Corrosion of palladium coated copper wire bonds under high temperature storage reliability test

Palladium coated copper (PCC) wire is emerging as an alternative to bare copper (Cu) wire in the semiconductor industry due to better manufacturing yield and reliability stress performance. However, the acceptance of PCC wire for automotive device is still low due to the stringent reliability requir...

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Main Author:	Cha, Chan Lam
Format:	Thesis
Language:	English English
Published:	2021
Subjects:	T Technology (General) TS Manufactures
Online Access:	http://eprints.utem.edu.my/id/eprint/25978/1/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf http://eprints.utem.edu.my/id/eprint/25978/2/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf
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spelling	my-utem-ep.259782022-09-29T12:31:21Z Corrosion of palladium coated copper wire bonds under high temperature storage reliability test 2021 Cha, Chan Lam T Technology (General) TS Manufactures Palladium coated copper (PCC) wire is emerging as an alternative to bare copper (Cu) wire in the semiconductor industry due to better manufacturing yield and reliability stress performance. However, the acceptance of PCC wire for automotive device is still low due to the stringent reliability requirement by Automotive Electronic Council (AEC) Q100 standard and limited proven record in automotive application. Previous works showed PCC wire fails the High Temperature Storage (HTS) stress test at temperature of 175°C. Corrosion was observed on ball bond and stitch bond, causing severe degradations in the ball shear and stitch pull values. This research aims to determine the performance of PCC wire, to characterize the critical influencing factors driving the PCC wire corrosion at HTS stress test in accordance to AEC Q100 Grade 0 requirement, and to model the PCC wire failure mechanism. Based on failure analysis (SEM) results, there are many voids observed on expose Cu surface on PCC wire after stress, EDX analysis result detected sulfur element on the void region, thus, it is confirmed the Copper Sulfide (CuS) formation had occurred and Cu void formation is leading the early failure of PCC wire under HTS stress test. This research work concluded there are three critical factors that need to be controlled to meet the AEC Q100 Grade 0 quality requirement, first is the mold compound sulfur parts per milliom (ppm) level should control <10 ppm to mitigate the CuS formation. The second factor was the gold silver (AuAg) plating thickness on lead frame, the CuS formation rate was slower if the AuAg plating thickness is thinner. 8 nanometer (nm) AuAg lead frame thickness passed the AEC Q100 Grade 0 requirements with minimum stitch pull value 3.65 gram force (gf), however, the low process capability index (Cpk) might be a concern for automotive application. Thus, controlling the lead frame plating thickness could not be recommended as one of the solutions to PCC wire application. The third factor was the PCC wire corrosion was more severe under 175°C at 1000 hours (hrs) if compare to 150°C at 2000 hrs, even both condition were defined as equivalent in AEC Q100 standard; This result indicates the activation energy for CuS formation was not equal to the typical value 0.7 eV used by the standard. Based on the experimental data analysis, a model on galvanic corrosion accelerated by the presence of metal catalyst was proposed. The sulfur element comes from the adhesion promoter in the mold compound. The palladium coated on the PCC wire acted as a catalyst to enables the corrosion reaction to happen at lower activation energy. This research study had also concluded the material selection especially the mold compound type is very crucial to prevent PCC wire corrosion issue. 2021 Thesis http://eprints.utem.edu.my/id/eprint/25978/ http://eprints.utem.edu.my/id/eprint/25978/1/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf text en public http://eprints.utem.edu.my/id/eprint/25978/2/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf text en public https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=121056 mphil masters Universiti Teknikal Malaysia Melaka Faculty of Manufacturing Engineering Lau, Kok Tee
institution	Universiti Teknikal Malaysia Melaka
collection	UTeM Repository
language	English English
advisor	Lau, Kok Tee
topic	T Technology (General) TS Manufactures
spellingShingle	T Technology (General) TS Manufactures Cha, Chan Lam Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
description	Palladium coated copper (PCC) wire is emerging as an alternative to bare copper (Cu) wire in the semiconductor industry due to better manufacturing yield and reliability stress performance. However, the acceptance of PCC wire for automotive device is still low due to the stringent reliability requirement by Automotive Electronic Council (AEC) Q100 standard and limited proven record in automotive application. Previous works showed PCC wire fails the High Temperature Storage (HTS) stress test at temperature of 175°C. Corrosion was observed on ball bond and stitch bond, causing severe degradations in the ball shear and stitch pull values. This research aims to determine the performance of PCC wire, to characterize the critical influencing factors driving the PCC wire corrosion at HTS stress test in accordance to AEC Q100 Grade 0 requirement, and to model the PCC wire failure mechanism. Based on failure analysis (SEM) results, there are many voids observed on expose Cu surface on PCC wire after stress, EDX analysis result detected sulfur element on the void region, thus, it is confirmed the Copper Sulfide (CuS) formation had occurred and Cu void formation is leading the early failure of PCC wire under HTS stress test. This research work concluded there are three critical factors that need to be controlled to meet the AEC Q100 Grade 0 quality requirement, first is the mold compound sulfur parts per milliom (ppm) level should control <10 ppm to mitigate the CuS formation. The second factor was the gold silver (AuAg) plating thickness on lead frame, the CuS formation rate was slower if the AuAg plating thickness is thinner. 8 nanometer (nm) AuAg lead frame thickness passed the AEC Q100 Grade 0 requirements with minimum stitch pull value 3.65 gram force (gf), however, the low process capability index (Cpk) might be a concern for automotive application. Thus, controlling the lead frame plating thickness could not be recommended as one of the solutions to PCC wire application. The third factor was the PCC wire corrosion was more severe under 175°C at 1000 hours (hrs) if compare to 150°C at 2000 hrs, even both condition were defined as equivalent in AEC Q100 standard; This result indicates the activation energy for CuS formation was not equal to the typical value 0.7 eV used by the standard. Based on the experimental data analysis, a model on galvanic corrosion accelerated by the presence of metal catalyst was proposed. The sulfur element comes from the adhesion promoter in the mold compound. The palladium coated on the PCC wire acted as a catalyst to enables the corrosion reaction to happen at lower activation energy. This research study had also concluded the material selection especially the mold compound type is very crucial to prevent PCC wire corrosion issue.
format	Thesis
qualification_name	Master of Philosophy (M.Phil.)
qualification_level	Master's degree
author	Cha, Chan Lam
author_facet	Cha, Chan Lam
author_sort	Cha, Chan Lam
title	Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
title_short	Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
title_full	Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
title_fullStr	Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
title_full_unstemmed	Corrosion of palladium coated copper wire bonds under high temperature storage reliability test
title_sort	corrosion of palladium coated copper wire bonds under high temperature storage reliability test
granting_institution	Universiti Teknikal Malaysia Melaka
granting_department	Faculty of Manufacturing Engineering
publishDate	2021
url	http://eprints.utem.edu.my/id/eprint/25978/1/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf http://eprints.utem.edu.my/id/eprint/25978/2/Corrosion%20of%20palladium%20coated%20copper%20wire%20bonds%20under%20high%20temperature%20storage%20reliability%20test.pdf
_version_	1747834146988752896

Corrosion of palladium coated copper wire bonds under high temperature storage reliability test

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