VM-LSDYNA-SOLVE-035

VM-LSDYNA-SOLVE-035
Evolution of the Solder Ball Shape Using 2197 Particles

Overview

Reference: Lin, H.C., Kung, C., Chen, R.S. (2007). Evaluations of the BGA solder ball shape by using energy method. Computers, Materials & Continua, 6(1), 43-50. https://doi.org/10.3970/cmc.2007.006.043
Analysis Type(s): ISPG
Element Type(s): 2197 Particle
Input Files:Link to Input Files Download Page

Test Case

In this test case, the LS-DYNA application simulates the solder standoff height of a solder ball using 2197 particles by reproducing the evolution and final shape of the solder. Results are compared to the reference. Figure 125 and Table 5 show the configuration details.

Figure 125: Problem sketch and location of the external force

Problem sketch and location of the external force

Table 5: Model parameters

rurlVTF
0.3175 mm0.3175 mm0.24132 mm332.5 dyne/mm0.0 dyne

where

ru is the radius of the upper solder pad.
rl is the radius of the lower solder pad.
V is the solder volume.
T is the surface tension.
F is the external force.

For material properties used in the simulation, see Table 6. The upper plate utilizes an elastic material while the lower plate is made of a rigid material. An IFPD material is used for the solder ball. This material is specifically designed for modeling fluid particles in incompressible free surface flow using incompressible SPG (smoothed particle Galerkin) methods.

Table 6: Material Properties

Elastic material for upper plate and rigid material for lower plate

Mass density = 10-5  kg/mm3

Young's module = 69 GPa

Poisson ratio = 0.3

IFPD material

Fluid density = 9.28 x 10-6 kg/mm3

Dynamic viscosity = 2 x 10-6 GPa/ms


Analysis Assumptions and Modeling Notes

See Figure 126 below. The mesh for the upper and lower plates is created using a solid mesh defined by the *SECTION_SOLID card, with ELFORM (Element Formulation) set to 1 to indicate a constant stress solid element. In contrast, the solder ball is meshed using an ISPG (incompressible smoothed particle Galerkin) element defined by the *SECTION_FPD card, with ELFORM set to 49.

The CONTROL_TERMINATION card is used to set the simulation time with ENDTIM. Simulation time is 50 ms.

Figure 126: (A) Model mesh and (B) Section cards in input deck

(A) Model mesh and (B) Section cards in input deck

Results Comparison

The following plot shows the evolution of the solder standoff height with respect to simulation time.

Figure 127: Solder height vs. time

Solder height vs. time

As shown below, the simulation result corresponds closely to the reference target.

ResultsTarget LS-DYNA SolverError (%)
Solder Standoff Height (mm)0.5240.5240.00