Darrel:
There are number of manufacturers in the market place offering good ESD
"guns", I'll name just a few:
- Schaffner NSG 435
- Keytek Minizap (MZ/15 EC)
- NoiseKen ESS-200AX
- Haefly (the model # escapes me)
All claim to meet the requirements of IEC 1000-4-2 electrical criteria and
for those I've evaluated, they do. There are some minor deviations,
however, that may translate into different results during testing. The
IEC spec is actually quite liberal and despite an attempt to create a
level playing field, the small changes in di/dt during (contact) discharges
can have a big impact on the nature of the outcome. Now that your totally
confused, bottom line is: choose a gun which satisfies these criteria:
- The manufacturer can demonstrate compliance to IEC 1000-4-2 with
actual single-shot waveform characteristics.
- Cost, also consider all the optional eqpt that you need for air/contact
tests and for indirect ESD: HCP/VCP (the bits and pieces add up).
- Ergonomics: hold the gun in your hands for an hour or so and then tell
me which one you like (weight, balance, grip)
- Recurring costs: How much to calibrate? How much to repair? How long
will it take to calibrate/repair (where does it need to be sent)?
- Features:
- How are the controls: is your preference towards a minimal user
interface or do you want the all-singing-all-dancing type?
- Does the vendor also offer optional eqpt to cover the full range of
IEC 1000-4-2 testing?
- Does the control section have an external interface (RS-232, GPIB)
that can be used for automation?
- Some manufacturers offer a built-in temp. and humidity sensor for
ease of testing.
- Upper voltage limit: some guns don't go beyond the 15 kV (Level 4)
limit, others go as high as 25kV (or higher). Some have different
limits for air and contact discharge.
- Are other discharge networks offered (i.e. HBM)? HBM testing is
called up in some military and consumer specs.
I've tested with all 4 above + the Keytek ESD System 2000 and have the
following comments:
Keytek System 2000 - I believe Keytek has discontinued these. Bulky (the
largest I've used) but fairly robust. High kVs (27). Minimal user
interface. Costly to maintain. Limited to 8 kV contact.
Keytek MiniZap - Easy to use, small and light-weight. Lots of attachments
for testing and engineering. Minimal user interface. When I last used
it, the MiniZap was limited to 15 kV but there may have been plans to
increase this. Limited to 8 kV contact.
Schaffner NSG 435 - Controls are great. You can interconnect the gun to
an external controller (PC) for automation--Schaffner offers supporting
S/W. I found the ergonomics rather clumsy (poor balance, top heavy,
tiring hand grip). 16kV air, 9 kV contact.
Schaffner NSG 432 - The old standby. Used this about 8 years ago and although
offers high kVs (25), it has the minimalist user interface (features)
and ergonomics are very basic.
Haefly - Tried it out, didn't particularly like it.
NoiseKen ESS-200AX - Really like the ergonomics and control features. Fairly
new entry into ESD test market. Has built-in temp. and humidity sensors.
Up to 30 kV (air and contact). External controller connections
available. Colleagues in Canada bought one and they like it. I recall
the discharge waveform was on the more severe side of the IEC 1000-4-2
current waveform.
Good luck with your selection. (Ask a local rep for a demo.)
Regards,
Geoff Skanes
Nortel Technology
RTP, NC
