CN116136435A

CN116136435A - Temperature sensor and manufacturing method

Info

Publication number: CN116136435A
Application number: CN202310097912.4A
Authority: CN
Inventors: 朱利安; 郑益; 夏晨强; 李哲楠
Original assignee: Hangzhou Gold Electronic Equipment Co Ltd
Current assignee: Hangzhou Gold Electronic Equipment Co Ltd
Priority date: 2023-01-13
Filing date: 2023-01-13
Publication date: 2023-05-19

Abstract

The invention relates to the field of temperature sensors, in particular to a temperature sensor and a manufacturing method, wherein the temperature sensor comprises a thermistor, the thermistor comprises a thermistor matrix made of a thermosensitive material, a first electrode layer and a second electrode layer which are arranged on the surface of the thermistor matrix, a first electrode pin is arranged on the first electrode layer, the temperature sensor further comprises a gold-tin eutectic layer which is arranged on the second electrode layer and completely covers the second electrode layer, and a heat conducting bottom plate which is connected with the gold-tin eutectic layer and made of a heat conducting material, and the heat conducting bottom plate is provided with the second electrode pin. The thermistor matrix and the heat conduction bottom plate are connected together through the gold-tin eutectic layer, silver paste is not used any more, therefore, the problems of silver migration and the like can not occur, and the temperature sensor has good resistance consistency. And secondly, the temperature of the measured object can be considered to be directly transmitted to the thermistor matrix through the heat conducting bottom plate, and compared with the indirect transmission through a plurality of layers of media in the prior art, the heat transmission efficiency is improved.

Description

Temperature sensor and manufacturing method

Technical Field

The invention relates to the field of temperature sensors, in particular to a temperature sensor and a manufacturing method thereof.

Background

The energy storage battery is provided with temperature sensors for detecting the temperature of the pole (or the temperature of other positions), and the temperature sensors are mostly made of heat-sensitive materials, and the packaging modes of the heat-sensitive materials generally comprise glass packaging and plastic packaging.

Glass encapsulation refers to: and (3) welding leads on two electrodes of the thermosensitive material respectively through silver paste, carrying out glass sealing through glass sintering, placing the glass-sealed temperature sensor into an OT terminal, packaging again through epoxy glue to achieve a sealing effect, and fixing the OT terminal with the temperature sensor on a pole post of a battery through screws. When the temperature sensor manufactured by the packaging mode detects the temperature, the temperature of the measured object needs to indirectly transfer heat to the thermosensitive material through the multi-layer medium, the heat conduction performance is poor, the temperature sensing efficiency is affected, and the temperature acquisition response is slow. In addition, when the temperature sensor is used for a long time in a severe environment, the problem of silver migration can occur, the accuracy of temperature acquisition is affected, and the sensor can be seriously disabled.

The plastic package means: the two electrodes of the thermosensitive material are respectively welded with leads through silver paste, and then are packaged through epoxy resin, the sensors are mostly installed on a measured object through a conductive adhesive mounting mode, and in the mounting process, the conductive adhesive is easy to overflow, so that the periphery of the thermosensitive material is climbed, the resistance value is influenced, the resistance value is drifting and unstable, and the sensors with different resistance values need to be screened through subsequent aging, so that the consistency is poor. In the subsequent long-term use process, the problem of silver migration can also occur, so that the resistance value of the resistor is changed, the precision of the sensor is affected, and the sensor can be seriously disabled.

As an essential explanation, silver migration in the above is referred to as: in the process of mounting the silver paste, the silver paste is caused to climb to the periphery of the thermosensitive material due to the characteristics of the silver paste, and the climbing heights of the silver paste are different due to the fact that the amount of the silver paste is not easy to control, so that the resistance value of the thermistor is changed, the consistency of the resistance value is poor, and a series of problems such as subsequent temperature drift and silver migration can occur.

Disclosure of Invention

The invention aims to solve the problems of poor consistency of resistance values and slow temperature response of temperature sensors caused by unreasonable packaging structure of heat-sensitive materials in the prior art.

Firstly, the invention provides a temperature sensor, which comprises a thermistor, wherein the thermistor comprises a thermistor matrix made of a thermosensitive material, a first electrode layer and a second electrode layer which are arranged on the surface of the thermistor matrix, a first electrode pin is arranged on the first electrode layer, the temperature sensor further comprises a gold-tin eutectic layer which is arranged on the second electrode layer and completely covers the second electrode layer, and a heat conducting bottom plate which is connected with the gold-tin eutectic layer and made of a heat conducting material, and the heat conducting bottom plate is provided with the second electrode pin.

Preferably, the first electrode pin is connected with the first electrode layer through a lead.

Preferably, the first electrode pins are provided in plurality and are respectively connected with the first electrode layer through respective leads; the lead wire is gold wire or copper wire.

Preferably, the thermistor is provided with silicone grease on the outside.

Preferably, the thickness of the first electrode layer is 0.01-0.06 mm; the thickness of the second electrode layer is 0.01-0.06 mm; the thickness of the gold-tin eutectic layer is 0.03-0.06 mm; the thickness of the heat conducting bottom plate is 0.2-0.5 mm.

Preferably, the heat conducting bottom plate comprises a connecting part and an extending part which is arranged on the connecting part and extends outwards, the thermistor is arranged on the connecting part, the connecting part is used for being contacted with the measured object to transfer temperature change to the thermistor, and the extending part is used for fixing the positions of the connecting part and the measured object.

Preferably, a heat conduction buffer hole is arranged between the connecting part and the extending part; the heat conduction buffer holes penetrate through two opposite sides of the heat conduction bottom plate so as to reduce the connection area of the connection part and the extension part.

Preferably, the second electrode pin is integrally formed on the heat conducting bottom plate; the second electrode pins are multiple and symmetrically arranged on the heat conducting bottom plate.

Preferably, the outer sides of the thermistor and the heat conducting base plate are provided with epoxy resin.

Secondly, the invention also provides a manufacturing method of the temperature sensor, which sequentially comprises the following steps:

s1: printing materials forming an electrode layer at different positions on the outer surface of the thermistor matrix respectively, and then forming a first electrode layer and a second electrode layer on the outer surface of the thermistor matrix respectively by a high-temperature sintering mode;

s2: printing a layer of gold-tin alloy material on the second electrode layer, and then forming a gold-tin eutectic layer by a high-temperature sintering mode; or electroplating a gold-tin eutectic layer on the second electrode layer;

s3: connecting the gold-tin eutectic layer of the thermistor with a heat conduction bottom plate in a mounting mode, and welding at the temperature of 300-310 ℃ after mounting;

s4: using a wire bonding process on the first electrode layer, and connecting the first electrode pins with leads;

s5: a layer of silicone grease is dotted on the thermistor;

s6: and packaging the thermistor and the heat conducting bottom plate through epoxy resin.

Compared with the prior art, the invention has the beneficial effects that: the thermistor matrix and the heat conduction bottom plate are connected together through the gold-tin eutectic layer, and silver paste is not used as in the prior art, so that the problems of silver migration and the like can be avoided, and the temperature sensor has good resistance consistency. And secondly, the temperature of the measured object can be considered to be directly transmitted to the thermistor matrix through the heat conducting bottom plate, so that compared with the indirect transmission through a plurality of layers of media in the prior art, the heat transmission efficiency is improved, and the accuracy of a detection result is improved.

Drawings

Fig. 1 is a cross-sectional view of a thermistor.

Fig. 2 is a schematic view of a thermistor mounted on a thermally conductive base plate.

Fig. 3 is a schematic diagram of a primary package of a thermistor on a thermally conductive base plate.

Fig. 4 is a perspective view of a temperature sensor.

Fig. 5 is a top view of the temperature sensor of fig. 4.

Fig. 6 is an exploded view of the temperature sensor of fig. 4.

Detailed Description

The temperature sensor in the present application is a sensor made using a characteristic that a thermosensitive material, which may be an NTC (negative temperature coefficient thermosensitive material), has different resistances to different temperatures.

Fig. 1 shows a cross-sectional view of a thermistor 4, in fig. 1, a first electrode layer 42 and a second electrode layer 43 are respectively disposed on the upper and lower surfaces of a thermistor substrate 41, and in this embodiment, the materials of the first electrode layer 42 and the second electrode layer 43 are gold, because gold has good electrical conductivity and thermal conductivity, is not easily oxidized, and does not cause problems of silver migration. In some embodiments, however, the material of the first electrode layer 42 may be silver. The first electrode layer 42 and the second electrode layer 43 are respectively spread over the upper and lower surfaces of the thermistor 4, and the thickness of each electrode layer is uniform, about 0.03mm. The first electrode layer 42 and the second electrode layer 43 serve as two electrodes of the thermistor substrate 41, facilitating wiring of subsequent temperature sensors. The bottom of the second electrode layer 43 is provided with a gold-tin eutectic layer 44, the bottom of the second electrode layer 43 (also referred to as the bottom of the thermistor substrate 41) is completely covered by the gold-tin eutectic layer 44, and the thickness of the gold-tin eutectic layer 44 is 0.03-0.06 mm.

The gold-tin eutectic is a solution in which gold and tin ions in a plating solution are deposited at a predetermined position by electrolysis at a content of 80% by mass of Au and 20% by mass of Sn. The gold-tin eutectic layer 44 has high strength, high corrosion resistance, high creep resistance, and good thermal, wetting, and electrical conductivity.

The position of the first electrode layer 42 is not limited to the upper surface of the thermistor base 41, and may be provided on the side surface in the circumferential direction of the thermistor base 41, but a reasonable design area is required, specifically, the design of the electrode and the sectional area of the side surface are designed according to the thermistor sensor parameters, and therefore, it is necessary to change the electrode position while simultaneously taking into consideration the sensor parameters and the design.

With continued reference to fig. 1, the bottom of the au-sn eutectic layer 44 is connected to a heat conducting base plate 5, and the heat conducting base plate 5 may be a material with better heat conducting performance, such as (copper, copper nickel plating), and the heat conducting base plate 5 is used as a component of the temperature sensor contacting with the measured object, in this embodiment, the heat conducting base plate 5 is in a sheet structure, and has a smaller thickness (0.2-0.5 mm), and the bottom surface is a plane, so as to be convenient for connection with the measured object. When in use, the bottom surface of the heat conducting bottom plate 5 is fixed on a measured object, so that the temperature of the measured object is sequentially transferred to the heat conducting bottom plate 5, the gold-tin eutectic layer 44 and the second electrode layer 43, and finally transferred to the thermistor matrix 41, and the resistance of the thermistor matrix 41 is changed.

The connection of the thermistor base 41 with the heat conducting base plate 5 through the gold-tin eutectic layer 44 has the following advantages: first, the eutectic layer 44 has high creep resistance and good thermal and electrical conductivity, so that the problems of silver migration and gel climbing caused by silver paste in the prior art are avoided, and the temperature sensor with the structure has controllable resistance and good consistency. In addition, although the gold-tin eutectic layer 44 and the second electrode layer 43 are also present between the thermistor substrate 41 and the heat conducting base plate 5, it is noted that the thicknesses of the gold-tin eutectic layer 44 and the second electrode layer 43 are very small, and only on the order of micrometers, so that it can be considered that the temperature is directly transferred from the heat conducting base plate 5 to the thermistor substrate 41, such a structure avoids the need to conduct indirect sensing heat through other multi-layer media as in the prior art, and greatly improves the heat transfer effect.

Referring to fig. 2, the heat conducting base plate 5 includes a connecting portion 51 for contacting with the object to be measured and an extending portion 52 disposed on the connecting portion 51 and extending outward, and the extending portion 52 is used for mounting the heat conducting base plate 5 relatively fixedly, so that the connecting portion 51 can be always connected to the object to be measured. In the present embodiment, there are two extending portions 52 and extend in opposite directions, so that the connecting portion 51 is located at the intermediate position of the heat conductive base plate 5. However, in other embodiments, the number of the extending portions 52 may be one or more than three, and the shape of the extending portions 52 is not limited, and may extend outward in a straight line as in fig. 2, or may extend outward in a fold line or a curve.

It should be noted that, the extension portion 52 and the connection portion 51 are relatively speaking, that is, the position where the thermistor 4 is mounted near the heat conducting base plate 5 may be defined as the connection portion 51, and the peripheral area of the connection portion 51 may be defined as the extension portion 52, so that the case where only the connection portion 51 and no extension portion 52 are provided in some embodiments is not excluded.

As shown in fig. 2, in this embodiment, the thermistor 4 is disposed at a position near the center of the upper end surface of the connection portion 51, so that the temperature of any position of the connection portion 51 can be quickly sensed by the thermistor 4 no matter what position is changed, and the sensitivity of the temperature sensor is improved.

In addition, considering that the extension portion 52 is also generally directly fixed to the object to be measured, particularly, in the case of mounting the temperature sensor on the battery post to detect the temperature of the post, in order to avoid the temperature change of the connection portion 51 due to the temperature change of the extension portion 52 as much as possible, a heat conduction buffer hole 53 is provided between the extension portion 52 and the connection portion 51, so that the contact area between the extension portion 52 and the connection portion 51 is reduced, which can reduce the speed of heat conduction and reduce the temperature change from the extension portion 52. Preferably, the number of the heat conduction buffer holes 53 is 1 to 3, and the connection strength between the extension portion 52 and the connection portion 51 is ensured while the buffer effect is ensured. The heat conduction buffer holes 53 preferably penetrate through the upper and lower surfaces of the heat conduction base plate 5 to further reduce the connection area between the extension portions 52 and the connection portions 51.

With continued reference to fig. 2, a plurality of

second electrode pins

501, 502, 503, 504 are also fixedly connected to the heat-conducting base plate 5, and in this embodiment, these second electrode pins are integrally formed on the heat-conducting base plate 5. These second electrode pins are typically of a metallic material, such as aluminum or copper, so that the second electrode pins are connected to the second electrode layer 43 via a thermally conductive base plate and a gold-tin eutectic layer 44 in sequence, i.e. the second electrode pins serve as one terminal of the temperature sensor. In addition, it is noted that the above-described second electrode pin is directly connected to the heat conductive base plate 5, so that the second electrode pin can also collect voltage information of the battery when the heat conductive base plate 5 is mounted on the battery post.

The first electrode layer 42 is provided with leads 201, 202 (which may be gold wires or copper wires), and the other ends of the

leads

201, 202 are connected to

first electrode pins

505, 506, so that the first electrode pins are indirectly connected to the first electrode layer 42, that is, the first electrode pins serve as the other terminals of the temperature sensor. In order to avoid the problem of direction when the sensor is wired, in this embodiment, the first electrode pins are provided in two and symmetrically on the heat conducting base plate 5.

After the

leads

201, 202 are provided as shown in fig. 3, in order to avoid damage to the thermistor 4 caused by stress in the subsequent epoxy 1 package, a layer of silicone grease 3 is provided on the outside of the thermistor 4 to buffer the stress. The silicone grease 3 is coated on the exposed part of the thermistor 4.

As shown in fig. 4 and 6, the outer sides of the heat conducting bottom plate 5 and the thermistor 4 are further wrapped with a layer of epoxy resin 1, so that the temperature sensor is packaged, and the sealing effect is achieved. The outer ends of the first electrode pin and the second electrode pin extend out of the epoxy resin 1 so as to facilitate wiring of a subsequent temperature sensor, and meanwhile, the connection strength of the first electrode pin and the second electrode pin can be improved, and particularly, the positions of the first electrode pin are relatively fixed.

In this embodiment, the mounting of the temperature sensor on the battery post illustrates how the mounting and detection of the temperature sensor is achieved. First, the bottom surface of the connection portion 51 of the heat conductive base plate 5 is mounted on the outer surface of the pole so that the two are closely attached, and then the extension portion 52 is fixed on the outer surface of the pole by means of laser welding, thereby achieving the fixation of the temperature sensor. And then wiring is performed, for example, one temperature acquisition wire is connected to the second electrode pin 501, and the other temperature acquisition wire is connected to the first electrode pin 505, so that the acquisition of the temperature of the pole can be realized.

The temperature sensor has the following technical effects: the thermistor substrate 41 and the heat conduction bottom plate 5 are connected together through the gold-tin eutectic layer 44, and silver paste is not used as in the prior art, so that the problems of silver migration and the like can be avoided, and the temperature sensor has good resistance consistency. Secondly, the temperature of the measured object can be considered to be directly transferred to the thermistor matrix 41 through the heat conducting bottom plate 5, so that compared with the indirect transfer through a plurality of layers of media in the prior art, the efficiency of heat transfer is improved, and the accuracy of a detection result is improved.

The invention also provides a method for manufacturing the temperature sensor, which sequentially comprises the following steps:

s1: a gold layer having a thickness of about 0.03mm was printed on each of the upper and lower surfaces of the thermistor base 41, and then a first electrode layer 42 and a second electrode layer 43 having good adhesion and conductivity were formed on each of the upper and lower surfaces of the thermistor base 41 by high-temperature sintering.

S2: printing a layer of gold-tin alloy material on the second electrode layer 43, and then forming a gold-tin eutectic layer 44 by means of high-temperature sintering; or electroplating a gold-tin eutectic layer 44 on the second electrode layer 43; the thickness of the gold-tin eutectic layer 44 is 0.03-0.06 mm.

S3: the gold-tin eutectic layer 44 of the thermistor 4 is connected with the heat conducting base plate 5 in a mounting mode, and welding is carried out at the temperature of 300-310 ℃ after mounting.

S4: the first electrode pins 505, 506 are connected with the

leads

201, 202 using a wire bonding process on the first electrode layer 42.

S5: a layer of silicone grease 3 is dotted on the thermistor 4.

S6: the thermistor 4 and the heat conducting base plate 5 are encapsulated by the epoxy resin 1.

The manufacturing method has the following technical effects: the first electrode layer 42 and the second electrode layer 43 are firmly connected to the outer surface of the thermistor base 41 by high-temperature sintering, and are prevented from falling off. The gold-tin eutectic layer 44 surrounds the heat conduction bottom plate 5 and is fixed in a mode of firstly attaching and then welding, so that the thermistor 4 can be accurately and firmly installed on the heat conduction bottom plate 5. The first electrode pins 505, 506 are connected to the first electrode layer 42 by the

leads

201, 202, improving reliability in use, in particular by connecting two pins simultaneously to one electrode, if one pin fails, the other pin can still operate. By arranging the silicone grease 3, stress can be buffered, and damage to the thermistor 4 caused by stress in the subsequent encapsulation of the epoxy resin 1 is avoided.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. The generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The temperature sensor comprises a thermistor (4), wherein the thermistor (4) comprises a thermistor matrix (41) made of a thermosensitive material, a first electrode layer (42) and a second electrode layer (43) which are arranged on the surface of the thermistor matrix (41), and first electrode pins (505 and 506) are arranged on the first electrode layer (42), and the temperature sensor is characterized by further comprising a gold-tin eutectic layer (44) which is arranged on the second electrode layer (43) and completely covers the second electrode layer (43), and a heat conducting bottom plate (5) which is connected with the gold-tin eutectic layer (44) and made of a heat conducting material, and second electrode pins (501, 502, 503 and 504) are arranged on the heat conducting bottom plate (5).

2. The temperature sensor according to claim 1, wherein the first electrode pins (505, 506) are connected to the first electrode layer (42) by leads (201, 202).

3. A temperature sensor according to claim 2, wherein a plurality of first electrode pins (505, 506) are provided and are connected to the first electrode layer (42) by respective leads (201, 202); the leads (201, 202) are gold wires or copper wires.

4. A temperature sensor according to claim 2, characterized in that the thermistor (4) is externally provided with silicone grease (3).

5. The temperature sensor according to claim 1, wherein the thickness of the first electrode layer (42) is 0.01-0.06 mm; the thickness of the second electrode layer (43) is 0.01-0.06 mm; the thickness of the gold-tin eutectic layer (44) is 0.03-0.06 mm; the thickness of the heat conducting bottom plate (5) is 0.2-0.5 mm.

6. The temperature sensor according to claim 1, wherein the heat conducting base plate (5) comprises a connecting portion (51) and an extending portion (52) which is arranged on the connecting portion (51) and extends outwards, the thermistor (4) is arranged on the connecting portion (51), the connecting portion (51) is used for being in contact with an object to be measured to transmit temperature change to the thermistor (4), and the extending portion (52) is used for fixing the position of the connecting portion (51) and the object to be measured.

7. The temperature sensor according to claim 6, characterized in that a thermally conductive buffer hole (53) is provided between the connection portion (51) and the extension portion (52); the heat conduction buffer holes (53) penetrate through two opposite sides of the heat conduction base plate (5) to reduce the connection area of the connection part (51) and the extension part (52).

8. The temperature sensor according to claim 1, wherein the second electrode pins (501, 502, 503, 504) are integrally formed on the heat conducting base plate (5); the second electrode pins (501, 502, 503, 504) are multiple and symmetrically arranged on the heat conducting bottom plate (5).

9. A temperature sensor according to claim 1, characterized in that the outer sides of the thermistor (4) and the heat conducting base plate (5) are provided with an epoxy resin (1).

10. A method for manufacturing a temperature sensor, comprising the steps of:

s1: printing materials forming electrode layers at different positions on the outer surface of the thermistor base body (41), and then forming a first electrode layer (42) and a second electrode layer (43) on the outer surface of the thermistor base body (41) respectively by a high-temperature sintering mode;

s2: printing a layer of gold-tin alloy material on the second electrode layer (43), and then forming a gold-tin eutectic layer (44) by means of high-temperature sintering; or electroplating a gold-tin eutectic layer (44) on the second electrode layer (43);

s3: the gold-tin eutectic layer (44) of the thermistor (4) is connected with the heat conducting bottom plate (5) in a mounting mode, and welding is carried out at the temperature of 300-310 ℃ after mounting;

s4: connecting the first electrode pins (505, 506) with leads (201, 202) using a wire bonding process on the first electrode layer (42);

s5: a layer of silicone grease (3) is dotted on the thermistor (4);

s6: and packaging the thermistor (4) and the heat conducting bottom plate (5) through the epoxy resin (1).