Interfacial reactions between Sn-based solders and AgPt thick film metallizations on LTCC

Olli Nousiainen, Tero Kangasvieri, Kari Rönkä, Risto Rautioaho, Jouko Vähäkangas

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)

Abstract

Purpose – This paper aims to investigate the metallurgical reactions between two commercial AgPt thick films used as a solder land on a low temperature co-fired ceramic (LTCC) module and solder materials (SnAgCu, SnInAgCu, and SnPbAg) in typical reflow conditions and to clarify the effect of excessive intermetallic compound (IMC) formation on the reliability of LTCC/printed wiring boards (PWB) assemblies. Design/methodology/approach – Metallurgical reactions between liquid solders and AgPt metallizations of LTCC modules were investigated by increasing the number of reflow cycles with different peak temperatures. The microstructures of AgPt metallization/solder interfaces were analyzed using SEM/EDS investigation. In addition, a test LTCC module/PWB assembly with an excess IMC layer within the joints was fabricated and exposed to a temperature cycling test in a 240 to 1258C temperature range. The characteristic lifetime of the test assembly was determined using DC resistance measurements. The failure mechanism of the test assembly was verified using scanning acoustic microscopy and SEM investigation. Findings – The results showed that the higher peak reflow temperature of common lead-free solders had a significant effect on the consumption of the original AgPt metallization of LTCC modules. The results also suggested that the excess porosity of the metallization accelerated the degradation of the metallization layer. Finally, the impact of these adverse metallurgical effects on the actual failure mechanism in an LTCC/PWB assembly was demonstrated. Originality/value – This paper proves how essential it is to know the actual LTCC metallization/solder interactions that occur during reflow soldering and to recognize their effect on solder joint reliability in LTCC module/PWB assemblies. Moreover, the adverse effect of using lead-free solders on the degradation of Ag-based metallizations and, consequently, on board level reliability is demonstrated. Finally, practical guidelines for selecting materials for second-level solder interconnections of LTCC module are given.
Original languageEnglish
Pages (from-to)15-25
JournalSoldering and Surface Mount Technology
Volume19
Issue number3
DOIs
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

Fingerprint

solders
Metallizing
Surface chemistry
Thick films
Soldering alloys
thick films
ceramics
wiring
modules
assembly
Temperature
Printed circuit boards
assemblies
intermetallics
low temperature tests
degradation
Intermetallics
cycles
scanning electron microscopy
soldering

Keywords

  • Solders
  • reliability management

Cite this

Nousiainen, Olli ; Kangasvieri, Tero ; Rönkä, Kari ; Rautioaho, Risto ; Vähäkangas, Jouko. / Interfacial reactions between Sn-based solders and AgPt thick film metallizations on LTCC. In: Soldering and Surface Mount Technology. 2007 ; Vol. 19, No. 3. pp. 15-25.
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abstract = "Purpose – This paper aims to investigate the metallurgical reactions between two commercial AgPt thick films used as a solder land on a low temperature co-fired ceramic (LTCC) module and solder materials (SnAgCu, SnInAgCu, and SnPbAg) in typical reflow conditions and to clarify the effect of excessive intermetallic compound (IMC) formation on the reliability of LTCC/printed wiring boards (PWB) assemblies. Design/methodology/approach – Metallurgical reactions between liquid solders and AgPt metallizations of LTCC modules were investigated by increasing the number of reflow cycles with different peak temperatures. The microstructures of AgPt metallization/solder interfaces were analyzed using SEM/EDS investigation. In addition, a test LTCC module/PWB assembly with an excess IMC layer within the joints was fabricated and exposed to a temperature cycling test in a 240 to 1258C temperature range. The characteristic lifetime of the test assembly was determined using DC resistance measurements. The failure mechanism of the test assembly was verified using scanning acoustic microscopy and SEM investigation. Findings – The results showed that the higher peak reflow temperature of common lead-free solders had a significant effect on the consumption of the original AgPt metallization of LTCC modules. The results also suggested that the excess porosity of the metallization accelerated the degradation of the metallization layer. Finally, the impact of these adverse metallurgical effects on the actual failure mechanism in an LTCC/PWB assembly was demonstrated. Originality/value – This paper proves how essential it is to know the actual LTCC metallization/solder interactions that occur during reflow soldering and to recognize their effect on solder joint reliability in LTCC module/PWB assemblies. Moreover, the adverse effect of using lead-free solders on the degradation of Ag-based metallizations and, consequently, on board level reliability is demonstrated. Finally, practical guidelines for selecting materials for second-level solder interconnections of LTCC module are given.",
keywords = "Solders, reliability management",
author = "Olli Nousiainen and Tero Kangasvieri and Kari R{\"o}nk{\"a} and Risto Rautioaho and Jouko V{\"a}h{\"a}kangas",
year = "2007",
doi = "10.1108/09540910710843748",
language = "English",
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Nousiainen, O, Kangasvieri, T, Rönkä, K, Rautioaho, R & Vähäkangas, J 2007, 'Interfacial reactions between Sn-based solders and AgPt thick film metallizations on LTCC', Soldering and Surface Mount Technology, vol. 19, no. 3, pp. 15-25. https://doi.org/10.1108/09540910710843748

Interfacial reactions between Sn-based solders and AgPt thick film metallizations on LTCC. / Nousiainen, Olli; Kangasvieri, Tero; Rönkä, Kari; Rautioaho, Risto; Vähäkangas, Jouko.

In: Soldering and Surface Mount Technology, Vol. 19, No. 3, 2007, p. 15-25.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Interfacial reactions between Sn-based solders and AgPt thick film metallizations on LTCC

AU - Nousiainen, Olli

AU - Kangasvieri, Tero

AU - Rönkä, Kari

AU - Rautioaho, Risto

AU - Vähäkangas, Jouko

PY - 2007

Y1 - 2007

N2 - Purpose – This paper aims to investigate the metallurgical reactions between two commercial AgPt thick films used as a solder land on a low temperature co-fired ceramic (LTCC) module and solder materials (SnAgCu, SnInAgCu, and SnPbAg) in typical reflow conditions and to clarify the effect of excessive intermetallic compound (IMC) formation on the reliability of LTCC/printed wiring boards (PWB) assemblies. Design/methodology/approach – Metallurgical reactions between liquid solders and AgPt metallizations of LTCC modules were investigated by increasing the number of reflow cycles with different peak temperatures. The microstructures of AgPt metallization/solder interfaces were analyzed using SEM/EDS investigation. In addition, a test LTCC module/PWB assembly with an excess IMC layer within the joints was fabricated and exposed to a temperature cycling test in a 240 to 1258C temperature range. The characteristic lifetime of the test assembly was determined using DC resistance measurements. The failure mechanism of the test assembly was verified using scanning acoustic microscopy and SEM investigation. Findings – The results showed that the higher peak reflow temperature of common lead-free solders had a significant effect on the consumption of the original AgPt metallization of LTCC modules. The results also suggested that the excess porosity of the metallization accelerated the degradation of the metallization layer. Finally, the impact of these adverse metallurgical effects on the actual failure mechanism in an LTCC/PWB assembly was demonstrated. Originality/value – This paper proves how essential it is to know the actual LTCC metallization/solder interactions that occur during reflow soldering and to recognize their effect on solder joint reliability in LTCC module/PWB assemblies. Moreover, the adverse effect of using lead-free solders on the degradation of Ag-based metallizations and, consequently, on board level reliability is demonstrated. Finally, practical guidelines for selecting materials for second-level solder interconnections of LTCC module are given.

AB - Purpose – This paper aims to investigate the metallurgical reactions between two commercial AgPt thick films used as a solder land on a low temperature co-fired ceramic (LTCC) module and solder materials (SnAgCu, SnInAgCu, and SnPbAg) in typical reflow conditions and to clarify the effect of excessive intermetallic compound (IMC) formation on the reliability of LTCC/printed wiring boards (PWB) assemblies. Design/methodology/approach – Metallurgical reactions between liquid solders and AgPt metallizations of LTCC modules were investigated by increasing the number of reflow cycles with different peak temperatures. The microstructures of AgPt metallization/solder interfaces were analyzed using SEM/EDS investigation. In addition, a test LTCC module/PWB assembly with an excess IMC layer within the joints was fabricated and exposed to a temperature cycling test in a 240 to 1258C temperature range. The characteristic lifetime of the test assembly was determined using DC resistance measurements. The failure mechanism of the test assembly was verified using scanning acoustic microscopy and SEM investigation. Findings – The results showed that the higher peak reflow temperature of common lead-free solders had a significant effect on the consumption of the original AgPt metallization of LTCC modules. The results also suggested that the excess porosity of the metallization accelerated the degradation of the metallization layer. Finally, the impact of these adverse metallurgical effects on the actual failure mechanism in an LTCC/PWB assembly was demonstrated. Originality/value – This paper proves how essential it is to know the actual LTCC metallization/solder interactions that occur during reflow soldering and to recognize their effect on solder joint reliability in LTCC module/PWB assemblies. Moreover, the adverse effect of using lead-free solders on the degradation of Ag-based metallizations and, consequently, on board level reliability is demonstrated. Finally, practical guidelines for selecting materials for second-level solder interconnections of LTCC module are given.

KW - Solders

KW - reliability management

U2 - 10.1108/09540910710843748

DO - 10.1108/09540910710843748

M3 - Article

VL - 19

SP - 15

EP - 25

JO - Soldering and Surface Mount Technology

JF - Soldering and Surface Mount Technology

SN - 0954-0911

IS - 3

ER -