Evaluation of a Novel Anisotropic Conductive Adhesive Shear Under Multiple Tin-Lead and Lead-Free Reflow Cycles for Package-on-Package (POP) Assembly

2012 ◽  
Author(s):  
Dustin D’Angelo ◽  
S. Manian Ramkumar ◽  
Luke Wentlent ◽  
Peter Borgesen
Keyword(s):  
Shear Stress ◽  
Thermal Cycling ◽  
Filler Particle ◽  
Base Material ◽  
Primary Objective ◽  
Shear Loading ◽  
Lead Free ◽  
The Novel ◽  
Conductive Adhesives ◽  
Pcb Assembly

The continued desire for an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). These create bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry. The novel ACA’s applicability for PCB-level assembly has been successfully demonstrated by RIT. The research at RIT has also characterized the base material properties, analyzed the effect of various process parameters, identified failures, and investigated the ACA’s long-term reliability for surface mount PCB assembly. Reliability testing included an investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing conditions. For example, it has been shown that by modifying the filler particle size and coating, reliability of >1500 hours in high temperature, high humidity aging (HTHH), and 100 hours in highly accelerated stress testing (HAST) can be successfully achieved. This paper highlights research comparing the shear loading performance of the novel ACA to that of tin-lead and lead free solders. Samples assembled with the adhesive and the solders were subjected to multiple tin-lead and lead free reflow cycles. The primary objective was to understand the deterioration in shear loading as influenced by multiple reflow cycles. Published research materials have shown the influence of the change in solder joint performance with multiple reflows due to the increase in intermetallic thickness. The results of a DOE study show the influence of the various factors and levels. Shear stress calculations indicate higher stress experienced by the adhesive joints as compared to the solder joints due to the spreading of the solder during wetting. Empirical relationships will be derived from the experimental data to help determine the required contact area for a given level of shear loading. The experimental results also reveal the rapid decrease in Shear stress between the first and second reflow and the slow decline in strength up to five reflows. Findings from this work will be used to assess the use and reliability of this adhesive for attaching the top component of Package-on-Package (PoP) 3D stacked components, in thermal cycling, HAST and HTHH environments.

Thermal Conductivity Performance Modeling and Characterization of a Novel Anisotropic Conductive Adhesive Used in Lead-Free Electronics Packaging

2012 ◽  
Author(s):  
Matthew J. Combs ◽  
S. Manian Ramkumar ◽  
Satish Kandlikar
Keyword(s):  
Thermal Conductivity ◽  
Base Material ◽  
Bond Line ◽  
Thermal Interface Material ◽  
The Novel ◽  
Conductive Adhesives ◽  
Curing Conditions ◽  
Bond Line Thickness ◽  
Significant Research ◽  
American Society

The continued desire to utilize an alternative to lead-based solder materials for electrical interconnections has led to significant research interest in Anisotropic Conductive Adhesives (ACAs). The use of ACAs in electrical connections creates bonds using a combination of metal particles and epoxies to replace solder. The novel ACA discussed in this paper allows for bonds to be created through aligning columns of conductive particles along the Z-axis. These columns are formed by the application of a magnetic field, during the curing process. The benefit of this novel ACA is that it does not require precise printing of the adhesive on pads and also enables the mass curing without creating shorts in the circuitry. This paper will present the findings of the thermal conductivity performance tests using the novel ACA and its applicability as a thermal interface material and for assembling bottom termination components, power devices, etc. The columns that act as electrical conduction paths also contribute towards the thermal conductivity. The thermal conductivity of the novel ACA was measured utilizing a system that is similar to that in ASTM (American Society of Testing Materials) D5470 standard. The goal was to examine the influence of Bond Line Thickness (BLT), particle loading densities, particle diameters and adhesive matrix curing conditions on the electrical and thermal performance of the novel ACA. This paper will also present a numerical model to describe the thermal behavior of the novel ACA. The novel ACA’s applicability for PCB-level assembly has also been successfully demonstrated by RIT, including base material characterization, effect of process parameters, failures, and long-term reliability. Reliability testing included the investigation of the assembly performance in temperature and humidity aging, thermal aging, air-to-air thermal cycling, and drop testing.

scholarly journals Design and manufacture of the novel drum worm pair

2020 ◽  
Vol 103 (4) ◽  
pp. 003685042098122
Author(s):  
Jingzi Zhang ◽  
Jin’ge Wang ◽  
Kai Wang
Keyword(s):  
Contact Stresses ◽  
Primary Objective ◽  
Structure Design ◽  
Worm Gear ◽  
The Novel ◽  
Bending Stress ◽  
Manufacturing Method ◽  
Design And Manufacture ◽  
Maximum Contact ◽  
Worm Drive

Although a significant amount of research on robot joint reducer was conducted, there are few systematic investigations on a novel joint reducer adopting inner worm-gear plane enveloping drum worm drive. To satisfy the development of modular robot joint, the primary objective of this paper was to systematically investigate the drum worm drive adopted in the novel joint reducer with integrated structure of drive, transmission, and support in the following aspects: meshing theory, design, analysis, and manufacture. According to the gear meshing theory, mechanical design method, classical mechanics, finite element method, and machining principle of virtual center distance, the systematic investigations around the drum worm pair applied in the novel joint reducer were conducted including the macro and micro meshing theory, structure design, mechanical and contact properties analyses, and manufacturing method. The novel joint reducer’s integrated structure was designed, and the drum worm pair’s mechanical and contact properties analyses were conducted, which showed: (1) the worm’s bending stress and deflection, worm-gear teeth’s shear stress and bending stress as well as the maximum contact stresses were all below their corresponding allowable values; (2) the maximum contact stresses appeared at the engage-in position of the worm pair opposing to the engaging-out position where the largest contact areas appeared. Then the manufacturing of drum worm’s spiral tooth was conducted via the modified 4-axis linkage CNC grinder according to the conjugate motion. Finally the novel joint reducer’s industrial prototype was assembled. The novel joint reducer with integrated structure of drive, transmission and support was designed and manufactured for the first time. The flowchart of design and manufacture of the reducer’s drum worm pair in this process was formulated, which provides a new insight on the research of joint reducers as well as other fields.

Excellent thermal-cycling stability caused by aging in Fe-doped (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free piezoceramic

2021 ◽  
Vol 202 ◽  
pp. 113990
Author(s):  
Yanshuang Hao ◽  
Liqiang He ◽  
Shuai Ren ◽  
Yuanchao Ji ◽  
Xiaobing Ren
Keyword(s):  
Thermal Cycling ◽  
Cycling Stability ◽  
Lead Free

Higher Copper Composition Shear Stress Analysis on Lead Free Solder Ball

2013 ◽  
Author(s):  
Vithyacharan Retnasamy ◽  
Zaliman Sauli ◽  
Phaklen Ehkan ◽  
Steven Taniselass
Keyword(s):  
Shear Stress ◽  
Stress Analysis ◽  
Solder Ball ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder

Solidification and Interface Reaction of Titanium Alloys in the BaZrO3 Shell-Mould

2015 ◽  
Vol 828-829 ◽  
pp. 106-111 ◽  
Author(s):  
Chong He Li ◽  
Jin He ◽  
Chao Wei ◽  
Hong Bin Wang ◽  
Xiong Gang Lu
Keyword(s):  
Titanium Alloy ◽  
Investment Casting ◽  
Interface Reaction ◽  
Base Material ◽  
Tini Alloy ◽  
The Novel ◽  
Coarse Powder ◽  
Elemental Diffusion ◽  
Shell Mould ◽  
Mould Base

The investment casting technology is one of the major methods to produce the parts of the titanium due to its low production cost. However, the high activity of titanium melt gives rise to the requirement of high chemical stability of shell materials, to avoid or decrease the interfacial reaction between the mould and the melt. In this paper, a novel BaZrO3 – coated Al2O3 shell was first introduced to the investment casting of titanium alloy. The grain size and baking temperature on the properties of the novel mould were investigated, and then the Ti6Al4V and TiNi alloys were successfully casted by means of this shell. The alloy-mould interaction was discussed. The results showed that the mould achieve high mechanical properties when the content of coarse powder was 50% after sintering 4 hours under 1500°C, and the BaZrO3 coating exhibited an effective barrier to avoid the direct contact between the mould base material and the melt, the thickness of reaction layer of TiNi alloy was about 8 μm, and 17 μm to Ti6Al4V alloy, no refractory particles and elemental diffusion were observed inside the metal. This may imply that BaZrO3 is a promising candidate material for the investment casting of titanium alloy.

scholarly journals An Experimental Study on Mechanical Behavior of Parallel Joint Specimens under Compression Shear

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Fei Wang ◽  
Ping Cao ◽  
Yu Chen ◽  
Qing-peng Gao ◽  
Zhu Wang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Failure Mode ◽  
Shear Failure ◽  
Strain Curve ◽  
Shear Loading ◽  
Plane Shear ◽  
Joint Spacing ◽  
Dip Angle ◽  
Joint Inclination

In order to investigate the influence of the joint on the failure mode, peak shear strength, and shear stress-strain curve of rock mass, the compression shear test loading on the parallel jointed specimens was carried out, and the acoustic emission system was used to monitor the loading process. The joint spacing and joint overlap were varied to alter the relative positions of parallel joints in geometry. Under compression-shear loading, the failure mode of the joint specimen can be classified into four types: coplanar shear failure, shear failure along the joint plane, shear failure along the shear stress plane, and similar integrity shear failure. The joint dip angle has a decisive effect on the failure mode of the specimen. The joint overlap affects the crack development of the specimen but does not change the failure mode of the specimen. The joint spacing can change the failure mode of the specimen. The shear strength of the specimen firstly increases and then decreases with the increase of the dip angle and reaches the maximum at 45°. The shear strength decreases with the increase of the joint overlap and increases with the increase of the joint spacing. The shear stress-displacement curves of different joint inclination samples have differences which mainly reflect in the postrupture stage. From monitoring results of the AE system, the variation regular of the AE count corresponds to the failure mode, and the peak value of the AE count decreases with the increase of joint overlap and increases with the increase of joint spacing.

Study on Thermal Cycling of Sn0.7Cu Solder

2013 ◽  
Vol 791-793 ◽  
pp. 362-365
Author(s):  
Li Yang ◽  
Ju Li Li ◽  
Jing Guo Ge ◽  
Meng Li ◽  
Nan Ji
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
High Temperature ◽  
Thermal Cycling ◽  
Shear Strain ◽  
Maximum Shear Stress ◽  
Steady State Creep ◽  
Maximum Shear Strain ◽  
Cycle Number ◽  
State Cycle

Thermal cycling of a unit Sn0.7Cu solder was studied based on the steady-state creep constitutive equation and Matlab software. The results show that there is a steady-state cycle for the thermal cycling of unit Sn0.7Cu eutectic solder. In steady-state thermal cycling, the shear stress is increased with the increase of temperature. There is a stage of stress relaxation during high temperature. A liner relationship between maximum shear stress and maximum shear strain is observed during thermal cycling. The metastable cycle number is declined greatly with the increase of maximum shear strain.

Sign in / Sign up

Export Citation Format

Share Document