digitalFAQ.com Forum - Polycarbonate Quality concerns for DVD recordables

I came across an interesting plastics industry article from 1998 that was discussing the challenges of producing the quality polycarbonates needed to manufacturer DVDs. While it was obviously a reference to pressed DVD-ROMs, the same general information could just as easily be applied to the yet-undeveloped DVD-R, DVD-RW, DVD+R, DVD+RW, DVD-R DL and DVD+R DL formats.

These were listed as the challenges

Quote:

Physical Attributes

Consistent pellet geometry
Minimal fines and chaff
Minimal particulates
Optical homogeneity
Low birefringence
Meets impact requirements

Chemical Attributes

Low polymerization by-products
Minimal additives
Narrow molecular weight distribution
Low glass transition temperature

Processing Attributes

No clouding, sticking, or staining
Good color with low yellowness index
A robust processing window
Fast cycling
Consistent viscosity
Minimal, uniform static charge on substrate surface

It's a safe assumption that the low-grade pressed and recordable discs we see probably fail at attaining the quality needed to produce quality in-spec blanks and metal DVD-ROMs. These two platters can be just as important as the glues/bonding, the DVD dyes and the silver or gold foils. Bad materials will usually equal a bad disc.

URL: plasticstoday.com/articles/meeting-new-molding-challenges-dvds
For archival purposes, a printout of the article is also attached below as a PDF.