JPH0921774A - Humidity and gas detecting element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity and gas detecting element capable of automating the mounting and assembling by using a general purpose unit and having excellent reliability and mass productivity by forming an insulating board together with a heater at a humidity and gas detector and to provide a method for manufacturing the element capable of simultaneously and easily conducting a plurality of current conduction agings, shortening the operating time, improving the reliability and providing a high yield and excellent mass productivity. SOLUTION: The humidity and gas detecting element 1 comprises an element unit having a humidity detector for detecting the humidity and a gas detector for detecting gas and a heater on an insulating board, a junction unit formed on the rear surface of the board to connect the board to a lead frame 2, a lead frame 2 for fixing the board and electrically connecting with the exterior, and a stationary part 3, a shut-off cover 4 and a ventilating cover 5 made of a square tubular resin or ceramic for fixing the frame 2 sandwiching from both sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for humidity detection and gas detection used in an automatic cooking function of a microwave oven, and humidity detection used for humidity control of electronic equipment such as general air conditioning equipment and copying machines. The present invention relates to a humidity and gas detection element and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, various humidity detecting elements and gas detecting elements have been developed and various manufacturing methods thereof have been studied. In particular, in a microwave oven with an oven, a detection element for detecting a change in the amount of humidity (absolute humidity) per unit area is required for automatic adjustment, and various methods have been developed. As one of the methods, there is a method of heating an oxide semiconductor with a heater and detecting a change in absolute humidity as a change in element resistance value. Similarly, a method has also been developed in which an oxide semiconductor is heated by a heater and a change in the concentration of a small amount of reducing gas is detected as a change in element resistance value.

The following is a conventional humidity and gas detection element (Nati
onal Technical Report Vol.29 No.3 Jun. 1983) will be described with reference to the drawings. FIG. 17 is a partially cutaway perspective view of a conventional humidity and gas detection element.
Reference numeral 41 is a conventional humidity and gas detection element, 42 is a humidity sensitive element made of an oxide semiconductor, 43 is a heat-resistant conductive adhesive, 44
Is a metal wire, 45 is a lead frame for electrically connecting the moisture sensitive element 42 to the metal wire 44, 46 is a resin base for fixing the lead frame 45, and 47 is the moisture sensitive element 42.
Is a coil heater that heats the moisture sensitive element 42 together with the resin base, and 48 is a fixing ring that fixes the metal mesh 48 to the resin base 46.

A method of manufacturing the conventional humidity and gas detection element having the above structure will be described below. First, the insulating substrate made of ceramic on which an electrode and an oxide semiconductor are formed is cut into chips to form the moisture sensitive element 42. Next, a metal wire 44 is bonded to the cut moisture sensitive element 42 using a heat resistant conductive adhesive 43. Resin base 46
The metal wire 44 with the moisture-sensitive element 42 is welded to the lead frame 45 with. Further, the coil heater 47 is welded to the lead frame 45. Next, the metal mesh 28 is fixed to the resin base 46 using the fixing ring 49. The coil heater 47 is energized and the energization aging process is performed until the characteristics of the moisture sensitive element 42 are stabilized. After that, a characteristic inspection is conducted,
The humidity and gas detection element 41 is completed.

[0005]

However, the above-mentioned conventional configuration has the following problems. That is, (1) each terminal has a special structure in which a plate-shaped oxide semiconductor is surrounded by a coil-shaped heater, and thin platinum is formed on each surface of the oxide semiconductor formed on the plate-shaped humidity and gas detection element. It is necessary to fix the conductive metal wire, further wire it to the lead frame, and intersect the metal wire from the coil heater part that heats the oxide semiconductor. Since all are assembled by welding, it is necessary to automate the manufacturing process. , It is necessary to develop a dedicated assembling machine and a welding machine, and it is difficult to control welding of a thin metal wire and a lead frame, and the yield is poor, so that mass production by complete automation is difficult.

(2) Since the lead frame is a single insert type, the lead frame in a state in which a plurality of lead frames are connected can only be processed in series until the assembly process.
In the next energization aging process, it is necessary to divide the lead frame into individual elements and energize the heater part, so when a large number of elements are energized by aging, the electrical connection between the lead frame terminals and the power supply terminals is ensured. It was difficult to manage whether or not

(3) Since the pitch between the terminals of the lead frame has a dimension other than the standard used in general electronic parts, it is difficult to mount the parts in the same process as general parts by using a commercially available automatic mounting machine. Met.

(4) Until the metal mesh, which is the protective cover, is fixed to the resin base, the heart of parts such as the humidity sensitive element and coil heater made of oxide semiconductor is exposed, and the element is damaged during assembly. However, there is a structural defect that a metal wire is easily broken. Further, since the protective cover is a dome type metal mesh, it is likely to be deformed by an external force, and in that case, there is a structural defect that the internal coil heater is damaged.

The present invention solves the above-mentioned problems of the prior art. A heater part is formed on an insulating substrate, and mounting and assembly using a general-purpose device can be automated, and the humidity is excellent in reliability and mass productivity. And a gas detection element, and a plurality of energization aging can be simultaneously and easily performed, which shortens the working time and improves reliability, and provides a method for manufacturing a humidity and gas detection element with high yield and excellent mass productivity. The purpose is to do.

[0010]

In order to achieve this object, the humidity and gas detection element according to claim 1 of the present invention comprises:
An insulating substrate, an element unit having a humidity detecting unit that detects humidity on the surface of the insulating substrate, a gas detecting unit that detects gas, and a heater unit that heats each detecting unit; And a joint portion formed on the back surface of the insulating substrate for joining the insulating substrate to the lead frame.

According to a second aspect of the present invention, in the humidity and gas detecting element according to the first aspect, the joint portion is composed of a plurality of island-shaped metal films or glass films.

In the humidity and gas detecting element according to claim 3 of the present invention, the lead frame is of dual insert type according to claim 1 or 2, and each electrode part of the element part and each lead frame are wire-bonded. Alternatively, a wiring portion electrically connected by welding is provided.

A humidity and gas detecting element according to a fourth aspect of the present invention has a structure in which the humidity and gas detecting element according to the third aspect is provided with a fixing portion made of a rectangular tubular resin or ceramic for fixing the lead frame by sandwiching it from both sides. doing.

According to a fifth aspect of the present invention, there is provided the humidity and gas detection element according to the fourth aspect, wherein the ventilation lid is made of resin, ceramic or metal having a ventilation hole in either the upper portion or the lower portion of the fixing portion. Is provided.

According to a sixth aspect of the present invention, the humidity and gas detecting element according to the fifth aspect has a structure in which the other fixing portion of the ventilation lid portion is provided with a blocking lid portion made of resin, ceramic or metal. Have

According to a seventh aspect of the present invention, there is provided a method of manufacturing a humidity and gas detecting element, wherein in the humidity and gas detecting element according to any one of the first to sixth aspects, a peripheral end portion of each lead frame is Connecting, using a comb that connects a plurality of lead frames in a row, a substrate bonding step of bonding an insulating substrate to each lead frame, and a wiring step of electrically connecting each lead frame and each element, An energization aging step of energizing and heating the heater parts of a plurality of insulating substrates at the same time via the lead frame part connected to the comb is provided.

Here, the insulating substrate has a thickness of 0.3.
Any alumina substrate having a size of 2 mm × 3 mm and a purity of 95% or an insulating substrate capable of withstanding 1000 ° C. may be used, and other insulating heat-resistant ceramic substrate, heat-resistant glass substrate or the like is used.

As the material of the lead frame, a 42 alloy alloy (iron-nickel alloy) having a thickness of 0.25 mm can be used. In addition, the entire surface of the lead frame is nickel-plated with a thickness of 2-3 μm,
Further, the lead frame inside the rectangular tubular fixing portion is gold-plated with a thickness of 2 to 3 μm.
The 42 alloy alloy used for the lead frame base material is
This is because it is inexpensive because it is generally used as a rade frame for ICs and the like at present, and has sufficient rigidity even with a thickness of 0.25 mm, and moreover, it is easy to perform die punching. As long as it has sufficient rigidity, metals and alloys such as stainless steel may be used.
Further, the reason why the surface is plated with nickel is to prevent the iron from rusting and to improve the adhesion of the gold plating. The thickness of nickel plating may be in the range of 1 to 5 μm, preferably 2 to 3 μm. When the thickness is less than 1 μm, the adhesion of the gold plating is insufficient, the connection strength with the metal wire is insufficient, and the possibility of disconnection increases,
If it exceeds 5 μm, there is no problem in characteristics, but the cost required for plating increases, which is not preferable. The reason why gold plating is applied only to the lead frame inside the rectangular tubular fixing portion is to prevent disconnection that tends to occur when the entire lead frame of the humidity and gas detection element is gold plated. That is, when solder is applied to the gold-plated part and continuously used for about 12 hours in a high temperature atmosphere of 150 ° C. or higher, the lead part of the solder alloys with gold and penetrates the gold-plated part, and it will continue for a long time or at high temperature. Then, the gold-plated part disappears, and if the metal wire itself is a gold wire,
The metal wire itself breaks due to alloying with the lead component of the solder. This is because the lead-gold alloy is mechanically very brittle. The thickness of gold plating is 0.25 to 4 μm, preferably 2 to 3 μm. If the thickness is less than 0.25 μm, the adhesion strength with the metal wire may be insufficient and peeling may occur. If the thickness exceeds 4 μm, not only the cost required for plating will increase, but also when the electrical connection is performed by wire bonding with a gold wire, the hardness of the lead frame surface may be insufficient due to gold plating, resulting in insufficient connection strength. , It may peel off.

Further, the ventilation lid is provided with a plurality of small holes and the like. This is for taking in atmospheric gas and humidity outside the element and protecting the element part at the same time.
Further, although the ventilation hole is provided in the ventilation hole lid portion, the ventilation hole may be provided in the blocking lid portion as long as the temperature change inside the element is kept within a small range. Moreover, you may provide a mesh-shaped metal as a ventilation hole.

A heat-resistant liquid crystal polymer is used as a resin material for the rectangular tubular fixing portion, the ventilation lid portion and the blocking lid portion. As a result, the resin is durable against a high temperature of 250 ° C. Further, when the resin and the lead frame are integrated by injection molding, gas is unlikely to be generated from the resin and the lead frame is not contaminated. The washing step can be omitted. If cleaning is performed after molding, a heat resistant PPS resin can be used as the resin material.

[0021]

With this structure, the following actions can be achieved. That is, (1) In an insulating substrate in which an element unit having a humidity detecting unit for detecting humidity, a gas detecting unit for detecting gas, and a heater unit for heating each operating unit is formed on the surface of the insulating substrate. Since the joining part is formed on the back surface opposite to the element part and the element part is joined to the lead frame, it is easy to rearrange and position the parts during assembly, and it is possible to use a general parallel welding device and wire bonder. In addition, the mounting and assembly can be fully automated, the number of assembly steps can be significantly reduced, mass productivity can be improved, and the cost of the element can be reduced. In addition, since the heater part is laminated on the insulating substrate, it can be mounted simultaneously with other element parts, and in particular, the bonding with the lead frame becomes extremely easy, the number of working steps can be reduced, and the yield can be improved. . Especially, the lead frame pitch is a general pitch (2.54 mm) or a half pitch (1.
By setting the thickness to 27 mm), mounting becomes extremely easy and mass productivity of parts and devices using the detection element can be improved. Sorting, positioning of parts during assembly,
Since the current-carrying wiring only needs to be done once per unit quantity, the number of assembly steps can be greatly reduced.

(2) Since the joint portion of the insulating substrate is formed of a plurality of island-shaped metal films and / or glass films,
The central surface of the joint surface rises due to surface tension, the joint area is increased, and the joint portions are evenly joined, so that the adhesion strength can be improved.

(3) The lead frame is of a dual insert type, and each electrode terminal of the element part and the lead frame can be easily electrically connected by wire bonding or welding, and a voltage is applied to the comb to simultaneously perform a plurality of energization aging. When performing, the electrical connection confirmation, energization aging, etc. are performed once for each set connected to the comb, so that defects due to insufficient energization aging due to contact defects can be prevented, and the yield can be improved.

(4) Since the lead frame and the element portion inside the fixing portion, the wiring portion such as the welding portion and the wire bond, are provided by providing the fixing portion made of a resin or ceramic in the shape of a rectangular tube for fixing the lead frame by sandwiching it from both sides. In addition, it is possible to prevent human touching, prevent element contamination and deformation, prevent deterioration of adhesiveness and damage of wire bond portions during and after assembly, and improve yield and reliability.

(5) A resin, ceramic or metal ventilation lid having a ventilation hole in either the upper part or the lower part of the fixed portion takes in atmospheric gas and humidity outside the element, protects the element portion, and is reliable. You can secure the sex.

(6) A blocking lid made of resin or metal on the other fixed portion of the ventilation lid not only protects the element but also stabilizes the air flow around the element, and
By efficiently reflecting the radiant heat from the heater part, the heat retention effect can be enhanced, the stability of the detection part can be secured, and the detection accuracy can be improved.

(7) Insulating substrate joining step of joining the insulating substrate to each lead frame by using a comb that connects peripheral ends of each lead frame and connects a plurality of lead frames in a row, and each lead frame Since the wiring process for electrically connecting each element and the current aging process for heating by simultaneously energizing the heater parts of a plurality of insulating substrates via the lead frame part connected to the comb are provided, the voltage is applied to the comb. Therefore, it is possible to simultaneously perform a plurality of energization aging, work efficiency can be improved, the electrical connection can be confirmed only once, and defects due to insufficient energization aging due to contact defects can be prevented.

[0028]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a perspective view of a humidity and gas detecting element in one embodiment of the present invention, FIG. 1 (b) is an exploded perspective view of the same, and FIG. 2 is a view of one embodiment of the present invention. FIG. 6 is a front view showing a state in which a composite sensor chip inside a humidity and gas detection element is mounted on a lead frame. 1 and 2, reference numeral 1 denotes a humidity and gas detection element in one embodiment of the present invention, which is used as a composite sensor for an automatic adjustment function of a microwave oven with an oven. The humidity and gas detection element 1, which is a composite sensor, has two functions of a humidity detection section that detects a change in absolute humidity and a gas detection section that detects a change in alcohol gas and a change in concentration in a single chip. A heater section for heating the humidity detecting section and the gas detecting section also has a composite sensor chip 6 described later formed on the same chip therein. Reference numeral 2 is a lead frame conforming to the standard of the pitch between terminals of general electronic components, and is a dual insert type in which the terminals are processed to have a pitch of 2.54 mm. Reference numeral 3 denotes a fixing portion made of a resin having a rectangular tubular shape, 4 denotes a cover portion made of a resin attached to a lower portion of the fixing portion 3 having a rectangular tubular shape, and 5 has a rectangular tubular shape having a ventilation hole attached to an upper portion of the fixing portion 3. The resin is a ventilation lid, and a heat-resistant liquid crystal polymer is used as each resin. Reference numeral 6 is a composite sensor chip inside the humidity and gas detection element, and 7 is a wire bond made of gold for electrically connecting the composite sensor chip 6 to the lead frame 2.

Here, in this embodiment, the rectangular tubular fixing portion 3, the shut-off lid portion 4 and the breathable lid portion 5 form a quadrangle to give directionality and facilitate handling at the time of mounting and assembling. I have to. The inner hollow shapes of the rectangular tubular fixing portion 3, the blocking lid portion 4, and the breathable lid portion 5 may be circular, hexagonal, or any other polygonal shape. Further, a recess is provided on one side wall of the fixing portion 3 or the like so that the polarity of the electrical connection of the lead frame 2 (element portion, heater portion, etc.) is clear.

Next, regarding the composite sensor chip used for the humidity and gas detection element in one embodiment of the present invention,
This will be described with reference to FIG. FIG. 3 is a front view of a composite sensor chip used in a humidity and gas detection element according to an embodiment of the present invention. Reference numeral 8 is an insulating substrate made of ceramics having a composition of Al ₂ O ₃ , and reference numerals 9, 10, 11, 12, and 13 are electrode portions made of gold printed on the insulating substrate 8. 14
Is an oxide semiconductor, which is a gas sensitive material whose resistance value changes in proportion to changes in humidity and alcohol gas concentration, 15 is protective glass for fixing the oxide semiconductor 14, 16 is proportional to humidity and alcohol gas concentration The coated glass forming a filter for removing the alcohol gas sensitivity of the oxide semiconductor 14 whose resistance value changes by giving only humidity sensitivity, 17 is a heater part 20 described later connected to the electrode parts 12 and 13 It is a protective glass for shielding from. As a result, 18 is a gas detection unit that detects the generation and concentration change of alcohol gas, 19 is a humidity detection unit that detects a change in absolute humidity, and 20 is a humidity detection unit 19 and a heater unit that heats the gas detection unit 18. To be done. That is, a voltage is applied to the gas detection part 18 by the electrode parts 9 and 10, and alcohol gas is detected by a resistance value change. Also, the electrode parts 10, 1
A voltage is applied to the humidity detector 19 by 1 to detect the absolute humidity by the change in resistance value. In addition, the electrode portions 12 and 13 are the heater portion 2
0 electrode.

A method of manufacturing the composite sensor chip 6 used in the humidity and gas detection element 1 of the first embodiment of the present invention constructed as described above will be described with reference to FIG. FIG. 4A is a front view of an insulating substrate showing an electrode part forming step in the method for manufacturing a composite sensor chip according to an embodiment of the present invention, and FIG. 4B is an element part in the method for manufacturing the composite sensor chip. FIG. 4C is a front view of the insulating substrate showing a forming step, and FIG. 4C is a front view of the insulating substrate showing a glass forming step in the method of manufacturing the composite sensor chip. First, as shown in FIG. 4A, a gold paste is printed on the insulating substrate 8 to form the gas detecting portion 18 and the humidity detecting portion 19, and the electrode portion 9 is baked at 850 ° C. for 30 minutes. , 10, 11, 12, and 13 were formed. Next, FIG.
As shown in (b), a paste containing glass frit of ruthenium oxide is printed to form the heater section 20,
And, in order to form the oxide semiconductor 14 whose resistance value changes in proportion to the humidity and the concentration change of the alcohol gas, a paste containing tin oxide organosilica sol is printed, and at the same time, 8
It was baked at 30 ° C. for 1 hour. Furthermore, adjustment was performed by laser trimming so that the resistance value of the heater section 20 was 18 ± 0.1Ω. Further, as shown in FIG. 4C, the protective glass 15, the coat glass 16, and the protective glass 17 are all the same glass and have a glass transition temperature of 60.
After printing using a glass paste having a characteristic of 0 ° C., a softening point of 700 ° C. and a linear expansion coefficient of 60 × 10 ⁻⁷ / K, 80
It is formed by firing at 0 ° C. for 1 hour.

Here, the insulating substrate 8 has a thickness of 0.
An alumina substrate having a size of 3 mm, a size of 2 × 3 mm, and a purity of 95% was used. Although the gap between electrodes of the electrode portion 9 and the electrode portion 10 for the gas detection portion 18 and the electrode portion 10 and the electrode portion 11 for the humidity detection portion 19 was formed to be 0.05 to 0.5 mm,
The thickness is preferably 0.1 to 0.2 mm.
If it is less than 0.05 mm, it is difficult to form a gap in the printing process, and if it exceeds 0.5 mm, the gas detection unit 1
8 and the resistance value of the humidity detection unit 19 exceeds the measurable range, which is not preferable. The glass used for the protective glass 15, the coated glass 16, and the protective glass 17 has a glass transition temperature of 600 ° C., a softening point of 700 ° C., and a linear expansion coefficient of 60 ×.
The one used was 10 ⁻⁷ / K. The composition of the paste containing tin oxide in the organosilica sol is shown in Table 1.

[0034]

[Table 1]

Here, silica sol and alumina sol exhibit the effect of a tin oxide sintering agent. 2- (2-ETHOXYETHOXY) ETHY ACE
TATE and ethyl cellulose were used as vehicles. The organosilica sol may be directly permeated into the element after printing the paste, or palladium oxide may be added as a catalyst in the form of chloride to the raw material or may be impregnated after printing and firing.

A method of manufacturing the humidity and gas detection element 1 of this embodiment manufactured as described above will be described below. FIG. 5 is a front view showing a lead frame connected by a comb in the method of manufacturing the humidity and gas detecting element according to the embodiment of the present invention. In FIG. 5, reference numeral 21 is a comb connecting a plurality of lead frames 2, and the humidity and gas detection elements 1 are continuously processed by each comb 21 at once. In the manufacturing process, first, the composite sensor chip 6
A cutting step for cutting the resin, a substrate bonding step for welding the composite sensor chip 6 to the lead frame 2 to which the fixing portion 3 made of resin is attached, and a wire bond 7 made of a gold wire for the composite sensor chip 6 and the lead frame 2. Wiring step for electrically connecting the comb 21 and a part of the terminal for cutting the lead frame 2 so that the series of heater portions 20 can be energized and aged.
(See FIG. 5 to be described later) For connecting the power source to heat the heater section 20, energization aging step, terminal cutting step for removing the comb 21, and inserting each terminal of the lead frame 2 into a printed circuit board or the like. The process includes a terminal forming step of bending the product into a rectangular shape, a characteristic checking step of inspecting a product, and a cover attaching step of finally attaching the covers of the blocking lid portion 4 and the ventilation lid portion 5 to the fixing portion 3.

Next, the substrate bonding process in the manufacturing process of this embodiment will be described in detail below. FIG. 6A is a rear view showing an example of a joint portion on the rear surface of the composite sensor chip in the humidity and gas detection element according to the embodiment of the present invention,
FIG. 6B is a sectional view of the same. In FIG. 6, 8 is an insulating substrate formed by the element portion, 22 is a joint portion formed on the back surface of the insulating substrate 8, and the shape is □ 1.8 × 2.8 mm, and gold paste is printed on the corners. It was baked at 850 ° C. for 30 minutes to form a gold pad for welding. Joining part 22 by printing method
Therefore, as shown in FIG. 6 (b), it has the shape of a recess whose center is recessed from the edge. As a result, during welding, since the recesses reduce the welding area, the welding strength varies, and the welding strength is low overall, in the present embodiment, further, an aggregate consisting of islands is formed. A joint having a body shape was also formed and studied.
FIG. 7A is a rear view showing a bonding portion formed in an island shape on the rear surface of the composite sensor chip in the humidity and gas detection element according to the embodiment of the present invention, and FIG. 7B is a sectional view of the same. .
Reference numeral 23 denotes a joint formed on the back surface of the insulating substrate 8
A plurality of 0.4 mm circular islands were formed. As a result, in the case of the circular shape having a diameter of 0.4 mm, the effect that the height of the printed body is made uniform by forming the lens-shaped bulging shape of the printed body by the surface tension of the gold paste was observed.
A plurality of joints 23 having a circular island shape of φ0.4 mm
Is the insulating substrate 8 compared to the square of □ 1.8 × 2.8mm
By welding to the lead frame 2, the welding was performed reliably, the variation in welding strength was small, and the yield was improved.

Further, as the structure of the joint, the joint shown in FIG. 8 was also examined. FIG. 8A is a rear view showing a joint portion formed of glass and gold on the rear surface of the composite sensor chip in the humidity and gas detection element of one embodiment of the present invention, and FIG. 8B is a sectional view of the same. FIG. 8C is a sectional view of the flattened joint. Reference numeral 24 is a glass bonding portion formed on the upper surface of the back surface of the insulating substrate 8, and 25 is a gold bonding portion made of a gold paste printed on the glass bonding portion 24 made of glass. First, as shown in FIG. 8A, the glass used in the glass forming step in the above-described method for manufacturing a composite sensor chip is printed on the back surface of the insulating substrate 8 made of alumina, and as shown in FIG. , Print gold on it,
It was baked at 830 ° C. for 15 minutes. Next, as shown in FIG. 8C, gold was wrapped to form a flat surface. As described above, by mechanically flattening the surface, the contact area with the lead frame 2 is significantly increased, and as a result of welding,
A significant increase in welding strength was obtained. Further, the glass bonding part 24 is provided between the insulating substrate 8 made of alumina and the gold bonding part 25.
By forming, the adhesion strength between the gold bonding portion 25 and the insulating substrate 8 also increased.

Next, the joining process of this embodiment will be described. FIG. 9 is an exploded cross-sectional schematic view showing a step of joining the composite sensor chip and the lead frame in the humidity and gas detection element in one embodiment of the present invention. The back surface of the insulating substrate 8 on which the composite sensor chip 6 is formed is brought into contact with the lead frame 2 so that the parallel electrodes 29a, 29
b is brought into contact with the lead frame 2 and an electric current is applied to the lead frame 2 to heat the lead frame 2 to weld the gold plating 28 and the joint portion 26 of the lead frame 2. When welding, the composite sensor chip 6
The lead frame 2 was placed on the bonding portion 26 on the back surface of the above, the parallel electrodes 29a and 29b were brought into contact with each other from above the lead frame 2, and a high current was supplied from the AC power source 30 to perform welding. In this embodiment, two parallel electrodes 29a and 29b are used, but three or four parallel electrodes can be used at the same time to optimally set the adhesive strength and reduce the working time. Here, the lead frame 2 is made of 42 alloy (iron-nickel alloy) and has a thickness of 0.25 mm. Further, the entire surface is nickel-plated 27 with a thickness of 2 to 3 μm, and further the lead frame 2 comes to the square tubular fixing portion 3.
For this, gold plating 28 was performed for 2 to 3 μm.

Next, in the wiring process, the lead frame 2 is set so that the composite sensor chip 6 is on the upper side, and the wire bonding is performed by using a wire bonder capable of automatically setting the bonding position in advance. went.

Next, the energization aging process is shown in FIG.
As shown in FIG. 5, a voltage of 5 V is directly applied to the comb portions at both ends to form the comb cutting portion 31. The electrical connection between the comb 21 and the power supply was performed by pressing a spring-loaded contact terminal having a needle-shaped tip against the comb 21. This was done in order to carry out the connection work in a short time and ensure the electrical connection. In this embodiment, the electric connection was made by pressing, but in order to make the electric connection surely, it may be connected by solder or screwed,
Contact terminals of the type that come into planar contact are liable to cause contact failure due to wear, adhesion of dust, and the like, which is not preferable when the electrical connection is repeated as in this embodiment.

The terminal cutting and the terminal forming were carried out by using a jig for cutting the lead frame 2 and the comb 21 together and bending the lead frame 2 continuously. FIG. 11 is a perspective view showing a state in which a plurality of humidity and gas detection elements according to an embodiment of the present invention are arranged in a line on a rail jig. The humidity and gas detection element 1 formed after the terminals are cut has a space in a direction perpendicular to the lead frame 2 as shown in FIG. 1, and a plurality of them are handled as one rail unit by arranging them in a rail jig 32. be able to. In this example, 20 humidity and gas detection elements 1 were arranged on one rail-shaped jig 32, and a characteristic inspection and an assembly work were performed as one work unit. Forming may not be performed depending on the humidity and the arrangement method and mounting method of the gas detection element 1 of the present embodiment.

Next, the characteristic checking process will be described. The characteristics were measured by pressing a contact terminal with a spring having a needle-shaped tip against the lead frame 2 for electrical connection. With this, the connection work can be performed in a short time, and the electrical connection can be surely performed. At the time of measuring the characteristics, the arrangement direction of the elements was such that the direction in which the composite sensor chip 6 was visible was upward. In this embodiment, the contact terminal is used, but since the lead frame 2 is a dual insert type that is processed into a pitch of 2.54 mm which is a standard for general electronic components, an IC connector is used. The characteristics may be measured by inserting the lead frame 2 into the IC connector.

A comparative experiment was conducted to measure the characteristics of the humidity and gas detecting element 1 of the present example manufactured as described above and the conventional example. The alcohol sensitivity in the gas detector is 1000p
It was defined as the ratio of the resistance value in the pm atmosphere to the resistance value in the 0 ppm atmosphere. The humidity sensitivity in the humidity detector is 2
Resistance value of 0 ℃, 90% RH atmosphere and 20 ℃, 65% R
It was defined as the ratio of H to the resistance value of the atmosphere. Five samples of the humidity and gas detecting elements of the present example and the conventional example thus obtained were sampled and their characteristics were measured, and the measurement results are shown in (Table 2) and (Table 3).

[0045]

[Table 2]

[0046]

[Table 3]

As is clear from the results of (Table 2) and (Table 3), the humidity and gas detection element 1 of this example has no characteristic difference from the conventional example. Therefore,
Compared with the conventional example, this example is structurally easy to assemble, the process can be automated, and the mass productivity can be improved.

Next, a method of installing the detecting element of this embodiment will be described below with reference to the drawings. FIG. 12 shows a method of mounting the IC connector 34 on the printed circuit board 33 and inserting the humidity and gas detection element 1 of this embodiment therein. FIG. 13 shows a method in which a through hole 35, which is a through hole, is provided in the printed circuit board 33, the humidity and gas detection element 1 of this embodiment is mounted therein, and is fixed to the back surface of the printed circuit board 34 by soldering. In FIG. 14, a through hole 35 is provided in a printed board 33 made of glass epoxy, and the humidity and gas detection element 1A having a structure without the shut-off lid portion 4 in the present embodiment is installed therein,
The method of fixing by soldering to the back surface of is shown. In this case, the printed circuit board 33 substitutes the blocking lid portion 4. FIG.
Reference numeral 5 denotes a humidity and gas detection element 1B of the present embodiment having a structure of the lead frame 2 without forming a hole 36 having a size into which the shut-off lid 4 of the humidity and gas detection element 1B is inserted in the printed circuit board 33. Shows how to install.
FIG. 16 shows a method of surface-mounting the humidity and gas detection element 1C of this embodiment having a structure in which the terminal portion of the lead frame 2 is bent along the outer walls of the fixing portion 3 and the blocking lid portion 4 on the printed circuit board 33. As another example, a wing for fixing the element may be attached to the shut-off lid portion 4 or the like, and when used in a microwave oven with an oven, a large number of small holes are made in the steel plate at the installation location to perform the present implementation. The humidity and the gas detection element 1 may be used as the ventilation lid 5 instead of the ventilation lid 5 as an example.

As described above, the following advantages can be obtained by feeding a plurality of lead frames with a resin base, which are connected to each other by the comb, as one unit amount in the assembling process.

(1) In the welding process, the positioning of the composite sensor chip welding may be performed for each unit amount, which shortens the working time.

(2) In the wire bonding process, the positioning of the wire bonding is completed for each unit amount, and the positions of the individual lead frames are evenly spaced.
One unit amount can be continuously bonded, and the work time is similarly shortened.

(3) The energization aging process is performed by cutting the terminals, applying a voltage directly to the comb and passing an electric current through the heater portion of the composite sensor chip as shown by the symbol A in FIG. Can be shortened.

As described above, according to this embodiment, the installation method with a high degree of freedom is possible, and since it has versatility, mass productivity can be improved and low cost can be realized. In particular, surface mounting is also possible, and mounting is extremely easy. Further, in the manufacturing method, since the rearrangement of parts, the positioning, and the energizing wiring at the time of assembly need only be done once per unit quantity, the number of assembly steps can be greatly reduced. In addition, when a voltage is applied to the comb to perform multiple energization aging at the same time, it is only necessary to confirm the electrical connection once, the defects due to insufficient energization aging due to contact defects are reduced, and the yield can be significantly improved. It was

[0054]

As described above, according to the present invention, it is possible to realize a humidity and gas detection element having the following excellent effects and a manufacturing method thereof. That is, (1) In an insulating substrate on which an element portion having a humidity detecting portion, a gas detecting portion, and a heater portion is formed, a bonding portion is formed on the back surface of the insulating substrate opposite to the element portion, and the element portion is used as a lead frame. Since they are joined together, the parts can be easily rearranged and positioned during assembly, a general parallel welding device and wire bonder can be used, and the mounting and assembly can be fully automated. Low cost can be realized,
Excellent reliability and mass productivity. Also, since the heater part is laminated on the insulating substrate, it can be mounted at the same time as other element parts. Especially, the bonding with the lead frame is extremely easy, the man-hours can be reduced, the yield is remarkably improved, and the reliability is improved. And excellent in mass productivity.

(2) Since the joint portion of the insulating substrate is formed of a plurality of island-shaped metal films and / or glass films,
The center of the joint surface rises due to the surface tension, the joint area is increased, and the joints are evenly joined to each joint, so that the adhesion strength is improved and the reliability is excellent.

(3) The lead frame is made of a dual insert type, and a voltage is applied to the comb by including each electrode terminal part of the element part and the lead frame and the wiring part electrically connected by wire bonding or welding. When conducting multiple energization aging at the same time, check the electrical connection, energize aging, etc. 1 for each set connected to the comb.
Therefore, the number of defects due to insufficient current aging due to poor contact is reduced, the yield is improved, and the reliability and mass productivity are excellent.

(4) Since the lead frame and the element portion inside the fixing portion, and the wiring portion such as the welded portion and the wire bond are provided by providing the fixing portion made of a resin or ceramic in the shape of a square tube for sandwiching and fixing the lead frame from both sides. In addition, it is possible to prevent human touching, prevent element contamination and deformation, and prevent adhesion deterioration and damage of the wire bond portion at the time of assembling and after assembly, resulting in high yield, high reliability, and excellent mass productivity.

(5) A resin or ceramic or metal ventilation lid having a ventilation hole in either the upper part or the lower part of the fixed part takes in atmospheric gas and humidity outside the device and protects the device part, thereby ensuring reliability. You can secure the sex.

(6) The other fixed portion of the ventilation lid is provided with a blocking lid made of resin, ceramic or metal so as to not only protect the element but also stabilize the air flow around the element. Further, the radiant heat from the heater section is efficiently reflected to enhance the heat retention effect, the stability of the humidity and gas detection section can be secured, the detection accuracy is high, and the element reliability is excellent.

(7) Insulating substrate joining step of joining an insulating substrate to each lead frame by using a comb connecting the peripheral ends of each lead frame and connecting a plurality of lead frames in a row, and each lead Since the wiring step for electrically connecting the frame and the element section and the energization aging step for energizing and heating simultaneously the heater sections of the plurality of insulating substrates via the lead frame section connected to the comb are provided, Multiple current aging can be performed, the reliability of the inspection is improved,
The working time can be significantly reduced and the mass productivity is excellent.

[Brief description of drawings]

FIG. 1A is a perspective view of a humidity and gas detection element according to an embodiment of the present invention. FIG. 1B is an exploded perspective view of a humidity and gas detection element according to an embodiment of the present invention.

FIG. 2 is a front view showing a state in which a composite sensor chip inside a humidity and gas detection element according to an embodiment of the present invention is mounted on a lead frame.

FIG. 3 is a front view of a composite sensor chip used for a humidity and gas detection element according to an embodiment of the present invention.

FIG. 4 (a) is a front view of an insulating substrate showing an electrode portion forming step in a method for manufacturing a composite sensor chip according to an embodiment of the present invention; and (b) an element in a method for manufacturing a composite sensor chip according to an embodiment of the present invention. (C) Front view of the insulating substrate showing the glass forming step in the method for manufacturing the composite sensor chip according to the embodiment of the present invention.

FIG. 5 is a front view showing a lead frame connected by a comb in a method of manufacturing a humidity and gas detection element according to an embodiment of the present invention.

FIG. 6 (a) is a rear view showing an example of a joint portion on the rear surface of the composite sensor chip in the humidity and gas detection element according to the embodiment of the present invention. (B) Composite in the humidity and gas detection element according to the embodiment of the present invention. Sectional drawing which shows an example of the junction part of a sensor chip back surface.

FIG. 7 (a) is a rear view showing a joint formed in an island shape on the rear surface of the composite sensor chip in the humidity and gas detection element of one embodiment of the present invention (b) Humidity and gas of one embodiment of the present invention Sectional drawing which shows the junction part formed in the island shape on the back surface of the composite sensor chip in a detection element.

FIG. 8 (a) is a rear view showing a joint formed by glass and gold on the back surface of the composite sensor chip in the humidity and gas detection element of one embodiment of the present invention; and (b) Humidity and one embodiment of the present invention. Sectional drawing which shows the junction part formed by glass and gold on the back surface of the composite sensor chip in a gas detection element (c) The humidity and gas of the embodiment of this invention WHEREIN: The back surface of a composite sensor chip is flattened by glass and gold. Cross section of a welded joint

FIG. 9 is an exploded cross-sectional schematic view showing a step of joining a composite sensor chip and a rade frame in a humidity and gas detection element in one embodiment of the present invention

FIG. 10 is a schematic front view showing an energization aging process of the humidity and gas detection elements connected in a line by a comb in one embodiment of the present invention.

FIG. 11 is a perspective view showing a state in which a plurality of humidity and gas detection elements according to an embodiment of the present invention are arranged in a line on a rail jig.

FIG. 12 is a perspective view showing a method of inserting the humidity and gas detection element into an IC connector mounted on a printed board according to an embodiment of the present invention.

FIG. 13 is a perspective view showing a method of fixing the humidity and gas detection element in a through hole for a terminal provided on a printed board according to an embodiment of the present invention.

FIG. 14 is a perspective view showing a method of fixing a humidity and gas detection element having no shut-off lid portion to a through hole for a terminal provided on a glass epoxy printed circuit board according to an embodiment of the present invention.

FIG. 15 is a perspective view showing a method for inserting and fixing the humidity and gas detection element without forming of the lead frame into a hole of a size provided with a fixing portion provided on a printed board according to an embodiment of the present invention.

FIG. 16 is a perspective view showing a method of surface-mounting and fixing a humidity and gas detection element, which is obtained by bending a lead frame along a fixing portion, according to an embodiment of the present invention.

FIG. 17 is a partially cutaway perspective view of a conventional humidity and gas detection element.

[Explanation of symbols]

 1, 1A, 1B, 1C Humidity and gas detection element 2 Lead frame 3 Fixing part 4 Blocking lid part 5 Ventilation lid part 6 Composite sensor chip 7 Wire bond 8 Insulating substrate 9, 10, 11, 12, 13 Electrode part 14 Oxide semiconductor 15,17 Protective glass 16 Coated glass 18 Gas detection part 19 Humidity detection part 20 Heater part 21 Com 22,23,26 Joint part 24 Glass joint part 25 Gold joint part 27 Nickel plating 28 Gold plating 29a, 29b Parallel electrodes 30 AC power supply 31 Comb cutting part 32 Rail jig 33 Printed circuit board 34 IC connector 35 Through hole 36 Hole part 41 Humidity and gas detection element 42 Moisture sensitive element 43 Heat resistant conductive adhesive 44 Metal wire 45 Lead frame 46 Resin Base 47 Coil heater 48 Metal mesh 49 Fixing ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Onaka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. An insulating substrate, an element unit having a humidity detecting unit for detecting humidity on a surface of the insulating substrate, a gas detecting unit for detecting gas, and a heater unit for heating each detecting unit, and the insulating substrate. And a bonding portion formed on the back surface of the insulating substrate for bonding the insulating substrate to the lead frame, and a lead frame for fixing and fixing the humidity to the outside. Gas detection element. 2. The bonding portion comprises a plurality of island-shaped metal films and / or
Alternatively, the humidity and gas detection element according to claim 1, which is formed of a glass film. 3. The lead frame is of a dual insert type, and is provided with a wiring portion for electrically connecting each electrode portion of the element portion and each lead frame by wire bonding or welding. Claim 1
Alternatively, the humidity and gas detection element according to any one of 2 above. 4. The humidity and gas detection element according to claim 3, further comprising a fixing portion made of a rectangular tube-shaped resin or ceramic for fixing the lead frame by sandwiching it from both sides. 5. The humidity and gas according to claim 4, wherein one of an upper portion and a lower portion of the fixing portion is provided with a ventilation lid made of resin, ceramic or metal having a ventilation hole. Detection element. 6. The humidity and gas detection element according to claim 5, wherein the other fixing portion of the ventilation lid portion is provided with a blocking lid portion made of resin, ceramic or metal. 7. A substrate bonding step of bonding the insulating substrate to each of the lead frames by using a comb connecting the peripheral ends of the lead frames and connecting a plurality of the lead frames in a line. A wiring step of electrically connecting each lead frame to each element, and an energization aging step of simultaneously energizing and heating the heater portions of the plurality of insulating substrates via the lead frame portion connected to the comb. The method for manufacturing a humidity and gas detection element according to any one of claims 1 to 6, further comprising: