Copper-Clad Laminates

Resists. Resists are temporary, thin coatings appHed to the surface of the copper-clad laminate. After patterning, these films act as masks that are chemically resistant to the cleaning, plating, and etching solutions used to define the circuit traces of the PWB. Both nonphotosensitive and photosensitive types are used. 

Flexible copper-clad laminates with nonthermoplastic polyimides were prepared in a two-step process entailing isolating the polyamic acid and then thermally imidizing to the corresponding polyimide. Plasma or thermal treatments of selected polyimides generated materials with excellent bonding strength when evaluated on laminated copper foil. 

BPA/DC was compounded with high-temperature resistant ladder and semi-ladder polymers. A composition, which contained BPA/DC, a polyimide resin, organic Zn salt and benzyldimethylamine in A -methylpyrrolidone solution was described. The binder was destined for the manufacture of copper clad laminates. Tg of the cross-linked material was 265 °C [50]. Another example is a binder obtained from BPA/DC and polyphenylquinoxaline in chloroform [51]. 

Instead of BPA/DC monomer, the corresponding prepolymer was heated with BMI to obtain a binder [62], In a similar composition, p-toluenesulfonic acid was used as the cyanate/maleimide prereaction catalyst. For the crosslinking stage Zn octoate was added [63], Both BPA/DC and BMI can be used in the form of prepolymers. The binder for copper clad laminates contains, moreover, a saturated polyester, Zn octoate and powdered fused quartz [64],... 

As an additional component, various thermoplastic polymers can be used. As a binder for copper clad laminates, a solution of solid epoxide resin (Epikote 1001), BPA/DC prepolymer, Zn acetate and poly(phenylene sulfide) was used [83], Other binders for reinforced plastics contain polysulfone. Such compositions consist of liquid BPA/ECH epoxide resin, BPA/DC prepolymer, polysulfone and bis(4-hydro-xyphenyl)sulfone [85]. Bis(4-aminophenyl)sulfone can be also added [86]. In such systems the bisphenol reacts with the epoxide resin as a chain extension agent, whereas the diamine crosslinks the diepoxide. The Tg values are close to 200 °C. They can be increased a little, if the BPA/ECH epoxide resin is replaced by the tetra-epoxide A,A,A, A -tetrakis(2,3-epoxypropyl)diaminodiphenylmethane [87]. 

As mentioned above, the main application of the epoxide /dicyanate systems are copper clad laminates. Other important uses are conductive materials with silver... 

A binder for copper clad laminates contains the prepolymer from BPA/DC and A -(3,5-dimethyl-4-vinylphenyl)maleimide in methylethylketone, an epoxynovolak resin, Zn acetate and tert.butyl peroxide [100], In a similar composition, a prepolymer obtained from epoxide resin, BMI and bis(4-aminophenyl)methane was mixed with BPA/DC, Zn acetate and tert.butyl peroxide in solution [101]. 

Two-layered GRPs for copper clad laminates are obtained with one layer consisting of the three-component system (e.g. BPA/DC, BMI, brominated epoxide resin, Zn octoate and triethylenediamine in methylethylketone). The other layer has the usual epoxy matrix (brominated epoxide resin, dicyandiamide as a hardener and 2-ethyl-4-methylimidazole as curing accelerator) [119]. As similar two-layered laminate contains BPA/DC, BMI, epoxynovolak resin, Zn acetate and triethylenediamine in the first layer and BPA/DC only with the same catalysts in the second layer [120]. 

The three-component cyanate/maleimide/epoxide compositions are mainly used as polymer matrix in copper clad laminates and in carbon fiber composites for engineering purposes. High heat resistance, water and solvent resistance, mechanical and impact strength is claimed. A composition for copper wire enamelling [121] and a resin for electric motor coil windings impregnation were described [107]. 

Binders for copper clad laminates consist of a solution of phenolic resol (part A) and of a composition obtained from a drying oil modified resol, hexamethylene-tetraamine and BPA/DC monomer or prepolymer [142, 143]. 

Shih TS, Hsieh AT, Liao GD, Chen YH, Liou SH. Haematological and spermatotoxic effects of ethylene glycol monomethyl ether in copper clad laminate factories. Occup Environ Med 2000 57(5) 348-52. 

As mentioned earlier, the cyanate-epoxy systems find many commercial applications. Many multifunctional formulations, principally based on CE/epoxy, have been claimed. Generally, the properties of epoxies are improved on co-cur-ing by cyanate ester and the blend is more cost-effective than cyanate alone. The applications of these blends, as covered by patents, has been referred to in a review by Penczek and Kaminska [184]. Most of their applications are in copper clad laminates [185-191], fire resistant formulations [192], aircraft structures [193], and in semiconductor devices [194-196]. Due to the commercial significance of the blends, the information on the epoxy-cyanate systems is still covered by patents and some of the most relevant and recent ones have been referred to in this review. 

Curable thermosetting resin compositions containing PPE are useful in electrical appUcations because they exhibit low dielectric constants. Such compositions are used as fiber reiirforced prepregs, for example as copper-clad laminates suitable for printed circuit boards (PCB)s... 

Epoxy/cyanate ester thermoset blend-based composites have low dielectric constant desirable for advanced radomes, microwave anteimas, and stealth aircraft composite applications. Other applications include its use in copper clad laminates, semiconductor devices, and fire-resistant aircraft structural composites. 

Composite laminate n. A term sometimes applied to a laminated plastic bonded to a non-plastic material such as copper, vulcanized fiber, rubber, asbestos, lead, aluminum, etc. An example is the copper-clad laminated plastic used for printed-circuit boards. 

Copper-clad laminate n. A laminated plastic surfaced with copper foil or plating, used for preparing printed circuits. 

Cyanate esters are used in circuit boards because of their low dielectric constant of 2.91 and a high Tg of 290°C. Prepregs and laminates are made with conventional technology, and they are tougher and more moisture resistant than FR-4 copper clad. Laminates are also used in radomes, antennas, and aerospace structures. 

NEMA standards include many variations for reinforcements, resins, and applications. Reinforcements include paper, fabrics, and glass mats. Resins include phenolic, melamine, silicone, epoxy, and polyester. Copper-clad laminates are covered with copper foil for use in printed wiring boards, whereas unclad laminates do not have a foil. Unclad laminates are used in many industrial applications, but NEMA s primary concern is when they are used as electrical insulation. 

See also electrical laminate copper-clad laminate printed circuit board, neoprene... 

PPE has been used in thermosets. In particular, PPE is used in the resin formulations to make GETEK copper-clad laminates for high-end, high-performance printed wiring boards. GETEK laminates were developed by GE Electromaterials. Epoxy-PPE based laminates were commercialized in 1991 [28]. In 2002, PPE-cyanate ester based laminates were... 

---