David:
Many connector companies have decided to use the JEDEC 020C document to
qualify SMT components for lead free applications. We test only at 260 C
with no regard to connector/product volume. This approach is endorsed by
Tyco, Molex, FCI and Amphenol.
Cheers,
Bob Hilty
Tyco Electronics
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of David Shaff
Sent: Monday, August 23, 2004 5:13 PM
To: [log in to unmask]
Subject: Re: [LF] Lead-free MICROWAVE Connectors
Mike,
Info only -- to rule out "areas of concern" -- I can only speak for a
portion of the microwave (and millimeter wave) connector industry, but
ours (and most similar suppliers) produce housings almost exclusively
using S30300 stainless steel (type 303) per ASTM-A582-88, which does not
have lead content. (Info only: There is one alloy within the spec,
S30360 Type XM-3 that has 0.12 to 0.30 % lead and there is a
lead-exudation test stated specifically for that alloy.) Contacts are
plated gold-over-nickel without any tin-lead (no pre-tined pins .....
microwave launchers normally are specified to have gold-plated tabs).
Many DC/signal-level connector suppliers (having worked for several)
provide tin-plated shells but try to keep the lead content under 3% to
prevent whisker growth. Regardless of the type of connector, users/OEMs
will need to create spec-control documentation and not trust inventory
that is "out there" especially due to the known "grey" market, etc.,
that seems to keep MIL-spec and commercial connectors around (at a cost
that makes them too attractive to buyers prompted to focus primarily on
cost). If a connector model number or product family "once had lead" in
its history, there must be a different P/N and some means of
identification since many do not have any markings at all. And think
about all the interchangeable components involved in most commercial
connectors (such as D-Sub)........ With all the 3rd party and
subcontract subassembly work done around the world, additional
requirements for materials content and traceability may need to be
imposed in self-defense if industry is to adhere to legislated
requirements.
However, there is another area of concern, prompted by your question
about "connectors, per se" and that relates to degradation caused by the
higher temperatures often used for lead-free processing. We have been
advised that this can exceed 230 degrees C for several minutes and that
some JEDEC considerations are up to 460 degrees C.
We have found that some connectors that use EPOXY for retention can
suffer degradation as the epoxy "turns" (softens) at about 10 degrees C
above the connector's rated temperature. Under compression, parts can
cause the epoxy (shaped like a retaining rod through the connector body)
to "turn"/soften/bend, which permits movement of the contact with
resultant change in microwave performance. Air bubbles may also cause
rupture under extreme heat (also "space vacuum test" problems).
Testing (that I have seen) to-date is insufficient to predict what
happens to the dielectric constant of the epoxy when it cools-back.
Connectors that use epoxy usually can be easily identified by the two
(2) epoxy-entry holes in the housings.
Some higher performance microwave and millimeter wave connectors are now
using materials such as Ultem for contact retention. Ultem is a GE
material that is good for 240+ C for extended periods. We have
tested using Ultem and after soaking at 240 degrees C, axial contact
retention was > 15 lbs. and max. contact movement within the total
sample lot was .0005 inches (confirming: 0.0005 = 1/2 mil). Contact
movement and dielectric growth due to temperature should not be a
concern at lower RF frequencies, but degradation is a significant
concern if you are operating in microwave or millimeter wave. (GE's
information regarding Ultem is online at
http://www.geplastics.com/resins/materials/ultem.html ).
My company is doing some self-funded testing and to-date results with
Ultem and some epoxies (due to special treatments) show no degradation
when tested to 245 degrees C for periods that represent lead-free
assembly processing. We are looking for information regarding
processing temp-time parameters that can be used for additional testing.
This IPC-forum probably may not be the place for further discussions of
this nature as there already is heavy email content and this testing is
a separate work-in-process. ........ just wanted to provide awareness
regarding the above "niche" failure modes/problems/solutions.
Regards,
David H. Shaff
General Manager
Microwave Products Division (Interconnect)
Southwest Microwave, Inc.
9055 S. McKemy Ave.
Tempe, AZ 85284-2946
Phone: (480) 783-0201, ext. 328
FAX: (480) 783-0360
E-mail: [log in to unmask]
See us on the web at: http://www.southwestmicrowave.com
-----Original Message-----
From: mhaff [mailto:[log in to unmask]]
Sent: Monday, August 23, 2004 8:45 AM
To: Leadfree
Subject: [LF] Lead free connectors
It was recently brought to my attention (rumored) that connector
manufacturers are not able to meet the 0.1% lead content for standard
I/O
connectors because they have to use high lead content steel in the
forming
of the connector shells in industry standard I/O connectors such as
ubiquitous D-subs, MDR's etc.
Does this ring true? If so does anyone have knowledge of how the
connector
manufacturers are planning on getting around this?
Thanks,
Mike Haff
Enhance, Inc.
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