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Article
Publication date: 6 June 2016

Roman Kolenak, Igor Kostolný and Martin Sahul

The work aims to study the direct bonding of silicon substrate with solders type Sn-Ag-Ti.

Abstract

Purpose

The work aims to study the direct bonding of silicon substrate with solders type Sn-Ag-Ti.

Design/methodology/approach

During the bonding process with ultrasound assistance, the active element (Ti,Ce,Mg) is distributed from the solder to interface with a silicon substrate, where it supports the bond formation.

Findings

Formation of a reaction layer, 1-2 μm in thickness, was observed. The new Si2Ti phases and Mg2Si phase were identified in the reaction layer.

Originality/value

The results of analysis suggest that the Si/Sn-Ag-Ti joint is of diffusion character. The highest average strength on silicon substrate (39 MPa) was achieved with Sn-Ag-Ti(Mg) solder.

Details

Soldering & Surface Mount Technology, vol. 28 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 2 April 2019

Roman Koleňák, Igor Kostolný, Jaromír Drápala, Martin Kusý and Matej Pašák

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was…

Abstract

Purpose

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied.

Design/methodology/approach

It was found to contain a Sn matrix, where both Ag phase – ɛ-Ag3Sn – and Ti phases ɛ-Ti6Sn5 and Ti2Sn3 – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials.

Findings

X-ray diffraction analysis proved the presence of new NTi and AlTi2 phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu3Sn and Cu6Sn5 phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa.

Originality/value

The present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.

Details

Soldering & Surface Mount Technology, vol. 31 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 5 June 2017

Roman Kolenak

This paper aims to investigate the effect of solder alloying with a small amount of La and Y on bond formation with the Si and Cu substrates.

Abstract

Purpose

This paper aims to investigate the effect of solder alloying with a small amount of La and Y on bond formation with the Si and Cu substrates.

Design/methodology/approach

Bi2La and Bi2Y solders were studied. Soldering was performed using a fluxless method in air and with ultrasonic activation.

Findings

It was found that in the process of ultrasonic soldering, the La and Y were distributed at the interface with Si and Cu substrates, which enhanced the bond formation. Addition of La or Y elements in a Bi-based solder also ensured wetting of non-metallic materials such as Si, Al2O3 and SiC ceramics.

Originality/value

The addition of lanthanides offers a method for ensuring wetting of non-metallic materials. The bond with Si was of an adhesive character without the formation of a new contact interlayer. This resulted in lower shear strength of the bond with Si (8-10 MPa). The shear strength of the bond with a Cu substrate was 22-30 MPa.

Details

Soldering & Surface Mount Technology, vol. 29 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 18 February 2019

Peng Yao, Xiaoyan Li, Xu Han and Liufeng Xu

This study aims to analyze the shear strength and fracture mechanism of full Cu-Sn IMCs joints with different Cu3Sn proportion and joints with the conventional interfacial…

Abstract

Purpose

This study aims to analyze the shear strength and fracture mechanism of full Cu-Sn IMCs joints with different Cu3Sn proportion and joints with the conventional interfacial structure in electronic packaging.

Design/methodology/approach

The Cu-Sn IMCs joints with different Cu3Sn proportion were fabricated through soldering Cu-6 μm Sn-Cu sandwich structure under the extended soldering time and suitable pressure. The joints of conventional interfacial structure were fabricated through soldering Cu-100 μm Sn-Cu sandwich structure. After the shear test was conducted, the fracture mechanism of different joints was studied through observing the cross-sectional fracture morphology and top-view fracture morphology of sheared joints.

Findings

The strength of joints with the conventional interfacial structure was 26.6 MPa, while the strength of full Cu-Sn IMCs joints with 46.7, 60.6, 76.7 and 100 per cent Cu3Sn was, respectively, 33.5, 39.7, 45.7 and 57.9 MPa. The detailed reason for the strength of joints showing such regularity was proposed. For the joint of conventional interfacial structure, the microvoids accumulation fracture happened within the Sn solder. However, for the full Cu-Sn IMCs joint with 46.7 per cent Cu3Sn, the cleavage fracture happened within the Cu6Sn5. As the Cu3Sn proportion increased to 60.6 per cent, the inter-granular fracture, which resulted in the interfacial delamination of Cu3Sn and Cu6Sn5, occurred along the Cu3Sn/Cu6Sn5 interface, while the cleavage fracture happened within the Cu6Sn5. Then, with the Cu3Sn proportion increasing to 76.7 per cent, the cleavage fracture happened within the Cu6Sn5, while the transgranular fracture happened within the Cu3Sn. The inter-granular fracture, which led to the interfacial delamination of Cu3Sn and Cu, happened along the Cu/Cu3Sn interface. For the full Cu3Sn joint, the cleavage fracture happened within the Cu3Sn.

Originality/value

The shear strength and fracture mechanism of full Cu-Sn IMCs joints was systematically studied. A direct comparison regarding the shear strength and fracture mechanism between the full Cu-Sn IMCs joints and joints with the conventional interfacial structure was conducted.

Details

Soldering & Surface Mount Technology, vol. 31 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

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