Shearing strength and materials interaction during reflow of Al/Cu/electroless nickel/solder bump

Kwang-Lung Lin, Yi Cheng Liu

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

63Sn-37Pb solder bump was produced on Al terminal of Si. The bump pad dimension is 100μm × 100μm while the pitch size is 250μm. The bump pattern contains 20 × 20 bumps. The UBM (under bump metallurgy) consists of Cu/Electroless Nickel. Cu was sputtering deposited on Al film. The solder bump was electroplated on the electroless nickel followed by reflow at 210°C or 250°C. The reflow was conducted for 1, 5, and 10 cycles. Intermetallic compounds Ni3Sn2, Ni3Sn4, and Ni4Sn were formed between electroless nickel plating and solder when reflowed at 250°C. The interdiffusion behavior of the solder bump constituents within the solder bump was investigated by scanning electromicroscope (SEM). Cu was found to penetrate the electroless nickel during reflow when the thickness of the electroless nickel plating is only 1.8μm. No penetration of Cu occurs through a 10μm electroless nickel during reflow. Sn and Al were not found to diffuse through the electroless nickel during reflow even for 1.8μm of electroless nickel plating. The shearing strength of the solder bump reflowed at 210°C is 53.5±3.3 g/bump while the shearing strength is 62.9±2.8 g/bump when reflowed at 250°C. The fracture after shearing test occurs within the solder. Repeating reflow tends to lower the shearing strength of the bump. The shearing strength of the bump becomes 37.6±6.0 g/bump after ten cycles of reflow.

Original languageEnglish
Pages (from-to)607-612
Number of pages6
JournalProceedings - Electronic Components and Technology Conference
Publication statusPublished - 1999

Fingerprint

Nickel
Shearing
Soldering alloys
Nickel plating
Electroless plating
Metallurgy
Intermetallics
Sputtering
Scanning

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Cite this

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title = "Shearing strength and materials interaction during reflow of Al/Cu/electroless nickel/solder bump",
abstract = "63Sn-37Pb solder bump was produced on Al terminal of Si. The bump pad dimension is 100μm × 100μm while the pitch size is 250μm. The bump pattern contains 20 × 20 bumps. The UBM (under bump metallurgy) consists of Cu/Electroless Nickel. Cu was sputtering deposited on Al film. The solder bump was electroplated on the electroless nickel followed by reflow at 210°C or 250°C. The reflow was conducted for 1, 5, and 10 cycles. Intermetallic compounds Ni3Sn2, Ni3Sn4, and Ni4Sn were formed between electroless nickel plating and solder when reflowed at 250°C. The interdiffusion behavior of the solder bump constituents within the solder bump was investigated by scanning electromicroscope (SEM). Cu was found to penetrate the electroless nickel during reflow when the thickness of the electroless nickel plating is only 1.8μm. No penetration of Cu occurs through a 10μm electroless nickel during reflow. Sn and Al were not found to diffuse through the electroless nickel during reflow even for 1.8μm of electroless nickel plating. The shearing strength of the solder bump reflowed at 210°C is 53.5±3.3 g/bump while the shearing strength is 62.9±2.8 g/bump when reflowed at 250°C. The fracture after shearing test occurs within the solder. Repeating reflow tends to lower the shearing strength of the bump. The shearing strength of the bump becomes 37.6±6.0 g/bump after ten cycles of reflow.",
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N2 - 63Sn-37Pb solder bump was produced on Al terminal of Si. The bump pad dimension is 100μm × 100μm while the pitch size is 250μm. The bump pattern contains 20 × 20 bumps. The UBM (under bump metallurgy) consists of Cu/Electroless Nickel. Cu was sputtering deposited on Al film. The solder bump was electroplated on the electroless nickel followed by reflow at 210°C or 250°C. The reflow was conducted for 1, 5, and 10 cycles. Intermetallic compounds Ni3Sn2, Ni3Sn4, and Ni4Sn were formed between electroless nickel plating and solder when reflowed at 250°C. The interdiffusion behavior of the solder bump constituents within the solder bump was investigated by scanning electromicroscope (SEM). Cu was found to penetrate the electroless nickel during reflow when the thickness of the electroless nickel plating is only 1.8μm. No penetration of Cu occurs through a 10μm electroless nickel during reflow. Sn and Al were not found to diffuse through the electroless nickel during reflow even for 1.8μm of electroless nickel plating. The shearing strength of the solder bump reflowed at 210°C is 53.5±3.3 g/bump while the shearing strength is 62.9±2.8 g/bump when reflowed at 250°C. The fracture after shearing test occurs within the solder. Repeating reflow tends to lower the shearing strength of the bump. The shearing strength of the bump becomes 37.6±6.0 g/bump after ten cycles of reflow.

AB - 63Sn-37Pb solder bump was produced on Al terminal of Si. The bump pad dimension is 100μm × 100μm while the pitch size is 250μm. The bump pattern contains 20 × 20 bumps. The UBM (under bump metallurgy) consists of Cu/Electroless Nickel. Cu was sputtering deposited on Al film. The solder bump was electroplated on the electroless nickel followed by reflow at 210°C or 250°C. The reflow was conducted for 1, 5, and 10 cycles. Intermetallic compounds Ni3Sn2, Ni3Sn4, and Ni4Sn were formed between electroless nickel plating and solder when reflowed at 250°C. The interdiffusion behavior of the solder bump constituents within the solder bump was investigated by scanning electromicroscope (SEM). Cu was found to penetrate the electroless nickel during reflow when the thickness of the electroless nickel plating is only 1.8μm. No penetration of Cu occurs through a 10μm electroless nickel during reflow. Sn and Al were not found to diffuse through the electroless nickel during reflow even for 1.8μm of electroless nickel plating. The shearing strength of the solder bump reflowed at 210°C is 53.5±3.3 g/bump while the shearing strength is 62.9±2.8 g/bump when reflowed at 250°C. The fracture after shearing test occurs within the solder. Repeating reflow tends to lower the shearing strength of the bump. The shearing strength of the bump becomes 37.6±6.0 g/bump after ten cycles of reflow.

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