Defense Speak Interpreted: Is DARPA Still Around After CHIPS?
Beyond the Board: Orbital High Ground—Why Space Superiority Is Slipping Away
The Government Circuit: Trump’s Trade War Disrupts the Electronics Ecosystem
Book Excerpt: The Printed Circuit Assembler’s Guide to... Low-Temperature Soldering, Vol. 2
June 18, 2024 | I-Connect007 Editorial TeamEstimated reading time: 1 minute
The Printed Circuit Assembler’s Guide to... Low-Temperature Soldering, Vol. 2, by Morgana Ribas, et al, MacDermid Alpha Electronics Solutions
Chapter 1: Introduction to Low-temperature Soldering
Low-temperature solders (LTS) continue to attract serious interest from the electronics industry. These solder alloys enable the use of lower glass transition temperature (Tg) substrates and components due to the lower processing temperature, promote long-term reliability by reducing exposure to thermal excursion, and enable organizations to meet sustainability targets. Perhaps more significantly, low-temperature soldering is an enabling technology that mitigates warpage-induced defects of the ultra-thin, high IO chip-scale packages used in complex electronic devices. Use of higher reflow temperature Sn-Ag-Cu (SAC) solders in package-on-package (PoP) bottom and PoP memory technology can potentially result in soldering defects such as non-wet opens, solder bridging, and head-in-pillow.
The eutectic 42Sn-58Bi alloy melts at 138°C and has been considered for SMT soldering since the transition from tin-lead to lead-free solders. This alloy is quite interesting as a solder, as bismuth is one of the few elements forming a solid solution in tin. Its binary composition, lamellar microstructure, and eutectic melting point resemble that of eutectic tin-lead. However, this first-generation LTS alloy lagged behind traditional lead-free alloys in solder joint thermomechanical and drop shock reliability and limited thermal cycling performance.
The transition to lead-free solders was motivated by regulatory compliance, and SAC305 (96.5% tin, 3% silver, 0.5% copper) was chosen as the best cost-benefit alternative. As the electronics industry evolved, so did solder joint reliability requirements. Several new solders were introduced to meet specific reliability requirements.
Share on:
Suggested Items
INEMI Interim Report: Interconnection Modeling and Simulation Results for Low-Temp Materials in First-Level Interconnect
05/30/2025 | iNEMIOne of the greatest challenges of integrating different types of silicon, memory, and other extended processing units (XPUs) in a single package is in attaching these various types of chips in a reliable way.
Laird Thermal Systems Unveils New Identity
05/05/2025 | Laird Thermal SystemsLaird Thermal Systems, a global leader in active thermal management solutions with more than 60 years of application expertise, today announced its rebrand to Tark Thermal Solutions.
INEMI Call-for-Participation Webinar: BiSn-Based Low-Temperature Soldering Process and Reliability Project Phase 3b
04/28/2025 | iNEMIIn 2015, INEMI initiated the BiSn-Based Low-Temperature Soldering Process and Reliability Project to assess the feasibility of using low-temperature solders (LTS) in the SnBi system to address various technological, economic and ecological drivers for assembly of consumer computer electronic board products.
NUS Physicists Discover a Copper-free High-temperature Superconducting Oxide
03/28/2025 | PRNewswireProfessor Ariando and Dr Stephen Lin Er Chow from the National University of Singapore (NUS) Department of Physics have designed and synthesised a groundbreaking new material—a copper-free superconducting oxide—capable of superconducting at approximately 40 Kelvin (K), or about minus 233 degrees Celsius (deg C), under ambient pressure.
Indium to Showcase Proven EV Products and High-Reliability Alloys at Productronica China
03/26/2025 | Indium CorporationAs a global materials supplier and trusted partner in electric vehicle (EV) and e-Mobility manufacturing, Indium Corporation® is proud to showcase its high-reliability alloys and soldering solutions at Productronica China, March 26-28, in Shanghai, China.