Лако-красочные материалы — производство

Isotropically conductive adhesive interconnections can be repaired using techniques simi­lar to those used for solder rework. By application of heat locally at a temperature above the Tg value, a section of adhesive can be softened and the device can be removed mechanically. Adhesive residue on the substrate can be removed, if desired, by a mild […]

The reliability of conductive adhesive electrical interconnections depends on the individual formulation and process employed [55]. In addition, the test vehicle configuration will strongly influence results. No comprehensive studies have been published, however, and no attempts to correlate chemical composition or a specific process variable to reliability performance have been reported. Most conductive adhesive failures […]

A. Dispensing Conductive adhesives are applied to the substrates using a wide range of standard tech­niques. For die attach applications, the isotropically conductive adhesive is applied using either a stamping tool or a syringe dispenser. To ensure complete void-free coverage, sophisticated multineedle syringe dispensers have been developed. Stencil and screen print­ing are used for the […]

Both thermoplastic and thermosetting adhesives are used to formulate anisotropically conductive adhesives. During assembly, thermoplastics must be heated above their glass transition temperature (Tg) to achieve good adhesion and electrical interconnection. The Tg value must be sufficiently high to avoid polymer flow during use but sufficiently low to prevent thermal degradation of the substrate and […]

1. Particle Specifications The goal in formulating anisotropically conductive adhesives is to maximize particle con­centration without compromising electrical isolation in the X-Y plane. Higher particle loadings increase the probability that an electrical interconnection will be made (especially for relatively small contact areas) and decrease contact resistance. Typical concentrations range from 5 to 15 vol % […]

Materials for use as anisotropically conductive adhesives must satisfy requirements even more stringent than those defined previously for isotropically conductive adhesives. No specifications, however, have been defined specifically for these materials. When used for flip-chip applications, the adhesive not only serves as a physical and electrical interconnec­tion between the device and the substrate, but also […]

Silicone-based polymers have characteristics that make them desirable as the matrix of a conductive adhesive system. Their excellent thermal stability, low ionic impurity content, and especially, low modulus make silicones desirable for bonding very large die. A typical formulation would include linear polydiorganosiloxane oligomers with both vinyl and silicon hydride functionality, a platinum catalyst, an […]

The development of polyimide-based conductive die attach adhesives resulted from the attractive properties exhibited by this generic class of materials. The high Tg value (typi­cally, 100°C higher than epoxies) offers superior performance during high-temperature processing, such as wirebonding, overmolding, soldering, and lid sealing. Other properties of interest include low ionic contamination levels and a low […]

1. Epoxy Some of the first commercial conductive epoxy adhesives were simply based on silver powder dispersed in a liquid epoxy resin [e. g., diglycidyl ether of bisphenol A (DGEBA)] with an aliphatic amine [e. g., triethylene tetramine (TETA)] as a curing agent. Although capable of room-temperature cure, commercialization of this type of system was […]

A U. S. military hybrid specification (MIL-A-87172 of MIL-STD-883) established the selection and qualification requirements for polymeric adhesives used in military hybrid circuits and is used as a guide for die attach materials for nonmilitary applications as well. Table 2 lists the requirements for a type I (electrically conductive) adhesive and test results of a […]