Influence of Material Properties on the Fluid-Structure Interaction aspects during Molded Underfill Process

This paper presents the investigation of the effects of epoxy moulding compound’ (EMC) viscosity on the FSI aspects during moulded underfill process (MUF). Finite volume (FV) code and finite element (FE) code were connected online through the Mesh-based Parallel Code Coupling Interface (MpCCI) method for fluid and structural analysis. The EMC flow behaviour was modelled by Castro-Macosko model, which was written in C language and incorporated into the FV analysis. Real-time predictions on the flow front, chip deformation and stress concentration were solved by FV- and FE-solver. Increase in EMC viscosity raises the deformation and stress imposed on IC and solder bump, which may induce unintended features on the IC structure. The current simulation is expected to provide the better understandings and clear visualization of FSI in the moulded underfill process

Conceptual Design of Automotive Compressor for Integrated Portable Air Conditioning System

This study introduces a new concept of portable air conditioner which integrated with some available components in automotive air conditioning system. This new idea intends to solve the storage problems as well as to reduce the price of current portable air conditioner since some devices could directly be used from the automotive air conditioning system. The primary emphasis of this study was on the modification of automotive compressor design so as the system may alternately be operated. The length of conventional compressor shaft is extended to place an additional clutch pulley, a drive plate and a clutch coil. The new concept particularly the shaft and pulley were analysed through slope deflection and computational finite element analyses. The result of engineering analyses exhibited that the new design of compressor shaft and clutch pulleys promote a low risk of failure as the data values recorded are lower than the critical value for each criterion investigated

Fatigue failure processes in pb-free solder joints using continuum damage and cohesive zone models

The mechanics of failure in a solder joint under cyclic mechanical loading is quantified and described in this paper. It is postulated that fatigue failure of the solder joint occurs through simultaneous competitive mechanisms of cyclic damage processes occurring through the bulk solder and across solder/IMC interface. Progressive damage in the bulk solder joint is described using continuum damage model while cohesive zone model simulates the fracture process of the solder/IMC interface. For this purpose, a single-solder joint assembly with Sn-4Ag-0.5Cu (SAC405) solder and SAC405/Cu6Sn5 interface is modeled using finite element (FE) method. Unified inelastic strain model (Anand’s) with optimized parameter values for SAC405 solder represents the strain rate-dependent response of the solder. Cyclic plastic work-based phenomenological continuum damage model and cyclic stress- and energy-based cohesive zone model are employed to simulate damage response of the bulk solder and solder/IMC interface, respectively. Cyclic displacement loading (Δδ = 0.003 mm, R = 0) is prescribed to the edge of the “rigid” tool. Results show that the solder/IMC interface fatigue cracking dominates the fracture process. Fatigue crack initiated at the leading edge of the solder/IMC interface on the tool side of the assembly after accumulated 18 fatigue cycles. Simultaneously, inelastic strain accumulates at the critical material point with a decreasing rate. The predicted bending stress with opposing tensile and compressive stress region shall favor shear-driven fatigue crack diagonally across the bulk solder

Damage progression in BGA solder joints during board-level drop test

This study examines the dynamic fracture propagation experienced by critical solder joints in a BGA test package during board-level single drop test. An Input-G loading method is employed to simulate a drop test condition with a peak acceleration of 1500G within a time duration of 0.5 ms. Unified inelastic strain model (Anand) describes the strain rate-dependent response of the SAC405 solder material. Damage process in the brittle solder/intermetallic (IMC) interface is predicted using cohesive zone model. Results show that the first board deflection mode induces tensile stresses on the BGA package. The most critically strained solder joint only begins to experience the load (stress) at 0.06 ms following the applied impulse load. Calculated stress can reach up to 68 MPa at such high impact straining rate. The highest inelastic strain rate experienced by the most critical solder joint is 66.7 sec-1, thus solder/IMC interface fracture is likely the dominant fracture mode, as observed experimentally. Limited propagation of fracture region is predicted during the simulated single board-level drop test. However, damage is predicted to propagate earlier in solder joints located along the outer row of the array parallel to the shorter length of the test board. The shape of the interface crack front can be inferred from the contour of damage/undamage solder/IMC interface region of fractured solder joints

Influence of Material Properties on the Fluid-Structure Interaction aspects during Molded Underfill Process

This paper presents the investigation of the effects of epoxy moulding compound’ (EMC) viscosity on the FSI aspects during moulded underfill process (MUF). Finite volume (FV) code and finite element (FE) code were connected online through the Mesh-based Parallel Code Coupling Interface (MpCCI) method for fluid and structural analysis. The EMC flow behaviour was modelled by Castro-Macosko model, which was written in C language and incorporated into the FV analysis. Real-time predictions on the flow front, chip deformation and stress concentration were solved by FV- and FE-solver. Increase in EMC viscosity raises the deformation and stress imposed on IC and solder bump, which may induce unintended features on the IC structure. The current simulation is expected to provide the better understandings and clear visualization of FSI in the moulded underfill process

Conceptual Design of Automotive Compressor for Integrated Portable Air Conditioning System

This study introduces a new concept of portable air conditioner which integrated with some available components in automotive air conditioning system. This new idea intends to solve the storage problems as well as to reduce the price of current portable air conditioner since some devices could directly be used from the automotive air conditioning system. The primary emphasis of this study was on the modification of automotive compressor design so as the system may alternately be operated. The length of conventional compressor shaft is extended to place an additional clutch pulley, a drive plate and a clutch coil. The new concept particularly the shaft and pulley were analysed through slope deflection and computational finite element analyses. The result of engineering analyses exhibited that the new design of compressor shaft and clutch pulleys promote a low risk of failure as the data values recorded are lower than the critical value for each criterion investigated

Conceptual Design of Automotive Compressor for Integrated Portable Air Conditioning System

This study introduces a new concept of portable air conditioner which integrated with some available components in automotive air conditioning system. This new idea intends to solve the storage problems as well as to reduce the price of current portable air conditioner since some devices could directly be used from the automotive air conditioning system. The primary emphasis of this study was on the modification of automotive compressor design so as the system may alternately be operated. The length of conventional compressor shaft is extended to place an additional clutch pulley, a drive plate and a clutch coil. The new concept particularly the shaft and pulley were analysed through slope deflection and computational finite element analyses. The result of engineering analyses exhibited that the new design of compressor shaft and clutch pulleys promote a low risk of failure as the data values recorded are lower than the critical value for each criterion investigated