2
\$\begingroup\$

I see these PCB material types often: FR4 epoxy resin, FR4 epoxy glass. I see epoxy resin is cheaper than epoxy glass (at least the price that I see from couple suppliers).

I wonder if there is a major difference between epoxy resin and epoxy glass, e.g. the way they are etched and transfer toner, or do they need different treatment on the manufacturing process? What are the main advantage or disadvantage to use epoxy resin?

\$\endgroup\$
  • 4
    \$\begingroup\$ As far as I know they are the same material. FR4 is a grade designation assigned to glass-reinforced epoxy laminate sheets, tubes, rods and printed circuit boards (PCB). FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing). \$\endgroup\$ – JIm Dearden Jun 24 '13 at 14:21
  • 1
    \$\begingroup\$ An older, cheaper material was SRBP - synthetic resin bonded paper. You seem to confusing epoxy resin with that. \$\endgroup\$ – Leon Heller Jun 24 '13 at 15:19
  • \$\begingroup\$ thank you for the information. please write the answer as reply, so that I can select it as an answer \$\endgroup\$ – sven Jun 24 '13 at 15:35
4
\$\begingroup\$

Like Jim said, it sounds like your vendors are using two names for the same thing. FR4 is a flame-resistant glass-epoxy composite material. The "resin" is the epoxy prior to curing, and the "glass" is a matt of fiberglass strands that gives the composite strength.

There are dozens of products out there that are generically sold as "FR-4" by fab shops that want to keep costs down by buying from whichever laminate manufacturer offers the lowest price at a given time. For hobby projects, it's mostly safe to treat these materials as equivalent.

One distinction to be aware of, especially if your design is using lead-free soldering process, is "high-temperature FR-4". This refers to a key property of epoxy called the glass transition temperature. Above a certain temperature, the cured epoxy will undergo a phase change that causes it to change volume (expand or contract) significantly (like 1%-2%, I think), which you don't want to happen.

With lead free solder, a higher processing temperature is needed compared to tin-lead solder, and high-temperature FR-4 should be used with this process.

\$\endgroup\$
  • 1
    \$\begingroup\$ Good addition +1 \$\endgroup\$ – JIm Dearden Jun 24 '13 at 15:43
1
\$\begingroup\$

All the information you need about FR4 material is here http://en.wikipedia.org/wiki/FR-4

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.