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste, and printing thereon second crystallized glass paste by 10 to 300 μ

m in thickness;

burning them together at 800 to 900°

C.;

further printing thereon non-crystalline glass paste by 10 to 300 μ

m in thickness followed by burning;

printing wiring, and printing a plurality of strain sensitive resistors so as to be partially connected to the wiring at least and burning them together at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

30. A method of manufacturing a load sensor, comprising the steps of:

printing first crystallized glass paste by 10 to 300 μ

m in thickness on an elastic metal body;

printing electrode paste, and printing thereon second crystallized glass paste by 10 to 300 μ

m in thickness;

burning them together at 800 to 900°

C.;

further printing thereon non-crystalline glass paste by 10 to 300 μ

m in thickness;

then printing wiring, and burning the non-crystalline glass and wiring together at 800 to 900°

C.;

printing a plurality of strain sensitive resistors so as to be partially connected to the wiring at least and burning them together at 800 to 900°

C.; and

printing glass paste so as to cover at least the strain sensitive resistor and burning at 400 to 700°

C., followed by mounting electronic parts thereon as specified.

31. A method of manufacturing a load sensor, comprising the steps of:

directly printing composite glass paste on an elastic metal body, which is formed from at least glass powder of 0.1 μ

m to 10 μ

m in average grain diameter and ceramic powder of 0.05 μ

m to 5 μ

m in average grain diameter dispersed in resin solution;

forming a composite glass layer by drying and burning at 800°

C. to 900°

C. in an oxidation atmosphere; and

forming a wiring pattern on the composite glass layer and a strain sensitive resistor so as to be partially connected to the wiring pattern.

32. A method of manufacturing a load sensor, comprising the steps of:

printing and drying composite glass paste on support film, which is formed from at least glass powder of 0.1 μ

m to 10 μ

m in average grain diameter and ceramic powder of 0.05 μ

m to 5 μ

m in average grain diameter dispersed in resin solution;

transferring the composite glass paste on the support film onto an elastic metal body and burning at 800°

C. to 900°

C. in an oxidation atmosphere, thereby forming a composite glass layer; and

forming a wiring pattern on the composite glass layer and a strain sensitive resistor so as to be partially connected to the wiring pattern.

33. A method of manufacturing a load sensor, comprising the steps of:

printing and drying composite glass paste on support film, which is formed from at least glass powder of 0.1 μ

m to 10 μ

m in average grain diameter and ceramic powder of 0.1 μ

m to 5 μ

m in average grain diameter dispersed in resin solution, followed by punching into specified shape; and

after placing it on an elastic metal body, burning at 800°

C. to 900°

C. in an oxidation atmosphere, thereby forming a composite glass layer; and

forming a wiring pattern on the composite glass layer and a strain sensitive resistor so as to be partially connected to the wiring pattern.