ThermechDIC

The ThermechDIC is a complete system used for optical, non-contact, thermal testing of electronic components which include, but are not limited to:

• Ball grid arrays (BGAs) packaging
• Flip-chip-packaging
• Printed circuit boards (PCBs)
• Solid-state drives (SSDs).

The system allows for accurate (sub-micron), full-field, 3D- contour (shape), displacement, and strain measurement for the determination of the Coefficient of Thermal Expansion (CTE), warpage, and strain measured under a thermal (or cooling) load.

Measurement results are used for evaluation of the thermal mismatch (CTE) within components. Additionally, they are used for warpage analysis, which can be used for FEA validation. DIC is a technique that can process information online, in real-time, allowing data to be acquired, evaluated, and visualized within seconds (during the measurement).

The ThermechDIC system consists of the following.

• Stereo-rig DIC system with a hot/cold stage
• Temperature controller
• Liquid N2 pump & controller
• Dewar/tank
  

The DIC stereo-rig can be mounted on a motorized mounting frame or used in combination with a stereoscopic microscope (µDIC).

The motorized mounting frame configuration (as shown in Figure 1) allows samples from 10×10 mm up to 40×40 cm in size to be measured. When BGAs or solder balls need to be measured, a stereoscopic microscope (µDIC) is required (as shown in Figure 2). This allows Fields-of-View (FoV) from 100×100 µm up to 15×15 mm to be measured. All hardware components are identical between both setup configurations. Therefore, they can be swapped and exchanged depending on the test application.

Temperature Loading Profiles

Temperature loading profiles, typically used for CTE and warpage measurements, are defined in the temperature controller software. A measurement profile can be defined as block function steps with temperature state conditions, additionally, the software also allows users to loop and repeat measurement profiles. Using analogue inputs provided by the temperature controller to the DAQ controller & Istra4D, the camera acquisition can be triggered at each stable temperature state. This can be programmed in Istra4D to run in parallel/sync with the temperature controller software, thus, allowing automatic measurements to be acquired.

Advantages of DIC

One of the many advantages of DIC, compared to using other techniques is DIC can measure full-shape deformation in X, Y & Z and not just in the Z-direction as with shadow moiré and/or digital fringe projection (DFP). DIC can measure 3D strain, required for the determination of CTE. Furthermore, the technique can also compensate for any Rigid Body Motion (RBM) that may occur due to environmental noise/vibration.

DIC is both robust and versatile, as a result, it is easily configurable with ultra-high resolution (UHRes) cameras. The resolution of DIC is dependent on the working Field-of-View (Fov) and camera resolution. Assuming a 100 mm FoV, the in-plane and out-of-plane resolution can go down to +/-0.5 µm and +/-1.0 µm, respectively.

Dantec Dynamics provides standard hot/cold stages for various component sizes. Sizes include 10×10 cm, 20×20 cm, 30×30, and up to 40×40 cm. The standard stage uses conduction heating and cooling via liquid nitrogen. Custom hot/cold stages can also be manufactured using convection heating as well as a closed coolant circulation via a chiller. Hot/cold stages allow users to perform measurements from -80°C to 400°C. Temperature uniformity is +/-0.1°C per cm (>25°C). The temperature controller consists of a 24-bit analogue-to-digital converter with a temperature control stability of +/-0.05°C (>25°C).