scholarly journals Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1044 ◽  
Author(s):  
Michail Samouhos ◽  
Antonis Peppas ◽  
Panagiotis Angelopoulos ◽  
Maria Taxiarchou ◽  
Petros Tsakiridis
Keyword(s):  
Base Material ◽  
Processing Temperature ◽  
Bond Quality ◽  
Bonding Parameters ◽  
Transmission Electron ◽  
Coarse Grains ◽  
Bond Interface ◽  
Copper Material ◽  
Electrical Components ◽  
Interdiffusion Phenomena

The optimization of the autogenous diffusion copper bonding via thermocompression at vacuum environment was investigated. The influence of various bonding parameters on the interdiffusion efficiency was studied in detail at the micro (SEM-EBSD) and nano (TEM) scales. Bonding at 1000 °C for 90 min under pressure (10 MPa) presented optimum structural and mechanical results. Under these conditions, interdiffusion phenomena were observed at a significant extent through the swelling transformation of existing fine grains or the formation of equiaxed copper grains with an orientation parallel to the bond interface. Transmission electron microscopy revealed the importance of the grain size of the base material on the bond quality. In the regions with fine-sized copper grains, the formation of small equiaxed recrystallized twins was observed. Their length within the bonding zone was in the order of 200 and 400 nm. On the contrary, in the regions with coarse grains the interdiffusion was poorer. The processing temperature and duration presented a significant effect on the bonding strength (BS). BS exceeded 100 MPa in case of processing conditions of T ≥ 850 °C and t ≥ 60 min, while the maximum BS value achieved (≈180 MPa) was comparable with the respective value of the base material. The microhardness of the optimum bond reached 55 HV—slightly higher in comparison to the hardness of the initial copper material. The results indicated that the proposed thermocompression process is appropriate for the production of Cu-Cu bonded structures that can be potentially used as electrical components under mechanical stress.

Development of Low-Temperature Sintering Cu Nanoparticles

2013 ◽  
Vol 1513 ◽  
Author(s):  
Toshitaka Ishizaki ◽  
Ryota Watanabe ◽  
Kunio Akedo ◽  
Toshikazu Satoh
Keyword(s):  
Electron Microscopy ◽  
Fatty Acids ◽  
Low Temperature ◽  
Decanoic Acid ◽  
Inert Atmosphere ◽  
Processing Temperature ◽  
Low Temperature Sintering ◽  
Cu Nanoparticles ◽  
Transmission Electron ◽  
Oleyl Amine

ABSTRACTCu nanoparticles capped with fatty acids and amines were developed as low-temperature sintering materials. The fatty acids and amines used were decanoic acid + decyl amine (C10) and oleic acid + oleyl amine (C18), respectively. The synthesized Cu nanoparticles were analyzed using X-ray diffraction, transmission electron microscopy, and thermogravimetric and differential thermal analysis. Because both of the capping layers could be decomposed at temperatures lower than 300°C even under an inert atmosphere, bonding and sintering experiments could be carried out in the absence of oxygen to prevent the oxidation of the Cu nanoparticles. The sintered structures were observed using scanning electron microscopy. The shear strengths of Cu plates bonded using the C18 Cu nanoparticles were larger than those of plates bonded using the C10 Cu nanoparticles. At 300°C, the strength was higher than 30 MPa, and of the same order as ordinary high-temperature solders, even though the processing temperature was low. The resistivity of a film sintered using the C18 Cu nanoparticles was 12 μΩcm at 300°C, which was lower than the values reported in previous studies.

An Study of Nanoscale Mechanical Twins in GH4169 Alloy by Laser Shot Peening Processing

2021 ◽  
Vol 1027 ◽  
pp. 155-162
Author(s):  
Qiang Wang
Keyword(s):  
Shot Peening ◽  
Electron Backscatter Diffraction ◽  
Laser Shot ◽  
Near Surface ◽  
Refined Grains ◽  
Transmission Electron ◽  
Coarse Grains ◽  
Mechanical Twins ◽  
Backscatter Diffraction ◽  
Gh4169 Alloy

In order to study the mechanism of the fatigue strengthening using laser shot peening in GH4169 alloy, micro-structural and nanoscale mechanical twins (MT) at different depth below the top surface subjected to laser shot peening processing (LSP) were investigated by means of electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) observations. In terms of the experimental observations and analyses, the formation of refined grains and nanoscale MT mechanism at the near surface of GH4169 alloy as a function of LSP treament can be summarized as follows: (i) two direction low density of MTs divide the initial coarse grains into submicron rhombic blocks; (ii) high density of MTs aligned in two directions subdivide the submicron rhombic blocks into nanoscale rhombic MT blocks; (iii) the third direction MT further refine the nanoscale rhombic MT blocks into nanoscale triangular MT blocks; (iv) some of subdivided blocks evolve into refined grains. An ultra-high strain rate induced by ultra-short laser pulse plays a key role in the formation of refined grains and nanoscale MT during plastic deformation of GH4169 alloy subjected to LSP treatment.

Surface crack propagation and morphology in cutting tools

2016 ◽  
Vol 68 (1) ◽  
pp. 141-148
Author(s):  
Mathias Linz ◽  
Franz Walzhofer ◽  
Stefan Krenn ◽  
Andreas Steiger-Thirsfeld ◽  
Johannes Bernardi ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Focused Ion Beam ◽  
Hydrodynamic Lubrication ◽  
Ion Beam ◽  
Cutting Tools ◽  
Base Material ◽  
In Situ Monitoring ◽  
Limited Region ◽  
Content Type ◽  
Transmission Electron

Purpose – The purpose of this paper is to investigate the driving mechanisms for crack propagation regarding the related microstructures. Cracks in white etching layers have been found at the surface of submerged steel blades subjected to frictional sliding conditions. Design/methodology/approach – In-situ monitoring revealed a fluctuation between mixed lubrication and hydrodynamic lubrication conditions. One lamella including a crack tip was prepared for transmission electron microscopy (TEM) using focused ion beam milling. Transmission electron microscope analysis was performed with the aim to understand the characteristics of the crack propagation, especially considering the influence of the microstructural configuration (grain refinement, carbides, martensite and ferrite grains). Findings – The investigations have shown a grain-refined plastically deformed layer (friction martensite with grain sizes of < 100 nm) which influences the propagation direction of cracks introduced at the frictionally stressed surface. Thereby, the crack propagation is dominantly parallel to the margin of the grain-refined martensitic layer at the surface and the base material. Cracks were split into side cracks what mostly appears at present carbides. In this case, the crack propagation might strike through the carbide or separate it from the matrix due to the mechanical misfit. Originality/value – For obtaining the results of this paper, a very special preparation of tribologically stressed samples was performed. Accordingly, specific findings of the crack propagation behavior under such conditions were achieved and are documented in the presented work. Moreover, the described crack propagation process is a combination of several mechanisms which occur in very limited region underneath the surface and are investigated by high-resolution TEM.

Transmission electron microscopy observation of second-phase particles in β–Si3N4 grains

1999 ◽  
Vol 14 (7) ◽  
pp. 2959-2965 ◽  
Author(s):  
Naoto Hirosaki ◽  
Tomohiro Saito ◽  
Fumio Munakata ◽  
Yoshio Akimune ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Silicon Nitride ◽  
Heat Treating ◽  
High Resolution Electron Microscopy ◽  
Second Phase ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Second Phase Particles ◽  
Coarse Grains ◽  
Sintered Silicon

Silicon nitride was fabricated by adding Y2O3 and Nd2O3 as sintering additives, sintering for 8 h at 1900 °C, and heat treating for 4 h at 2200 °C to enhance grain growth. The microstructure was investigated by scanning electron microscopy, high-resolution electron microscopy, energy dispersive x-ray spectroscopy (EDS), and electron microdiffraction. This material had a duplex microstructure composed of many fine grains and a few coarse grains. In β–Si3N4 grains, second-phase particles with the composition of liquid phase, Y–Nd–Si–O or Y–Nd–Si–O–N, in the size of 10–30 nm were observed. EDS spectra and microdiffraction patterns revealed that those were amorphous or crystalline particles of Y–Nd–apatite, (Y,Nd)10Si6O24N2. These particles were presumably formed during cooling by the precipitation of Y–Nd–Si–O–N, which was trapped in the β–Si3N4 grains as solid solution or trapped liquid. The results suggest that attention should be paid to the trace amounts of trapped elements in β–Si3N4 grains in trying to improve the thermal conductivity of sintered silicon nitride.

Thermal Effects in Plasma Treatment of Patterned PDMS for Bonding Stacked Channels

2003 ◽  
Vol 782 ◽  
Author(s):  
Jin Zou ◽  
Peter Y. Wong
Keyword(s):  
Silicon Nitride ◽  
Hybrid Systems ◽  
Thermal Effects ◽  
Room Temperature ◽  
Work Of Adhesion ◽  
Chemical Components ◽  
Hydroxyl Groups ◽  
Processing Temperature ◽  
Plasma Oxidation ◽  
Bond Quality

ABSTRACTThis paper presents the results of a study to identify the effects of preheating for plasma oxidation (ashing) of patterned Polydimethylsiloxane (PDMS) for Bio-MEMS applications. PDMS creates an irreversible seal to itself as well as strong seals with glass, silicon, and silicon nitride. This process activates the surface by producing hydroxyl groups that last for several minutes to allow bonding. Several channels can be stacked to create 3D systems for microfluidic applications using PDMS alone or in combination with other materials to develop hybrid systems. For PDMS, bonding temperatures typically occur at room temperature. This research investigates the effect of preheating the materials prior to ashing. The investigators successfully demonstrate good bonding of PDMS to slides with a work adhesion on the order of 100 mJm-2. Preheating the samples at 65°C results in significant increase in work adhesion depending on mixture. The effects of processing temperature and chemical components on bond quality and work of adhesion are reported.

scholarly journals Study of Micro Structural Material Changes after WEDM Based on TEM Lamella Analysis

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 949 ◽  
Author(s):  
Katerina Mouralova ◽  
Radim Zahradnicek ◽  
Libor Benes ◽  
Tomas Prokes ◽  
Radim Hrdy ◽  
...  
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Subsurface Layer ◽  
Base Material ◽  
Wire Electrical Discharge Machining ◽  
Transmission Electron ◽  
Machined Parts ◽  
Tem Lamella ◽  
Unconventional Machining

Wire electrical discharge machining is an unconventional machining technology that is crucial in many industries. The surface quality of the machined parts is carefully monitored, but the condition of the subsurface layer also plays a crucial role, especially in case of defects occurrence such as cracks or burnt cavities. The subsurface layer of individual materials is affected differently due to wire electrical discharge machining. For this reason, this study was carried out focusing on a detailed analysis of transmission electron microscope (TEM) lamella made of Ti-6Al-4V titanium alloy, AlZn6Mg2Cu aluminum alloy, pure molybdenum, Creusabro 4800 steel, and Hardox 400 steel. The attention was first of all paid to the concentration and distribution of individual elements in the recast layer and also in the base material, which was often affected by wire electrical discharge machining. Further, a diffraction analysis was performed for each TEM lamella in the adhesive area and in the base material area. In order to assess the macro-effects on the machined material, the topography analysis of the machined surfaces and the morphology analysis were performed using electron microscopy.

Growth of Intermetallics at Coated Silver Wire Bond Interfaces

2018 ◽  
Vol 2018 (1) ◽  
pp. 000578-000582 ◽  
Author(s):  
Sarangapani Murali ◽  
Wong Chin Yeung Jason
Keyword(s):  
Solid Solution ◽  
Thin Layer ◽  
Precise Measurement ◽  
Ion Beam ◽  
Thermal Ageing ◽  
X Ray ◽  
Transmission Electron ◽  
Free Air ◽  
Bond Interface ◽  
Focus Ion Beam

Abstract The newly developed gold (Au) coated silver (Ag) wire exhibits axi-symmetrical free air ball (FAB) formation under atmosphere similar to Au wire. FAB of coated Ag showed better corrosion resistance than FAB of alloyed Ag, as Au dissolved along the periphery of Ag FAB forming into a solid-solution, Ag-Au alloy. Composition of the solid-solution Ag-Au alloy along the periphery ranges between 10 and 28wt% of Au. The diffusion depth of Au is 4μm from surface towards the center of FAB. For precise measurement of the diffusion length of Au into Ag, a solid thin layer is been parted using focus-ion beam (FIB). The solid thin layer is further thinned down to observe in Transmission Electron Microscope (TEM) and analyzed using line scan energy dispersive X-ray analysis (EDX) attached to it. Near the neck of FAB and wire, Au diffusion is high up to 58wt%. On thermal ageing at 150/175°C for 500/1000h, the coated Ag wire bonded to Al-0.5wt%Cu pad revealed no degradation on ball pull/shear. Bond interface revealed significant growth of silver aluminide (AgAl) to a thickness of 3μm for 1000h of ageing and the growth rate fits to square-root power law.

Pd-coated Cu Wire Bonding Reliability Requirement for Device Design, Process Optimization and Testing

2012 ◽  
Vol 2012 (1) ◽  
pp. 000396-000404 ◽  
Author(s):  
Inderjit Singh ◽  
Shin Low ◽  
Syu Fu Song ◽  
Chen Shih Jung ◽  
Lin Ming San ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Industry ◽  
Quality Measures ◽  
Wire Bonding ◽  
Bond Quality ◽  
Related Factors ◽  
Molding Compound ◽  
Bonding Parameters ◽  
Bonding Technology

One of the biggest technology drivers in the semiconductor industry today is the fast transition from Au wire bonding to Cu wire bonding. The fast adaptation of Cu and Pd-coated Cu (PCC) wire has focused the whole packaging industry to develop understanding, equipment and processes that can produce a more reliable and robust Cu wire bonding technology. Although the fundamentals of wire bonding technology are very similar between Au and Cu wire bonding, there are a lot of new challenges in Cu wire bonding. Compared to Au wire bonding, Cu wire bonding needs different bond quality measures and metrology. Traditional ball diameter, ball height and shear measurements are not adequate to quantify a Cu wire bonding process. Some of the additional bond quality measures include pad material push out (pad splash), Al layer peel off (pad peel) and crack in the barrier and dielectric layer (pad crack). Another area that is quite different between Au and Cu is the reliability test requirement. In Au wire bonding, because of the fast intermetallic compound (IMC) growth rate, the HTS test is normally the hardest to pass. Due to the corrosion of Cu wire, the HAST test is the most challenging in Cu wire bonding. Reliability requirements still need more knowledge. In this paper, we conduct reliability tests for devices with 3 sets of wire bonding parameters. The bonded samples have IMC coverage between 94% and 97%, well above the industry level of 80%. The reliability (HAST) test passed for all samples at 96 hours. However, there are some failures in the HAST test at 192 hr. There are many factors that can influence reliability outcome including wire bonding and non-wire bonding related factors. The failure analysis identified two potential causes in our case. In one failure case, an abnormally high Chlorine level and void in molding compound were detected next to the failed bond while no Chlorine and void were detected elsewhere. In the 2nd failure case, the bonded ball seems to be off centered and results in poor bonded ball to pad interface. These two factors will be more tightly controlled in future tests to verify the reliability outcome. Intermetallic growth and phase transformation, aluminum oxide, and behavior of palladium in PdCu wire bonds are analyzed using transmission electron microscopy (TEM) of dual beam focused ion beam (FIB) thinned specimens. Results are compared to wire bonding measurement and reliability outcome.

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