SU958458A1 - Stencil ink for printed circuit boards - Google Patents

Description

(54) SCREENING PAINT FOR PCB

The invention relates to printing inks, in particular, screen-protective inks for screen printing, intended for the manufacture of printed circuit boards by chemical means in the radio, aircraft, instrument, machine building, electronic and other industries.

Known screen printing ink based on rosin-maleic resin esterified with pentaerythritol 13.

The paint does not dissolve in alkalis.

Closest to the proposed composition is a paint containing, in wt.%: Inorganic pigment 2-6, pentaerythritol ester of rosin-fumaric adduct 21-36, melamine-formaldehyde resin 6-12, fillers alumina hydrate 5-13, titanium dioxide 3-10, aerosil 2-3, organic solvent benzyl alcohol 8-11, ethyl cellosolve 18 ,, 5-21, plasticizer (oligoester) 8-12, polymethylsiloxane the rest 2.

The known paint is characterized by insufficient quality, has solubility in alkalis, has a low mechanical strength of the dry paint film (100-150 cycles on the device), which leads to poor protection of copper during etching, and dries in the printing form cells, resulting in an impression on the print defects (non-printed point spots, injections), which leads to marriage when etching boards.

The aim of the invention is to improve the quality of the paint.

The goal is achieved by the fact that screen paint for printed circuit boards containing rosin ester, a dye component, a plasticizer and

15 organic solvent additionally contains ethyl cellulose, and as rosin ester it contains phthalic anhydride pentaerythritol ester rosin 20 but maleic adduct in the following content of component, wt.%:

adduct, 24-38

Ethylcellulose 2-4 Dye component 1-10

30 Plasticizer 1-3 Filling agent 5-42 Organic solvent Remaining It has been established experimentally that the content of rosin in the printing ink of phthalene anhydride modified pentaerythritol ester of rosin-maleic adduct and additionally ethylcellulose can increase the quality of the paint, i.e. increase the mechanical strength of the paint film to 400-600 cycles and at the same time eliminate its drying in the printing plate cells. In addition, the proposed paint dries faster than the paint of the prototype, which leads to an increase in productivity on printing machines. The printing capacity of the automat ink by prototype is 1000-1200 boards per hour, and the proposed -2000-2200 boards per hour. The pentaerythritol ester of rosin-maleic adduct modified with phthalic anhydride is obtained by polycondensation using 57.8 cf. rosin-maleine adduct, 19.1 cp of pentaerythritol and 23.1 cc. phthalic anhydride. The synthesis process is carried out in the temperature ranges of 150 - 185 C until reaching

Modified by phthalic anhydride pentaerythritol ester of rosin-maleine adduct

Ethyl cellulose

The main dye

blue

Titanium dioxide

Yellow lightfast 2

Pigment red C

MiloriCron greenAerosilBarium sulphate

Aluminum hydroxide

DybutilftJatatDioctylphthalate38 4

30 2.5

32 3

3 3

17.5 3 of the acid number of 130–180 mgKOH / g and viscosity of a 50% resin solution in ethanol at 20 ° C. 200–250 cSt of VSH-2. As a dye component, organic pigments are used: azo pigments (yellow light resistant 2 h, orange pigment durable with filler, burgundy pigment K, red pigment C) j inorganic pigments — milori (ferrocyanide of iron), crown green, titanium dioxide, etc .; dyes - the main (main blue K, etc.) or their mixture. Aerosil, barium sulphate, aluminum hydroxide, or their mixture is used as a naphthaler. Phthalic esters or oligoesters (polyoxyethylene glycol, polyoxypropylene glycol) are used as plasticizers. As a solvent, ethyl cellosolve, butyl cellosolve, ethyl carbitol, benzyl alcohol, diacetone alcohol, benzyl acetate, tetralin or their mixture are used. The paint may additionally contain a surfactant; Alcomon OC-2 (0.1-0.5%) for improving bottling, polymethylsiloxane PMS-200A (0.1-0.5%) for eliminating printing bubbles. The invention is illustrated by the examples given in table. 1. Table 1

Polyoxyethylene glycol

Polyoxypropylene glyco

Butyl celloslose

Benzyl alcohol

Tetralin

Diacetone alcohol

Ethyl cellosolve

Ethyl carbitol

Ethyl glycol acetate

Benzyl acetate

Alcomon OS-2

Polymethylsilox

The paints are prepared as follows.

The phthalic anhydride-modified pentaerythritol ester of the rosin-maleic adduct and ethyl cellulose are dissolved in the solvent mixture in a dissolver at room temperature for 5-6 hours. Next, Prepare the kneading in a vertical kneader by mixing all the components taken in the recipe ratio and stirring. swath cycles

100-150

10 min

To continue, it is necessary to wash the paint off.

As can be seen from Table 2, the ink of the proposed composition has a high mechanical strength, which provides reliable protection of copper from acid electrolytes, and during continuous printing in a period of 8 hours does not dry out in the printing plates.

39 30,527

20

- - .ig.

- -20

14,5 20

13

five

0.5

.0,5

to get a milling no more than 15 microns.

Determine (Table 2) the mechanical strength of the ink films by the IMR device in cycles and the drying of the ink in the cells of the printing form at the boundary time, during which, during continuous printing, the drying of the ink in the cells of the printing form is not observed (TU 29-02-725- 77).

table 2

600

450

500 600

600

8h, 8h, 8h, 8h, 8h, 8h8h During the printing process, no intermediate paint washes are required.

The proposed paint makes it possible to obtain on prints an image of conductors 0.2 mm wide with an accuracy of 0.05 mm. The ink is applied to the foiled dielectric through a screen printing form. After drying, the uncovered parts of the metal surface are etched in a solution of ferric chloride or in other acidic compounds and. then the paint film dissolves in a 2.5% -5% aqueous solution; caustic soda. The paint dries for 5-10 minutes at 80-90 ° C. It can be used for the production of printed circuit boards in a continuous production line, using domestic equipment (printing machine PT-2p, drying device SL, pickling installation and installation for alkaline removal of paint film).

Claims (2)

1. USSR author's certificate 519461, .kl. C 09 D 11/10, 1976. 2. USSR author's certificate No. 595352, cl. C 09 D 11/10, 1978.