4
m at erials 10
6
or great er. The SRM320 w ill aut om at ically
generat e proper volt age according t o t est m easurem ent .
TEM PERATURE AN D H UM I D I TY
Hum idit y and t em perat ure affect t he elect r ical propert ies
of t he m ost m at erials being t est ed. I t is possible t o t est or
m anufact ure a m at er ial at high hum idit y and pass all t he
t est specificat ions, but w hen t he cust om er receives t he
m at erial and used it at a low er hum idit y or t em perat ure
t he m at erial fails t o pass t he specificat ions. This can cause
rej ect s and loss of product . ANSI / ESD Associat ion and
European CECC recognize t he env ironm ent al effect s t o t est
m easurem ent s and specify in t heir st andar ds t hat t hey
m easured and recorded.
At high hum idit y a t hin layer of w at er is condensed or ab-
sorbed on or in t he m at erial and w ill increase t he elect rical
conduct iv it y. Conversely, t he com binat ion of low hum idit y
and low t em perat ure will give t he m at er ial t he highest
elect r ical resist ance r esult s ( or slow est dissipat ion t im es) .
At elevat ed t em perat ures t he m obilit y of fr ee elect rons is
increased t hereby increasing t he m at er ials conduct iv it y.
When t he m at erial is at a low er t em perat ur e, built in
st resses occur w hich m ight increase t he resist ance due t o
increased dist ance bet ween t he conduct ive addit ives.
Thus, hum idit y and t em perat ure m ust be known and
should be recorded w it h t est result s.
Ope r a t ion
The SRM320 can t est m at erials in t wo ways, using int ernal
parallel resist ivit y probes locat ed on t he back of t he m et er
or w it h ext ernal 5lb elect rode probes ( sold separat ely) .