Plastic package type thermistor

Abstract

The utility model discloses a plastic package type thermistor, and relates to a thermistor. The utility model aims to solve the problems that the conventional thermistor is generally circular, and two terminal pins of the thermistor can become yellow and black after being baked at high temperature. The chip packaging structure comprises a shell, a chip and two leads, the chip is plastically packaged in the shell, the two leads are symmetrically fixed on the outer surface of the shell, the chip is connected with the leads, and the surface of the chip is plated with an electrode layer; the shell is composed of a sealing ring, a sealing cover and a sealing bottom. The sealing ring is arranged between the lower surface edge of the sealing cover and the upper surface edge of the sealing bottom. The utility model belongs to the technical field of electrical components.

Description

Technical Field

[0001] The utility model relates to a thermistor, belonging to the technical field of electrical components. Background Art

[0002] A thermistor is a sensor resistor whose resistance value changes with the change of temperature. According to different temperature coefficients, it is divided into a positive temperature coefficient thermistor and a negative temperature coefficient thermistor. The resistance value of the positive temperature coefficient thermistor increases with the increase of temperature, and the resistance value of the negative temperature coefficient thermistor decreases with the increase of temperature. They both belong to semiconductor devices. The positive temperature coefficient thermistor will be in an inoperative state for a long time; when the ambient temperature and current are in region c, the heat dissipation power of the thermistor is close to the heating power, so it may or may not operate. When the ambient temperature is the same, the action time of the thermistor decreases sharply with the increase of current; the thermistor has a shorter action time, a smaller holding current and action current when the ambient temperature is relatively high.

[0003] The negative temperature coefficient thermistor can also be used as an electronic circuit element for instrument circuit temperature compensation, cold junction temperature compensation of thermocouples and inrush current suppression at startup, etc. By using the self-heating characteristic of the NTC thermistor, automatic gain control can be realized, and an RC oscillator amplitude stabilization circuit, a delay circuit and a protection circuit can be constituted. When the self-heating temperature is much higher than the ambient temperature, the resistance value is also related to the ambient heat dissipation conditions. Therefore, this characteristic of the thermistor is often used in flow meters, gas analyzers, thermal conductivity analyzers, etc. to make special detection elements. The PTC thermistor is mainly used for overheat protection of electrical equipment, non-contact relays, constant temperature, automatic gain control, motor starting, time delay, automatic degaussing of color TVs, fire alarms and temperature compensation, etc. The product of the utility model is used for inrush current suppression at startup. Existing thermistors are generally circular plug-in products, which have high requirements for the space of the circuit board and have certain potential risks of moisture and humidity prevention. The client cannot use a large-scale automatic chip mounting production process for assembly, which affects the efficiency and product consistency. And the two lead pins of the thermistor will turn yellow and black after high-temperature baking. Summary of the Utility Model

[0004] The utility model aims to solve the problems that existing thermistors are generally circular and the two lead pins of the thermistor will turn yellow and black after high-temperature baking, and further provides a plastic-encapsulated thermistor.

[0005] The technical solution adopted by the utility model to solve the above problems is: the utility model includes a housing, a chip and two leads;

[0006] The chip is plastic-encapsulated in the housing, the two leads are symmetrically fixed on the outer surface of the housing, the chip is connected to the leads, and an electrode layer is plated on the surface of the chip;

[0007] The housing consists of a sealing ring, a cover, and a bottom cover;

[0008] The sealing ring is arranged between the edge of the lower surface of the cover and the edge of the upper surface of the bottom cover.

[0009] Furthermore, the housing is a rectangular block made of epoxy resin, and the lead is a rectangular thin sheet printed on the surface of the housing.

[0010] Furthermore, the sealing ring is provided with a cavity, and the cross-section of the sealing ring is an elliptical ring.

[0011] Furthermore, the cavity is filled with grease.

[0012] Furthermore, the sealing ring is made of heat-resistant silica gel.

[0013] Furthermore, the edge of the lower surface of the cover is provided with continuous wavy protrusions, and the edge of the upper surface of the bottom cover is provided with continuous wavy grooves that match the wavy protrusions.

[0014] Furthermore, the edge of the lower surface of the cover is provided with continuous serrated protrusions, and the edge of the upper surface of the bottom cover is provided with continuous serrated grooves that match the wavy protrusions.

[0015] Furthermore, the edge of the lower surface of the cover is provided with continuous isosceles trapezoidal protrusions, and the edge of the upper surface of the bottom cover is provided with continuous isosceles trapezoidal grooves that match the wavy protrusions.

[0016] The beneficial effects of the present utility model are as follows:

[0017] 1. The lead of the thermistor of the present utility model is attached to the surface of the housing and will not turn yellow or black after high-temperature baking;

[0018] 2. The thermistor of the present utility model is square, and the chip is encapsulated in the housing. The overall volume is small, the chip power is large, and the working current is high;

[0019] 3. The thermistor of the present utility model is a plastic-encapsulated thermistor with the chip encapsulated in the housing. The lightning protection performance is nearly doubled compared with the same-specification plug-in products, meeting the higher lightning protection test requirements put forward by many users at present.

[0020] 4. The thermistor of the present utility model has the electrical characteristics of small volume and high power. Compared with the same-specification products of round plug-ins, the working current is increased by about one-third.

[0021] 5. The thermistor of the present utility model has better moisture-proof characteristics than round plug-in products because it is a plastic-encapsulated process.

[0022] 6. The thermistor of the present utility model has a lower temperature rise and longer product life under the same usage conditions because the chip is a square structure and rectangular pins.

[0023] 7. Since the thermistor of the present utility model adopts a horizontal patch process, the space limitation for the circuit is small, and it can be used in a small space.

[0024] 8. Since the thermistor of the present utility model adopts a plastic-encapsulated horizontal patch process, the using end can adopt an advanced automated patch assembly process, greatly improving production efficiency and saving labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the thermistor;

[0026] Figure 2 is a process flow chart of manufacturing the thermistor;

[0027] Figure 3 is a schematic structural diagram of the outer shell in the first embodiment of the present utility model;

[0028] Figure 4 is a schematic structural diagram of the outer shell in the second embodiment of the present utility model;

[0029] Figure 5 is a schematic structural diagram of the outer shell in the third embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] DETAILED DESCRIPTION OF THE EMBODIMENT 1: As Figure 1 shown, a plastic-encapsulated thermistor includes an outer shell 1, a chip 2 and two leads 3;

[0031] The chip 2 is plastic-encapsulated in the outer shell 1, the two leads 3 are symmetrically fixed on the outer surface of the outer shell 1, the chip 2 is connected to the leads 3, and an electrode layer is plated on the surface of the chip 2;

[0032] The outer shell 1 is composed of a sealing ring 101, a cover 102 and a bottom cover 103;

[0033] The sealing ring 101 is arranged between the edge of the lower surface of the cover 102 and the edge of the upper surface of the bottom cover 103.

[0034] In this embodiment, the chip 2 is square, and the square chip can prevent subsequent counterfeiting.

[0035] DETAILED DESCRIPTION OF THE EMBODIMENT 2: As Figure 1 shown, the outer shell 1 is a rectangular block made of epoxy resin, and the lead 3 is a rectangular thin sheet printed on the surface of the outer shell 1.

[0036] DETAILED DESCRIPTION OF THE EMBODIMENT 3: As Figures 3 to 5 shown, a cavity 104 is provided in the sealing ring 101, and the cross-section of the sealing ring 101 is an elliptical ring.

[0037] DETAILED DESCRIPTION OF THE EMBODIMENT 4: AsFigures 3 to 5 As shown, the cavity 104 is filled with grease.

[0038] Specific Embodiment Five: As Figures 3 to 5 shown, the sealing ring 101 is made of heat-resistant silica gel.

[0039] Embodiment One: As Figure 3 shown, a continuous wavy protrusion 105 is provided at the edge of the lower surface of the cover 102, and a continuous wavy groove 106 that matches the wavy protrusion 105 is provided at the edge of the upper surface of the bottom cover 103.

[0040] Embodiment Two: As Figure 4 shown, a continuous serrated protrusion 107 is provided at the edge of the lower surface of the cover 102, and a continuous serrated groove 108 that matches the wavy protrusion 105 is provided at the edge of the upper surface of the bottom cover 103.

[0041] Embodiment Four: As Figure 5 shown, a continuous isosceles trapezoidal protrusion 109 is provided at the edge of the lower surface of the cover 102, and a continuous isosceles trapezoidal groove 110 that matches the wavy protrusion 105 is provided at the edge of the upper surface of the bottom cover 103.

[0042] The present utility model is manufactured through the following steps:

[0043] Step One: Assemble and weld;

[0044] Step Two: Encapsulate and cure;

[0045] Step Three: Trim the leads and electroplate;

[0046] Step Four: Inspect the semi-finished product obtained in Step Three;

[0047] Step Five: Mark and package the product.

[0048] Among them, the specific process of assembling and welding in Step One is: Assemble and weld the chip 2, the lead 3, and the solder paste into a semi-finished product.

[0049] Set key control points in Step One, and monitor the product quality during the assembling and welding process in real time by sampling and detecting some performance indicators.

[0050] Among them, the specific process of encapsulating and curing in Step Two is: The welded semi-finished product and the epoxy resin are encapsulated and cured into an encapsulated semi-finished product under suitable temperature and time conditions.

[0051] Set key control points in Step Two, and monitor the product quality during the encapsulating and curing process in real time by sampling and detecting some performance indicators and appearance indicators.

[0052] Among them, the specific process of die cutting and electroplating in step three is as follows: The semi-finished product after plastic encapsulation undergoes lead 3 shaping and electroplating to form an untested semi-finished product.

[0053] Set key control points in step three. Monitor the appearance structure of the product through appearance dimensions, and monitor whether the electroplating is carried out in place in real time by sampling and testing some performance indicators.

[0054] Among them, the specific process of testing the semi-finished product in step four for the semi-finished product in step three is as follows: Adopt a full inspection method to conduct a comprehensive quality monitoring of the semi-finished product in step three to ensure that the product quality is qualified.

[0055] Among them, the specific process of marking and packaging the product in step five is as follows: The qualified finished products in step four are packaged in a reel and put into a box.

[0056] Set key control points in step five. Monitor the laser engraving effect and the uniformity and integrity of the paper tape and the box through visual observation.

[0057] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments within the spirit and principle of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A plastic-encapsulated thermistor, characterized in that: It comprises a housing (1), a chip (2) and two leads (3); The chip (2) is plastic-sealed in the housing (1), two leads (3) are symmetrically fixed on the outer surface of the housing (1), the chip (2) is connected to the leads (3), and the surface of the chip (2) is plated with an electrode layer; The housing (1) is composed of a sealing ring (101), a sealing cover (102) and a bottom cover (103); The sealing ring (101) is arranged between the edge of the lower surface of the cover (102) and the edge of the upper surface of the bottom cover (103).

2. A plastic-encapsulated thermistor according to claim 1, characterized in that: The shell (1) is a rectangular block made of epoxy resin, and the lead (3) is a rectangular sheet printed on the surface of the shell (1).

3. A plastic-encapsulated thermistor according to claim 1, characterized in that: A cavity (104) is provided in the sealing ring (101), and the cross section of the sealing ring (101) is an elliptical ring.

4. A plastic-encapsulated thermistor according to claim 3, characterized in that: The cavity (104) is filled with grease.

5. A plastic-encapsulated thermistor according to claim 3, characterized in that: The sealing ring (101) is made of heat-resistant silicone.

6. The plastic-encapsulated thermistor according to claim 1, characterized in that: The edge of the lower surface of the cover (102) is provided with a continuous wave-shaped protrusion (105), and the edge of the upper surface of the bottom cover (103) is provided with a continuous wave-shaped groove (106) matched with the wave-shaped protrusion (105).

7. The plastic-encapsulated thermistor according to claim 1, characterized in that: The edge of the lower surface of the cover (102) is provided with a continuous sawtooth-shaped protrusion (107), and the edge of the upper surface of the bottom cover (103) is provided with a continuous sawtooth-shaped groove (108) matched with the wave-shaped protrusion (105).

8. The plastic-encapsulated thermistor according to claim 1, characterized in that: The edge of the lower surface of the cover (102) is provided with a continuous isosceles trapezoidal protrusion (109), and the edge of the upper surface of the bottom cover (103) is provided with a continuous isosceles trapezoidal groove (110) matched with the wavy protrusion (105).

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