Selecting the Right Product for Your Application
Selecting the right product for your application is critical. To
help you with this decision, the following table compares the properties
between polybutadiene, silicone and flexible epoxies and the requirements
of the electronic encapsulants. As you can see, Dolph polybutadiene
systems are the right choice.
| Flexible Requirements |
Polybutadiene |
Silicone |
Epoxy |
| Ease of Mixing |
Good |
Good |
Good |
| Ease of Pouring |
Good |
Good |
Fair to Good |
| Cure At Room Temperature |
Good |
Good |
Good |
| Cure At Elevated Temps |
Good |
Good |
Good |
| Primer Required |
No |
Yes |
No |
| Electrical Properties |
Good |
Good |
Good |
| Physical Properties |
Good |
Good |
Good |
| Water Absorption |
Good |
Poor |
Fair |
| Moisture Vapor Transmission |
Good |
Poor |
Fair |
|
| After heating to 150°C |
|
|
|
| Electrical Properties |
Excellent |
Excellent |
Poor |
| Physical Properties(a) |
Excellent |
Excellent |
Poor |
|
| Low temperature to -30°C
|
| Electrical Properties |
Excellent |
Good |
Fair |
| Physical Properties(b) |
Excellent |
Poor |
Poor |
| Ease of Repair |
Yes |
Yes |
No |
| Cost |
Medium |
High |
Medium |
(a) Resistance to thermal shock, tearing and degradation
(b) Resistance to bending and thermal shock
Some of the common terms used in MSDS's and labels
ACUTE TOXICITY - The ability of a substance to cause toxic effects
which appear soon after a single exposure or dose.
AMBIENT - An encompassing atmosphere: as the ambient
air.
CAA - Clean Air Act
CAS - Chemical Abstract Service
LC 50 - (Lethal Concentration 50): The concentration
of a chemical substance in air or water which is expected to cause
the death of half the test animal population under controlled administration.
LD 50 - (Lethal Dose 50): The dose of a chemical
taken by mouth or absorbed by the skin which is expected to cause
death in half the test animal population under controlled administration.
LEL - (Lower Exposure Limit): The concentration
of a flammable gas or vapor in air below which a flame will not propagate
if the mixture is ignited. Below this, the mixture is too "dilute"
to burn or explode.
LOEL - (Lowest Observed Effect Level): The
lowest dose in a controlled experiment which produced an observed
effect.
MATC - (Maximum Allowable Toxicant Concentration):
A term used in aquatic toxicology.
NCI - (National Cancer Institute): A part
of the National Institute of Health (NIH) that studies cancer causes
and prevention.
PSN - Proper Shipping Name as defined by
DOT.
RCRA - Resource Conservation and Recovery Act
STEL - (Short Term Exposure Limit): Defined
as the concentration to which a worker can be exposed continuously
for no longer than 15 minutes up to four times a day.
>TLV - (Threshold Limit Value): Represents
the air concentration of a chemical substance to which it is believed
that workers may be exposed daily without adverse effect.
