FLO/STRESS Product Introduction

Transcription

1 FLO/STRESS Product Introduction John D. Parry, PhD. Research Manager Ian W. Clark, PhD. FLOTHERM Product Manager

2 2/13 Topics FLO/STRESS Product Introduction What is FLO/STRESS? How does FLO/STRESS work? FLO/STRESS Pros and Cons FLO/STRESS An Example FLO/STRESS Future Developments

3 3/13 What is FLO/STRESS? FLO/STRESS is a thermo-mechanical stress module built into FLOTHERM. Results from a collaborative research project between Flomerics and Greenwich University, UK.

4 4/13 What is FLO/STRESS? FLO/STRESS is a thermo-mechanical stress module built into FLOTHERM. Results from a collaborative research project between Flomerics and Greenwich University, UK. The main focus of the module is to provide a fast, first-order accurate calculation within the product design process. Primarily to predict the thermal stress and strain fields within packages and PCBs. It is aimed at engineers concerned with product design and who currently use FLOTHERM, rather than engineers and scientists who use high-end tools to qualify the impact of adopting future technologies (e.g. lead-free solder, flip chip, etc.), and who are the traditional users of finite element tools.

5 5/13 How does FLO/STRESS work? The user will: Initialize or solve the thermal problem in FLOTHERM - in the usual way. Select an assembly for the stress analysis. Define material properties: values are provided for many materials in the updated materials library available with FLOTHERM V3.11. Define constraints on the assembly for the stress calculation. Activate solve stress. Inspect/display stress or strain fields and displacements. All within FLOTHERM.

6 6/13 How does FLO/STRESS work? FLO/STRESS uses the Finite Element Method. Uses standard FE solution technology: Solves Hooke s Law for displacements. Uses an unstructured mesh: Currently uses 8-node brick elements A convenience to enable FLO/STRESS to use the FLOTHERM grid. Uses a best-in-class solver: Coupled conjugate gradient solver with an incomplete Cholesky pre-conditioner.

7 7/13 FLO/STRESS Pros and Cons Pros: The main advantages of FLO/STRESS are that the software requires minimum model build-up as it uses the FLOTHERM model, and that it directly uses FLOTHERM-generated temperatures to drive the stress analysis. FLO/STRESS handles temperature dependent material properties which can be either isotropic, or orthotropic. Stress-free temperatures can be applied on an object-by-object basis.

8 8/13 FLO/STRESS Pros and Cons Cons: The capabilities of the first release, based on FLOTHERM V3.1, are limited to linear elastic calculations. In addition, the stress module only performs calculations in cuboids within a chosen FLOTHERM assembly.

9 9/13 FLO/STRESS - Example Package on a test board in a wind tunnel. Motorola PowerPC 604 in 21mm 255-C4/CBGA on a 2 inch test coupon. Centerline Flow Field.

10 10/13 FLO/STRESS - Example Package on a test board in a wind tunnel. Motorola PowerPC 604 in 21mm 255-C4/CBGA on a 2 inch test coupon: Surface Temperature Distribution.

11 11/13 FLO/STRESS - Example Package on a test board in a wind tunnel. Motorola PowerPC 604 in 21mm 255-C4/CBGA on a 2 inch test coupon: Surface Von Mises Stress Distribution.

12 FLO/STRESS Future Developments There are a number of issues that will be addressed as soon as possible: Extending the calculation to include SmartParts, such as blocks with holes, heat sinks and enclosures Adding Principal stresses and strains Extended tabular output of maximum and minimum stresses on an object-by-object basis 12/13

13 FLO/STRESS Future Developments Beyond that, there are a number of potential developments that will be prioritized based on customer feedback, e.g.: a treatment for prisms a treatment collapsed cuboids implement a restart capability a treatment for plasticity output other stress invariants (e.g. Tresca stress) a treatment for special shapes (e.g solder balls) display geometry distorted by displacements in FLOMOTION 13/13