Silver Carbonaceous Conductive Ink in Electronic Screen Printing Technology (middle)

Second, the silver, carbon conductive ink requirements

1, silver conductive ink

It is used for membrane switches, palladium-based flexible printed circuits, carbon conductive inks, and adhesion to polyester (PET) films and PCB substrates. Its properties:

(1) Conductive, performance (square resistance) for conductive circuits

(2) Viscosity

(3) Recommended printing thickness 8-13um (0.3-0.5mil)

(4) Recommended thickness of printing plate or photosensitive film

20-38um (0.8-1.5mil)

(5) Button life

10 million times

(6) Through-hole resistance (when the hole is filled)

a, silver conductive ink 100mΩ

b. Carbon conductive ink 1Ω

(7) Screen material and mesh number

High tension, single yarn, plain weave polyester mesh

Imperial: 158-196 mesh (inches)

Metric: 62T-77T (cm)

ED725A 6S-61 claims that it can use 305 mesh (120T) screen, if this indicator is true, then it has a very fine quality, usually silver conductive ink fineness of not more than 10um, of course, its net , printability and other properties can be called "excellent".

(8) Excellent flexibility

Five folds (that is, the number of times the silver printed circuit is repeatedly twisted until the resistance value increases by 50%).

(9) Good printability

Try printing 10mil line width silver conductive circuit, arranged in a distance of 10mil parallel, the printed conductor image after printing is complete and clean.

(10) Excellent adhesion

After the adhesive tape test, the resistance of the silver conductive circuit increased by less than 5%.

(11) Pencil hardness

2H (ED725A6S-61)

Good quality can reach 3-6H

(12) Easy to use

(13) No dilution

(14) Dry curing method

100-135°C

(15) VOC (Organic Volatile Substances)

VOC is a harmful substance that pollutes the environment and seriously threatens the health of operators. For example, the ED725A 6S-61, which is called high-performance conductive silver ink for keyboard circuit and flexible circuit, has a VOC content of 824 g/liter (6.87 pounds). /gallon)

(16) Improvement Suggestions

a. It is hoped that it may be dried and cured in UV form, which can save energy, speed up the production cycle, benefit the establishment of new production modes such as high speed printing/rapid curing.

b. It is desirable to remove the VOC from the silver conductive ink. The solvent-based silver conductive ink is a water-based silver conductive ink.

c. In addition, in the conductive circuit formed by silver carbon conductive ink, insulation resistance and withstand voltage are also very important indicators. According to my understanding of the market and many customers in recent years, the technical parameters of these two indicators are:

●Insulation resistance

Test voltage: 500VDC

Test time: 1 minute, 10 minutes, 10 minutes or more

Insulation resistance: 500MΩ

● Withstand pressure

Test voltage: 250AC; 1000VAC

Inrush current: 1MA

Test time: 1 minute, 10 minutes, 10 minutes or more

Test results: No surface flash, sweep discharge, corona and breakdown.

2, carbon conductive ink

For membrane switch, heating element, flexible circuit, hybrid circuit, etc., its performance:

(1) Conductive properties (square resistance)

<50Ω/port (carbon film thickness 1mil)

(ED423SS)

250Ω/mouth (carbon film thickness 1mil)

(ED581SS)

(2) Viscosity

40000 or more CPS (mPa.S)

(ED423SS) (According to BR00KF1ELDRVT Viscometer, #7 Stir Bar, 20rpm, 20°C)

1.5 to 25,000 CPS

(ED581SS) (According to BR00KF1ELDRVT Viscometer, #7 Stir Bar, 20rpm, 20°C)

(3) Comprehensive quality

a, low resistance

b, excellent adhesion

c, there is a good environment, wow (such as resisting moisture, etc.)

3. Resistive Carbon Print Quality (PR400 Series)

(1) Resistive materials

Carbon/insulation

(2) Viscosity

2-35 thousand (according to BR00KF1ELDRVT viscometer, #7 stirring rod, speed 20rpm, 20°C)

(3) Screen Material and Mesh

Polyester (PET) 62-90T (158-230 mesh) or HD. With stainless steel yarns available 77-100T (196-255 mesh) mesh or HD.

(4) The thickness of the ink film after drying is 10um

(5) Thickness 20-40um of screen printing paste or photosensitive film

(6) Drying curing temperature

150-180°C

(7) Adhesion

Class B (excellent)

(8) The resistances are

Third, silver carbon conductive ink quality and process quality

Process technology has always been a subject of greatest interest to everyone. What is the relationship between circuit quality, material quality and process quality in a silver carbon conductive circuit? I would like to sum it up. There are three things:

1. Excellent silver, carbon conductive ink quality is the basis and premise of high-quality silver, carbon conductive circuit. For example: When we purchase silver conductive ink in the market, we can usually see the solid content index, we should say "Solid content" is a relatively vague concept. It is not so much the solid content as the content of the metallic silver is more direct and easy to judge its quality.

2. High-quality silver and carbon conductive inks may not be able to elicit excellent silver and carbon conductive circuits.

3, high-quality silver, carbon conductive circuit is not only related to the quality of silver, carbon conductive ink

At the same time, it is also related to the correct process technology, both of which require our special attention. One-sided emphasis on material quality and ignoring process quality, or pushing each other is not correct.