JPH03227380A - Ink for screen printing - Google Patents

Abstract

PURPOSE:To provide the subject ink composed of a solvent, an organic powder insoluble in said solvent and a specific polyimide precursor, having excellent screen printing performance and adhesivity to a substrate, developing small residual stress and useful as an interlayer insulation film, etc., in electronic field such as semiconductor. CONSTITUTION:The objective ink is composed of (A) a solvent (preferably >=70% is polar solvent such DMF), (B) an organic powder insoluble in said solvent (preferably polyimide silicone having an average particle diameter of <=10mum) and (C) a polyimide precursor of formula [x, n and m are >1 and satisfy the formula 10<n/(n+m)X100<=100; R1 is tetravalent organic group; R2 and R4 are bivalent organic group; R3 is univalent organic group].

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a screen printing ink useful for forming interlayer insulating films and protective films in the field of electronics such as semiconductors and electronic components.

[Prior Art] Conventionally, screen printing inks are known that are made of a polyimide precursor containing a solvent, an organic powder or an inorganic powder, and a small amount of silicon diamine.

However, although such inks have good screen printability and good adhesion to substrates such as silicone wafers, they have the disadvantage that residual stress is large, causing warping of the substrate and even cracking of the substrate.

[Problems to be solved by the invention] The present invention has good screen printability and good adhesion to the substrate,
The present invention provides a screen printing ink with low residual stress.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a screen printing ink comprising the following composition: a solvent, an organic powder insoluble in the solvent, and a polyimide precursor. , the polyimide precursor has the general formula (1) (1) (where x, n, m are integers greater than 1, and R1 is 4
Valid organic group, R2, R4 R3 represents a monovalent organic group. ) is characterized by a screen printing ink that is a polymeric substance shown in the following.

The solvent used in the present invention may be any solvent as long as it dissolves the polyimide precursor, but from the viewpoint of solubility,
It is desirable that at least 0%, preferably at least 70%, be composed of a polar solvent. Polar solvents have a solubility parameter (δ
) or 9.5 or more is a divalent organic group. Examples of polar solvents include dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-
Examples include methyl 2-pyrrolidone and hexamethylphosphoramide, which may be used alone or in combination.

The organic powder insoluble in the solvent used in the present invention may be any organic powder insoluble in the above-mentioned solvent, and usually has a number average particle size of 20 microns or less, preferably 10 microns or less. Specifically, polyimide powder, polyimide silicone powder, wholly aromatic polyamide powder, wholly aromatic polyester powder, unsaturated polyester powder, polyamide powder, polyester powder, etc. are mentioned, but among these, polyimide silicone powder has the highest flexibility. It is particularly preferable from the viewpoint of Moreover, an inorganic powder insoluble in a solvent can be added simultaneously with the organic powder. Inorganic powders that can be used include 5IO2, Al2O3, CaCO3, A1 (O
I]) 3, ZrO2, 5iC1BN, SiN powder, etc., and the particle size used is usually a number average particle size of 20 microns or less, preferably 10 microns or less.

The amount of organic powder added is not particularly limited, but from the viewpoint of screen printability and film properties, the ratio of organic powder/polyimide precursor is preferably in the range of 9/1 to 2/8 by weight, and more preferably Preferably it is 7/3 to 3/7.

In the polyimide precursor in the present invention, in the above general formula (1), R1 is a tetravalent organic group having 6 to 20 carbon atoms, preferably an aromatic ring or an aromatic heterocycle, and the carbonyl group is ortho or peri what is attached to the position,
R2 is a divalent organic group having 1 to 10 carbon atoms, preferably an aliphatic group, an aromatic ring, or an aromatic ring having a substituent;
R3 is a monovalent organic group having 1 to 15 carbon atoms, preferably an aliphatic group or an aromatic ring, and R4 is a divalent organic group having 6 to 20 carbon atoms, preferably an aromatic ring or an aromatic heterocycle. It is desirable that

Examples of R1 include, but are not limited to, a phenyl group, a naphthalene group, a perylene group, a diphenyl group, a diphenyl ether group, a diphenylsulfone group, a 2,2-diphenylpropane group, and a benzophenone group.

Examples of R2 include ethylene group, trimethylene group, isopropylidene group, isobutylene group, tetramethylene group,
Examples include, but are not limited to, a pentamethylene group, a phenylene group, a tolylene group, a xylene group, and the like.

Examples of R3 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group,
Examples include, but are not limited to, a vinyl group, an allyl group, a metaallyl group, a phenyl group, a biphenyl group, a tolyl group, and an ethylphenyl group.

Examples of R4 include, but are not limited to, diphenyl ether group, phenyl group, tolylene group, diphenylmethane group, diphenyl sulfone group, and the like.

Two or more types of monomers having R1 and R4 groups may be used in the polyimide precursor represented by formula (1) as long as the film-forming ability, adhesiveness and flexibility are not significantly impaired. Also, two or more types of silicone monomers may be used.

(n/n+m)X100 in formula (1) of the present invention is
The value is greater than 10 and less than 100, but if this value is less than 10, the residual stress in the film will be large, which is undesirable. More preferably it is 20 or more.

Next, the method for manufacturing the ink of the present invention will be explained.

Uniformly disperse a predetermined amount of organic powder or organic powder and inorganic powder in a solvent, add silicone diamine and aromatic diamine to this suspension, and add small amounts of tetraorganic carboxylic acid anhydride as indicated by the dissolution. When reacted, printing ink is obtained.

The ink of the present invention can be used as a protective film for electronic components, an interlayer insulating film for multilayer wiring using conductors such as AI on ceramic substrates, a stress absorbing film in VLSI, an α-ray protective film, etc. during the manufacture of electronic components. .

It is particularly useful as a coating type protective film for flexible printed circuit boards and a stress absorbing film for VLSI.

[Effects of the Invention] As mentioned above, the screen printing ink of the present invention uses a polyimide copolymerized with a large amount of flexible and heat-resistant silicone component as a binder component, and to this, fine organic powder is added. The ink has excellent screen printability, good adhesion to the substrate, and low residual stress, and has remarkable practical effects such as forming a flexible film after printing and heat treatment.

(Measurement of physical properties) (1) Using a spinner (IHDS-2 manufactured by Mikasa), apply residual stress ink at 200 rpm to a 50 x 50 mm 35 μ thick electrolytic copper foil to a thickness of 50 μ after heat treatment. ,
80℃x3Qmin+200℃X30m1n-4-3
It was cured in three curing steps of 00'CX30mln. After cooling to room temperature, place the copper foil coated with this polyimide on a horizontal table and measure the height of the end from the table.
The magnitude of residual stress was evaluated from the value.

Items with a height of less than 1 cm from the table are 0. Items with a height of 1 cm or more and less than 2 cm from the table are Δ. Items with a height of 2 cm or more from the table are ×.

(2) Apply the adhesive ink on a 4-inch silicone wafer at 200 rpm using a spinner so that the film thickness after heat treatment is 50μ, 80℃ x 30m1n + 200℃ x 3
It was cured in three curing steps: 0 min + 300°C x 30 ml.

Using an NT cutter, cut this coating film vertically and horizontally at 1mm intervals.
One line was inserted to create a grid of 100 squares with each side measuring 1 mm. Chiban Co., Ltd. for this and “Serotep”
Press the tape with your fingers to apply it accurately, then hold one end in your hand and pull it off. The adhesion strength of the ink to the wafer was evaluated by the number of grids that peeled off together with the Sellotape.

Less than 10 samples were rated as ○, 10 or more but less than 50 samples were rated △, and 50 or more samples were rated as ×.

(Number average particle size) A small amount of varnish was collected, diluted with a varnish solvent, applied ultrasonic waves to uniformly disperse it in the solvent, and then spread on a glass with a size of 26 x 76 mm and a thickness of 1 mm. of,
"quant im" manufactured by Cambridge Instrument Co.
The measurement method was to place the above sample on the measuring table of an optical microscope, magnify it 180 times through the microscope, and measure the projected area and number of particles projected onto a cathode ray tube. Measure.

Next, calculate the diameter of the circle corresponding to this projected area.

The diameter of the circles taken at 1 micron intervals is d (for example, if the diameter is from 1 micron to 2 microns, d = 1.5).
, the number of particles is n, the total number of particles is N1, the number average particle diameter is [d], then Σdn [d].

"Example" Hereinafter, the present invention will be explained based on Examples.

Example I 437 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) solvent is weighed into a three-necked 21 flask. Add to this 60g of diaminodiphenyl ether (hereinafter abbreviated as DAE)
Add the solvent at 50°C while stirring to completely dissolve.

After the DAE is completely dissolved, bis(aminopropyl)
Polydimethylsiloxane (amine equivalent = 450 or less B
Add 88g (abbreviated as AS) and mix.

(x = 10 to 11) When the solution becomes homogeneous, add pyromellitic anhydride (hereinafter referred to as P
Add 87.2 g of MDA (abbreviated as MDA) little by little to the solution while stirring. After reacting for 30 minutes, the mixture was further reacted at 80°C for 30 minutes, and then heated to 150°C and reacted for 90 minutes to produce polyimide silicone powder. After that 7
Lower the temperature to 0℃.

When the temperature reached 70°C, 27.3 g of DAE was added and dissolved. Then add 8120 g of BA. Then benzophenonetetracarboxylic anhydride (hereinafter abbreviated as BTDA)
87.9g was added and reacted. After reacting for about 1 hour, the viscosity was measured using a BS type viscometer (manufactured by Tokyo Keiki Co., Ltd.) using a No. 60-tar at 25°C and 10 rpm, and the viscosity was 150±.
Tune in to 50 voices. If the viscosity is low, add more raw materials; if the viscosity is high, dilute with NMP. When the viscosity matches, the mixture is allowed to react for another hour and taken out.

After curing this ink on a 4-inch silicone wafer, 50μ
It was applied to a thick layer and cured. As a result of testing the adhesive strength of this film, no peeling from the wafer was observed, indicating that the adhesive strength was very good.

This ink was applied to a 50 x 50 mm copper foil to a thickness of 50 μm after curing, and after it was cured and cooled to room temperature, the board was observed for warpage. As a result, almost no warpage was observed.

In this example, [n, , / (n + m) xl[l
[l] was 50.

Example 2 437 g of NMP solvent is weighed into a three-necked 21 flask. To this, 60 g of DAE is added at 50° C. while stirring the solvent, and completely dissolved. After the DAE is completely dissolved, the RA
Add 88g of S and mix.

When the solution becomes homogeneous, 87.2 g of PMDA is added little by little while stirring the solution. After reacting for 30 minutes,
The reaction was further carried out at 80°C for 30 minutes, and then the temperature was raised to 150°C and the reaction was carried out for 90 minutes to produce polyimide silicone powder. After that, the temperature is lowered to 70°C. When the temperature reached 70°C, 50.6 g of DAE was added and dissolved. Then RAS7
Add 5.9g. After that, 108.7 g of BTDA is added and reacted. After reacting for about 1 hour, measure the BS viscometer (
No. 60-tar (manufactured by Tokyo Keiki Co., Ltd.) at 25℃, IQr.
Measure the viscosity in pm and adjust the viscosity to 150±50 poise. After reacting for an additional hour, it was taken out, applied to a substrate, and after curing, adhesive strength and warpage were observed. The adhesive strength was extremely good, and only about 0.5 mm of warpage was observed.

In this example, [n/(n0m)xloo] is 2
It was 5.

Comparative Example I 437 g of NMP solvent is weighed into a three-necked 21 flask. To this, 71.6 g of DAE is added at 50° C. while stirring the solvent, and completely dissolved. After the DAE is completely dissolved,
When the solution becomes homogeneous, 74.1 g of PMDA is added little by little while stirring the solution. After reacting for 30 minutes,
The reaction was further carried out at 80°C for 30 minutes, and then the temperature was raised to 150°C and the reaction was carried out for 90 minutes to produce polyimide powder. After that, the temperature is lowered to 70°C. DAE51 at a temperature of 70℃
．． Add 6g and dissolve. Then 1,3-bis-γ-
Aminopropyltetramethyldisiloxane (hereinafter referred to as ATM)
Add 4.8g (abbreviated as S).

CH3CH3 Thereafter, 89.3 g of BTDA was added and reacted.

After about 1 hour of reaction, a BS viscometer (Tokyo Keiki Co., Ltd.)
The viscosity was measured using a No. 6 o-tar (manufactured by the company) at 25°C and 10 rpm, and the viscosity was adjusted to 150 ± 50 voids. After reacting for another hour, take it out, apply it to the substrate, and after curing, the adhesive strength
I observed the sleigh. Although the adhesion was very good, the substrate warped and became cylindrical.

Claims (1)

[Scope of Claims] 1. A screen printing ink comprising a solvent, an organic powder insoluble in the solvent, and a polyimide precursor, the polyimide precursor having the general formula (1)▲mathematical formula, chemical formula, table etc.▼ (1) (Here, x, n, m are integers greater than 1, and 10<[
n/(n+m)]×100≦100, R_
1 is a tetravalent organic group, R_2 and R_4 are divalent organic groups, R
_3 represents a monovalent organic group. ) A screen printing ink characterized by being a polymeric substance represented by: 2. The screen printing ink according to claim 1, wherein the organic powder insoluble in a solvent is a polyimide silicone powder.