CN100335879C - Method for improving high-temp-resistant micro-low cost pressure sensor - Google Patents

Abstract

The present invention provides a method for improving a high-temp-resistant miniature low-cost pressure sensor. A silicon chip is connected with a glass cup to form a whole through electrostatic bonding, and annealed gold wires are selected to be used to complete inner-leading wire bonding through thermal pressure welding; high-temperature resistance adhesive is adopted to make the compound elastic body of the silicon chip/a glass cup stuck on a stainless steel inner buckle and to make the inner buckle stuck on a stainless steel base; a stuck union body is solidified under room temperature and then is put into an oven to be solidified so as to make the union body have early strength; high-temperature resistant conducting wires are welded on a high-temperature resistant circuit board by high-temperature resistant soldering wires, and the sensor is put into the high-temperature oven to be solidified in order to make the sensor obtain final bonding strength; a resistor R<P1> is connected between a red line and a yellow line AC in parallel, a resistor R<P2> is connected between a red line and a green line AB, and a resistor R<S> is connected between a red line and a black line AE. In such a way, the pressure-resistance type high-temperature resistant miniature low-cost pressure sensor which has the capacity of instantaneous high-temperature impact resistance, the capacity of overload resistance and optimal high-accuracy stability is obtained; the measuring range of the pressure sensor is from 0 to 40MPa, and the range of temperature resistance is from 40 DEG C below zero to 220 DEG C.

Description

A kind of method that improves high-temp-resistant micro-low cost pressure sensor

Technical field

The invention belongs to electronic information field, refer in particular to a kind of method that improves high-temp-resistant micro-low cost pressure sensor.

Background technology

The competition of sensor technology not only comprises the competition of chip fabrication technique, and comprises the competition of encapsulation technology, and encapsulation accounts for the very most of of total cost, and the failure that is caused by encapsulation accounts for 3/4 of rejection rate.In sensor technology; connect and encapsulate the accurate microstructure that needs protection on the one hand and be not damaged and etching; need on the other hand microstructure is exposed in the environment as much as possible obtaining eigenwerts such as distortionless physics and chemistry, so encapsulation technology plays an important role.Traditional piezoresistive pressure sensor packaging technology adopts common glue bond technology, and more than 100 ℃ the time, sensor can't be worked, and can not satisfy the needs of measuring under the hot environment.

On the other hand, the piezoresistive pressure sensor distinct disadvantage is very high to the susceptibility of ambient temperature, its temperature drift is big to be to limit one of the raising of such device precision and principal element of range of application, temperature drift is the key index of decision semiconductor pressure sensor, must carry out the compensation of temperature drift coefficient to the sensor after the encapsulation.

Traditional temperature drift coefficient compensation method has: diode compensation method, triode penalty method, thermistor compensation method and thick film circuit compensation or the like, and these compensation method costs are higher, and complicated operation all not too is fit to produce in enormous quantities and requirement cheaply.

Summary of the invention

The purpose of this invention is to provide a kind of method that improves high-temp-resistant micro-low cost pressure sensor, be suitable for high-temp-resistant micro-low cost pressure sensor and produce in enormous quantities.

Its objective is such realization:

(1) adopting high temperature resistant piezoresistive pressure sensor chip and glass ring electrostatic bonding is composite elastic body;

(2) adopt the hot bonding technology, after the spun gold annealing in process, heating makes the terminal sphere that forms of spun gold, then spun gold is pressed on silicon, finishes the internal lead solder bonds;

(3) adopt high-temperature resistance adhesive, silicon/glass ring composite elastic body is adhered in the stainless steel and detains, and interior button is gluing in the stainless steel pedestal, with the association after bonding, at room temperature solidified 1～2 hour, put into the baking oven of temperature between 60 ℃～80 ℃ scopes again and solidified 4～7 hours, make it have early strength; Adopt high temperature resistant solder stick that high temperature resistant wire is welded in the high temperature wiring board that copper-clad plate is made then, sensor is put in the high temperature oven of temperature between 160～180 ℃ of scopes solidifies more than 16 hours, make it obtain final bonding strength, finished the key component of high temperature resistant encapsulation;

(4) resistance value in parallel between red-yellow line AC then ${\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20051003810000061.png"\; state="\{\{state\}\}">R</figure-callout>}}_P=-\frac{\mathrm{\&alpha;}}{\mathrm{\&alpha;}+{\mathrm{TCR}}_B}{R}_B$ Resistance, realize the thermal sensitivity drift compensation; Resistance value of parallel resistance between red-green line AB $R_P$ $2_{}=\frac{(1+K)(\sqrt{1+K}+1)}{K}{R}_B\&ap;\frac{{2R}_B}{K}$ Resistance, realize the thermal zero drift compensation, resistance value of series connection is R between red-black line AE _S=KR _BResistance, adjust output at zero point.

Adopted the wrapped silver-plated copper core insulation of polytetrafluoroethylene film electric wire as high temperature resistant wire, adopt copper-clad plate to make high temperature resistant wiring board, adopted the solder stick that contains 10% silver medal as high temperature resistant solder stick, pad differs from the spun gold pad when adopting high temperature resistant solder stick that high temperature resistant wire is welded in the high temperature resistant wiring board that copper-clad plate makes.

Description of drawings

Fig. 1 is a structural representation of the present invention

Fig. 2 is a sensor temperature drift compensation synoptic diagram of the present invention

1. air inlet (or liquid) mouth; 2. tack interface; 3. connecting thread; 4. set nut; 5. stainless steel pedestal; 6. heat radiator; 7. silicon; 8. glass ring; 9. detain in the stainless steel; 10. high temperature resistant wiring board; 11. spun gold; 12. locking hole; 13. high temperature resistant wire 14. thermal sensitivity drift compensating resistance R _P115. thermal zero drift compensating resistance R _P216. zero point, resistance R was adjusted in output _S17. 2 milliamperes of constant current sources; 18. chip force sensing resistance R

Embodiment

Describe its method for making in detail in conjunction with Fig. 1.

In one, select the high temperature resistant chip (7) after cleaning and glass ring (8) electrostatic bonding for use spun gold (11), after the annealing in process,, be connected, finish leading wire bonding with golden contact on the silicon (7) by the hot bonding technology.

With high-temperature resistance adhesive with silicon/glass ring composite elastic body be adhered in the stainless steel buckle buckle in (9), the stainless steel (9) gluing and be threadedly connected to stainless steel pedestal (5), spun gold (11) is transferred in high temperature wiring board (10) then.

Selected high-temperature resistance adhesive, should under high temperature (160～180 ℃), be cured as good, but because used spun gold (11) is annealed in nitrogen or vacuum, under this temperature, become fragile easily for a long time, be that brittle strength becomes greatly, elongation diminishes, when it being welded to high temperature wiring board (10), come off easily, and cause failure, way of the present invention is: after glue is stirred, at glass ring (8) bonding plane, button (9) two sides and homemade high temperature wiring board (10) back side (bonding plane) are coated with even glue in the stainless steel, with the association after bonding, at room temperature solidify about 1 hour, put into 70 ℃ in baking oven, solidified 6 hours, make it have early strength, then spun gold (11) is welded on the high temperature wiring board (10), then high temperature resistant wire (13) is welded to the pad that high temperature wiring board (10) differs from spun gold (11), it is that 170 ℃ high temperature oven solidified 18 hours that sensor is put into temperature, makes it obtain final bonding strength,, finished the key component of high temperature resistant encapsulation.

High temperature wiring board (10) has adopted high temperature resistant copper-clad plate, has adopted the high temperature solder stick of argentiferous, has improved temperature capacity and has increased electric conductivity, has selected for use silver-plated copper core polytetrafluoroethylene film lapped insulation electric wire as high temperature wire (13)

Describe the high temperature resistant piezoresistive pressure sensor method for temperature drift compensation that is suitable for producing in enormous quantities in detail in conjunction with Fig. 2.

As shown in Figure 2, parallel resistance R between red-yellow line AC _P1, realize the thermal sensitivity drift compensation.Its computing formula:

${\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20051003810000061.png"\; state="\{\{state\}\}">R</figure-callout>}}_P=-\frac{\mathrm{\&alpha;}}{\mathrm{\&alpha;}+{\mathrm{TCR}}_B}{R}_B---\left(1\right)$

In formula (1), through first temperature cycles, α can be obtained by following formula:

$\mathrm{\&alpha;}=\frac{[V_M\left(T\right)-V_{\mathrm{OS}}\left(T\right)]-[V_M\left(T_0\right)-V_{\mathrm{OS}}\left(T_0\right)]}{(T-T_0)[V_M\left(T_0\right)-V_{\mathrm{OS}}\left(T_0\right)]}\&times;100\%---\left(2\right)$

V in the formula _OS(T), V _OS(T ₀) be respectively temperature T and reference temperature T ₀The time zero-bit output; V _M(T), V _M(T ₀) be at temperature T and reference temperature T ₀The time full scale output.With digital display meter record temperature T and reference temperature T ₀The time, the variation of bridge pressure value; TCR is obtained in the variation that is obtained the bridge resistance by Ohm law _BAnd bridge resistance R _BDirectly measure with multimeter.

Select parallel resistance R between red-green line AB for use _P2Realize thermal zero drift compensation compensation, resistance in series R between red-black line AE _SAdjust output at zero point.Its computing formula:

R _S＝KR _B (3)

$R_{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="C20051003810000061.png"\; state="\{\{state\}\}">P</figure-callout>}2}=\frac{(1+K)(\sqrt{1+K}+1)}{K}{R}_B\&ap;\frac{{2R}_B}{K}---\left(4\right)$

K determines K=4V by zero-bit output _OS/ V _B, (5)

In-20 ℃～200 ℃ compensation warm areas, demarcate by temperature cycles, the value of thermal sensitivity drift compensation and thermal zero drift is all less than 1.0 * 10 after compensating ^-4/ ℃ FS; Nonlinearity erron is less than 0.1%FS, and not repeated and lag error is all less than 0.05%FS, and resultnat accuracy is less than 0.2%FS, floats during high and low temperature all less than 0.1mV/8h, has higher performance.

Claims (2)

1. method that improves high-temp-resistant micro-low cost pressure sensor, it is characterized in that: adopting high temperature resistant piezoresistive pressure sensor silicon (7) and glass ring (8) electrostatic bonding is composite elastic body, after spun gold (11) annealing in process, heating makes the terminal sphere that forms of spun gold (11), then spun gold (11) is pressed on silicon (7), finishes the internal lead solder bonds; Adopt high-temperature resistance adhesive, silicon/glass ring composite elastic body is adhered to button (9) in the stainless steel, and interior button (9) is gluing in stainless steel pedestal (5), with the association after bonding, at room temperature solidified 1～2 hour, put into the baking oven of temperature between 60 ℃～80 ℃ scopes again and solidified 4～7 hours, make it have early strength; Adopt the high temperature solder stick that high temperature resistant wire (13) is welded on the high temperature resistant wiring board (10) as outer guide line, sensor is put in the high temperature oven of temperature between 160～180 ℃ of scopes solidifies more than 16 hours resistance value in parallel between red-yellow line AC $R_{P1}=-\frac{\mathrm{\&alpha;}}{\mathrm{\&alpha;}+{\mathrm{TCR}}_B}{R}_B$ Resistance R _P1(14), realize the thermal sensitivity drift compensation, after the first temperature cycles of sensor process, R _P1Calculating formula in α can obtain by following formula: $\mathrm{\&alpha;}=\frac{[V_M\left(T\right)-V_{\mathrm{OS}}\left(T\right)]-[V_M\left(T_0\right)-V_{\mathrm{OS}}\left(T_0\right)]}{(T-T_0)[V_M\left(T_0\right)-V_{\mathrm{OS}}\left(T_0\right)]}\&times;100\%;$ V _OS(T), V _OS(T ₀) be respectively temperature T and reference temperature T ₀The time zero-bit output, V _M(T), V _M(T ₀) be at temperature T and reference temperature T ₀The time full scale output, with digital display meter record temperature T and reference temperature T ₀The time, the variation of bridge pressure value; TCR is obtained in the variation that is obtained the bridge resistance by Ohm law _BAnd bridge resistance R _BDirectly measure with multimeter; Resistance value of parallel resistance between red-green line AB $R_{P2}=\frac{(1+K)(\sqrt{1+K}+1)}{K}{R}_B\&ap;\frac{{2R}_B}{K}$ Resistance R _P2(15), realize the thermal zero drift compensation, resistance value of series connection is R between red-black line AE _S=KR _BResistance R _S(16), adjust output at zero point, K determines K=4V by zero-bit output _OS/ V _B

2. a kind of method that improves high-temp-resistant micro-low cost pressure sensor according to claim 1, it is characterized in that: made high temperature resistant wiring board (10) with high temperature resistant copper-clad plate, the solder stick that has adopted argentiferous 10% at least is as the high temperature solder stick, adopted the wrapped silver-plated copper core insulation of polytetrafluoroethylene film electric wire as high temperature resistant wire (13), pad differed from the spun gold pad when high temperature resistant wire (13) was welded in high temperature resistant wiring board (10).

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