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Prepregs are prepared using resins containing both an epoxy and an acrylate function in the same molecule and using electron beam radiation.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
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Electron Beam Fabrication of Prepregs
Prepregs are prepared using resins containing both an epoxy and an acrylate
function in the same molecule and using electron beam radiation.
In the fabrication of circuit boards a solution of oligomeric resin, usually an
epoxy type, is imbibed into woven glass cloth. This is then passed through a
heater in order to cure the resin partially and to drive off the solvent. The
composition at this stage is known as "prepreg". It is non-tacky to the touch and
can be cut into convenient sizes and stored until it is ready for further processing
into a circuit board. This is accomplished by heating several prepreg elements
together under pressure, which completes the curing, creating a hard durable
laminate which is then used as a substrate for mounting electronic devices. The
preparation of the prepreg is a critical and costly step. If the resin is cured to too
great an extent, which can happen if the dryers are a little too hot, or if the
concentration of the catalyst required to initiate the epoxy reaction is too high,
then the prepreg will not laminate properly and the resultant board will be
unusable. If, on the other hand, the cure has not advanced sufficiently, the
resultant prepreg is tacky and storage and handling are very difficult.
The present procedure eliminates these problems. Imbibition of the resin on
glass cloth and exposure to an electron beam of a commercial electron beam
apparatus polymerizes the acrylate group but...