CN100439909C - Method for preparing high-molecular resistance type composite thick film sensor - Google Patents

Abstract

The invention provides a preparation method of a polymer resistance type composite thick film sensor, which aims to solve the problems that: the conventional humidity sensor has poor stability, narrow test range, large hysteresis and low linearity. The key points of the invention are as follows: the method comprises the steps of preparing a compact ceramic substrate, symmetrically screen-printing rectangular porous graphite electrodes on one surface of the compact ceramic, screen-printing gold paste on the tail ends of the electrodes, welding pins after metallization, quantitatively dripping a reaction type humidity-sensitive medium on the surfaces of the porous electrodes by using a dispenser, heating, curing to form a network polymer, and finishing physical entanglement and rivet-riveting with the porous electrodes. The invention has the positive effects that: (1) the water resistance, the electrical aging performance and the mechanical aging performance of the element are improved. (2) The porosity of the electrode provides both physical entanglement and clinching points of the network polymer, as well as adequate space to contain contaminants. (3) The humidity sensing medium adopts an environment-friendly solvent and a high-precision glue dispenser, and the batch production process is simple and convenient. (4) The element has the characteristics of high linearity, extremely low wet hysteresis, wide range, proper sensitivity and the like.

Description

The preparation method of composite thick film sensor of high molecular resistance type

Technical field

The present invention relates to a kind of preparation method of humidity sensor, particularly a kind of wide-range, low humidity hysteresis, high linear, the preparation method of the high molecular resistance type composite thick film humidity sensor of little drift.

Background technology

In recent years, along with the widespread use of humidity observation and control technology at industry and civil area, the homemade humidity-sensitive element performance particularly performance of resistance type humidity sensor has had rapid progress, but their performance can't satisfy the needs that segment market.Its reason is that traditional conventional humidity sensor long-time stability are poor, test specification is narrow, humidity hysteresis is big, the linearity is low etc.

Summary of the invention

The object of the present invention is to provide a kind of preparation method of composite thick film sensor of high molecular resistance type, the humidity sensor for preparing with this method has wide-range, low humidity hysteresis, high linear, characteristics such as little drift.

The object of the present invention is achieved like this: it has the ceramic of compact substrate, at the symmetrical silk-screen rectangle porous graphite electrode of ceramic of compact one side, at electrode end silk-screen gold paste, metallization back welding pin, on the porous electrode surface with the quantitative dropwise reaction type of point gum machine humidity-sensitive medium, be solidified into network polymer after the heating, and finish and the physical entanglement of porous electrode and nail riveting.

The present invention compares with the prior art scheme, and its advantage is:

(1) based on the polymer design and the electrode design that improve long-time stability: humidity-sensitive medium is heating self-cross linking type quaternary polymkeric substance, at the crosslinked micropore that advances into porous graphite electrode, be solidified into network polymer after the heating, and finish and the physical entanglement of porous electrode and nail riveting, greatly increase the bond strength of humidity-sensitive film and graphite electrode, thereby given element excellent in water resistance and fabulous electric ageing properties and mechanical aging performance.

(2) aim at raising element rugged surroundings tolerance and the porous graphite electrode of independent research: the poriness of electrode both provided the physical entanglement and the nail riveting point of network polymer, the suitable space that holds pollutant is provided again, make element that certain breathing and function of exchange be arranged in the environment of high pollution, thereby give element excellent anti pollutant performance.

(3) humidity-sensitive medium adopts the environment-friendly type solvent of fast levelling, fast volatilization, adopts the high precision point gum machine, and the technology of batch process is extremely easy, has guaranteed interelement height consistance simultaneously.

(4) by adjusting, can produce and be applicable to that different places gets humidity-sensitive element, enlarge the application of element each component of humidity-sensitive medium.

(5) the synthetic humidity-sensitive medium of patented method combines with the porous graphite electrode of independent research, gives the element heights linearity, extremely low humidity hysteresis, wide-range, characteristics such as suitable sensitivity.

Further specify the present invention below by embodiment.

Embodiment

One, embodiment

1, the ceramic of compact sheet 1 of 6mm * 5mm * 0.5mm is used ultrasonic cleaning 10min in acetone solution, descend air-dry at 50 ℃ after leaching ceramics, drying is 0.5 hour under 120 ℃, the silk-screen spacing is 0.5mm on ceramics then, size is the symmetrical porous graphite electrode 2 of 4.5mm * 2mm, at the gold paste of ceramics bottom silk-screen 2mm * 1mm, then 140 ℃ dry 0.5 hour down, after change in the batch-type furnace at 900 ℃ ± 50 ℃ following sintering of temperature.

2, be fixed on the coating tool equably after the ceramics welding pin that sintering finishes, drip humidity-sensitive medium with the amount of 0.01-0.05ml/ sheet to electrode surface with point gum machine, dropwise and treat solvent evaporates, behind the surface filming profile member is sent into baking oven, with 60-120 ℃ of baking 3-5 hour.

2.1 humidity-sensitive medium is synthetic:

A) at first, synthesize humidity sensitive medium substrate with following backbone structure:

B) add second component with moisture sensitivity and reaction active groups in humidity sensitive medium substrate, along with the difference of second component, temperature of reaction changes between 30-80 ℃, and the structural formula of second component is as follows

X is F, Cl, and Br, one of them of I etc., q=2p+1p=2-6,

R ₃For-OH ,-NH ₂,-CH ₂NH ₂,-CH ₂N (CH ₃) ₂Or-CH ₂N (CH ₂CH ₃) ₂Deng group;

R ₄Be allyl, epoxy radicals or benzyl ethylene base, the group that the organic silica-based grade of alkoxy has reactivity.R ₅Be C ₁-C ₅Alkyl, aryl or benzyl

R ₆, R ₇-CH ₂N (CH ₃) ₂,-CH ₂N (CH ₂CH ₃) ₂,-CH ₂CH ₂N (CH ₂CH ₃) ₂Or-CH ₂CH ₂N (CH ₃) ₂

R ₈Be hydroxyl, amino, C ₄-C ₆Alkyl benzyl, C ₄-C ₆Alkyl halide or C ₄-C ₆α alkyl alkene.

C) have the 3rd component of catalytic activity:

Phenol: formaldehyde: dimethylamine (or diethylamine)=1: 1: 1-1: ratio was mixed the hydrochloric acid that drips phenol amount 1-5% simultaneously in 3: 3, reacted 6-12 hour down at 40-80 ℃, generated wet quick component 3

N=2m+1 m=2-6, R can be the alkyl that carbon number is 2-6, F, Cl, Br, one of them of I etc.

D) with b) product and the c of step) product in molar ratio 10 of step: 1-10: 3 ratio is mixed, airtight preservation in less than 20 ℃ environment.

3, humidity-sensitive medium is the response type quaternary ammonium salt, is characterized in having the polyquaternium of stronger crosslinked ability, and the degree of polymerization is between 40-80, and crosslinked group is that group is closed in epoxy radicals, alkoxy silane or two key insatiable hunger.

4, the element for preparing under the relative humidity of 80-95%, adds aging 40-80 hour of 2-4V, 1000-5000Hz alternating current under 40-60 ℃ temperature.

5, the demarcation of element and sorting

Is one batch with the aging element that finishes only with 500-1000, is installed on the computing machine multiple spot testing impedance frock at 20-25 ℃ testing element impedance and carry out sorting under the relative humidity of 50-60%.

Two, element function is referring to accompanying drawing.

Fig. 1 is the temperature coefficient curve figure of an element.

Fig. 2 is the anti-aging performance diagram of element.

Fig. 3 is the temperature coefficient curve figure of two elements.

Fig. 4 is series of products temperature coefficient curve figure.

1, the linearity of element and humidity hysteresis:

Referring to Fig. 1, be 25 ℃ of@, the test value of relative humidity element when 10-95%rh, visible element has high linear low The characteristic of humidity hysteresis, and suitable response characteristic is arranged in wider range ability.

2, the anti-aging characteristic (referring to Fig. 2) of element:

40 ℃ of aging condition :@apply 2V to element under the 80%rh humiture environment, the alternating current of 1KHz, and every day is aging 16 hours, all the other times, at the appointed time, at 25 ℃, test hindered under the temperature and humidity conditions of 60%rh in indoor placement Anti-value, element increases 0.01575k Ω every day under this environment, is equivalent to a year drift-1.5%rh, surveys and be used for actual environment 30 element years of examination drift about all＜1%rh.

3, the replaceability of element (referring to Fig. 3):

Appoint and get 2 elements at 25 ℃, the element that the Impedance measurement value is identical under 60% the relative humidity carries out gamut to be demarcated, and sends out Existing the two response characteristic is almost completely consistent.

4, temperature coefficient:

Referring to Fig. 4, this figure is the temperature coefficient curve of these series of products, and as calculated, impedance is with temperature in the constant situation of humidity The B value that degree changes is 3900-4000, just can be by the full remuneration of offset-type thermistor, and this is the another greatly excellent of this invention The point.

5, batch production uniformity:

Owing to the autoreaction characteristic of humidity-sensitive medium with based on the technological design of producing in batches, not only so that interelement has exchange The property, have extraordinary uniformity between batch.

The performance tabulation of high molecular resistance type composite thick film humidity sensor

Index and evaluation criterion
		Between linear zone (wide)	20-80％RH
The linearity (height)	0.6
		25 ℃ of 10%～90%～10%RH of humidity hysteresis (little)@	＜1％RH
25 ℃ of response time (weak point)@, 63%	60S
		Temperature coefficient*℃ (little)	0.6％RH
MF12 compensates situation	Total temperature section compensation performance excellence
		Measurement category (wide)	10％～90％RH，5～50℃
Year drift value (little)	＜1.5％RH

Claims (2)

1, the preparation method of composite thick film sensor of high molecular resistance type, it is characterized in that: it has the ceramic of compact substrate, at the symmetrical silk-screen rectangle porous graphite electrode of ceramic of compact one side, at electrode end silk-screen gold paste, metallization back welding pin, quantitatively drip the poly-quaternary ammonium salt response type humidity-sensitive medium of the degree of polymerization between 40-80 on the porous electrode surface with point gum machine, be solidified into network polymer after the heating, and finish and the physical entanglement of porous electrode and nail riveting.

2, according to the preparation method of the described composite thick film sensor of high molecular resistance type of claim 1, it is characterized in that:

(1), the ceramic of compact sheet of 6mm * 5mm * 0.5mm is used ultrasonic cleaning 10min in acetone solution, descend air-dry at 50 ℃ after leaching ceramics, drying is 0.5 hour under 120 ℃, the silk-screen spacing is 0.5mm on ceramics then, size is the symmetrical porous graphite electrode of 4.5mm * 2mm, at the gold paste of ceramics bottom silk-screen 2mm * 1mm, then 140 ℃ dry 0.5 hour down, after change in the batch-type furnace at 900 ℃ ± 50 ℃ following sintering of temperature;

(2), be fixed on the coating tool equably after the ceramics welding pin that sintering finishes, drip humidity-sensitive medium with the amount of 0.01-0.05ml/ sheet to electrode surface with point gum machine, dropwise and treat solvent evaporates, behind the surface filming profile member is sent into baking oven, with 60-120 ℃ of baking 3-5 hour;

(2.1) humidity-sensitive medium is synthetic:

A) at first, synthesize humidity sensitive medium substrate with following backbone structure:

B) add second component with moisture sensitivity and reaction active groups in humidity sensitive medium substrate, along with the difference of second component, temperature of reaction changes between 30-80 ℃, and the structural formula of second component is as follows

X is F, Cl, and Br, one of them among the I, q=2p+1 p=2-6,

R ₃For-OH ,-NH ₂,-CH ₂NH ₂,-CH ₂N (CH ₃) ₂Or-CH ₂N (CH ₂CH ₃) ₂Group;

R ₄Be allyl, epoxy radicals or benzyl ethylene base, the organic silica-based group of alkoxy, R with reactivity ₅Be C ₁-C ₅Alkyl, aryl or benzyl

R ₆, R ₇-CH ₂N (CH ₃) ₂,-CH ₂N (CH ₂CH ₃) ₂,-CH ₂CH ₂N (CH ₂CH ₃) ₂Or

-CH ₂CH ₂N(CH ₃) ₂；

R ₈Be hydroxyl, amino, C ₄-C ₆Alkyl benzyl, C ₄-C ₆Alkyl halide or C ₄-C ₆α alkyl alkene;

C) have the 3rd component of catalytic activity:

Phenol: formaldehyde: dimethylamine or diethylamine=1: 1: 1-1: ratio was mixed the hydrochloric acid that drips phenol amount 1-5% simultaneously in 3: 3, reacted 6-12 hour down at 40-80 ℃, generated wet quick component 3

N=2m+1 m=2-6, R are that carbon number is the alkyl of 2-6, F, Cl, Br, one of them of I

D) with b) product and the c of step) product in molar ratio 10 of step: 1-10: 3 ratio is mixed, airtight preservation in less than 20 ℃ environment;

(3), humidity-sensitive medium is the response type quaternary ammonium salt, is characterized in having the polyquaternium of stronger crosslinked ability, the degree of polymerization is between 40-80, crosslinked group is that group is closed in epoxy radicals, alkoxy silane or two key insatiable hunger;

(4), the element for preparing under 40-60 ℃ temperature, under the relative humidity of 80-95%, add aging 40-80 hour of 2-4V, 1000-5000Hz alternating current;

(5), the demarcation of element and sorting

Is one batch with the aging element that finishes only with 500-1000, is installed on the computing machine multiple spot testing impedance frock at 20-25 ℃ testing element impedance and carry out sorting under the relative humidity of 50-60%.

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