Angular velocity sensor

The present invention relates to an angular velocity sensor useable for electronic devices, such as stabilizing prevention systems for digital still cameras, or vehicle systems, such as car navigation systems, and to a method for manufacturing the sensor.

JP11-325908A discloses a conventional angular velocity sensor including a vibration element and an integrated circuit (IC) which are mounted on a single surface of a substrate, and further including case for sealing the vibration element and the IC. This structure prevents the angular velocity sensor from have a small size. JP11-325908A does not disclose any method of mounting the vibration element and the IC. Chip components are usually mounted and fixed onto the substrate with a solder. The vibration element and the IC may be mounted with a thermosetting resin. The reflow of the solder connection of the chip components and the curing of the thermosetting resin are performed under temperature profiles different from each other. More specifically, the reflow is performed at a relatively high temperature for a short duration, whereas the heat-curing of the resin is performed at a relatively low temperature for a long duration. Thus, it is difficult to use both the different temperature profiles together.

JP5-92635U discloses another angular velocity sensor including two vibration elements having detection axes perpendicular to each other.

JP2000-74674A discloses a method for manufacturing an angular velocity sensor, in which a vibration element is tested in characteristics every time. This method prevents the angular velocity sensor from being manufactured efficiently.

JP8-170918A discloses an angular velocity sensor used for a stabilizing system. This angular velocity sensor includes a vibration element which is sealed in a case, and is manufactured by complicated processes.

An angular velocity sensor includes a substrate having an upper surface having a first recess provided therein, an electronic component mounted in the first recess, and a vibration element mounted onto the upper surface of the substrate. The first vibration element has a portion located directly above the electronic component.

This angular velocity sensor has a small size.

FIG. 1 is a cut-away perspective view of an angular velocity sensor according to Exemplary Embodiment 1 of the present invention.

FIG. 2 is an exploded perspective view of the angular velocity sensor according to Embodiment 1.

FIG. 3 is a plan view of the angular velocity sensor according to Embodiment 1.

FIG. 4 is a sectional view of the angular velocity sensor at line 4 - 4 shown in FIG. 3 .

FIG. 5 is a sectional view of the angular velocity sensor at line 5 - 5 shown in FIG. 3 .

FIG. 6 is a flowchart illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 7 is a plan view of a sheet substrate used for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 8 is a plan view illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 9 is a sectional view illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 10 is a plan view illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 11 is a plan view illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 12 is a plan view illustrating processes for manufacturing the angular velocity sensor according to Embodiment 1.

FIG. 13 is a perspective view of the angular velocity sensor according to Embodiment 1.

FIG. 14 is a plan view illustrating processes of manufacturing an angular velocity sensor according to Exemplary Embodiment 2 of the invention.

FIG. 15 is a flowchart illustrating processes for manufacturing the angular velocity sensor according to Embodiment 2.

1 Substrate

2 Recess (First Recess)

3 IC (Electronic Component)

3 C Bump Terminal (Terminal)

4 A Leg

4 B Base

5 A Leg

5 B Base

6 Chip Component

7 Case

7 C Lower End of Case

7 D Portion of Lower End of Case (First Portion)

7 E Portion of Lower End of Case (Second Portion)

10 Recess (Second Recess)

11 Recess (Second Recess)

12 Element Electrode (Electrode)

13 A Component Electrode (Electrode)

13 B Component Electrode

15 Wire

20 Sheet Substrate

23 Adhesive (Second Adhesive)

24 Adhesive (First Adhesive)

25 Conductive Adhesive

26 Rotation Axis

51 Electrode

52 Adhesive

54 Vibration Element (First Vibration Element)

55 Vibration Element (Second Vibration Element)

125 Conductive Adhesive

1001 Angular Velocity Sensor

Exemplary Embodiment 1

FIGS. 1 , 2 , and 3 are a perspective view, an exploded perspective view, and a plan view of angular velocity sensor 1001 according to of Exemplary Embodiment 1 of the present invention, respectively. FIGS. 4 and 5 are sectional views of angular velocity sensor 1001 at line 4 - 4 and line 5 - 5 shown in FIG. 3 , respectively.

Angular velocity sensor 1001 includes substrate 1 formed by laminating and sintering ceramic sheets. Substrate 1 has upper surface 1 A having recess 2 provided therein. Recess 2 has bottom 2 A. Integrated circuit (IC) 3 as an electronic component is mounted onto bottom 2 A in recess 2 . Base 4 B of vibration element 54 is joined to joint portion 1 C of upper surface 1 A of substrate 1 . Vibration element 54 has a tuning fork shape including two legs 4 A extending in parallel to each other and base 4 B. Each of legs 54 has open end 104 A and end 104 B. Legs 54 can vibrate and extend in direction 1001 A. Base 4 B fixes end 104 B of each of legs 54 . Joint portion 1 D of upper surface 1 A of substrate 1 is joined to base 5 B of vibration element 55 . Vibration element 55 has a tuning fork shape including two legs 5 A extending in parallel to each other and base 5 B. Each of two legs 5 A has open end 105 A and end 105 B, and can vibrate. Base 5 B fixes end 105 B of each of two legs 5 A. Two legs 5 A extend in direction 1001 B perpendicular to direction 1001 A. Vibration elements 54 and 55 are connected electrically to IC 3 . IC 3 supplies driving signals to vibration elements 54 and 55 to drive the elements. Vibration element 54 has detection axis 4 C extending in direction 1001 A between two legs 4 A, and sends, to IC 3 , a detection signal corresponding to an angular velocity at which vibration element 54 rotates about detection axis 4 C. Vibration element 55 has detection axis 5 C extending in direction 1001 B between two legs 5 A, and sends, to IC 3 , a detection signal corresponding to an angular velocity at which vibration element 55 rotates about detection axis 5 C. IC 3 performs a predetermined signal processing to the detection signals received from vibration elements 54 and 55 . Chip components 6 are mounted onto upper surface 1 A of substrate 1 to form an electric circuit together with IC 3 . Chip components 6 include chip resistor 6 A. Case 7 is mounted onto upper surface 1 A of substrate 1 to cover recess 2 , IC 3 , vibration elements 54 and 55 , and chip components 6 .

IC 3 is mounted onto mounting portion 8 of bottom 2 A of recess 2 such that IC 3 does not protrude from upper surface 1 A of substrate 1 . IC 3 has upper surface 3 A and lower surface 3 B opposite to upper surface 3 B. Upper surface 3 A of IC 3 is positioned under upper surface 1 A of substrate 1 . In other words, recess 2 has depth 2 B larger than the distance from bottom 2 A of recess 2 to upper surface 3 A of IC 3 . Lower surface 3 B of IC 3 faces bottom 2 A of recess 2 , i.e., mounting portion 8 . Bump terminals 3 C are provided on lower surface 3 B of IC 3 . Electrodes 51 connected to bump terminals 3 C of IC 3 are provided on mounting portion 8 of substrate 1 . Injection portion 9 which is a portion of bottom 2 A of recess 2 is adjacent to mounting portion 8 , and is exposed even while IC 3 is mounted onto mounting portion 8 . Injection portion 9 provides a space to which a nozzle is inserted for injecting adhesive to join IC 3 to substrate 1 . Upper surface 1 A of substrate 1 has recesses 10 and 11 provided therein. Recesses 10 and 11 communicate with recess 2 , and are shallower than recess 2 . Recess 10 is located beneath vibration element 54 and between joint portion 1 C and recess 2 . Recess 11 is located beneath vibration element 55 and between joint portion 1 D and recess 2 , and communicates directly with recess 2 .

Element electrodes 12 are provide on upper surface 1 A of substrate 1 , and connected electrically with vibration elements 54 and 55 via wires 15 . Component electrodes 13 A and 13 B are provided on substrate 1 and connected with chip components 6 . Groove 14 is provided in upper surface 1 A of substrate 1 and between component electrodes 13 A and 13 B. Positioning mark 16 is provided on upper surface 1 A of substrate 1 to position substrate 1 during the manufacturing of angular velocity sensor 1001 .

A method for manufacturing angular velocity sensor 1001 will be described below. FIG. 6 is a flowchart illustrating processes for manufacturing angular velocity sensor 1001 .

FIG. 7 is a plan view of sheet substrate 20 used for manufacturing angular velocity sensor 1001 . First, sheet substrate 20 is prepared by laminating and sintering ceramic sheets (Step S 1 of FIG. 6 ). Sheet substrate 20 includes chip substrates 53 connected to each other. Each of chip substrates 53 is arranged to provide substrate 1 . Sheet substrate 20 has plural dividing grooves 21 extending between chip substrates 53 (substrates 1 ). Sheet substrate 20 is divided into chip substrates 53 along dividing grooves 21 to provide individual substrates 1 .

FIG. 8 is a plan view of substrate 1 having IC 3 mounted thereon. FIG. 8 does not entirely show sheet substrate 20 , but does show only a portion of sheet substrate 20 which constitutes one angular velocity sensor 1001 . IC 3 is mounted on mounting portion 8 in recess 2 of each substrate 1 of sheet substrate 20 (Step S 2 of FIG. 6 ). Bump terminals 3 C on lower surface 3 B of IC 3 are pressed against electrodes 51 provided on each substrate 1 , and melted with ultrasonic waves to be joined with electrodes 51 .

FIG. 9 is a sectional view of substrate 1 having IC 3 mounted thereon. FIG. 9 does not entirely show sheet substrate 20 , but does show only a portion of sheet substrate 20 which constitutes one angular velocity sensor 1001 . Nozzle 22 is inserted in recess 2 from directly above injection portion 9 which a portion of bottom 2 A of recess 2 , and injects adhesive 23 to injection portion 9 (Step S 3 of FIG. 6 ). Adhesive 23 injected from nozzle 22 flows from injection portion 9 into a gap between lower surface 3 B of IC 3 and bottom 2 A of recess 2 . Adhesive 23 may employ an underfill material, and more specifically, may be a thermosetting resin, such as an epoxy-based resin.

FIG. 10 is a plan view of substrate 1 having adhesive 24 and conductive adhesive 25 applied thereto. FIG. 10 does not entirely show sheet substrate 20 , but does show only a portion of sheet substrate 20 which constitutes one angular velocity sensor 1001 . Adhesive 24 is applied to joint portions 1 C and 1 D to which vibration elements 54 and 55 are joined on sheet substrate 20 , respectively (Step S 4 of FIG. 6 ). Conductive adhesive 25 is applied to component electrodes 13 A and 13 B on upper surface 1 A of each substrate 1 (sheet substrate 20 ). Adhesive 24 may employ an epoxy-based thermosetting resin. Conductive adhesive 25 may employ a conductive thermosetting resin paste containing silver and resin.

FIG. 11 is a plan view of substrate 1 (Sheet substrate 20 ) having vibration elements 54 and 55 and chip components 6 mounted thereon. FIG. 11 does not entirely show sheet substrate 20 , but does show only a portion of sheet substrate 20 which constitutes one angular velocity sensor 1001 . Vibration elements 54 and 55 are joined to joint portions 1 C and 1 D on each substrate 1 (sheet substrate 20 ) with adhesive 24 ( FIG. 10 ), respectively (Step S 5 of FIG. 6 ). Chip components 6 are joined to component electrodes 13 A and 13 B with conductive adhesive 25 (Step S 5 of FIG. 6 ).

After vibration elements 54 and 55 and chip components 6 are joined to upper surface 1 A of each substrate 1 (sheet substrate 20 ) at Step S 5 , sheet substrate 20 is heated to heat adhesives 23 and 24 and conductive adhesive 25 so as to heat-cure adhesives 23 , 24 , and 25 simultaneously (Step S 6 of FIG. 6 ). In this heat-curing, sheet substrate 20 is heated at a temperature not lower than a temperature at which adhesives 23 and 24 and conductive adhesive 25 are cured. According to the embodiment, sheet substrate 20 is heated at 150° C. for 90 to 120 minutes depending on the composition of the adhesives.

Then, vibration elements 54 and 55 are bonded to element electrodes 12 on upper surface 1 A of each substrate 1 (sheet substrate 20 ) via wires 15 by wire bonding, thereby providing a sensor circuit including vibration elements 54 and 55 , chip components 6 , and IC 3 . The wire bonding connects vibration elements 54 and 55 electrically to element electrodes 12 reliably even if vibration element 54 or 55 deviates from a predetermined position during the joining to substrate 1 .

FIG. 12 is a plan view of sheet substrate 20 having vibration elements 54 and 55 and chip components 6 mounted thereon and connected thereto. Sheet substrate 20 is rotated about rotation axis 26 so as to apply angular velocity 26 A to vibration elements 54 and 55 about rotation axis 26 , thereby detecting characteristics of signals output from angular velocity sensor 1001 , i.e., the sensor circuit corresponding to the angular velocity (Step S 7 of FIG. 6 ). Rotation axis 26 is angled by 45 degrees with respect to detection axis 4 C of vibration element 54 ( FIG. 1 ), i.e., with respect to direction 1001 A, and is angled by 45 degrees with respect to detection axis 5 C of vibration element 55 ( FIG. 1 ), i.e., with respect to direction 1001 B. When angular velocity 26 A is applied about rotation axis 26 , vibration elements 54 and 55 output signals having values several times the values provided by multiplying the reciprocal of the square root of 2 with the values of signals output from elements 54 and 55 having angular velocities having the same magnitude as angular velocity 26 A about detection axes 4 C or 5 C, respectively. Thus, the values of the signals output from vibration elements 54 and 55 having angular velocity 26 A applied thereto about rotation axis 26 are multiplied by the square root of 2, thereby calculating the values of the signals output from vibration elements 54 and 55 having angular velocities having the same magnitude as angular velocity 26 A about detection axes 4 C and 5 C, respectively. In other words, the characteristics of the signals corresponding to the angular velocity applied to angular velocity sensor 1001 including two vibration elements 54 and 55 can be detected by rotating sheet substrate 2 about rotation axis 26 to apply angular velocity 26 A to vibration elements 54 and 55 . Sheet 20 is rotated at various angular velocities 26 A, and the values of the signals output from vibration elements 54 and 55 corresponding to angular velocities 26 A are stored in a storage medium, such as a memory.

The sensor circuit of angular velocity sensor 1001 is adjusted so that the values of the signals which are output from vibration elements 54 and 55 and stored in the storage medium are within a predetermined range (Step S 8 of FIG. 6 ). At Step S 8 , zero points of the values of the signals output from vibration elements 54 and 55 are adjusted. More specifically, chip resistors 6 A are trimmed with laser to change their resistances based on the stored values.

After the sensor circuit of angular velocity sensor 1001 is adjusted at Step S 8 , case 7 is mounted to each of substrates 1 of sheet substrate 20 (Step S 9 of FIG. 6 ). Then, sheet substrate 20 is divided into individual substrates 1 along dividing grooves 21 (Step S 10 of FIG. 6 ) to provide angular velocity sensors 1001 each including two detection axes 4 C and 5 C extending in directions 1001 A and 1001 B, respectively.

Portions (legs 4 A and 5 A) of vibration elements 54 and 55 are located directly above upper surface 3 A of IC 3 , reducing the area of substrate 1 . Bump terminals 3 C on lower surface 3 B of IC 3 are connected directly to electrodes 51 of substrate 1 , thereby allowing upper surface 3 A to have no wire or no terminal for connecting to IC 3 . This structure allows the portions of vibration elements 54 and 55 to be located directly above IC 3 . In angular velocity sensor 1001 including two vibration elements 54 and 55 having detection axes 4 C and 5 C perpendicular to each other, vibration elements 54 and 55 cross IC 3 longitudinally and laterally. Therefore, if IC 3 is connected via wires, at least one of vibration elements 54 and 55 may contact with the wires. Angular velocity sensor 1001 according to Embodiment 1 has no wire connected to IC 3 , which is provided on upper surface 3 A, and allows the portions of vibration elements 54 and 55 to be located directly above upper surface 3 A of IC 3 , thus having a small size.

Legs 4 A and 5 A of vibration elements 54 and 55 are located directly above recess 2 , and upper surface 3 A of IC 3 is located under upper surface 1 A of substrate 1 , so that a space is provided beneath legs 4 A and 5 A. This space prevents legs 4 A and 5 A from contacting substrate 1 or IC 3 while vibrating, and allows vibration elements 54 and 55 to be joined to upper surface 1 A of substrate 1 . This structure eliminates a portion protruding from upper surface 1 A to be joined to vibration elements 54 and 55 , thus providing angular velocity sensor 1001 with a thin profile.

Bottom 2 A of recess 2 has mounting portion 8 having IC 3 mounted thereon and injection portion 9 communicating with mounting portion 8 . Nozzle 22 to inject adhesive 23 is inserted to injection portion 9 , and puts adhesive 23 securely between IC 3 and mounting portion 8 of bottom 2 A of recess 2 , thereby adhering IC 3 onto bottom 2 A securely. Since adhesive 23 can hardly be injected between IC 3 and an inner wall of recess 2 , injection portion 9 facilitates adhesive 23 to be put between bottom 2 A and lower surface 3 B of IC 3 .

Upper surface 1 A has recess 10 provided therein. Recess 10 is shallower than mounting portion 8 and injection portion 9 , i.e., than bottom 2 A of recess 2 , and communicates directly with injection portion 9 . Recess 10 is located away from mounting portion 8 by distance 1 E. Recess 10 increases a creeping distance from injection portion 9 to upper surface 1 A of substrate 1 , accordingly preventing adhesive 23 from overflowing from recess 2 onto upper surface 1 A of substrate 1 . Recess 10 is shallower than injection portion 9 (bottom 2 A of recess 2 ), and may have electric wiring on bottom 10 A.

Recess 10 communicates with recess 2 of substrate 1 and is located between recess 2 and joint portion 1 C of substrate 1 joined to vibration element 54 , and therefore, recess 10 is closest to joint portion 1 C in recess 2 . Recess 11 communicates with recess 2 of substrate 1 and is located between recess 2 and joint portion 1 D of substrate 1 joined to vibration element 55 , and therefore, recess 11 is closest to joint portion 1 D in recess 2 . This structure allows creeping distances to joint portions 1 C and 1 D to be large enough to prevent adhesive 23 from contacting vibration elements 54 and 55 , thereby preventing adhesive 23 from influencing the vibration of vibration elements 54 and 55 .

At Steps S 7 and S 8 of FIG. 6 , an angular velocity is applied to sheet substrate 20 having substrates 1 so as to detect the characteristics of the sensor circuits including angular velocity sensors 1001 . Then, the characteristics of the sensor circuits including angular velocity sensors 1001 are adjusted to reduce variations in the characteristics of angular velocity sensors 1001 . Then, sheet substrate 20 is divided into individual substrates 1 (angular velocity sensors 1001 ). This process can manufacture angular velocity sensors 1001 more efficiently than a process in which the characteristics of angular velocity sensors 1001 are detected and adjusted after sheet substrate 20 is divided into individual angular velocity sensors 1001 .

Case 7 is mounted to each substrate 1 of sheet substrate 20 at Step S 9 to cover vibration elements 54 and 55 before sheet substrate 20 is divided at Step S 10 . Case 7 may have burrs when sheet substrate 20 is divided into individual substrates 1 . Case 7 reliably prevents the burrs from contacting vibration element 54 or 55 , thus protecting vibration elements 54 and 55 securely at Step S 10 . Case 7 also covers IC 3 , and can protect IC 3 at Step S 10 .

FIG. 13 is a perspective view of angular velocity sensor 1001 . Case 7 includes cover plate 7 A and side walls 7 B. Cover plate 7 A is located directly above vibration elements 54 and 55 , recess 2 , IC 3 , and chip components 6 . Side walls 7 B extend from outer periphery 7 F of cover plate 7 A downward towards upper surface 1 A of substrate 1 . Side walls 7 B have lower end 7 C facing upper surface 1 A of substrate 1 . Lower end 7 C of case 7 is joined to upper surface 1 A of substrate 1 with adhesive 52 at Step S 9 of FIG. 6 such that gap 1 F is provided in between lower end 7 C and upper surface 1 A. In other words, lower end 7 C of case 7 includes portion 7 D having adhesive 52 applied thereto, and portion 7 E which does not have adhesive 52 applied thereto. Gap 1 F is provided between portion 7 E of lower end 7 C and upper surface 1 A of substrate 1 so that case 7 protects vibration elements 54 and 55 . Case 7 is not sealed, thus allowing angular velocity sensor 1001 to be manufactured easily. The space in case 7 accommodating vibration elements 54 and 55 can be vacuum-sealed or filled with gas, such as helium gas, having a small molecular weight. In these cases, case 7 is hermetically sealed on substrate 1 (sheet substrate 20 ). This structure requires a process for inspecting the air-tightness of the space, making processes for manufacturing the sensor complicated. In the case that zero-point shift does not matter, for example, in the case that angular velocity sensor 1001 is used in a stabilizing system, case 7 may not necessarily be sealed, hence simplifying processes for manufacturing the structure shown in FIG. 13 .

Adhesives 23 and 24 for joining IC 3 and vibration elements 54 and 55 to substrate 1 contain thermosetting resin. Conductive adhesive 25 joining chip components 6 to component electrodes 13 A and 13 B also contains thermosetting resin. Adhesives 23 and 24 and conductive adhesive 25 can be cured simultaneously in a process at Step S 6 of FIG. 6 , thereby allowing angular velocity sensors 1001 to be manufactured efficiently. The thermosetting resin contained in conductive adhesive 25 has a surface tension smaller than conductive metal adhesive, such as solder, and may protrude from component electrodes 13 A and 13 B on upper surface 1 A of substrate 1 . Grooves 14 provided in upper surface 1 A of substrate 1 and between component electrodes 13 A and 13 B increase a creeping distance between component electrodes 13 A and 13 B, accordingly preventing a short-circuit between the electrodes.

Angular velocity sensor 1001 according to Embodiment 1 includes two vibration elements 54 and 55 having detection axes 4 C and 5 C perpendicular to each other, but may include only one vibration element.

Sheet substrate 20 is divided into plural angular velocity sensors 1001 according to Embodiment 1, alternatively, a single angular velocity sensor 1001 may be formed from a single substrate 1 .

Angular velocity sensor 1001 according to Embodiment 1 is small enough for use in an electronic device, such as a stabilizing system of a digital still camera or a vehicle system, such as a car navigation system.

Exemplary Embodiment 2

FIG. 14 is a plan view of an angular velocity sensor according to exemplary Embodiment 2 of the present invention for illustrating processes for manufacturing the sensor. In FIG. 14 , components identical to those of angular velocity sensor 1001 shown in FIGS. 1 to 5 and 7 to 13 are denoted by the same reference numerals, and their description will be omitted. The angular velocity sensor according to Embodiment 2 includes conductive adhesive 125 instead of conductive adhesive 25 of angular velocity sensor 1001 shown in FIGS. 1 to 5 and 7 to 13 . FIG. 14 does not entirely show sheet substrate 20 , but does show only a portion of sheet substrate 20 which constitutes one angular velocity sensor.

FIG. 15 is a flowchart illustrating processes for manufacturing the angular velocity sensor according to Embodiment 2.

Similarly to the processes of manufacturing angular velocity sensor 1001 according to Embodiment 1 shown in FIG. 6 , adhesive 23 is put between IC 3 and bottom 2 A of recess 2 of substrate 1 through injection portion 9 of recess 2 at Step S 3 .

As shown in FIG. 14 , adhesive 24 is applied to joint portions 1 C and 1 D of substrate 20 to be joined to vibration elements 54 and 55 , respectively. Conductive adhesive 125 is applied to component electrodes 13 A and 13 B on upper surface 1 A of each substrate 1 (sheet substrate 20 ) (Step S 101 of FIG. 15 ). Adhesive 24 may be made of epoxy-based thermosetting resin. Conductive adhesive 125 is made of conductive metal adhesive, such as solder, containing metal.

Then, vibration elements 54 and 55 are joined to joint portions 1 C and 1 D of each substrate 1 (sheet substrate 20 ) with adhesive 24 , respectively (Step S 5 of FIG. 15 ). Chip components 6 are joined to component electrodes 13 A and 13 B with conductive adhesive 125 (Step S 5 of FIG. 15 ).

After vibration elements 54 and 55 and chip components 6 are joined to upper surface 1 A of each substrate 1 (sheet substrate 20 ) at Step S 5 , sheet substrate 20 is heated to cure adhesives 23 and 24 (Step S 6 of FIG. 15 ). In this heat curing, sheet substrate 20 is heated at a temperature not lower than a temperature at which adhesives 23 and 24 are cured. According to the embodiment 2, sheet substrate 20 is heated at 150° C. for 90 to 120 minutes depending on the composition of adhesives 23 and 24 .

Consecutively after adhesives 23 and 24 are heated and cured at Step S 5 , a reflow process is performed in which sheet substrate 20 is heated at a temperature higher than the above temperature so as to melt conductive adhesive 125 , thereby fixing chip components 6 to component electrodes 13 A and 13 B (Step S 102 ). At Step S 102 , sheet substrate 20 is heated at a temperature higher than that at Step S 6 , for example, at 260° C. just for 5 minutes, which is shorter than the duration at Step S 6 . Thus, conductive adhesive 125 as the conductive metal adhesive is melted consecutively after adhesives 23 and 24 made of thermosetting resin are cured. This process allows both the resin and the conductive metal adhesive to exhibit adhesion property. In other words, both the heat-curing process and the reflow process can be performed in the same heating process by changing the temperature profiles so as to manufacture the angular velocity sensor according to Embodiment 2 in a simple production process, accordingly increasing energy efficiency for heating.

The reflow process is performed after vibration elements 54 and 55 and IC 3 are jointed, hence preventing vibration elements 54 and 55 and IC 3 from being displaced.

Conductive adhesive 125 as the conductive metal adhesive joins chip components 6 to component electrodes 13 A and 13 B reliably. Adhesives 23 and 24 made of thermosetting resin are cured by being heated at a lower temperature for a longer duration. In contrast, conductive adhesive 125 , the conductive metal adhesive, is melted by being heated at a higher temperature for a shorter duration. The temperature and the heating duration appropriate for the thermosetting resin do not allow the conductive metal adhesive to melt, and hence, does not join chip component 6 . The heating temperature and heating duration appropriate for the conductive metal adhesive raise the temperature of substrate 1 before the thermosetting resin is cured. If the temperature of substrate 1 rises excessively, substrate 1 may sag, thereby preventing IC 3 and vibration elements 54 and 55 from being properly joined. At Step S 102 , sheet substrate 20 is heated at a temperature higher than that at Step S 6 , for example, at 260° C. just for 5 minutes, which is shorter than that at Step S 6 . This process allows the thermosetting resin and the conductive metal adhesive to exhibit adhesion property appropriately. Conductive adhesive 125 as the conductive metal adhesive has a surface tension higher than that of conductive adhesive 25 made of the thermosetting resin according to Embodiment 1, hence being located within component electrodes 13 A and 13 B. This structure can eliminate grooves 14 provided in upper surface 1 A of substrate 1 for preventing short-circuits between component electrodes 13 A and 13 B.

The angular velocity sensor according to Embodiment 2 has a size small enough for use in an electronic device, such as a stabilizing system of a digital still camera, or a vehicle system, such as a car navigation system.

An angular velocity sensor according to the present invention has a size small enough for use in an electronic device or a vehicle.