- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Influence of laser parameters on tensile shear strength of copper welds
摘要： The electrification of the power train in the automotive industry leads to the requirement of electrical connectors with high ampacities. These connectors are often realized using ultrasonic bonding technology. Substitution of ultrasonic welding by laser welding allows an increase of ribbon cross section by a factor of 5 and thus a similar increase of the maximum transferred current. The increased cross section leads to higher loads (at least by a factor of 5) applied to the weld seam during the process. To minimize the heat input, the weld seam strength in shear direction shall be maximized. The influence of different laser parameters on the ultimate tensile shear stress in lap joint configuration is investigated, based on representative specimen geometries (10 × 0.3 mm2). The variable parameters are: laser wavelength (IR around 1050 nm + frequency doubled 515 nm), focal diameters (42–300 μm), different temper conditions of the base material, process parameters (laser power 0.6–4 kW and feed rate 50–800 mm/s), and welding strategies (single pass welding, spatial beam modulation). The material used is Cu-ETP (>99.9% Cu). For all the investigated parameters, the observed failure mode is “fracture in the fusion zone.” The ultimate tensile shear stress for all experiments is around 188 N/mm2 even for parameter changes in the order of one magnitude. This is in contrast to the assumed relation between laser parameters and the mechanical properties. This contrast will be discussed.
关键词： load-carrying capacity,ductile welds,wobbling,fiber laser welding,shear strength
更新于2025-11-28 14:24:20
-
SiC chip attachment sintered by nanosilver paste and their shear strength evaluation
摘要： In this study, a nanosilver paste was prepared by silver nanoparticles and organics, by which an SiC ship could be sintered on the direct bonding copper (DBC) substrate at 250–300 °C. The nanosilver paste firmly sintered the SiC chip and DBC substrate, and die attachment had an excellent bonding interface. Die-shear results showed that the shear strength increased with the increase of sintering temperature and was more than the value required by the MIL-STD-883J standard. When high assisted pressure was applied, the sintering temperature could be lowered and sintering time also could be shortened to realize attaching high bonding strength. The assisted pressure also influenced the porosity of the bondline. X-ray non-destructive method was used to measure the porosity of die attachment. The results showed that the shear strength of die attachment decreased with the increase of bondline porosity.
关键词： Nanosilver paste,Bondline,Die attachment,Shear strength
更新于2025-11-21 11:18:25
-
The normal and shear strength properties of laser lap weld
摘要： The study was aimed to clarify the shear strength and the normal strength properties of the lap joint. The welds were characterized with respect to hardness, tensile and fatigue properties. The test materials of this study were low strength carbon steel (LSS) and ultra high strength wear resistant steel (UHSS). The shear strength, perpendicular strength and fatigue resistance of the lap joint laser weld was determined by tensile and fatigue tests. The shear strength of the LSS weld was higher than the strength of the base material. The shear strength of UHSS weld was higher than the LSS weld. However, compared to strength of the base material of the UHSS the weld was weaker even though the weld was harder than the base material. The normal strength of the UHSS and LSS welds was over two times higher than the shear strength of the same welds.
关键词： Shear strength,Laser weld,Normal strength
更新于2025-09-19 17:13:59
-
Laser Dissimilar Joining of Al7075T6 with Glass-Fiber-Reinforced Polyamide Composite
摘要： Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic and composite parts have been held together and heated with a laser beam while pressure is applied to allow the melted polymer to flow into the cavities of the metal part. The main issue of this process relates to reaching the same joint strength repetitively with appropriate process parameters. In this work, both initial texturing and laser joining parameters are studied for Al 7075-T6 and glass-fiber-reinforced PA6 composite. A groove-based geometry was studied in terms of depth-to-width aspect ratio to find an optimal surface using a nanosecond fiber laser for texturing. Laser joining parameters were also studied with different combinations of surface temperature, heating strategy, pressure, and laser feed rate. The results are relatively good for grooves with aspect ratios from 0.94 to 4.15, with the widths of the grooves being the most critical factor. In terms of joining parameters, surface reference temperature was found to be the most influential parameter. Underheating does not allow correct material flow in textured cavities, while overheating also causes high dispersion in the resulting shear strength. When optimal parameters are applied using correct textures, shear strength values over 26 kN are reached, with a contact area of 35 × 45 mm2.
关键词： metal polymer joint,groove aspect ratio,laser structuring,laser direct joining,shear strength
更新于2025-09-16 10:30:52
-
Pressureless joining of SiC ceramics at low temperature
摘要： Pressureless joining of SiC ceramics at low temperature was developed using Ti powder interlayer. Phase assemblage and microstructure of SiC joint revealed that the products after diffusion bonding mainly consisted of Ti5Si3 and TiC owing to the comparatively low joining temperature. Additionally, Si and C elements were found to be with higher penetration depth in the Ti interlayer. Benefitting from the lower proportion of the brittle Ti5Si3 phase and porosity, shear strength reached a relatively higher value of 41 MPa after joining at 1200oC for 30 min.
关键词： SiC ceramics,Shear strength,Ti powder,Diffusion bonding,Pressureless joining
更新于2025-09-10 09:29:36
-
Assessment of the Microstructure and Mechanical Properties of a Laser-Joined Carbon Fiber-Reinforced Thermosetting Plastic and Stainless Steel
摘要： The thermosetting plastic and stainless steel were joined with a fiber laser. The influence of processing parameters on the joint was studied. The laser scanning on stainless steel is shown to result lathy ferrite precipitates along the boundary, which modifies austenite, while in the second zone, ferrite forms the skeleton structure and separates austenite into a small cellular structure. The laser joining improves the microstructure of both zones. With an increase in the laser scanning speed and power, the shear strength of the stainless steel/plastic joint first increases and then decreases. A low laser scanning speed or high laser power would overheat polyphenylene sulphide and lead to its decomposition. Those factors would also reduce heat transfer and lead to its insufficient melting. The stainless steel/plastic joint acquires a maximum shear strength at a laser scanning speed of 4–5 mm/s and laser power of 320-350 W.
关键词： bonding interface,laser joining,microstructure,carbon fiber-reinforced thermoplastic,stainless steel,shear strength
更新于2025-09-10 09:29:36
-
Effects of sintering pressure on the densification and mechanical properties of nanosilver double side sintered power module
摘要： Modern power electronics has increased demands in current density and high temperature reliability. However, these performance factors are limited due to the die attach materials used to affix power dies microchips to electric circuitry. Although several die attach materials and methods exist, nanosilver sintering technology has received much attention in attaching power dies due to its superior high temperature reliability. This paper investigated the sintering properties of nanosilver film in double side sintered power packages. X-ray diffraction (XRD) results revealed that the size of nanosilver particles increased after pressure-free sintering. Comparing with the pressure-free sintered nanosilver particles, the 5 MPa sintered particles showed a higher density. When increasing sintering pressure from 5 to 30 MPa, the shear strength of the sintered package increased from 8.71 MPa to 86.26 MPa. When sintering at pressures below 20 MPa, the fracture areas are mainly located between the sintered Ag layer and the surface metallization layer on the fast recovery diode (FRD) die. The fracture occurs through the FRD die and the metallization layer on bottom Mo substrate when sintering at 30 MPa.
关键词： fracture,power electronics,nanosilver sintering,shear strength
更新于2025-09-09 09:28:46