Glass crack on Aluminum and Copper tungsten

[andy203]

Homework Statement

Here is the issue I met.Could you refer to attached file?

1.We glued one piece aluminum block and one piece copper tungsten block on substrate.
The aluminum and copper tungsten block have different height.The glue thickness underneath them
is different.
2.Then,we glued one piece glass on aluminum block and copper tungsten block.

3.However,after 120°C storage for overnight,we found crack as marked in the red.
We suspect the crack is due to thermal strain/stress.
4.We want to find a way to calculate the thermal strain/stress on the glass.

Here are some information that I can provide at this moment.

Glass material Silicon: 2.6X10E-6/°C
Copper tungsten:CuW, 6.5X10E-6/°C
Aluminum: 22X10E-6/°C
Glue20E epoxy CTE ,31X10E-6 /°C
Substrate:AlN 5.3X10E-6/°C

Homework Equations

ΔL=κ∇T.

The Attempt at a Solution

I am trying to use solidworks to simulate this design.The most hard thing for me is to define the glue property.Since the height of aluminum and copper tungsten is different.

Highly appreciated if anyone can give me some help.

 

[KataKoniK]

Thank you for sharing your issue with us. From what you have described, it does seem like the crack in the glass is likely due to thermal strain or stress caused by the different coefficients of thermal expansion (CTE) of the materials involved.

To calculate the thermal strain on the glass, you can use the equation you have provided: ΔL=κ∇T, where ΔL is the change in length, κ is the coefficient of thermal expansion, and ∇T is the temperature gradient.

For this specific case, you will need to calculate the thermal strain for each individual material (glass, copper tungsten, aluminum, glue, and substrate) and then add them together to get the total thermal strain on the glass. This will help you determine the level of stress that the glass is experiencing and whether it is within its limits of elasticity.

As for simulating the design in Solidworks, you will need to define the properties of the glue as a separate material with its own CTE. You can then apply this material to the glue layer in your simulation model.

I hope this helps. Please let me know if you have any further questions or need clarification on any of the steps. Good luck with your simulation!