SLVAEU0 September   2020 LM117HVQML-SP , LM117QML-SP , LM136A-2.5QML-SP , LM137JAN-SP , LM137QML-SP , LM185-1.2QML-SP , LM185-2.5QML-SP , LM2940QML-SP , LM2941QML-SP , LM4050QML-SP , LM723JAN-SP , LP2953QML-SP , TL1431-SP , TPS50601-SP , TPS50601A-SP , TPS7A4501-SP , TPS7H1101-SP , TPS7H1101A-SP , TPS7H1111-SP , TPS7H1121-SP , TPS7H2201-SP , TPS7H2211-SP , TPS7H3301-SP , TPS7H4001-SP , TPS7H4002-SP , TPS7H4011-SP , TPS7H5001-SP , TPS7H5002-SP , TPS7H5003-SP , TPS7H5004-SP , TPS7H6003-SP , TPS7H6013-SP , TPS7H6023-SP , UC1525B-SP , UC1611-SP , UC1705-SP , UC1707-SP , UC1708-SP , UC1709-SP , UC1710-SP , UC1715-SP , UC1823A-SP , UC1825-SP , UC1825A-SP , UC1825B-SP , UC1832-SP , UC1834-SP , UC1842-SP , UC1842A-SP , UC1843-SP , UC1843A-SP , UC1843B-SP , UC1844-SP , UC1844A-SP , UC1845-SP , UC1845A-SP , UC1846-SP , UC1856-SP , UC1863-SP , UC1875-SP , UC1901-SP , UC19432-SP , UCC1806-SP

 

  1.   Trademarks
  2. 1Reflow Profiles
  3. 2Critical Considerations for Gold-Plated Termination-Finishes
  4. 3Considerations for Leadless Ceramic Chip Carrier Packages
  5. 4Lead Forming
  6. 5Ceramic Packaging
  7. 6References

1 Reflow Profiles

Board-level solder reflow profiles are dependent on numerous factors including, but not limited to, solder type, flux, package type, the number of components, the number of board layers, the board size, reflow oven type, and accuracy as well as pre- and post-cleaning processes. Because of the number of variables it is not possible to provide a single reflow profile that is representative of every board using a specific package type. Typically, manufacturing houses have reflow profiles in place and modify them for specific hardware.

TI suggests using the flux manufacturer’s recommended profile as a starting point. Variations of course need to be comprehended based on the time required to volatize the flux prior to the solder reaching liquidus. In general, ceramic parts are compatible with ramp-up rates of < 3°C/s and ramp-down rates of < 6°C/s with a maximum peak temperature of 260°C.

A hermetic package will withstand three passes of reflow if the peak temperature and ramp rates are not exceeded.

Most metal lid packages use an 80%Au-20%Sn solder preform to attach the lid. Gold-tin solder will begin to soften at 270°C and has a eutectic point of 280°C. The package body temperature must not exceed 260°C at any time or the hermetic seal of the package will be damaged. Note that through-hole hermetic devices specify a maximum temperature for soldering as a lead-temperature of 300°C for 10 seconds. This is not a reflow temperature.

GUID-20200709-SS0I-5LDK-CVNF-TDN8R11CTTHK-low.gifFigure 1-1 Starting Profile for Typical Pb/Sn Solder Paste.