JP2018138882A - Pressure sensor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pressure sensor capable of shortening an adjustment time, and improving adjustment accuracy in an adjustment process for adjusting an output value of a sensor chip.SOLUTION: In a sealing process, a mold resin part 40 is formed in a state where the other end part 19 of a sensor chip 10 and a circuit chip 20 are mounted on a metal frame 30, and a probe 50 for temperature detection for detecting the temperature of a center part of the mold resin part 40 is provided. In an adjustment process posterior to the sealing process, the center temperature of the center part of the mold resin part 40 is detected by the probe 50 for temperature detection in a state where the mold resin part 40 is heated to a reference temperature, and a sensor signal is acquired, and a signal value of the sensor signal is adjusted on the basis of the center temperature to adjust a signal processing value, and the adjusted signal processing value is set in the circuit chip 20.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pressure sensor and a manufacturing method thereof.

  Conventionally, for example, Patent Document 1 proposes a sensor device including a sensor chip that detects the pressure of a pressure medium. The sensor chip is configured by bonding one substrate and the other substrate. The other substrate has a locally thinned diaphragm and has a piezoelectric element formed on the diaphragm. The piezoelectric element is formed so that four gauge resistors constitute a bridge circuit.

  Moreover, one board | substrate has the recessed part for airtightly sealing a piezoelectric element in the part corresponding to a diaphragm. Each substrate is bonded to seal the piezoelectric element in a space surrounded by each substrate.

  Furthermore, the sensor device includes a mold resin portion in which a part of the sensor chip is sealed so that a portion of the sensor chip where the diaphragm is formed is exposed. That is, the sensor device has a cantilever structure of the sensor device by the mold resin portion.

JP 2011-191273 A

  In the above sensor device, it is possible to detect the temperature of the pressure medium using the temperature characteristics of the bridge circuit. Further, a configuration including a circuit chip for processing a sensor chip signal is conceivable. In this case, the circuit chip is mounted on the metal frame, and the side of the sensor chip opposite to the diaphragm side is fixed to the metal frame, and a part of the sensor chip, the circuit chip, and the metal frame are sealed in the mold resin portion. .

  However, in the above configuration, in the adjustment process for adjusting the output value of the sensor chip at the time of manufacturing the sensor device, the heat of the circuit chip is generated due to the heat generated by the circuit chip when data is stored in the circuit chip. It is transmitted to the sensor chip via Thereby, the temperature of the sensor chip becomes the same as the value obtained by adding the temperature of the self-temperature rise to the measurement object, that is, the internal temperature of the mold resin portion. For this reason, the temperature for the self-temperature rise cannot be corrected, and the adjustment accuracy of the output value cannot be ensured.

  In addition, in the adjustment process, it is necessary to accurately measure the actual temperature of the detection part of the sensor chip, but temperature measurement in contact with the sensor chip involves destruction of the sensor chip and heat escape to the temperature measurement probe. Measurement is difficult. Although non-contact temperature detection with infrared detection is also conceivable, the detection accuracy is poor and is not suitable for the adjustment process.

  In addition, when heat is applied to the sensor device from the outside and the temperature is raised toward the measurement set temperature, a shift occurs between the measurement target temperature and the sensor chip temperature due to the heat capacity of the mold resin part, It takes time for the temperature of the sensor chip to stabilize. Therefore, it takes adjustment time.

  In view of the above points, the first object of the present invention is to provide a pressure sensor manufacturing method capable of reducing both the adjustment time and the adjustment accuracy in the adjustment step of adjusting the output value of the sensor chip. To do. A second object is to provide a pressure sensor obtained by the manufacturing method.

  The inventors have sealed a part of the sensor chip in the mold resin part, and the thermal resistance between the sensor chip and the mold resin part is low, and the temperature of the sensor chip is the same as the temperature of the mold resin part. We focused on the point of becoming.

  In order to achieve the above object, the invention according to claim 1 has a diaphragm (11) to which the pressure of the pressure medium is applied, and a plurality of gauge resistors (12) formed on the diaphragm, A plate-like sensor chip (10) that outputs a resistance change of a plurality of gauge resistors according to the strain of the diaphragm as a sensor signal, and the sensor signal is input from the sensor chip, and the sensor signal is based on a preset signal processing value A circuit chip (20) that performs the signal processing, and a plate having one surface (31), of the sensor chip, the other end (19) opposite to the one end (18) on the diaphragm side, and the circuit chip And a metal frame (30) mounted on one surface and a sensor chip in which the other end of the sensor chip, the circuit chip, and the metal frame are sealed so that the diaphragm of the sensor chip is exposed. Cold resin portion (40), a manufacturing method of the pressure sensor with a comprises the following steps.

  That is, the mold resin portion is formed in a state where the other end portion of the sensor chip and the circuit chip are mounted on the metal frame, and a temperature detection probe (50) for detecting the temperature of the center portion of the mold resin portion is provided. A sealing process is performed.

  After the sealing step, the center temperature of the mold resin portion is detected by the temperature detection probe while the mold resin portion is heated to the reference temperature, and a sensor signal is obtained. Based on the center temperature, the sensor signal signal is obtained. The signal processing value is adjusted by adjusting the value, and an adjustment process for setting the adjusted signal processing value in the circuit chip is performed.

  In the invention according to claim 11, the mold resin portion is a hole portion in which the temperature detection probe (50) for detecting the temperature of the center portion of the mold resin portion is arranged during the adjustment process for adjusting the signal processing value. (41).

  According to this, in the adjustment step, the center temperature of the mold resin portion is detected by the temperature detection probe in a state where the mold resin portion is heated to the reference temperature. For this reason, the temperature of the sensor chip having the same temperature as that of the mold resin portion can be indirectly detected with high accuracy. Therefore, the adjustment accuracy of the signal value of the sensor signal can be ensured.

  Further, at the time of transition when setting the measurement temperature for heating the mold resin portion, the temperature of the mold resin portion that is the same as the temperature of the sensor chip can be detected even during the temperature change of the sensor chip. For this reason, it is not necessary to wait until the temperature of the sensor chip is stabilized, and the adjustment time can be shortened. As described above, it is possible to achieve both reduction in adjustment time and adjustment accuracy.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the pressure sensor which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the adjustment process among the manufacturing processes of a pressure sensor. In 2nd Embodiment, it is sectional drawing which showed the post process. It is sectional drawing which showed the adjustment process which concerns on 3rd Embodiment. It is sectional drawing which showed the modification of the adjustment process which concerns on 3rd Embodiment. It is sectional drawing which showed the adjustment process which concerns on 4th Embodiment. It is sectional drawing which showed the sealing process and adjustment process which concern on 5th Embodiment. It is sectional drawing which showed the adjustment process which concerns on 6th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The pressure sensor according to the present embodiment is used, for example, for detecting the pressure of intake air taken into a vehicle engine. As shown in FIG. 1, the pressure sensor 1 includes a sensor chip 10, a circuit chip 20, a metal frame 30, and a mold resin portion 40.

  The sensor chip 10 is configured as a plate-like sensor IC that detects the pressure of the pressure medium. The sensor chip 10 includes a diaphragm 11, a plurality of gauge resistors 12, a first substrate 13, and a second substrate 14. The diaphragm 11 is configured as a thin layer that is distorted when the pressure of the pressure medium is applied.

  The plurality of gauge resistors 12 are elements that are formed in the diaphragm 11 and whose resistance values change according to the distortion of the diaphragm 11. Each gauge resistor 12 is electrically connected to form a Wheatstone bridge circuit. Thereby, the voltage according to the distortion of the diaphragm 11 can be detected as a pressure using the piezoresistance effect of each gauge resistor 12.

  Each gauge resistor 12 has a temperature characteristic in which the resistance value changes with temperature. The temperature of the bridge circuit is the same as the temperature of the sensor chip 10. Each gauge resistor 12 is a diffused resistor formed by ion implantation into the diaphragm 11, for example. Each gauge resistor 12 may be configured as a thin film resistor formed on the diaphragm 11.

  The 1st board | substrate 13 has the opening part 15 corresponding to the sensing area | region in which each gauge resistance 12 was provided among the diaphragms 11. FIG. The second substrate 14 has a recess 16 in which a portion corresponding to the sensing region is recessed. The first substrate 13 and the second substrate 14 are composed of a semiconductor substrate, a glass substrate, or the like. On the second substrate 14, wiring portions, pads, etc. (not shown) connected to the gauge resistors 12 are formed.

  In the sensor chip 10, the first substrate 13 and the second substrate 14 are configured as a laminated body with the diaphragm 11 interposed therebetween. As a result, the sensing area of the diaphragm 11 is exposed to the opening 15 of the first substrate 13. Further, the space 17 sealed by the recess 16 of the second substrate 14 and the diaphragm 11 is a vacuum chamber. Each gauge resistor 12 is provided on the space 17 side of the diaphragm 11. The sensor chip 10 outputs resistance changes of the plurality of gauge resistors 12 according to the strain of the diaphragm 11 as sensor signals.

  The configuration of the sensor chip 10 described above is an example, and other configurations may be used. For example, the diaphragm 11 may be formed on the first substrate 13 and the second substrate 14 may be stacked on the first substrate 13.

  The circuit chip 20 is an IC chip on which a semiconductor integrated circuit such as a memory is formed. The circuit chip 20 is formed using a semiconductor substrate or the like. The circuit chip 20 receives a sensor signal from the sensor chip 10 and performs signal processing of the sensor signal based on a preset signal processing value. The signal processing value is an adjustment value for amplifying or calculating the signal value of the sensor signal. The circuit chip 20 is electrically connected by a bonding wire (not shown).

  The metal frame 30 has a plate shape having one surface 31 and has an island portion 32 for supporting the sensor chip 10 and the circuit chip 20. In the island portion 32, the other end portion 19 on the side opposite to the one end portion 18 on the diaphragm 11 side of the sensor chip 10 and the circuit chip 20 are mounted on one surface 31. In the present embodiment, the sensor chip 10 and the circuit chip 20 are bonded and fixed to the island part 32.

  The metal frame 30 is formed by pressing a metal plate into a predetermined shape. The metal frame 30 is separated from the island portion 32 and also has a terminal electrically connected to the circuit chip 20 by a bonding wire (not shown).

  The mold resin portion 40 is a sealing component in which the other end portion 19 of the sensor chip 10, the circuit chip 20, and the metal frame 30 are sealed with a resin material so that the diaphragm 11 of the sensor chip 10 is exposed. The mold resin portion 40 is blended with a filler such as ceramics in order to improve thermal conductivity.

  The mold resin portion 40 has a hole 41. The hole portion 41 is a portion where a temperature detection probe for detecting the temperature of the center portion of the mold resin portion 40 is arranged in the adjustment process for adjusting the signal processing value of the circuit chip 20. In the present embodiment, the hole 41 is provided on the one surface 31 side of the metal frame 30 and on the side opposite to the sensor chip 10 in the circuit chip 20. Further, the island part 32 is exposed at the bottom of the hole part 41.

  The above is the overall configuration of the pressure sensor 1 according to the present embodiment. The sensor chip 10 outputs a sensor signal corresponding to the pressure of the pressure medium. Moreover, the sensor chip 10 detects the temperature of the measuring object which is a pressure medium using the temperature characteristic of a bridge circuit. The circuit chip 20 processes the sensor signal based on the signal processing value and outputs it to the external device.

  Next, a method for manufacturing the pressure sensor 1 will be described. First, the sensor chip 10, the circuit chip 20, and the metal frame 30 are prepared, and a preparation process for mounting the other end portion 19 of the sensor chip 10 and the circuit chip 20 on the island portion 32 of the metal frame 30 is performed.

  Subsequently, a sealing process is performed. Specifically, a mold (not shown) is prepared, and the metal frame 30 is fixed. Here, a mold having a portion corresponding to the hole 41 of the mold resin portion 40 is used.

  Then, the resin material is poured into a mold, and the resin material is cured. Thus, the mold resin portion 40 is formed in a state where the other end portion 19 of the sensor chip 10 and the circuit chip 20 are mounted on the metal frame 30. Further, in the mold resin portion 40, a hole 41 is provided on the circuit chip 20 on the side opposite to the sensor chip 10.

  Subsequently, an adjustment process for setting a signal processing value in the circuit chip 20 is performed. Therefore, as shown in FIG. 2, a temperature detection probe 50 for detecting the temperature of the central portion of the mold resin portion 40 is provided in the hole 41 of the mold resin portion 40.

  The temperature detection probe 50 is a small resistance temperature detector or thermistor type. Thereby, the heat capacity is small, the temperature change to the mold resin part 40 and the metal frame 30 is reduced, and the time until the temperature detection of the temperature detection probe 50 itself is stabilized is effective.

  Further, the mold resin part 40 is sandwiched between the heaters 100, and the mold resin part 40 is heated to a reference temperature. The heater 100 is a measuring temperature setting heating device. The temperature of the mold resin part 40 and the temperature of the sensor chip 10 also coincide with each other even during a temperature change transient, and the temperature and sensor output can be measured during the temperature change transient. Since the metal frame 30 is connected and fixed to the sensor chip 10, the temperature of the sensor chip 10 is more reflected. That is, the temperature of the sensor chip 10 can be indirectly detected with high accuracy by the temperature detection probe 50.

  Therefore, the center temperature of the center portion of the mold resin portion 40 is detected by the temperature detection probe 50 while the mold resin portion 40 is heated. Since the temperature detection probe 50 is disposed in the hole 41, the temperature of the sensor chip 10 can be accurately measured as compared with the surface of the mold resin portion 40 that is greatly affected by the temperature of the heater 100.

  Further, the temperature of the measurement object is measured by each gauge resistor 12. That is, a sensor signal is acquired. Then, the self-temperature rise of the sensor chip 10 included in the signal value of the sensor signal is corrected. That is, the signal processing value is adjusted by adjusting the signal value of the sensor signal based on the center temperature of the mold resin portion 40, and the adjusted signal processing value is written in the memory of the circuit chip 20. The signal processing value is an adjustment value such as a gain or offset of the sensor signal. After the adjustment, the temperature detection probe 50 is taken out from the hole 41, and the pressure sensor 1 is completed.

  As described above, in this embodiment, the center temperature of the mold resin portion 40 is detected by the temperature detection probe 50. That is, the signal value of the sensor signal is not adjusted based on the temperature of the measurement target detected by each gauge resistor 12, but the signal is based on the temperature (center temperature) of the mold resin portion 40 having the same temperature as the sensor chip 10. The value is adjusted. For this reason, when heat is applied to the sensor chip 10 from the outside and the temperature is raised toward the reference temperature, there is a difference between the temperature of the measurement target and the temperature of the sensor chip 10 due to the influence of the heat capacity of the mold resin portion 40. do not do. That is, the temperature difference for the self-temperature rise of the sensor chip 10 is not affected. Therefore, the adjustment accuracy of the signal value of the sensor signal can be ensured.

  Further, when the mold resin portion 40 is heated, the temperature of the mold resin portion 40 that is the same as the temperature of the sensor chip 10 can be detected even while the temperature of the sensor chip 10 is changing. For this reason, time is not required until the temperature of the sensor chip 10 is stabilized due to the influence of the heat capacity of the mold resin portion 40, and the adjustment time can be shortened.

  Therefore, in the adjustment process of the pressure sensor 1, both shortening of the adjustment time and adjustment accuracy can be achieved.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. In the present embodiment, after the adjustment process, as shown in FIG. 3, a post process for filling the hole 41 with another mold resin part 60 is performed. Thereby, the environmental resistance of the pressure sensor 1 can be improved.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. As shown in FIG. 4, in the sealing process, a hole 41 is provided between the circuit chip 20 and the sensor chip 10. Thereby, since the temperature detection probe 50 is disposed at a position close to the sensor chip 10, a temperature closer to the temperature of the sensor chip 10 can be detected.

  As a modification, as shown in FIG. 5, the wall surface 42 of the hole 41 may be tapered so that the plane size on the inlet side of the hole 41 is larger than the plane size on the bottom side. That is, the insertion opening of the hole 41 is formed in a widened shape. Thereby, the temperature detection probe 50 can be easily inserted into the hole 41. In addition, it is possible to shorten the alignment time of the temperature detection probe 50 with respect to the hole 41, and further shorten the adjustment time.

  Further, a hole 41 having a depth that does not expose the metal frame 30 is formed. That is, the island portion 32 is protected by leaving a portion where the mold resin portion 40 is thinned at the bottom of the hole portion 41. Thereby, environmental resistance can be improved, without forming another mold resin part 60. FIG. Further, since no post-process is required, the manufacturing cost can be reduced.

(Fourth embodiment)
In the present embodiment, parts different from the first to third embodiments will be described. In the present embodiment, in the preparation step, a metal frame 30 having a dam part and a terminal integrated with the island part 32 is prepared. A dam part is a part used for positioning of each component at the time of formation of mold resin part 40, for example.

  Further, in the sealing step, as shown in FIG. 6, the mold resin portion 40 is formed so as to expose a part of the terminal 33 and the dam portion 34. In the adjusting step, the temperature detection probe 50 is brought into contact with the dam portion 34 exposed from the mold resin portion 40, and the center temperature of the center portion of the mold resin portion 40 is detected in this state. The heat at the center of the mold resin part 40 is transmitted from the island part 32 to the temperature detection probe 50 via the dam part 34.

  After the adjustment process, the dam portion 34 is cut. In the present embodiment, it is not necessary to form the hole 41 and the environmental resistance of the pressure sensor 1 can be improved.

(Fifth embodiment)
In the present embodiment, parts different from the first to fourth embodiments will be described. In the present embodiment, in the preparation step, a metal frame 30 having a terminal 33 that is separated from the island portion 32 and is electrically connected to the circuit chip 20 is prepared.

  In the sealing step, as shown in FIG. 7, the mold resin portion 40 is formed so as to expose a part of the terminal 33. In the adjustment step, the temperature detection probe 50 is brought into contact with a part of the terminal 33 exposed from the mold resin portion 40, and the center temperature of the center portion of the mold resin portion 40 is detected in this state. The heat at the center of the mold resin part 40 is transmitted to the temperature detection probe 50 via the terminal 33.

  In this embodiment, since the dam part 34 is not provided in the metal frame 30, handling of the measurement object in the adjustment process can be improved.

(Sixth embodiment)
In the present embodiment, parts different from the first to fifth embodiments will be described. In the sealing step, the temperature detection probe 50 is sealed in the mold resin portion 40 as shown in FIG. In the adjustment step, after the signal processing value is adjusted, the wiring 51 of the temperature detection probe 50 is cut. By such a method, since the temperature detection probe 50 is in contact with the mold resin portion 40, the center temperature of the mold resin portion 40 can be measured more accurately.

(Other embodiments)
The configuration and adjustment process of the mold resin portion 40 shown in each of the above embodiments are merely examples, and the present invention is not limited to the configuration shown above, and other configurations that can realize the present invention can be used. For example, the hole 41 may be provided on the side opposite to the one surface 31 of the metal frame 30.

  Further, the above embodiments can be implemented in combination as much as possible. For example, the taper shape of the hole 41 or a configuration in which a part of the mold resin portion 40 is left at the bottom of the hole 41 can be applied to the hole 41 according to the first embodiment. When the temperature detection probe 50 is embedded in the mold resin portion 40 as in the sixth embodiment, it may be embedded between the sensor chip 10 and the circuit chip 20.

DESCRIPTION OF SYMBOLS 10 Sensor chip 11 Diaphragm 12 Gauge resistance 18 One end part 19 Other end part 20 Circuit chip 30 Metal frame 31 One side 40 Mold resin part 50 Temperature detection probe

Claims (11)

A diaphragm (11) to which pressure of a pressure medium is applied, and a plurality of gauge resistors (12) formed on the diaphragm, and detecting a change in resistance of the plurality of gauge resistors according to the strain of the diaphragm A plate-shaped sensor chip (10) that outputs a signal;
A circuit chip (20) for inputting the sensor signal from the sensor chip and performing signal processing of the sensor signal based on a preset signal processing value;
A metal frame having a plate-like shape having one surface (31), wherein the other end portion (19) of the sensor chip opposite to the one end portion (18) on the diaphragm side and the circuit chip are mounted on the one surface. (30),
A mold resin portion (40) that seals the other end of the sensor chip, the circuit chip, and the metal frame so that the diaphragm of the sensor chip is exposed;
A method of manufacturing a pressure sensor comprising:
A temperature detection probe for detecting the temperature of the center portion of the mold resin portion while forming the mold resin portion with the other end portion of the sensor chip and the circuit chip being mounted on the metal frame ( 50) a sealing step;
After the sealing step, the center temperature of the mold resin part is detected by the temperature detection probe in a state where the mold resin part is heated to a reference temperature, and the sensor signal is acquired, and the center temperature is obtained. Adjusting the signal processing value by adjusting the signal value of the sensor signal based on the adjustment, and setting the adjusted signal processing value in the circuit chip,
The manufacturing method of the pressure sensor containing this.   The method for manufacturing a pressure sensor according to claim 1, wherein in the sealing step, a hole (41) is provided in the mold resin portion, and the temperature detection probe is disposed in the hole portion.   The method for manufacturing a pressure sensor according to claim 2, further comprising a post-process for taking out the temperature detection probe from the hole and filling the hole after the adjustment process.   The method of manufacturing a pressure sensor according to claim 2 or 3, wherein, in the sealing step, the hole is provided on the circuit chip on a side opposite to the sensor chip.   The pressure sensor manufacturing method according to claim 2 or 3, wherein, in the sealing step, the hole is provided between the circuit chip and the sensor chip.   The wall surface (42) of the hole is formed in a taper shape so that the planar size on the inlet side of the hole is larger than the planar size on the bottom side in the sealing step. The manufacturing method of the pressure sensor as described in one.   The pressure sensor manufacturing method according to any one of claims 2 to 6, wherein, in the sealing step, the hole is formed to a depth at which the metal frame is not exposed. In the sealing step, as the metal frame, the other end portion of the sensor chip and the island portion (32) on which the circuit chip is mounted, and a dam portion (34) integrated with the island portion, Preparing the mold resin portion so as to expose the dam portion,
2. The pressure sensor according to claim 1, wherein in the adjustment step, the center temperature of the center portion of the mold resin portion is detected in a state where the temperature detection probe is in contact with the dam portion exposed from the mold resin portion. Production method. In the sealing step, as the metal frame, the other end portion of the sensor chip and an island portion (32) on which the circuit chip is mounted are separated from the island portion and electrically connected to the circuit chip. A terminal having a terminal (33) to be connected, and forming the mold resin portion so as to expose a part of the terminal;
2. The pressure according to claim 1, wherein in the adjustment step, the center temperature of the center portion of the mold resin portion is detected in a state where the temperature detection probe is in contact with a part of the terminal exposed from the mold resin portion. Sensor manufacturing method. In the sealing step, the temperature detection probe is sealed in the mold resin portion,
The pressure sensor manufacturing method according to claim 1, wherein, in the adjustment step, the temperature detection probe wiring (51) is cut after the signal processing value is adjusted. A diaphragm (11) to which pressure of a pressure medium is applied, and a plurality of gauge resistors (12) formed on the diaphragm, and detecting a change in resistance of the plurality of gauge resistors according to the strain of the diaphragm A plate-shaped sensor chip (10) that outputs a signal;
A circuit chip (20) for inputting the sensor signal from the sensor chip and performing signal processing of the sensor signal based on a preset signal processing value;
A metal frame having a plate-like shape having one surface (31), wherein the other end portion (19) of the sensor chip opposite to the one end portion (18) on the diaphragm side and the circuit chip are mounted on the one surface. (30),
A mold resin portion (40) in which the other end portion of the sensor chip, the circuit chip, and the metal frame are sealed with a resin material so that the diaphragm of the sensor chip is exposed;
With
The mold resin portion has a hole (41) in which a temperature detection probe (50) for detecting the temperature of the center portion of the mold resin portion is arranged during an adjustment process for adjusting the signal processing value. Pressure sensor.

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