Hmmm, Ashok , once i did build a smt switch mode assembly plant from
untreated planed pine .
owner insisted, i agreed (know some classy labs in Nippon crafted that way
too)
1
All coats were deemed out right from start .
Doesn't look quite as new after 5 years, but still the functionality of
antistatic (not dissipative);
humidity , work surface, safety, etc. aspects works flawlessly .
When you say enamel ; that from my ol skool means ceramic ;
however in the woody case I doubt you bake the "enamel" at 800+'C .
Therefore yo' guilty of naked plastic static generator (apply fox tail for
validations)
In that case 'd go for one of (desco) hand static meters and check :
i'd bet you have a charge sitting there .
Chain dragging Metal trolleys are more common, with dissisipative floor that
is (as you know)
Quick fix is dissipative rubber mat , grounded .
Can't understand why don't you treat side table same as main table.
In this case the auditor is correctly gunning after yo
2
wOOdie slide is fine as long as the varnish (oil preferable, plain planed
ply better) does not in function as charged plastic .
3
Natural bristle in wood proved fine , carbon bristles earthed are optional
luxuries found at intel's washrooms
4
This one's more interesting : the reels are too often plastic,
often my geiger got surprising beeb in areas unexpected .
Chained metal optimal (dissipation, not only antistatic desirable);
notwithstanding with RH above 50% you have none of above worries.
Or use woodie stands with earthed metal rods as back support ;
the wood/metal(may be SSteel in your parts of world)combinations can be very
good on all counts:
looks/cheap/dissipative/etc.
The modern melamines (discount clean room likes) habits converted with
horrendous costs back to dissipations test my sanity way too often.
cu paul
-----Original Message-----
From: Ashok Dhawan [mailto:[log in to unmask]]
Sent: Friday, 10 March 2000 4:18
To: [log in to unmask]
Subject: [TN] Use of wood in PCB Assembly ?? ESD ??
I have a question (s) on ESD- all related to use of wood in a typical
PCB Assembly line:
1. How a wooden mini stool if used for holding tote box ( card board
with static protecive coat, black color) can affect static sensitive
devices inside the tote box / shipping tubes/bags/ PCB assemblies
parially bilt ? The wooden stool sits besides operators seat and
operator is wearing wrist strap and attached to grounded table. The
point of contension is : Wooden mini-table is coated with enamel paint.
What kind of mini table / stool is used in general ?
2. To manual assembly, if woodem slide is used , can it affect
components being hand inserted ? Wood is varnished but no enamel paint
on this ?
3.For spot cleaning, if brushes with wooden handles are used ? What if
bristles of brush are made of Nylon/plastic material ? - Assumption is
that brush is soaked in solvent ISO-Propyl when used for cleaning.
4.For storage of Tape feeders on wooden stands -Partially used tapes
carrying components on tape feeders. Can a wooden feeder stands affect ?
It might appear 4 questions in one, I will appreciate answers toching
all aspects as mentioned above. Thanks in advance.
--
Ashok Dhawan P.Eng
Engineering
C-Mac Electronic Systems Inc.
1455 Mountain Avenue
Winnipeg, Manitoba R2X 2Y9
Canada
Phone: (204) 631-7208
Fax: (204) 631-7294
E-mail: [log in to unmask]
www.cmac.ca
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