The cheapest industrial laminates (Class X) are used in large quantities where the dielectric properties are less important. It is made from unbleached kraft paper and about 30% phenolic resin. It has a very high water absorption, but its strength and workability are very good. Another product with better electrical properties, containing a higher percentage of resin (usually denatured epoxy resin). Paper is often a cellulose or cotton linters. In the highest technical performance of the laminate with woven and non-woven Woven fiberglass instead of paper. The percentage of resin increased to about 60%.
The largest amount of laminate is a color copper laminate for the board. In the manufacture of such laminates, one or both sides of the laminate have a copper foil as the outer layer. The other layer is typically a fabric impregnated with a flame retardant epoxy resin. Some paper or non-woven fiberglass can be used as the outer layer. The outer glass fabric greatly increases the strength and dimensional stability of the laminate. Eight steps are required to prepare an applicable color copper laminate.
The required wiring pattern was printed on the copper foil with an anti-corrosive coating, and then all unprinted copper was eroded away, and the resist coating was left behind. Solder mask and component identification are then performed using a screen process. The component holes and the individual small plates are punched out from the original size laminate. Embed people by hand or machine components. The molten solder is then welded to the small plate. Special industrial laminates are engraved versions for the manufacture of nameplates and identification signs. The top two layers of the laminate are covered with two contrasts, for example with a black or brown layer, on the white layer, and then the desired content is sculpted on the finished laminate. The enamel removes the top layer and reveals a second contrasting color. The order of the layers can also be reversed to make the dark print look like a light background. The top layer can be monochrome, wood grain or other images. The second layer is often monochromatic. The top layer is a--cellulose paper impregnated with 40% melamine-formaldehyde resin. It is also possible to add a few phenolic resin impregnated unbleached paper layers to the underside of the second color layer. Another industrial laminate is a plywood overlay where the phenolic resin is impregnated without bleaching (sometimes bleaching). Paper is bonded to one or both sides of the plywood.
The resin impregnated paper was compressed and resinized on a low cycle press of a short cycle. Cured laminates are often coated with a primer resin coating to prevent cracking of the plywood surface, greatly improving its ability to withstand climate change.
The cover layer also masks the defects of the plywood surface. An engraved polishing plate is used in the press to obtain a relief-like surface. After the anti-adhesive compound treatment, when the plywood has a cover layer on both sides, the laminate can be used as the bottom plate of the outdoor signboard, and the single-sided cover plywood can be used as the concrete formwork.
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