CN204792276U

CN204792276U - Glass encapsulates PTC thermistor

Info

Publication number: CN204792276U
Application number: CN201520574553.8U
Authority: CN
Inventors: 杨敬义
Original assignee: CHENGDU SHUNKANG ELECTRONICS Co Ltd
Current assignee: CHENGDU SHUNKANG ELECTRONICS Co Ltd
Priority date: 2015-08-03
Filing date: 2015-08-03
Publication date: 2015-11-18
Anticipated expiration: 2025-08-03

Abstract

The utility model discloses a glass encapsulates PTC thermistor, this PTC thermistor is including sealed glass pipe and locate the intraductal PTC chip of this glass, the upper and lower surface of PTC chip all is equipped with the conductive adhesive layer, and the conductive adhesive layer links to each other with the upper and lower surface distribution's of PTC chip electrode, and every conductive adhesive layer still links to each other with a strip lead, the lead wire passes the glass pipe and communicates with each other with the external world. The utility model provides a glass encapsulates PTC thermistor, will go between with the conductive adhesive layer bonds on the upper and lower surface of PTC chip, has avoided the harmful effects of welding high temperature to the production of PTC chip, glass pipe messenger PTC chip through sealing keeps good completely cutting off with the external world, guarantees the durability of product, through the selection to the material, make the final structure of product have good stability simultaneously, and can satisfy the target requirement.

Description

A kind of glass packaging PTC thermistor

Technical field

The utility model belongs to thermistor technology field, is specifically related to a kind of glass packaging PTC thermistor.

Background technology

Space flight thermistor serves as watch-dog and the temperature sensor that rocket main body and artificial satellite are exposed to space environment.Also in the circuit of space flight machine, do temperature-compensating, a rocket and artificial satellite are with nearly hundreds of is individual simultaneously.Present aerospace thermistor has import product to have transition metal oxide system NTC thermistor, uses silicon PTC thermistor and the platinum temperature detecting resistance body of silicon single crystal.Temperature-compensating PTC thermistor has been developed and commercialization, employing be the civilian middle two fin types extensively adopted axial lead type glass encapsulating thermistor based on product.But space flight thermistor has high requirement to product itself, traditional thermistor cannot reach requirement.

What this patent was selected is highly sensitive in the scope of actual serviceability temperature (-30 ~ 95 DEG C), accuracy of detection is high, and as the actual a large amount of barium titanate ceramics semiconductor (PTC thermistor) used of civil goods, study the requirement condition of each complete machine producer, MIC specification, NASA is about analysis and investigation foreign country aerospace element equivalent product processed while specification and foreign country's universe processed component specification etc., the main target of set patented product is that resistance is at 220 ~ 22K Ω, certainty of measurement is ± 5%, the temperature range used is-55 ~ 125 DEG C, and require the guarantee reliability of 10 years, wherein maximum problem is in this special space of universe, to ensure the reliability of 10 years, this is that existing product does not reach far away.

Utility model content

The purpose of this utility model solves the problem, and provides a kind of glass packaging PTC thermistor reaching target call.

For solving the problems of the technologies described above, the technical solution of the utility model is: a kind of glass packaging PTC thermistor, the glass tube comprising sealing and the PTC chip be located in this glass tube, described PTC chip upper and lower surface is all provided with conductive adhesive layer, the electrode that conductive adhesive layer distributes with PTC chip upper and lower surface is connected, each conductive adhesive layer also goes between with one and is connected, and described lead-in wire communicates with the external world through glass tube.

Preferably, the material of described PTC chip is (Ba ₁- _xsr _x) TiO ₃, wherein the value of X is more than or equal to 0.5.

Preferably, the material of described glass tube, PTC chip and lead-in wire is thermal coefficient of expansion material close to each other.

The beneficial effects of the utility model are: glass packaging PTC thermistor provided by the utility model, with conductive adhesive layer, lead-in wire are bonded in the upper and lower surface of PTC chip, avoid the harmful effect that welding high temperature produces PTC chip; Make PTC chip keep good completely cutting off with extraneous by the glass tube of sealing, ensure the durability of product; Simultaneously by the selection to material, make the final structure of product have good stability, and can target call be met.

Accompanying drawing explanation

Fig. 1 is the structural representation of the utility model glass packaging PTC thermistor;

Fig. 2 is the sectional view of the utility model glass packaging PTC thermistor.

Description of reference numerals: 1, glass tube; 2, PTC chip; 3, conductive adhesive layer; 4, glass tube.

Embodiment

Below in conjunction with the drawings and specific embodiments, the utility model is described further:

As depicted in figs. 1 and 2; the utility model provides a kind of glass packaging PTC thermistor; in order to make this PTC thermistor resistance at 220 ~ 22K Ω; certainty of measurement is ± 5%; the temperature range used is-55 ~ 125 DEG C; and require the guarantee reliability of 10 years, the most basic reliability that will solve thermistor chip, then consider how to make thermistor chip be protected in this special space of universe.

Curie point 120 DEG C, with BaTiO ₃for principal component, utilize the PTC thermistor of crystal boundary phenomenon, the feature large according to its change in resistance, uses in switch element, heating element widely, but is used as the little of temperature-compensating.The Curie point of the material corresponded also arrives-30 DEG C at most.The change in resistance linearity under required wide temperature range (-55 ~ 125 DEG C) or Standard resistance range can not be met.Especially for linearity scope, study picture in the past silicon thermistor that raising sharpness will be very difficult, but must possess 2 points for the requirement of its material behavior is known:

1, linearity: Curie point is below-50 DEG C, and resistance should below 200 DEG C to temperature during peak value;

2, Standard resistance range: because the size of chip limits to some extent, therefore the resistivity at 25 DEG C should be at least include the complete kind of 200 Ω cm ~ 2k Ω cm scopes.

BaTiO ₃curie point total moisture content be 120 DEG C, for making it change, solid solution must be added in a part of the Ti at Ba or the B position at perovskite type crystal structure A position and be referred to as the element of mobile agent.In addition, according to valence control theory, so-called semiconductor transformation element (Nb, Y, La, Ce etc.) will similarly must be added, as the mobile agent to low temperature side in order to make PTC semiconductor transformation, Ca or Sr that ripe well known oriented Ba position is moved, to Sn or Zr that Ti position is moved.Original Curie-point temperature is-30 DEG C of persons, " mobile agent " is added Sr semiconductor transformation element and is used Nb, comprise these compositions to tie up to the result of carrying out all research and show, the displacement solid solution seeing mobile agent Sr from the viewpoint of Curie point as is the most effective, from the viewpoint of the uniformity of resistivity and ceramic microstructure, be the most effective as semiconductor words element Y; Add SiO ₂then more there is the effect of acceleration of sintering, simultaneously its reverse side, the effect that reliable liquid level is formed and suppresses crystal grain shaping.Resistivity can be given to affect greatly by the effect of crowded the pros and cons, so draw this basic composition: (Ba simultaneously ₁- _xsr _x) TiO ₃+ aY ₂o ₃+ bSiO ₂.

According to the result of study of basic composition, make more than Sr solid solution 0.5 molar concentration that Curie-point temperature then can be made to drop to less than-50 DEG C.Be limited for the target of the expansion of linearity and Standard resistance range by the method for Sr solid solution capacity or micro-additive, by various research, this target particularly changes cooling conditions to reach by the firing condition changing pottery.

What the discovery phenomenon PTC about resistance utilized is crystal boundary phenomenon.The main points of PTC chip manufacture how to obtain homogeneous, and fine and close pottery, also obtains homogenizing of powder just like by pre-burning, reach homogenizing of formed body with rubber press.PTC thermistor is due to the exploitation homogeneous of just composition system, and compactness also improves, but how to play its homogeneous, fine and close speciality, also will solve the problem of ohmic contact, and what adopt after deliberation is double-decker without electrolytics nickel plating silver ink firing again.

In sum, universe thermistor material is being conceived to the homogenizing of crystal structure, stabilisation as the PTC used time, uses (Ba ₁- _xsr _x) new material of TiO3 system, be replaced by Sr solid solution the Ba position more than 50% of BaTiO3, namely the material of PTC chip is Ba ₁- _xsr _xtiO ₃, wherein the value of X is more than or equal to 0.5.

For guaranteeing that long-term reliability will reach chip and external environment under aerospace environment, and ensure the stable of electric connection part structure.Glass packaging PTC thermistor in the present embodiment comprises glass tube 1, PTC chip 2, conductive adhesive layer 3 and lead-in wire 4, glass tube 1 is the tubular body of sealing, it is inner that PTC chip 2 is positioned at glass tube 1 all over, the upper and lower surface of PTC chip 2 is distributed with electrode, two conductive adhesive layers 3 are bonded in the upper and lower surface of PTC chip 2 respectively and are connected with electrode, each conductive adhesive layer 3 also goes between with one and 4 to be connected, lead-in wire communicates with the external world through glass tube 4, make PTC chip keep good completely cutting off with extraneous by the glass tube of sealing, ensure the durability of product.

In the present embodiment, glass tube is selected not select epoxy resin encapsulated as encapsulating material, because without outer package person and epoxy resin encapsulated product 150 DEG C of high-temperature tests, the change in resistance of PCT test is large, and glass packaging product show highly stable numerical value, think that resin can not seal, in the moisture be through, resistance is increased.

Room temperature is dropped to after glass packaging is over, but arrive between room temperature from the temperature of solidification glass and the distortion point temperature of glass, if the thermal coefficient of expansion of various material and glass has difference, the generation of thermal stress can be caused, so the material that each structural material selects thermal coefficient of expansion close to each other the scope planted agent that other performances allow as far as possible, namely the material of glass tube 1, PTC chip 2 and lead-in wire 4 is thermal coefficient of expansion material close to each other.

The utility model also provides a kind of manufacture method of glass packaging PTC thermistor, for making above-mentioned glass packaging PTC thermistor, comprises the following steps:

Step one, with conducting resinl lead-in wire 4 is bonded in the upper and lower surface of PTC chip 2 and conducting resinl is cured;

Step 2, the PTC chip 2 of the lead-in wire 4 that bondd is enclosed glass tube 1;

Step 3, completed the encapsulation of glass tube 1 by glass packaging blowtorch, and drop to room temperature.

Owing to adopting welding procedure to add man-hour to PTC thermistor, the impact of the heat produced during welding can make PTC chip degenerate, therefore have employed the method for conductive adhesive and the structure of conductive adhesive layer in the present embodiment.

In step 3, glass packaging temperature is Di Yeyaoji Baidu again, for preventing the oxidation that in the process of heating, atmosphere affects PTC chip and goes between, and the harmful effect to glass capsulation, the concentration of its oxygen to be changed during the encapsulation of each material system of thermistor, enclose glass according to each encapsulation condition.The oxidation states of pilot survey lead-in wire, hermetically sealed property, the change in resistance before and after encapsulation and high temperature change in resistance high-volume, NTC thermistor Mn-Ni-Co-Cu system thermistor process variations is about-10%.High temperature is placed high temperature durability in experiment and is reduced along with oxygen concentration and show the trend that resistance stability increases, but oxygen concentration little to sealing after 0.001% by bad, make durability degenerate on the contrary.So glass packaging oxygen concentration is most suitable with 0.1%; although leaded surface oxidation phenomenon under concrete this oxygen concentration; and this surface oxidation contributes to the encapsulation of glass, the oxide layer of the part simultaneously exposed in outside can remove, and can plating again.

Concrete, in step 3, glass tube encapsulation process completes in the atmosphere of the oxygen being mixed into 0.1% in argon gas, if but this ratio becomes 0.01%, and change in resistance becomes large.This is because lead-in wire generates insufficient for guaranteeing with the oxide-film of the sealing of glass, and when causing glass packaging, sealing property is bad.Meanwhile, also can cause poor sealing when glass produces breach for a certain reason, leaking-in air when also having a glass packaging and cause the phenomenon that change in resistance becomes large.

For further analysis to the glass packaging PTC thermistor of the present embodiment:

PTC thermistor is glass capsulation hollow structure, and its thermal stress can be ignored, but the joins that its reverse side is then lead-in wire is added with external force.Chip weight is 0.0049g when the minimum model of chip (8.2k Ω), be 0.0641g time the maximum model of chip (220 Ω), after adding 1500g external force in impact experiment, wire connections is often located loading and is respectively about 3.79g and 48g, and the adhesion strength of lead-in wire is respectively about 280g and about 1400g.Its level known can guarantee no problem.

The utility model is also in order to ensure that 10 year life-span of PTC thermistor has carried out various reliability evaluation test, and long-term life-test mainly does high temperature and shelves, and also will do normal temperature load in addition, thermal shock test.Mechanical test does random vibration, high-frequency vibration, shock test.Space environment test does resistance to radiation, thermal vacuum test etc.

Result of the test illustrates that the change in resistance that the high temperature in various test of PTC thermistor is shelved under (4000 hours) is 5%, next is the change in resistance under thermal shock (1000 cycle) is 4%, and the change in resistance under load life (4000 hours) is about 1.8%; Change in resistance under the stress test of machinery is within 1%, and the change in resistance under the resistance to radiation test of space environment is within 1%, and the change in resistance under thermal vacuum is about 1.5%.These result of the tests show that products made thereby has reached development goal value, ensure that stable quality level.

The long term life of thermistor is stablized by the resistance representing key property and is evaluated, and the experience of contact is all be conceived to change in resistance to become large at high temperature, and at high temperature changes temperature level and test.Also study with same method for PTC thermistor, result shows that products made thereby has the reliability of 10 years, has had obvious progress compared with 3 ~ 5 year life-span of traditional product.

Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present utility model, should be understood to that protection range of the present utility model is not limited to so special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combination of not departing from the utility model essence according to these technology enlightenment disclosed in the utility model, and these distortion and combination are still in protection range of the present utility model.

Claims

1. a glass packaging PTC thermistor, it is characterized in that: the glass tube (1) comprising sealing and the PTC chip (2) be located in this glass tube (1), described PTC chip (2) upper and lower surface is all provided with conductive adhesive layer (3), the electrode that conductive adhesive layer (3) distributes with PTC chip (2) upper and lower surface is connected, each conductive adhesive layer (3) also go between with one (4) be connected, described lead-in wire communicates with the external world through glass tube (4).

2. glass packaging PTC thermistor according to claim 1, is characterized in that: the material of described PTC chip is (Ba _1-Xsr _x) TiO ₃, wherein the value of X is more than or equal to 0.5.

3. glass packaging PTC thermistor according to claim 1 and 2, is characterized in that: the material of described glass tube (1), PTC chip (2) and lead-in wire (4) is thermal coefficient of expansion material close to each other.