Etching lamination process

Etch laminate 3. Standard image and etch process... 

Another foil type offered by laminate supphers, reverse-treated foil (RTF), offers an advantage for producing fine lines. The RTF copper has adhesion promoter applied to both sides and is classified by 4562 as code R (reverse-treated bond enhancement [cathode side] stain-proofing on both sides).This approach provides advantages to imaging fine lines. When the copper tooth is reversed, the fabricator can improve fine definition by allowing the etch chemistry process to stop at the surface of the laminate. 

As in the case of the panel-plate additive method, the partly additive process starts with copper-clad laminate.The essence of this process is to minimize the problem encountered in etching fineline conductors through thick copper which results from through-hole plating (in the conventional etched foil process, throu -hole is plated first), by forming conductors first, prior to through-hole plating. 

Copper foils thinner than 5 micron will be demanded for the semi-additive process to generate 10 micron wide traces or finer since the beginning of 2000s. Two types of technologies have been developed to have ultra thin copper foils. The first one is the etch-down process used to reduce the copper thickness from standard thick RA copper foils. Through this process, foils 3-5 micron thick can be obtained from 12 micron RA copper foils.The second is the use of ultrathin foils. ED copper foils 1-5 micron thick have been commercialized with the carrier copper foils. Ultrathin copper layers have been built on the smooth surface of other copper foils with standard thickness. The carrier copper foils are removed mechanically after the lamination with the base layers. Ultra thin copper foils have been applied to adhesiveless laminates through casting or lamination processes. 

Most priated circuit board (PCB) production uses the subtractive process (41). In the simplest version, a thin copper foil is laminated to a nonconductor, holes are fabricated, and the unwanted copper etched off. These siagle-sided boards do not require plating. Known as ptint-and-etch, this version is used for the most simple priated circuit boards. 

Fig. 2. Schematic of the RISTON dry film photoresist process, (a) Removal of polyolefin separator sheet and laminate resist to clean surface, using special laminator (b) exposure to uv source using positive or negative phototool (positive to plate negative for print-and-etch) (c) removal of the protective Mylar, which is readily removed by hand and (d) development using a special processor (3).

A number of fabrication techniques meet the general requirements for constructing an efficient and compact microreactor. Popular methods include LIGA, wet and dry etching processes, micromachining, lamination, and soft lithography. 

This chapter presents an overview of performance plastic polymers in commercial planar and 3-dimensional circuit board products, and describes in detail one approach (two-shot molding) developed as an integrated 3-D circuit manufacturing technology. The distinctions between conventional planar (2-dimensional) circuitry, based on thermoset laminates and "subtractive etching processes, and the enhanced design flexibility afforded by expanded interconnection capacity in three axes are discussed. Specific examples of 3-dimensional interconnect protoypes and products are described and pictured. 

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