External Lead Finish for Plastic Packages
For plastic packages, National Semiconductor offers two pri-
mary lead finishes: solder plate and solder dip. The compo-
nent lead finish serves as a protective coating to prevent oxi-
dation of the lead base material prior to use. The lead finish
will ensure the leads are solderable for board mount applica-
tions as well as provide long term protection against lead
corrosion. The lead finish composition and thickness is de-
pendent on the package type and the applications in which
the package is used.
SOLDER PLATE
For National’s plastic packages, the most common lead fin-
ish is electroplated solder. Solder plating provides a uniform
coating conforming to the shape of the lead. A tin-lead alloy
plating is used and the typical composition is approximately
85%tin and 15%lead. A plating thickness of 200 micro-
inches minimum is required.
SOLDER DIP
A solder dip lead finish is applied to plastic pin grid array
packages (PPGA) and selected molded dual in-line pack-
ages (MDIP). Typical solder dip composition for application
to MDIPs is a eutectic alloy of approximately 60%tin and
40%lead. The PPGA external lead finish is approximately
90%tin and 10%lead. A thickness of 200 microinches mini-
mum is required and is measured at the major flat of the
lead.
SOLDER BALL
Tin-lead eutectic solder balls with a composition of 63
tin and 37
lead are specified for array based packages ( FBGA,EB-
GA,SBGA,PBGA ) . Depending on the type of package , the
solder ball diameters vary from 0.13 mm to 0.6 mm and the
pitch varies from 0.5 to 1.27 mm with details specified in the
relevant market outline drawings.
GOLD FLASH
The laminate based CSP packages are supplied with gold
plated pads ( 0.5 micron nominal gold over 5 micron nickel )
and meet the solderability requirements after 8 hr steam
ageing.
For either lead finish, the cleaning and plating or dipping pro-
cess is designed such that the component meets solderabil-
ity requirements after 8 hours steam aging.
The following table is provided as a reference to determine
which lead finish is used for each plastic package type of-
fered at National Semiconductor.
Lead Finish for Plastic Packages
Package Type Package External
(Code) Designator Lead Finish
Small Outline Transistor (SOT) M; MA Solder Plate
Small Outline Package—EIAJ and JEDEC (SOP) M; MA Solder Plate
Shrink Small Outline Package—EIAJ and JEDEC (SSOP) ME; MQ; MS Solder Plate
Very Small Outline Package (VSOP) M; MA Solder Plate
Thin Small Outline Package (TSOP) MB Solder Plate
Thin Shrink Small Outline Package (TSSOP) MT Solder Plate
Molded Dual-In-Line Package (MDIP) N; NA Solder Plate
or Solder Dip
Plastic Pin Grid Array (PPGA) UP Solder Dip
Plastic Leaded Chip Carrier (PLCC) V; VA Solder Plate
Plastic Quad Flat Pack (PQFP) V (xx) Solder Plate
Plastic Transistor Outline Package (TO) C; P; PA; R; RA; Solder Plate
RC; T; TA; TS; Z
Laminated Plastic Chip Scale Package (CSP) SLB Gold Flash
Laminated Plastic Fine Pitch Ball Grid Array (FBGA) SLC Solder Ball
Enhanced Ball Grid Array (EBGA) UCK Solder Ball
Super Ball Grid Array (SBGA) UBC; UCC; UCD;
UCG; UDB; UFD Solder Ball
August 1999
External Lead Finish for Plastic Packages
© 2000 National Semiconductor Corporation MS011799 www.national.com
Lead Finish for Plastic Packages (Continued)
Package Type Package External
(Code) Designator Lead Finish
Plastic Ball Grid Array (PBGA) UBA; UBB; UBD;
UBE; UCB; UCE;
UDA; UDC; UDD;
UEA; UFA; UFB;
UFC
Solder Ball
micro-SMD BPA Solder Ball
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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www.national.com
External Lead Finish for Plastic Packages
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
