In general, because component finishes pass through more difficult assembly
operations and therefore need to be more robust than PWB surface finishes.
These operations include a variety of thermal excursions and mechanical
deformation in the trim/form operation.  Organic coatings would not
withstand the thermal excursions of the wire bonding, die attach, and
molding operations combined with the bending and shearing operation in the
trim & form.
Rob Schetty
Shipley Co.
Shipley Ronal EIF Division
Freeport, NY  USA





                    Chris Hunt
                    <Chris.Hunt@N        To:     [log in to unmask]
                    PL.CO.UK>            cc:
                    Sent by:             Subject:     [LF] lead free terminations
                    Leadfree
                    <Leadfree@IPC
                    .ORG>


                    07/12/00
                    12:46 PM
                    Please
                    respond to
                    "Leadfree
                    Electronics
                    Assembly
                    E-Mail
                    Forum.";
                    Please
                    respond to
                    Chris Hunt






I am interested to learn why component terminations are all metal finishes
and haven't taken a leaf out of the PCB industry and used an organic
coating
as a solderability preservative.
Any offers?

Chris Hunt
NPL

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