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Selection And Use Requirements For Film Switch Printing Inks​

Selection and use requirements for film switch printing inks

Conductive inks are used for film switch circuit printing. Conductive inks are mainly made of conductive fillers (including metal powders, metal oxides, non-metals and other composite powders) and bonding agents (mainly synthetic resins, photosensitive resins, low-melting plexiglass, etc.). Additives (mainly dispersants, regulators, thickeners, plasticizers, lubricants, inhibitors, etc.), solvents (mainly aromatic hydrocarbons, alcohols, ketones, esters, alcohol ethers, etc.). Conductive ink is one of the most critical materials for printing film switches. The quality and price of the film are directly related to the quality of the film switch products and the cost of product manufacturing. Conductive ink is a kind of functional ink. In printing, there are mainly conductive inks such as carbon paste and silver paste.

Carbon paste ink is a liquid type thermosetting ink. It has the function of protecting copper foil and conducting current after film curing. It has good conductivity and low impedance; it is not easy to oxidize, its performance is stable, and it is resistant to acids, alkalis and chemical solvents. Erosion: It has the characteristics of strong wear resistance, anti-wear and good thermal shock resistance. Silver paste ink is a one-component ink composed mainly of ultrafine silver powder and thermoplastic resin. It can be used on most substrates and has strong adhesion and hiding power. Low temperature cure, controlled conductivity and very low resistance. The printed materials printed by the switch circuit are mostly viscous paste-like silver paste, which is a method of screen printing and a common material for processing electronic components. However, since most of the silver paste belongs to the high-temperature sintering reduction type, and the silver paste used in the switching circuit is limited by the temperature resistance of the substrate, it is necessary to use a low-temperature curing type silver paste. There are many types of silver paste for printed switch circuits, and the performance and quality are also very different. The performance of silver paste should be evaluated mainly from the aspects of resistivity, solid content, particle size of metal particles, bonding strength and curing temperature. Then choose. Since the quality of the silver paste is expensive and its quality is related to the electrical properties of the membrane switch, it should be used with caution. Since the viscosity of the silver paste is thicker than ordinary inks and also contains a solid metal component, it is necessary to pay attention to returning to light scraping. The presence of various solvents and auxiliaries in the conductive silver paste has a certain influence on the electrical resistivity, so that they are released from the conductive circuit, and mainly rely on hot air drying to volatilize. The drying temperature is generally controlled at 85 ° C to 90 ° C, and is kept at a constant temperature for 40 min under hot air. Practice has proved that the conductive pattern with incomplete drying is often several times higher than the dry pattern resistance. Therefore, the drying quality is also a major aspect of the quality of the membrane switch. In addition, on the metal silver contact of the switch, the conductive carbon paste protective layer should be screen printed, and the characteristics of the carbon paste are utilized to facilitate rapid separation after the contacts are closed, thereby improving the wear resistance of the switch contacts and ensuring the switch contact. The point can withstand millions of contacts and protect the underlying metal silver contacts from oxidation. The 1 carbon slurry is a non-metallic substance. The dense carbon coating can prevent the metal silver from contacting the narrow gas and hinder the migration of the silver ions, thereby effectively protecting the electrical stability of the switch circuit. When the carbon coating acts on the lead socket, It can facilitate the insertion and removal of the lead wires and the wiring terminals. However, the excessively thick carbon coating is prone to flaking failure, so the screen of the printed conductive carbon paste should not be too thick.

Hangzhou Kaike Electronics Co., Ltd.

Address: No. 2. Dadi Road, Haining Agricultural External Development Zone 314408,

Zhejiang, China

Contact Person: May Wong

Telephone: 86-571-86830690     Fax: 86-571-86687367

Cell Phone: 86-15158112598