Home / Examples / Fluid Analysis [Bernoulli] / Example 17: Solder Wicking Analysis

Example 17: Solder Wicking Analysis

General

The shape of the solder bridging the terminal and copper foil is analyzed using the VOF method.
The volume fractions of soler and air each are solved.
Unless specified in the list below, the default conditions are applied.

Results will vary depending on Femtet version and the PC environment.

Analysis Space

Item	Settings
Analysis Space	2D
Model Unit	mm

Analysis Conditions

Item

Tab

Settings

Solver

Fluid Analysis [Bernoulli]

Analysis Type

Fluid Analysis

Transient Analysis

Multiphase Flow Setting

Fluid Analysis
Multiphase Flow Setting

Execute free surface analysis (VOF method): Select

Phase Setting: Register [000_Air] and [LiquidSolder]

The material [LiquidSolder] needs to be registered beforehand.
(See [ How to Create New Material Property] for more information)

Take into account weight: Select

Take into account surface tension: Select

Phase Pair Setting:

Phase 1	Phase 2	Surface Tension	Contact Angle
000_Air	LiquidSolder	0.349	60

Setup Details

Fluid Analysis

Setup Details

Volume Control Type: Cell-centered Base

Timestep

Transient Analysis

Item	Settings
Timestep	Specified by 100 [us]
Calculation Steps	400
Output Interval	1

Meshing Setup

Mesh

Item	Settings
General Mesh Size:	Specified by 0.1 [mm]
Element Type	Rectangle

Model

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Face	Air	000_Air *
1/Face	Board	006_Glass_epoxy *
2/Face	Foil	008_Cu *
3/Face	Terminal	008_Cu *
4/Face	Solder	LiquidSolder

* Available from the material DB

The material property of LiquidAir is set as follows. For a stable calculation of the steady state, a high viscosity value is set.

Material Name	Tab	Settings
LiquidSolder	Solid/Fluid	Liquid
	Density	7400 [kg/m3]
	Viscosity	400 x 10^-3 [Pa s]

The contact angle is set in the body attributes of Board.

Body Attribute Name

Tab

Settings

Board

Solid

Multiphase Flow Setting (Contact Angle Setting):

Specify for each body attribute: Select

Phase Pair Setting:

Phase 1	Phase 2	Contact Angle
000_Air	LiquidSolder	180

Boundary Condition

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Sym/Edge	Symmetry/Continuity	Symmetry(*)	Select [Symmetric Face]
Outer Boundary Condition	Fluid	Inlet/Outlet	Natural Inflow/ Natural Outflow

Results

The volume fraction contours of phase 2 at 0 [s], 0.01 [s], 0.03 [s], and 0.04 [s] are shown below.

The part of phase 2 (LiquidSolder) is illustrated in red.

The results at 0.03 [s] and 0.04 [s] are similar. They show the solder shape in equilibrium.

0.0 [s]
0.01 [s]
0.02 [s]
0.03 [s]
0.04 [s]