JP5001129B2 - Thermal sensor - Google Patents

Description

  The present invention relates to a heat sensor used in a differential heat sensor that closes a contact and outputs a fire signal when a time change rate of a temperature rise due to a fire exceeds a predetermined value.

  A conventional differential heat sensor has a metal chamber of several tens of millimeters in the sensor, which is partitioned by a diaphragm. The temperature rises due to a fire, and the air in the airtight air chamber expands. A continuous diaphragm is pressed and a fire signal is output by closing the contact. Moreover, the expansion | swelling by the slow temperature change by heating etc. is leaked outside with the leak pipe provided in the airtight air chamber, and the contact is not closed.

As described above, the conventional differential heat detector has only a contact point as an electrical element, and requires a simple mechanical structure without requiring a special electric circuit. Widely used as a detector for fire alarm equipment

JP 2003-132457 A JP 2000-132760 A JP-A-5-250580 JP 2001-243567 A

  However, in such a conventional diaphragm type differential heat sensor, there is a structural restriction that a diaphragm is arranged in the chamber to form an airtight air chamber, and the size of the sensor is 100 mm. Therefore, there is a possibility that the indoor design may be damaged when installed in a building, and there is a problem that adoption is restricted from the viewpoint of design.

  On the other hand, a miniaturized pressure sensor using MEMS (Micro Electro Mechanical System) technology has been commercialized, and is housed in a semiconductor package of several millimeters, and outputs an electrical signal corresponding to the pressure.

  Therefore, it is conceivable to reduce the size of the differential fire detector using such a pressure sensor, but this type of pressure sensor applies a piezoelectric element or a capacitance as a detection element, In order to have the same function as an existing differential heat sensor that requires an electrical circuit unit to process and output a signal from the detection element and only requires a mechanical structure, it can be downsized. There is also a problem that the price is high.

  An object of the present invention is to provide a thermal sensor unit that can realize a differential thermal sensing function only by a mechanical structure without requiring an electric circuit unit and can be greatly reduced in size.

The present invention provides a thermal sensor,
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in a package chamber;
And the sensor chip is
A chip displacement part integrally forming a membrane part (thin film part) which is displaced by a change in pressure of the package chamber at one end of a support wall forming a cavity;
A chip contact portion that forms a contact chamber that is disposed in close contact with the other end of the support wall in the chip displacement portion and is sealed inside;
A contact with a normally open structure placed in the contact chamber and closed by displacement of the membrane part,
A vent formed in the chip contact portion and the package, and opening the contact chamber to the outside air via the chip contact portion and the package;
A leak structure that suppresses the pressure change by leaking the air in the package chamber to the outside through the vent hole when the outside air slowly rises in temperature;
It is provided with.

  In another form of the thermal sensor according to the present invention, the vent hole that is formed in the chip contact portion and the package and opens the contact chamber to the outside air through the chip contact portion and the package is eliminated.

That is, the thermal sensor of the present invention is
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in a package chamber;
And the sensor chip is
A chip displacement portion in which a membrane portion that is displaced by a change in pressure in the package chamber is integrally formed at one end of a support wall forming a cavity;
A chip contact portion that forms a contact chamber that is disposed in close contact with the other end of the support wall in the chip displacement portion and is sealed inside;
A contact with a normally open structure placed in the contact chamber and closed by displacement of the membrane part,
A leak structure that suppresses the displacement of the membrane part by causing the air in the package chamber to leak into the contact chamber when the outside air slowly rises in temperature;
It is provided with.

In another embodiment of the present invention, a normally closed contact structure is provided. That is, the thermal sensor of the present invention is
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in a package chamber;
And the sensor chip is
A chip displacement portion in which a membrane portion that is displaced by a change in pressure in the package chamber is integrally formed at one end of a support wall forming a cavity;
A chip contact portion, which is disposed in close contact with the membrane portion side of the chip displacement portion and forms a contact chamber that communicates with the package chamber relative to the membrane portion;
A contact of a normally closed structure that is arranged in the contact chamber and opens by displacement of the membrane part;
A vent hole for opening the cavity of the chip displacement portion to the outside air through the package;
A leak structure that suppresses the pressure change by leaking the air in the package chamber to the outside through the vent hole when the outside air slowly rises in temperature,
It is provided with.

In another embodiment of the present invention, a normally closed contact structure is provided without a vent hole. That is, the thermal sensor of the present invention is
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in a package chamber;
And the sensor chip is
A chip displacement portion in which a membrane portion that is displaced by a change in pressure in the package chamber is integrally formed at one end of a support wall forming a cavity;
A chip contact portion, which is disposed in close contact with the membrane portion side of the chip displacement portion and forms a contact chamber that communicates with the package chamber relative to the membrane portion;
A contact with a normally closed structure that is placed in the contact chamber and opens by displacement of the membrane part,
A leak structure that suppresses the displacement of the membrane part by causing the air in the package chamber to leak into the contact chamber when the outside air slowly rises in temperature;
It is provided with.

  Here, the chip displacement portion and the chip contact portion constituting the sensor chip are made of silicon or a silicon compound, and the membrane portion of the chip displacement portion is formed by anisotropic etching or dry etching.

The leak structure is formed by microfabrication of silicon or a silicon compound in the sensor chip, and includes a leak groove having a polygonal cross-sectional shape with a width of 100 μm or less and a depth of 100 μm or less horizontally with respect to the membrane portion. Or a portion of the membrane site, following a circular diameter 5 0 .mu.m, or a leak hole having one side 5 0 .mu.m or less polygonal hole shape, provided perpendicular to the membrane sites.

  The thermal sensor of the present invention is incorporated in a differential heat sensor that detects a rate of change in temperature with time and sends a fire detection signal. In this case, the heat sensor package is provided on the outer cover of the differential heat sensor so as to be exposed to the outside. Further, the package of the heat sensor may be formed integrally with the outer cover of the differential heat sensor.

  The heat sensor of the present invention is incorporated in a differential heat sensor that detects a time change rate of temperature due to a fire from an air expansion amount due to a fire of an air pipe arranged in a monitoring section and sends a fire detection signal. In this case, the air pipe is directly connected to the package portion of the heat sensor, and the air in the air pipe is introduced into the package chamber.

  The sensor chip has a rectangular hollow portion with a side of about 1 mm or less or a cylindrical shape with a diameter of about 1 mm or less obtained by processing a part of a substrate made of silicon or a silicon compound, and the membrane portion has a thickness. It is made of silicon compound or metal having a thickness of 1 μm to 10 μm.

  According to the present invention, the sensor chip structure that functions as a mechanical differential heat sensor manufactured by a semiconductor process is used. Not only can the size be reduced, but the design of the installation location is not impaired by significant downsizing, and resource saving and cost reduction can be achieved through significant downsizing.

  In addition, the sensor chip is made of silicon and silicon compound, and it is known that silicon and silicon compound will not corrode even after long-term use and will not cause fatigue failure, realizing stable quality over a long period of time. Can improve reliability.

Furthermore, in the manufacturing by semiconductor process, can Ru FIG leveling properties, can be made unnecessary sensitivity adjustment as benefits in manufacture.

  FIG. 1 is a sectional view showing an embodiment of a thermal sensor according to the present invention. In FIG. 1, the thermal sensor 10 includes a package 12 and a sensor chip 20 housed therein. The package 12 has a stem 14 fixed to a lower part of a cap-shaped container to form a package chamber 16 sealed inside, and a pair of leads 18 are taken out from the stem 14 to the outside.

  As the package 12, for example, a general CAN package known as a package of a semiconductor element can be used. The CAN package includes a cylindrical container made of a metal thin film such as iron or nickel and a lead for outputting an electric signal, and the sensor chip 20 of the present embodiment is disposed inside as shown in FIG.

  The sensor chip 20 arranged in the package chamber 16 includes an upper chip displacement portion 22 and a lower chip contact portion 24. The chip displacement portion 22 is formed by a semiconductor process using silicon and a silicon compound, and a membrane portion (thin film portion) 26 that is displaced by a change in pressure in the package chamber 16 is integrally formed on the upper end side of a support wall 25 that forms a cavity. The lower cavity formed through and formed to form the membrane part 26 is a contact chamber 28.

  On the other hand, the chip contact portion 24 side is formed by a semiconductor process using a silicon and silicon oxide substrate in the same manner as the chip displacement portion 22, and is placed in close contact with the lower end side of the support wall 25 in the chip displacement portion 22. Thus, the contact chamber 28 sealed inside is formed.

A contact 30 is disposed below the membrane portion 26 on the contact chamber 28 side, and another contact 32 is disposed on the chip contact portion 24 side opposite to the contact 30. The contacts 30 and 32 realize a normally open contact structure.

  The contact 30 provided on the lower side of the membrane portion 26 is electrically connected to the upper electrode 34 disposed outside, and the upper electrode 34 is electrically connected to one lead 18 by a bonding wire 36.

  The contact 32 provided on the chip contact portion 24 side is taken out to the package chamber 16 side through the lower electrode 35, and is electrically connected to the other lead terminal 18 through the bonding wire 36 therefrom.

  Further, a vent hole 38 communicating with the contact chamber 28 is formed in the chip contact portion 24 in the vertical direction, and the vent hole 38 opens the contact chamber 28 to the outside air through an opening 14 a formed in the stem 14. ing.

A leak structure 40 is provided in the lateral direction at the position of the contact surface with the tip displacement portion 22 above the vent hole 38 formed in the tip contact portion 24. The leak structure 40 is a fine leak groove that connects the package chamber 16 and the vent hole 38, and leaks air in the package chamber 16 to the outside through the vent hole 38 when the outside air slowly rises in temperature. Suppresses changes in pressure.

  FIG. 2 is a plan view showing the sensor chip 20 of FIG. 2A is a plan view showing the separation surface side by separating the upper chip displacement portion 22 of the sensor chip 20 of FIG. 1, and by forming a support wall 25 through a cavity in the center, A membrane part 26 is formed on the end face, and a contact 30 is provided at the center of the membrane part 26.

  FIG. 2B shows the chip contact portion 24 on the lower side of the sensor chip 20 of FIG. 1 from the separation surface. In the chip contact portion 24, a contact 32 is disposed in a portion facing the contact chamber 28 facing the membrane portion 26 in FIG. 2A, and a lower electrode 35 is drawn out from the contact 32.

  Further, a vent hole 38 is provided at a position that opens to the contact chamber 28, and the contact chamber 28 communicates with the outside. A leak structure 40 is provided from the outside of the chip contact portion 24, that is, from the package chamber 16 side, to the opening of the vent hole 38, and the package chamber 16 is exposed to the outside via the leak structure 40 and the vent hole 38. Communicate.

  In the thermal sensor 10 of the present embodiment shown in FIGS. 1 and 2, when the temperature in the building at the installation site suddenly rises due to a fire, the package 12 is first heated, and the heat of the package chamber 16 is received by receiving the heat. The internal air warms up.

  Although the package chamber 16 communicates with the outside air through the minute leak structure 40, the amount of air leakage from the leak structure 40 due to the pressure rise when the air in the package chamber 16 is warmed by receiving heat from the fire is It can be considered that it is almost zero in a short time, and that the package chamber 16 is sealed when the temperature rises due to a fire.

  When the internal air of the package chamber 16 receives a temperature increase due to a fire, the internal pressure increases as the temperature increases. The increased pressure of the internal air in the package chamber 16 pushes down the thin film of the membrane portion 26 on the chip displacement portion 22 side provided in the sensor chip 20 and is provided on the contact chamber 28 side by the downward displacement of the membrane portion 26. Contact 30 contacts the lower contact 32 and outputs a fire contact signal.

  For the output of such a fire contact signal, no special electric circuit is required, and the fire contact signal can be output only by a simple mechanical structure.

  The thermal sensor 10 has a pair of leads 18 connected to the sensor line from the receiver, and when the contact 30 contacts the contact 32, an alarm current flows through the sensor line, and this alarm current is received by the fire receiver. A fire alarm can be issued.

  On the other hand, the thermal sensor 10 should not malfunction due to a slow change in the internal pressure of the package chamber 16 due to seasonal fluctuations, air conditioning or the like. For this reason, a leak structure 40 capable of slowly leaking the expanded air with respect to the slow pressure change of the package chamber 16 is provided so that the internal pressure of the package chamber 16 becomes the same as the external pressure.

  Next, the details of the structure in which the membrane portion 26 is displaced and the contact is closed as the internal pressure of the package chamber 16 in the present embodiment in FIG. 1 increases will be described.

In the present embodiment, for example, when the thermal sensor 10 is constructed by adopting the standard CAN package TO-18 as the package 12, the capacity in the CAN package is 38.2 mm ³ . Here, to construct a sensor chip 20 having a rectangular shape shown in FIG. 2 in vertical and horizontal = 1.5 mm × 1.5 mm, the diameter R of the membrane portion 26 and has a R = 1.2 mm. It is also assumed that the external temperature has increased from room temperature of 25 ° C. to 65 ° C. due to a fire.

When the external temperature rises, it is assumed that the temperature of the air in the package chamber 16 suddenly rises through the package 12 using the CAN package, for example, reaches 60 ° C. Assuming that the membrane portion 26 is not displaced at this time, the internal pressure P of the package chamber 16 is P = (273 + 60) / (27 3 +25) = 1.12 (atm).
To rise.

  The membrane portion 26 is pushed down in the contact direction by the internal pressure P, and the contact 30 is closed to the contact 32. On the other hand, the contact chamber 28 is opened to the outside by pressure through the vent hole 38 and the opening 14a, and the pressure in the contact chamber 28 indicates 1 atm.

If the bending strength of the membrane part 26 is ignored here, the air expansion amount Q of the package chamber 16 due to the temperature rise is Q = 38.2 × ( 1.12 −1) = 4.58 (mm ³ ).
It becomes.

The air expansion amount Q corresponds to the volume depressing H = 2.4 mm across the membrane portion 26 of the diameter R = 1.2 mm. In practice, it is necessary to overcome the strength of the membrane portion 26 and close the contacts 30 and 32.

  Next, the strength of the membrane portion 26 is calculated, and the displacement amount of the contact due to the difference in membrane size (thickness) when the pressure is constant is calculated. Consider the case where the membrane portion 26 is constructed of silicon oxide SiO2.

The displacement δ when pressure is applied to the thin film constituting the disc-shaped membrane portion 26 is δ = k · ΔP · D4 / (E · t3) (1)
Is required.

Here, [Delta] P is the temperature on the pressure, D is the membrane diameter, E is the Young's modulus of silicon oxide SiO2, t is the membrane thickness, k is a constant.

  The graph of FIG. 3 shows the result of obtaining the relationship between the membrane thickness t when ΔP = 1.12 (atm) is added and the displacement δ generated in the membrane portion 26 by the equation (1). FIG. 3 shows the characteristic 42 when the membrane diameter R = 0.8 mmφ and the characteristic 44 when R = 1.2 mmφ with the membrane thickness t on the horizontal axis and the contact displacement amount δ on the vertical axis. ing.

  In this case, for example, according to the membrane portion having a membrane diameter R = 0.8 mmφ, δ = 55 (μm) can be obtained as the contact displacement δ from the characteristic 42 at the membrane thickness t = 4 (μm).

In FIG. 3, the necessary dimensions are obtained assuming that the operating temperature for fire detection is 60 ° C., but in the thermal sensor 10, an appropriate membrane is used depending on the size of the chip for obtaining the target operating temperature. diameter R, may be determined a membrane thickness t. In FIG. 3, the membrane portion 26 is constructed of silicon oxide SiO2, but the membrane diameter R and the membrane thickness t for obtaining the required contact displacement amount are obtained by the same process for other materials. Can do.

Next, the leak structure 40 provided in the embodiment of FIG. 1 will be described. Now, let us consider a leak structure with the goal of preventing malfunctions due to a slow temperature rise caused by heating. Assuming that the heating capacity is 10 ° C./10 min, the air volume of the package chamber 16 when the CAN package is used as the package 12 of the embodiment of FIG. 1 is ΔQ = 38.2 ( ( 299/298) per minute. ) -1) = 0.128 (m m 3 / min)
= 1.28E-4 (cc / min) (2)
Only inflates. The leak structure 40 is determined so as to cancel such air expansion ΔQ.

Here, as a leak groove in the leak structure 40, as shown in FIG. 4B, a long hole leak structure 40 having a rectangular cross section is an object. In this leak structure 40, the leakage groove depth D, and leakage groove width is W, the leakage groove length and L.

The gas passing through the long hole having the rectangular cross section shown in the leak structure 40 of FIG. 4B is affected by viscosity, and its volume Qv is expressed by the following equation.
Qv = Δp · d · W3 / K · η · L (3)
The amount of leaked air from the leak structure 40 is calculated from the equation ( 3 ).

FIG. 4 (A) shows the change in the amount of leaked air due to the difference between the leak groove depth D and the leak groove width W when the leak groove length L of the leak structure 40 having a rectangular cross section is constant at L = 500 μm. Shown in the graph. In the graph of FIG. 4A, the horizontal axis represents the leakage groove width W, the vertical axis represents the amount of leakage air, the characteristic 46 is the case where the leakage groove depth D is D = 10 μm, and the characteristic 48 is the leakage groove. This is a case where the depth D is D = 20 μm.

Here, ΔQ = 1.28E−4 (cc / min), which is the air expansion due to heating calculated by the equation (2).
In order to cancel the above, when the leak groove depth D in FIG. 4A is 10 μm, the leak groove width W given by the point B of the characteristic 46 is 4 μm.

  A similar optimum leak structure can be set even when other cross-sectional shapes, lengths, and groove depths are adopted as the leak structure 40.

  On the other hand, when the leak hole is provided perpendicular to the membrane part on the membrane part, the leak hole length is shorter or equivalent to that of the membrane having a thickness of 10 μm at the maximum. In this case, a hole of 50 μm or less has an appropriate size. Become.

  This was calculated | required by experiment and simulation about the thermal sensor of this embodiment which this inventor implemented. FIG. 5A shows the result of the simulation. According to the Ministerial Decree (No. 17 of 1981), “Ministerial Ordinance for Establishing Technical Standards for Detectors and Transmitters for Fire Alarm Equipment”, for example, a differential spot type detector For example, it is specified that it operates at a temperature increase rate of 10 ° C. per minute and should not operate at a temperature increase rate of 2 ° C. per minute. Furthermore, it is specified that the airflow is 20 seconds higher than the room temperature and the airflow is higher than 30 seconds, and the airflow higher than 10 ° C is not operated within 1 minute.

  FIG. 5A shows the membrane thickness and the leak hole diameter for satisfying both conditions. According to FIG. 5 (A), the leak hole diameter suitable for one type of differential spot type sensor is different for each membrane thickness, and the maximum dimension is 50 μm under the condition that the membrane thickness is 10 μm or less. .

  In addition to one type of differential spot type sensor, there are two types defined with lower sensitivity. When a similar simulation was performed for this, the result shown in FIG. 5B was obtained, and it was confirmed that desired characteristics were obtained with a leak hole diameter of 50 μm or less.

FIG. 6 shows the characteristics of the leaked air amount with respect to the leak groove width W for obtaining a leak structure dimension that requires a larger leak amount used in, for example, an air tube type differential heat sensor. Show.

  In FIG. 6, the characteristic 50 is obtained with respect to the leakage groove length D = 100 μm while the leakage groove length L is L = 2000 μm, and the characteristic 52 is obtained with respect to the leakage groove depth D = 100 μm.

With regard to FIG. 4C, for example, if the maximum leakage air amount is 1.0E-1 (cc / min), the optimum leak structure is a leak from the point C in the characteristic 52 of the leak groove depth D = 100 μm. A groove width W = 100 μm is obtained. That is, the optimum leak structure is a leak groove depth D = 100 μm
Leakage groove width W = 100μm
Leak groove length L = 2000μm
It becomes.

  The depth, width, and length values of this optimum leak structure give the optimum values for the air tube type differential heat sensor, which will be described later.

FIG. 7 is an explanatory view showing a manufacturing process by a semiconductor process of the chip displacement portion 22 in the present embodiment. The machining process of the tip displacement portion 22 is as follows (A) to (E). These (A) to (E) correspond to FIGS. 7 (A) to (E).
(A) An Si substrate 54 that is a rectangular block constituting the chip displacement portion 22 shown in FIG.
(B) A contact chamber 28 penetrating in a cylindrical shape is formed on the lower side of the Si substrate 54 by anisotropic wet etching or dry etching, thereby forming a membrane portion 26 having a predetermined thickness t on the upper portion. . By forming the membrane portion 26, a support wall 25 having a substantially annular inner periphery is formed around the periphery. Here, the membrane portion 26 is opened so that the diameter D is 1.2 mmφ and the thickness t is t = 4 μm.
(C) An electrode film of the contact 36 is formed on the contact chamber 28 side below the membrane portion 26.
(D) A through hole 56 for taking out the electrode from the contact 30 is dug in the membrane part 26.
(E) The upper electrode 34 is formed for wire bonding.

FIG. 8 is an explanatory view showing the details of the semiconductor processing process for forming the membrane portion 26 of FIG. 7B, and includes the following processing processes (A) to (F). It corresponds to A) to (F).
(A) Similar to FIG. 7A, a Si substrate 54 having a predetermined rectangular block shape is prepared.
(B) A SiO 2 layer 58 for forming a thin film at the membrane portion is formed on the Si substrate 54 in an oxidation furnace or the like.
(C) The Si3N4 layer 60 is formed on the SiO2 layer 58 by chemical vapor deposition CVD (Chemical Vapor Deposition) or the like.
(D) A photoresist film 62 is applied to the lower side of the Si substrate 54, and the photoresist film to be etched is removed by photolithography.
(E) The Si substrate 54 is etched by anisotropic wet etching or dry etching to form a hollow portion corresponding to the contact chamber 28.
(F) The chip displacement portion 22 is completed by removing the remaining photoresist 62.

  In FIG. 8, a thin film is formed with the SiO2 layer 58 and the Si3N4 layer 60 as the membrane portion 26. However, the present invention is not limited to this. For example, by using a SiO substrate, the processes of FIGS. Can be omitted.

The edging besides anisotropic wet etching or dry etching, TMAH (Tetra Methyl Ammoniu m Hydroxide ), dry etching may be performed, such as wet etching or RIE (Reactive Ion Etching) with an etching solution such as potassium hydroxide KOH . In other processes as well, a desired film formation and molding may be performed using the photolithography method.

FIG. 9 shows a semiconductor processing process of the chip contact portion 24 of FIG. 1 and includes the following processes (A) to (D), which correspond to FIGS. 9 (A) to (D).
(A) A Si substrate 64 having a block shape corresponding to FIG.
(B) The vent hole 38 that passes from the contact chamber side to the outside of the stem is processed by anisotropic wet etching or dry etching.
(C) A leak groove that realizes a leak structure 40 extending from the contact chamber to the package chamber is processed by anisotropic wet etching or dry etching in the opening of the vent hole 38 on the contact chamber side.
(D) An electrode constituting the contact 32 is formed on the surface on the contact chamber side, whereby the chip contact portion 24 is completed.

  FIG. 10 is an explanatory view showing an assembling process of the chip displacement part 22 and the chip contact part 24 in the present embodiment. In the assembly process of FIG. 10, the sensor chip 20 is formed by joining the chip displacement part 22 on the chip contact part 24 side as a base. By this bonding, a sealed contact chamber 28 is formed on the chip displacement portion 22 side, and the contact chamber 28 communicates with the outside through the vent hole 38.

  After the sensor chip 20 is formed in this way, the sensor chip 20 is mounted on the stem 14 shown in FIG. At this time, an opening 14 a that communicates with the vent hole 38 on the tip contact portion 24 side is provided on the stem 14 side.

  Subsequently, a bonding wire 36 is connected to each of the upper electrode 34 on the membrane part 26 side and the lower electrode 35 on the chip contact part 24 side, and is connected to the lead 18 on the stem 14 side. Finally, the CAN package used as the package 12 is joined to the stem 14. At this time, the package 12 is bonded to the stem 14 by bonding or welding so that there is no air leak in the package chamber 16.

  FIG. 11 is a cross-sectional view showing a differential heat sensor to which the heat sensor of this embodiment is applied. In FIG. 11, the differential heat sensor 66 includes a main body 68 and an outer cover 70. The thermal sensor 10 of the present embodiment shown in FIG. 1 is disposed on the outer cover 70 side.

  The thermal sensor 10 is arranged so that the package 12 is exposed at the center of the outer cover 70, thereby efficiently transferring heat from an external fire to the package chamber 16. A sensor chip 20 having the structure shown in FIG. 1 is built in the package 16 chamber.

  The lead 18 taken out to the bottom side of the thermal sensor 10 is attached to the main body 68 side, and further connected to a conductive fitting 72 for connecting to a signal line from a fire detector provided in the main body 68.

  In the actual sensor installation, the sensor base is fixed on the ceiling side connected to the signal line from the receiver, and it is different from the conduction bracket provided on the sensor base on the ceiling side. By pressing and turning the main body 68 side of the thermal sensor 66, the conduction fitting 72 is mechanically and electrically connected to the conduction receptacle fitting on the sensor base side.

  The thermal sensor 10 is exposed and disposed at a substantially central position where the thermal airflow from the fire can be efficiently captured with respect to the outer cover 70. In order to avoid this, a guard may be provided on the top of the thermal sensor 10.

FIG. 12 is a cross-sectional view showing another differential heat sensor to which the heat sensor of this embodiment is applied. In the differential heat sensor 66 of FIG. 12, the package portion 74 of the heat sensor 10 is formed integrally with the outer cover 70, and the sensor chip 20 is disposed in a sealed state in the package portion 74.

In this way, the package portion 74 is configured as a single structural component together with the outer cover 70 by plastic molding or the like, and only the sensor chip 20 is integrated with this structural component, so that the cost can be further reduced.

The applying and three-dimensional injection molding circuitry technology (MID technique), a sensor chip 20 together with the direct packaging section 74 may be arranged in an integral part of the outer cover 70.

It is desirable that the portion of the package portion 74 that is integrated with the outer cover 70 that comes into contact with the outside air has a thin structure so as to efficiently transfer heat to the air inside the package portion 74.

  FIG. 13 is a sectional view showing an air tube type differential heat sensor to which the heat sensor of the present embodiment is applied. In FIG. 13, an air tube type differential heat sensor 76 has a sealed air tube (tube) 80 laid on the ceiling of a room serving as a warning area, and the air tube is attached to a sensor installed outside the room. It has a connected structure.

  In the present embodiment, the thermal sensor 10 is used as the sensing unit, the joint part 78 is formed integrally with the package 12 of the thermal sensor 10, and the air pipe 80 is directly connected to the joint part 78. For this reason, when the air pipe 80 laid in the warning area receives heat from the fire and the air inside the air pipe 80 expands, the expanded air is directly transmitted to the package chamber 16 of the heat sensor 10 and the sensor chip. A fire contact signal can be output by displacing the 20 membrane portions 26 and closing the contacts.

  Here, the air expansion amount in the air tube 80 is much larger than that of the package chamber 16, and the diameter, thickness, etc. of the membrane portion 26 for closing the contact point may be determined in consideration of the air expansion amount in the air tube. . As for the leak structure for preventing a malfunction due to a slow temperature change due to air conditioning or the like, the leak groove depth D = 100 μm as a value corresponding to the air tube type differential heat sensor already shown in FIG. A leak groove width W = 100 μm and a leak groove length L = 2000 μm can be used.

  FIG. 14 is a cross-sectional view showing another embodiment in which the chip displacement portion 22 is provided with a vertical leak structure. FIG. 15 shows the sensor chip 20 in the embodiment of FIG. .

The heat sensor 10 of FIG. 14 is basically the same as the embodiment of FIG. 1, but suppresses the pressure change by leaking the air in the package chamber 16 to the outside when the outside air slowly rises in temperature. In this embodiment, the leak structure 40 is provided in the direction perpendicular to the membrane portion 26 in the tip displacement portion 22 as the leak structure.

  The leak structure 40 becomes clear from FIG. FIG. 15A is a plan view of the sensor chip 20, and a leak structure 40 is opened on the upper surface of the chip displacement portion 22.

  FIG. 15B is a cross-sectional view of the sensor chip 20, and a leak structure 40 that connects the contact chamber 28 and the outer package chamber 16 is provided on the right side of the membrane portion 26 formed in the chip displacement portion 22. The chamber 28 communicates with the outside through a vent hole 38, as in the embodiment of FIG.

  FIG. 15C is a plan view showing the chip displacement portion 22 separated by the joint surface of the sensor chip 20 of FIG. 15B from the separation surface side, and the leak structure 40 is opened on the right side of the contact chamber 28. Yes.

  FIG. 15D is a plan view showing the chip contact portion 24 side of the sensor chip 20 of FIG. 15B separated from the separation surface, and a vent hole 38 is opened at a position facing the contact chamber 28. .

  In the embodiment shown in FIGS. 14 and 15, since the leak structure 40 is in the vertical direction, the leak groove length L is small, and therefore the maximum amount of leak air required from the package chamber 16 is small. The leak structure 40 opened in the vertical direction of this embodiment can be used.

  FIG. 16 is a cross-sectional view showing another embodiment in which a vent hole to the outside is eliminated. FIG. 17 shows a sensor chip in the embodiment of FIG.

  In the thermal sensor 10 of the embodiment of FIG. 1, in order to capture the air expansion due to the temperature of the package chamber 16 with high sensitivity, the contact chamber 28 is changed from the contact chamber 28 to the outside air so that the pressure in the contact chamber 28 is always the same as the outside air. A connected vent 38 is provided. However, there may be a problem that foreign matter or moisture enters the contact chamber 28 via the vent hole 38 and adversely affects the operation of the contacts 30 and 32. Therefore, in the embodiment of FIG. 16, by eliminating the air holes, adverse effects due to the entry of foreign matter and moisture into the contact chamber 28 are eliminated.

  When the membrane portion 26 is displaced due to the pressure change from the package chamber 16 by eliminating the air holes in this manner, the pressure in the contact chamber 28 also increases with the displacement of the membrane portion 26. For this reason, when the vent hole for the contact chamber 28 is eliminated, it is necessary to have a structure in which the internal pressure due to the displacement of the membrane portion 26 is hardly increased as much as possible.

  In the embodiment of FIG. 16, the diameter R of the membrane portion 26 is made smaller than that of the embodiment of FIG. 1, and the contact portion is formed by forming the dug portion 82 on the tip contact portion 24 side that partitions one side of the contact chamber 28. The volume of the chamber 28 is increased, and the pressure change in the contact chamber 28 due to the displacement of the membrane portion 26 is reduced.

  FIG. 17A is a plan view of the sensor chip 20 provided in the thermal sensor 10 of FIG. 14, and FIG. 17B shows a cross-sectional view thereof. As apparent from the sectional view of FIG. 17B, the contact chamber 28 is expanded in volume by forming the dug portion 82 on the tip displacement portion 22 side, and the membrane portion 26 is displaced by reducing its diameter. I try to suppress it.

  17 (C) and 17 (D) show the planes on the separation side by separating the chip displacement portion 22 and the chip contact portion 24 of FIG. 17 (B), respectively.

  Here, as shown in FIG. 17D, the leak structure 40 has a groove shape having a rectangular cross section formed by a semiconductor processing process on the chip contact portion 24 side. When the temperature of the package chamber 16 rises slowly, the leak structure 40 By causing air to leak into the contact chamber 28 via the, the pressure change between the package chamber 16 and the contact chamber 28 is eliminated.

  FIG. 18 is a cross-sectional view showing another embodiment having a normally closed contact structure. FIG. 19 shows the sensor chip 20 of FIG. 18 taken out together with a separation plane.

  In FIG. 18, in order to realize a normally closed contact structure with respect to the normally open contact structure shown in FIG. 1, a chip displacement portion 22 is disposed on the lower side, and a chip contact portion 24 is disposed on the upper side. The relationship is the reverse of the embodiment of FIG. A membrane portion 26 is formed in the tip displacement portion 22 by forming a cavity portion 84.

  On the other hand, the tip contact portion 24 is formed with a contact chamber 28 at a portion of the contact surface with the tip displacement portion 22. In the contact chamber 28, a contact 30 provided on the membrane portion 26 and a contact 32 provided on the chip contact portion 24 side are arranged, and the contact 30 comes into contact with the contact 32 in the initial state of assembly shown in FIG. Constructs a closed contact.

  For the contact chamber 28 in which the contacts 30 and 32 are arranged, a communication hole 86 is formed from the chip contact portion 24 side, and the contact chamber 28 communicates with the package chamber 16.

  Further, a leak structure 40 is provided for leaking air accompanying the slow temperature rise of the package chamber 16 to the outside. The leak structure 40 communicates with an opening 14 a formed in the stem 14.

Figure 19 (A) is a sectional view of a sensor chip 20 in FIG. 1 8, FIG. 19 (B) (C) is to separate the tip displacement portion 22 and the chip contact portion 24, a plan of the separating side Yes.

  Here, as shown in FIG. 19C, the leak structure 40 is formed as a leak groove having a rectangular cross section by a semiconductor processing process on the surface of the chip displacement portion 22 that is in close contact with the chip contact portion 24, and FIG. ), A leak groove is formed in the vertical direction at the depth portion of the leak groove, and the leak groove is opened below the chip displacement portion 22.

The leak structure 40 causes the increase in air pressure accompanying the slow temperature rise of the package chamber 16 in FIG. 18 to leak air to the opening 14a of the stem 14 via the leak structure 40, so that the outside air and the package chamber The pressure difference of 16 is eliminated.

  The operation of the thermal sensor 10 having the normally closed contact structure shown in FIG. 18 is such that when the air in the package chamber 16 is pressurized and expanded by receiving heat from a fire, the pressure associated with the expansion of the air is contacted through the communication hole 86. Acting on the chamber 28, the membrane portion 26 is deformed and pushed down, whereby the contact 30 is separated from the contact 32, and a fire contact signal can be output to turn the contact off.

  As for the expansion of air in the package chamber 16 due to a gradual change in temperature, air leaks from the package chamber 16 to the outside due to the leak structure 40, so that the space between the contact chamber 28 in the membrane portion 26 and the cavity 84 that communicates with the outside air. There is no pressure difference between them and the contacts do not open.

  In the heat sensor 10 of FIG. 18 having a normally closed contact structure, the contact chamber 28 is not directly communicated with the outside air, and the package chamber 16 is communicated with the outside air via the leak structure 40. In the leak structure 40, there is almost no entry of foreign matter and moisture, and adverse effects due to the entry of foreign matter and moisture to the contact chamber 28 can be prevented.

  FIG. 20 is a cross-sectional view showing another embodiment provided with a normally closed contact structure in which a vent hole to the outside is eliminated. FIG. 21 shows the sensor chip 20 in FIG. 20 taken out together with a separation plane.

  The heat sensor 10 in FIG. 20 is basically the same in structure as the heat sensor 10 having the normally closed contact structure shown in FIG. 18, but communicates with the outside air provided in the stem 14 in FIG. The opening 14a is eliminated, and the package chamber 16 is sealed from the outside air. Along with the sealing structure of the package chamber 16, the leak structure 40 communicates the package chamber 16 with the cavity 84.

FIG. 21A is a cross-sectional view of the sensor chip 20 of FIG. 20, and FIGS. 21B and 21C show a plan view of the separation side with the chip contact portion 24 and the chip displacement portion 22 separated. In the leak structure 40, as shown in FIG. 21C, a leak groove 40 having a rectangular cross section is formed on the bonding surface side of the chip displacement portion 22 by a semiconductor processing process, and then the leak structure 40 is vertically leaked as shown in FIG. By forming a hole and further forming a leak groove in the lateral direction at the bottom, the cavity 84 communicates with the outer package chamber 16.

  In the embodiment having no vent hole in FIGS. 20 and 21, the package chamber 16 is completely sealed from the outside air, so that the entry of foreign matter and moisture from the outside can be completely prevented.

  In the above embodiment, the case where a CAN package is used as the package 12 is taken as an example. The diameter R and thickness t of the membrane portion 26, the leakage groove depth D in the leakage structure 40, the leakage groove width W, and the leakage groove Although the length L is determined, an appropriate value corresponding to the internal volume can be determined as necessary for an appropriate package other than this.

  The present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

Sectional drawing which showed embodiment of the thermal sensor by this invention FIG. 1 is a plan view of the sensor chip shown in FIG. Graph showing the relationship between membrane thickness and contact displacement with the membrane part diameter in this embodiment as a parameter Graph showing the leak groove depth parameter and the leakage groove width and the leakage amount of air relationship in this embodiment Graph showing the simulation results of the relationship between the leak hole diameter and membrane thickness for the differential spot type sensor Graph showing the leak groove depth parameter and the leakage groove width and the leakage amount of air relationship in the present embodiment a large amount of leakage is calculated Explanatory drawing which showed the manufacturing process of the chip | tip displacement part in this embodiment. Explanatory drawing which showed the detail of the semiconductor processing process which forms the membrane part of FIG.7 (B) Explanatory drawing which showed the semiconductor processing process of the chip contact part in this embodiment Explanatory drawing which showed the assembly process of the chip | tip displacement part and chip | tip contact part in this embodiment Sectional drawing which showed the differential heat sensor to which the heat sensor of this embodiment is applied Sectional drawing which showed the other differential-type heat sensor to which the heat sensor of this embodiment is applied Sectional drawing which showed the air pipe | tube type differential heat sensor to which the heat sensor of this embodiment is applied Sectional drawing which showed other embodiment which provided the leak structure of the perpendicular direction in the chip | tip displacement part. Explanatory drawing which took out the sensor chip in embodiment of FIG. 14, and showed with the separation plane Sectional drawing which showed other embodiment which eliminated the vent hole with respect to the exterior Explanatory drawing which took out the sensor chip in embodiment of FIG. 16, and showed with the separation plane Sectional view showing another embodiment with a normally closed contact Explanatory drawing which took out the sensor chip in embodiment of FIG. 18, and showed with the separation plane Sectional drawing which showed other embodiment provided with the normally closed contact which lost the ventilation hole with respect to the exterior Explanatory drawing which took out the sensor chip in embodiment of FIG. 20, and showed with the separation plane

10: Thermal sensor 12, 74: Package part 14: Stem 16: Package part 18: Lead 20: Sensor chip 22: Chip displacement part 24: Chip contact part 25: Support wall 26: Membrane part 28: Contact chamber 30, 32: Contact 34: Upper electrode 35: Lower electrode 36: Bonding wire 38: Vent hole 40: Leak structure 54, 64: Si substrate 58: Si02 layer 60: Si3N4 layer 62: Photoresist film 66: Differential heat sensor 68: Main body 70: Outer cover 72: Conductive fitting 76: Air pipe type differential heat sensor 78: Joint part 80: Air pipe 82: Digging part 84: Cavity part

Claims (13)

A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in the package chamber;
The sensor chip has
A chip displacement part integrally forming a membrane part that is displaced by a change in pressure of the package chamber at one end of a support wall forming a cavity;
A tip contact portion that forms a contact chamber that is tightly disposed at the other end of the support wall in the tip displacement portion and is sealed inside;
A contact of a normally open structure disposed in the contact chamber and closed by displacement of the membrane part;
A vent hole formed in the chip contact portion and the package and opening the contact chamber to the outside air through the chip contact portion and the package;
A leak structure that suppresses the pressure change by leaking the air in the package chamber to the outside through the vent hole when the outside air slowly rises in temperature;
A thermal sensor comprising:
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in the package chamber;
The sensor chip has
A chip displacement part integrally forming a membrane part that is displaced by a change in pressure of the package chamber at one end of a support wall forming a cavity;
A tip contact portion that forms a contact chamber that is tightly disposed at the other end of the support wall in the tip displacement portion and is sealed inside;
A contact of a normally open structure disposed in the contact chamber and closed by displacement of the membrane part;
A leak structure that suppresses displacement of the membrane part by causing air in the package chamber to leak into the contact chamber when the outside air slowly rises in temperature;
A thermal sensor comprising:
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in the package chamber;
The sensor chip has
A chip displacement part integrally forming a membrane part that is displaced by a change in pressure of the package chamber at one end of a support wall forming a cavity;
A chip contact portion, which is disposed in close contact with the membrane portion side of the chip displacement portion and forms a contact chamber communicating with the package chamber relative to the membrane portion;
A contact of a normally closed structure disposed in the contact chamber and opened by displacement of the membrane part;
A vent hole for opening the cavity of the chip displacement portion to the outside air through the package;
A leak structure that suppresses the pressure change by leaking the air in the package chamber to the outside through the vent hole when the outside air slowly rises in temperature;
A thermal sensor comprising:
A package that receives the heat of the outside air and forms a package chamber partitioned from the outside air inside;
A sensor chip housed in the package chamber;
The sensor chip has
A chip displacement part integrally forming a membrane part that is displaced by a change in pressure of the package chamber at one end of a support wall forming a cavity;
A chip contact portion, which is disposed in close contact with the membrane portion side of the chip displacement portion and forms a contact chamber communicating with the package chamber relative to the membrane portion;
A contact of a normally closed structure disposed in the contact chamber and opened by displacement of the membrane part;
A heat sensor comprising: a leak structure that suppresses displacement of the membrane portion by causing air in the package chamber to leak into the cavity of the chip displacement portion when outside air slowly rises in temperature.
5. The thermal sensor according to claim 1, wherein the chip displacement portion and the chip contact portion of the sensor chip are made of silicon or a silicon compound, and the membrane portion of the chip displacement portion is anisotropically etched or A thermal sensor formed by dry etching.
5. The thermal sensor according to claim 1, wherein the leak structure is formed by fine processing of silicon or a silicon compound in the sensor chip, and has a polygonal cross-sectional shape having a width of 100 μm or less and a depth of 100 μm or less. A heat sensor characterized by comprising a leak groove horizontally with respect to the membrane part.
5. The thermal sensor according to claim 1, wherein the leak structure includes a circular hole having a diameter of 50 μm or less or a polygonal hole having a side of 50 μm or less in a part of the membrane part with respect to the membrane part. A thermal sensor characterized by being installed vertically.
5. The thermal sensor according to claim 1, wherein the thermal sensor is incorporated in a differential heat sensor that detects a temporal change rate of temperature due to a fire and sends a fire detection signal. .
9. The heat sensor according to claim 8 , wherein a package of the heat sensor is provided on an outer cover of the differential heat sensor so as to be exposed to the outside.
9. The thermal sensor according to claim 8 , wherein a package of the thermal sensor is formed integrally with an outer cover of the differential thermal sensor.
The thermal sensor according to any one of claims 1 to 4, wherein a time change rate of temperature due to fire is detected from an amount of air expansion caused by fire of an air pipe arranged in a monitoring section, and a fire detection signal is transmitted. A heat sensor characterized by being incorporated in a differential heat sensor.
In the thermal sensor of claim 11, wherein the thermal sensor, characterized in that the introduction of air in the air tube into the package chamber by connecting the air tube into the package directly.
  5. The thermal sensor according to claim 1, wherein the sensor chip is a rectangle having a side of about 1 mm or less or a diameter of about 1 mm or less obtained by processing a part of a substrate made of silicon or a silicon compound. A thermal sensor, comprising: a cylindrical depression-shaped membrane portion, wherein the membrane portion is made of a silicon compound or metal having a thickness of 1 μm to 10 μm.

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