External Lead Finish for Hermetic Packages For hermetic packages, National Semiconductor offers three primary lead finishes: solder dip, gold plate and tin plate. The component lead finish serves as a protective coating to prevent oxidation of the lead base material prior to use. The lead finish will ensure the leads are solderable for board mount applications as well as provide long term protection against lead corrosion. The lead finish composition and thickness is dependent on the package type and the applications in which the package is used. Lead finish for Mil/Aero product and all commercial product except Cerquad and selected metal cans conforms to the requirements of Mil-M-38510. SOLDER DIP The solder dip lead finish for hermetic packages is a 60%-63% tin, 40%-37% lead alloy. The finish is applied by dipping the package leads or terminals into the molten solder. Solder dipped leads provide excellent solderability. Solder dip lead finish is typically lower in cost as compared to gold or tin plating. The solder thickness and composition conforms to the requirements of Mil-M-38510. GOLD PLATE Gold plated leads are used for many multilayer ceramic packages and metal can packages. For multilayer ceramic packages, pure gold is electroplated over an electrolytic nickel underplate. The gold plating for metal can packages is also pure electrolytically plated, but it may be applied over an electroless or an electrolytic nickel plate. Gold plate is used on package types that cannot be solder dipped or as process simplification. Multilayer ceramic packages such as ceramic quad flatpacks (CQFP) and ceramic pin grid arrays (CPGA) are gold plated. Many metal cans are offered with gold plated leads. TIN PLATE A lead finish of 100% tin plate is used on fine pitch Cerquad packages used in commercial applications. A plating thickness of 200 microinches minimum is supplied. The following table is provided as a reference to determine which lead finish is used for each hermetic package type offered at National Semiconductor. Lead Finish for Hermetic Packages Package Type Package Specific External (Code) Designator Package Lead Finish Lead Finish Mil-Aero Commercial Gold Plate or Solder Dip Gold Plate or Solder Dip Ceramic Dual-In-Line D; DA External Package -- Sidebrazed (SB) Leadless Chip Carrier (LCC) E; EA Solder Dip Gold Plate or Solder Dip Ceramic Quad J-Bend (CQJB) EL Gold Plate Gold Plate Ceramic Quad Flatpack (CQFP) EL Gold Plate Gold Plate Gold Plate Ceramic Flatpack Ceramic Dual-In-Line Package (Cerdip) Small Outline Integrated Circuit, Wide F Gold Plate J; JA Solder Dip Solder Dip MC Gold Plate Gold Plate Ceramic Pin Grid Array (CPGA) U; UA Gold Plate Gold Plate Cerpack W; WA Solder Dip Solder Dip Cerquad W; WA Solder Dip Solder Dip or Tin Plate Metal Can Package (TO) H; HA TO-5/18/39 Gold Plate or Solder Dip Gold Plate or Solder Dip H; HA TO-46/52/72 Gold Plate or Solder Dip Gold Plate or Solder Dip K; KA TO-3 Solder Dip Metal Leaded Chip Carrier MQuad AA Solder Dip Solder Plate (85/15) ACC ACE ALE AUL AUA Solder Plate (85/15) AUW AUY AUZ (c) 2000 National Semiconductor Corporation MS011796 www.national.com External Lead Finish for Hermetic Packages August 1999 External Lead Finish for Hermetic Packages LIFE SUPPORT POLICY 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. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: support@nsc.com www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Francais Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 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. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: sea.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 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.