JP2508411B2 - Acceleration sensor- - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a cantilever type acceleration sensor chip with an impact force,
The present invention relates to a damage prevention device that prevents excessive displacement so that a cantilever type acceleration sensor chip will not be damaged when an excessive acceleration due to a drop or the like is applied.

[Conventional technology]

FIG. 5 is a perspective view showing a configuration of a conventional cantilever type acceleration sensor, and FIG. 6 is a perspective view showing a state of a conventional cantilever type acceleration sensor before assembly of a cap and viscous oil.
FIG. 7 is a cross-sectional view taken along the line xx shown in FIG. 5, FIG. 8 is a cross-sectional view showing the relative dimensions of the weight tip in FIG. 7, and FIG.
FIG. 7 is a sectional view showing the displacement of the tip of the weight when 1 G is applied to the weight in FIG. 7, FIG. 10 is an enlarged sectional view of the tip for explaining the displacement of the weight shown in FIG. 7, and FIG. FIG. 10 is an enlarged cross-sectional view when the tip of the weight is displaced when the acceleration sensor is rotated 180 ° from the position shown in FIG. 9 and attached, that is, when −1 G is applied. In the figure, (1) is a weight,
(2) is a cantilever type acceleration sensor chip, (3), (3
a), (3b), (3c) and (3d) are piezoresistors for performing strain-resistance conversion provided on the surface of the cantilever type acceleration sensor chip (2) by a wafer process, and (4) is metal Thin wire, (5) external terminal, (6) glass seal, (7)
Is a stem, (100) is a weight stopper, (9) is a pedestal,
(10), (40) adhesive, (11) cap, (12) viscous oil, (20) first die bond material, (30) second
Die bond material, (50) is a cantilever type acceleration sensor (2)
Piezoresistors (3a), (3b), (3
c), (3d) and wire bond pads connected by diffusion wiring or metal wiring in the wafer process. Figures 5 and 7
As shown in the figure, the acceleration sensor includes a cantilever type acceleration sensor chip (2) and a pedestal (9) as the first die bonding material (2).
(2) and the cantilever type acceleration sensor chip (2) and the pedestal (9) which are integrated with each other on the stem (7).
It is constructed integrally using the die bond material (30). afterwards,
The tip of the cantilever type acceleration sensor chip (2), the pedestal (9), the stem (7) and the weight (1) which are integrated by using the adhesive (10). Adhere to the part. After that, the weight stopper (100) is bonded to the stem (7) using an adhesive (40) with a spacer inserted so as to secure clearances L, M, N as shown in FIG. After adhering, the spacer is removed, and as shown in FIG. 6, the stem (7) with the above assembly completed is inserted into the cap (11) filled with the necessary amount of viscous oil (12) from above, and in that state. Cap (11) and stem (7)
And are integrally formed by electric welding.

Next, the operation will be described. In FIG. 8, the acceleration sensor has a tip A _{1 and a} point C ₁ of the weight, the length of the neutral axis R ₂ -B ₁ which is the bending center of the cantilever type acceleration sensor chip (2) and R ₂ -A ₁ and The lengths of R ₂ -C ₁ are different, and the angles are different by θ _A1 and θ _C1 as shown in the figure. As shown in FIG. 9, when the cantilever type acceleration sensor chip (2) is attached, the weight (1) makes a displacement proportional to the gravity of 1G,
Point B ₁ moves to point B _{2 and} is displaced by Δθ in angle. As shown in Fig. 10, when B ₁ point is displaced to B ₂ point, A ₁ point becomes A ₂ point,
C ₁ point is displaced to C ₂ point. In the figure, the conventional weight stopper (100) is constructed with the clearance N shown in FIG. 7 so as to regulate the displacement of C ₁ -C ₂ . The displacement proportional to the gravity of -1 G due to the weight (1) when the acceleration sensor is attached in the direction of 180 ° in Fig. 9 is as shown in Fig. 11, and the weight stopper (100) is A ₁ -A ₂ . The weight stopper (100) that regulates the displacement is configured with the clearance L shown in FIG. Further, in FIG. 7, the clearance M of the weight stopper (100) must be configured to be larger than the larger displacement of the displacements B ₁ -S ₁ and B ₁ -S ₂ shown in FIGS. 10 and 11. There is.

[Problems to be Solved by the Invention]

Since the conventional cantilever type acceleration sensor is configured as described above, it is necessary to accurately assemble the clearances L, M and N when assembling the weight stopper, and the shape of the weight stopper is U-shaped. Therefore, there was a problem that automatic assembly could not be performed.

The present invention has been made to solve the above problems. Since the weight stopper is composed of the clearances of M and N and the clearance L is unnecessary, it can be mounted from the outside of the weight at the time of assembly, and the assembly is automated. It is possible to obtain an acceleration sensor that does not require an assembling spacer for obtaining the clearances M and N.

[Means for solving the problem]

An acceleration sensor according to the present invention includes an acceleration sensor chip having one end fixed to a pedestal, a weight connected to the other end of the acceleration sensor chip, an L-shaped weight stopper that limits displacement of the weight, and A stem having the pedestal and the L-shaped weight stopper fixed on the main surface is provided, and when the weight is displaced in a direction approaching the main surface of the stem, the L-shaped weight stopper is provided. Limiting the displacement of the weight in a plane parallel to the main surface of the stem, when the weight is displaced in a direction away from the main surface of the stem, with respect to the main surface of the stem of the weight stopper The displacement of the weight is limited by a vertical surface.

Further, in the acceleration sensor according to the present invention, one end is fixed to a pedestal, an acceleration sensor chip, a weight connected to the other end of the acceleration sensor chip, and an I-shaped weight stopper that limits displacement of the weight, The pedestal and the stem in which the I-shaped weight stopper is fixed on a main surface are provided, and the displacement of the weight is defined by a surface perpendicular to the main surface of the stem of the I-shaped weight stopper. The displacement of the weight is limited.

Tip A ₁ of the weight in the Figure 8, B _1, the points of C ₁ is the axial length L ₁ of the neutral axis R ₂ -B ₁ (this direction is referred to as X-axis) when the acceleration is displaced hanging and R Let the length of _2- A _{1 be} L _A1 and the length of R _2- C _{1 be} L _C1 . If the X-axis is a line connecting the points A ₁ , C ₁ , and D ₁ at right angles to the Y-axis, and the point R ₂ is the origin, the coordinates of the point A ₁ are (L _A1 c
osθ _A1 , L _A1 sin θ _A ), the coordinates of C ₁ point are (L _C1 cos θ _C1 , L _C1
sin θ _C1 ). As shown in Fig. 9, when B ₁ point is displaced by B ₂ point by Δθ, the coordinate of B ₂ point is (L ₁ cos Δθ, L ₁ sin Δθ) and the coordinate of A ₂ point is {L _A , cos (θ
_A1− Δθ), L _A1 sin (θ _A1 −Δθ)}, and the coordinates of the C ₂ point are {L _C1 cos (θ _C1 + Δθ), L _C1 · sin (θ _C1 + Δθ)}. A ₁ point in Figure 10 is displaced on a circumference shown in beta-beta when displaced _two points A, than the displacement X coordinate of the B ₁ point as indicated by S ₁ -B ₁ on the X-axis Comes out. This backwards as shown in FIG. 11 when displaced by -Derutashita, displacement on the X-axis of the C ₁ point is displaced in the C ₂ points C ₂ points B ₁ -S ₂ becomes B ₁ - S ₂ =
X coordinate of the _{LC 1 · cos (θc 1 -Δθ} ) -L C1 cosθc 1 and represented C ₂ points than the X coordinate of _a point B is as shown exiting outward. The weight stopper according to the present invention is constructed so as to regulate the displacement in the Y-axis direction of the displacement of C ₁ -C _{2 in} FIG. 10 when the + direction acceleration is applied, and as shown in FIG. 11 when the unidirectional acceleration is applied. The displacement of C ₁ -C ₂ in the X direction, B ₁ -S _2, is regulated.

At this time, displacement regulation when unidirectional acceleration is applied is designed in the X direction displacement B ₁ −S ₂ = L _C1 cos (θ c ₁ −Δθ) −L _C1 cos θ _C1 with a clearance N, and Y direction displacement = L _C1 sin (θ _C1
+ Δθ) -L _C1 sin θ Design a clearance M equivalent to _C1 .

[Action]

The acceleration sensor according to the present invention detects the displacement of the weight by L
It is possible to restrict the measurement of the acceleration in the + -direction by simply restricting it with a letter-shaped or I-shaped weight stopper, and when excessive acceleration is applied, the cantilever support is converted into a double-supported beam sensor. It is possible to prevent damage to the chip.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the structure of a cantilever type acceleration sensor, and FIG. 2 is a sectional view taken along the line yy shown in FIG. In the figure, (1), (2), (3a) ~ (3d), (4) ~
Since (7), (9) and (50) are the same as those shown in the conventional example of FIG.

(8) is a weight stopper, (10) is an adhesive material for adhesively fixing the weight (1) and the cantilever type acceleration sensor chip (2), and (20) is a cantilever type acceleration sensor chip (2).
A first die-bonding material for fixing the pedestal (9),
(30) is a second die bond material for fixing the pedestal (9) and the stem (7), and (40) is an adhesive material for fixing the weight stopper (8) to the stem (7). FIG. 3 is a perspective view showing the structure of a cantilever type acceleration sensor according to another embodiment of the present invention, and FIG. 4 is a sectional view taken along the line z--z shown in FIG. In the figure, (8a) is an I-shaped weight stopper.

Next, the operation will be described. If an acceleration sensor is attached as shown in the conventional example of FIG. 9, the gravitational acceleration IZ (980c
m / S ² works and the fixed end is R ₂ point with respect to the neutral axis indicated by R ₂ −B ₁ , and the tip B ₁ point is B ₂ point due to the weight of the weight ₁ and the cantilever type acceleration sensor chip (2). Is displaced to. Further, as shown in the conventional example of FIG. 10, point B ₁ is displaced to point B ₂ . At this time B ₂
The X-axis coordinate of the point is displaced by (L ₁ −L ₁ cos Δθ) so that it approaches the R ₂ point from the B ₁ point. At the same time the y-axis coordinates of B ₂ points are only in the same direction as the displacement of [Delta] [theta] (counterclockwise direction) displacement (L _i sinΔθ. In FIG Te at A ₁ of -A ₂ displacement and C ₁ -C ₂ About displacement Next, in FIG. 9, the displacement when the accelerometer is mounted after rotating 180 ° from that in FIG. 9 is displaced by −Δθ as shown in the conventional example of FIG. At this time, it corresponds to when the acceleration of -G is applied. The displacement at this time is Becomes Among these formulas, conventionally, the displacement of the formula and the formula or the formula or the large dimension of the formula was regulated. Therefore, the shape of the weight stopper is configured as shown in the weight stopper (100) shown in the conventional example of FIG. When the weight stopper (100) is bonded to the stem (7) with the adhesive (40) so that the clearances L, M and N can be secured in three directions with high precision, the clearances L, M , The spacer had to be removed after the weight stopper (100) was bonded via a spacer corresponding to N, whereas according to the present invention, the displacement shown by the formula and the formula was regulated. Since the L-shaped weight stopper (8) shown in FIG. 1 is used, the weight stopper (8) can be automatically assembled by simply inserting it from the tip of the weight (1) to the lower side of the weight (1). The weight stopper (8) can be easily assembled on the machine. Things can be. Further, in the embodiment of FIG. 1, the displacement represented by the formula is regulated, but the weight stopper (8a) is configured as shown in FIG. 3 to secure the clearance M as shown in FIG. If the weight stopper (8a) is configured in this manner, the dimension to be regulated can regulate the displacement in the X-axis direction represented by the equation and the displacement in the X-axis direction represented by the equation.

If the weight stopper (8a) shown in FIG. 4 is used, the weight (1) and the stem (7) can be assembled so as to provide the clear lance M shown in the figure without inserting the stopper (8a) into a narrow dimension. It can be easily automated.

Regarding the positioning of the weight stoppers (8), (8a) according to the present invention, when a dummy weight having the same weight as the weight (1) is placed on the weight (1) during assembly, it is shown in FIG. 9B. since displacement from _one point to _two points B, weight is doubled
Since it will be in a state where displacement occurs when 2 G acceleration is applied,
In this state, place the weight stopper (8a) so that the weight (8a) shown in FIG. 4 and the tip A ₂ point of the weight (1) shown in FIG. 10 are in contact with each other.
Assemble a). When the dummy weight is removed when the assembly is completed, the displacement at A ₂ point is reduced by the amount corresponding to the acceleration of 1 G, so that the displacement is returned in the direction of A _{1 and} an accurate clearance M can be obtained. In this example, the clearance M is measured when measuring up to ± 2G. However, if the dummy weight is appropriately changed in the same manner, the stopper (8a ) Can be assembled.

In the above embodiment, the tip of the weight (1) is described as the weight (1) having the end face perpendicular to the bending neutral axis generated in the cantilever type acceleration sensor chip (2) shown in the conventional example of FIG. As shown in FIG. 10 and the conventional example of FIG. 11, the tip A ₁ point, B ₁ point, and C ₁ point of the weight (1) are displaced by the acceleration Δθ in the X-axis direction and the Y-axis direction. The amount of change is that the A ₁ point changes on the circular arc β-β, the B ₁ point changes on the circular arc α-α, and the C ₁ point changes on the circular arc γ-γ, so the tip of the weight (1) If the shape is changed, the loci of the arcs α-α, β-β, and γ-γ can be made the same or the difference can be increased. If the shape of the weight (1) is changed and the length of ▲ ▼ and the length of ▲ ▼ are designed to be the same size, A ₁ point is obtained.
The point C ₁ can be displaced in the same circular arc shape, and the regulation of displacement in the X-axis direction can also provide a weight stopper with high accuracy and easy assembly.

〔The invention's effect〕

As described above, according to the present invention, since the weight stopper is formed in the L-shape or the I-shape, it is possible to easily assemble and obtain a highly accurate acceleration sensor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a cantilever type acceleration sensor according to an embodiment of an acceleration sensor according to the present invention, and FIG.
FIG. 3 is a sectional view taken along the line y-y, and FIG. 3 is a perspective view showing a cantilever type acceleration sensor according to another embodiment of the present invention.
FIG. 4 is a sectional view taken along line z-z shown in FIG. 3, FIG. 5 is a perspective view showing a conventional cantilever type acceleration sensor, and FIG. 6 is a cap and viscous oil of a conventional cantilever type acceleration sensor. FIG. 7 is a cross-sectional view taken along line xx shown in FIG. 5, FIG. 8 is a cross-sectional view showing relative dimensions of the tip of the weight in FIG. 7, and FIG. 9 shows acceleration 1G in FIG. FIG. 10 is a sectional view showing the displacement of the weight when it is hung, FIG. 10 is an enlarged sectional view of the tip for explaining the displacement of the weight shown in FIG. 7, and FIG.
FIG. 6 is an enlarged cross-sectional view showing details of displacement of the tip of the weight when an acceleration of −1 G is applied in the figure. In the figure, (1) is a weight, (2) is a cantilever type acceleration sensor chip, (3), (3a), (3b), (3c), (3
d) is piezo resistance, (4) is thin metal wire, (5) is external terminal, (6) is glass seal, (7) is stem, (8),
(8a) is a weight stopper, (9) is a pedestal, (10), (4
0) adhesive, (20) first die bond material, (30) second die bond material, (11) cap, (12) viscous oil, (50) wire bond pad, (100) stopper Is. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. An acceleration sensor chip having one end fixed to a pedestal, a weight connected to the other end of the acceleration sensor chip, and an L-shaped weight stopper for limiting displacement of the weight, the pedestal and the pedestal. An L-shaped weight stopper and a stem fixed on the main surface, and when the weight is displaced in a direction approaching the main surface of the stem, the L-shaped weight stopper has a stem of the stem. If the weight is displaced in a direction parallel to the main surface and the weight is displaced in a direction away from the main surface of the stem, a surface of the weight stopper that is perpendicular to the main surface of the stem. The acceleration sensor is characterized in that the displacement of the weight is limited by. 2. An acceleration sensor chip having one end fixed to a pedestal, a weight connected to the other end of the acceleration sensor chip, an I-shaped weight stopper for limiting displacement of the weight, the pedestal and the pedestal. An I-shaped weight stopper and a stem fixed on the main surface are provided, and the displacement of the weight is adjusted in a plane perpendicular to the main surface of the stem of the I-shaped weight stopper. Accelerometer characterized by limiting.