The research activities in this research laboratory can be divided into three categories:
- reliability testing and
- prognostic of remaining useful life.
The assembly part of the activities focuses on preparation and assembly of the bonded microelectronic joints. The reliability testings deal with the mechanical, electrical, and thermal integrity of the bonded microelectronic joints. By monitoring the state of a component it is possible to predict the remaining useful life of a component. Below the list of the equipment for these three set of research activities are provided.
Semi-automatic printing machine
UNIPRINT GO3 is a third generation of table-top exact printing system with camera alignment system and automatic snap-off. This machine has various capabilities such as:
- Motorized squeegee with spring- adjustable print pressure, exactly vertical separation with very fine adjustable snap-off speed.
- Easy and exact re-setting of table vertical position enables a fast change-over for different PCB thicknesses, PCB supporting bars can be easily adjusted upon to PCB thickness.
- Thus an exact level of PCB and squeegee supporting area along the print stroke can be secured. This helps to prolong the stencil lifetime.
- Machine is capable to print small chip structures, BGA, CSP and other similar fine structures.
- A pneumatic servo-system of upper frame balancing helps to open/close upper frame with only minimally force. It is not sensitive to stencil tensioning weight. One can operate with upper frame with only push by finger!
The Fineplacer is a cost effective bonder designed for prototyping or low-volume production, R&D labs and universities. This versatile platform is used in a wide range of micro assembly applications – such as flip-chip bonding, die attach and components requiring a novel bonding approach.
This wire bonder can be configured for aluminum or gold wire bonding. Each uses its own spool and bond tool(s). Ball bonding can also be performed with gold wire. The stereo microscope has an adjustable focus and zoom, and is equipped with a CCD camera. The heated stage allows substrate temperatures up to 250° C. Bond Parameters in this machine (for Bonds 1 and 2) are:
- Ultrasonic power (analog of “power” on K&S and MEI bonders) in arbitrary units
- Time – Duration of ultrasonic application in milliseconds
- Force – Downward force applied by bonding tool during bond in grams
Benchtop reflow oven
The Mistral 260 is a small conveyorised convection reflow oven with 3 heating zones. This oven is suitable for lead-free applications.
2. Reliability testings
Benchtop heating chamber (Universal Oven UF30)
The universally applicable lab oven U is Memmert’s classic appliance for temperature control in science, research and material tests in industry. The technologically perfected masterpiece made of high-quality, hygienic, and easy-to-clean stainless steel.
Thermal cycling machine
The thermal cycling machine (TSA-72EL) can provide many different types of temperature shock over a wide range of frequencies and acceleration levels. Parameters in this test are minimum temperature, maximum temperature, ramp rate, and the dwell time.
3D optical microscope
This digital Keyence microscope (VHX-900F) has various features such as large depth-of-field, free-angle observation, and depth composition and 3D display functions. The large depth-of-field is a fundamental feature of the VHX Digital Microscope that greatly increases ease-of-use and image quality. The lenses, camera, and graphics engine are designed to optimize depth-of-field, resolution, and brightness. The free-angle observation provides the view an object from any angle by tilting the lens up to 90 degrees and rotating the stage 360 degrees. Because the optics can be moved, observing a target from various angles can be done without having to manipulate the part by hand. Even when a target’s surface has significant variation in height, a fully-focused image can be obtained instantly by compiling images at different focal planes. After creating the composite image, the focal position data can then be used to construct a 3D model.
Automated transient thermal analysis (TTA)
The research lab has developed an automatic panel level TTA tester. The tester targets to ease TTA during reliability assessment and for production inspection. Thus, this TTA can be applied for reliability testing, which the location of failures can be identified.
For instance, it is possible to distinguish between failures such as delamination of LED die or cracking of solder interconnect from the LED package to the printed circuit board (PCB).
Scanning acoustic microscope (SAM)
SAM uses ultrasound waves to image interfaces and detect possible defects such as voids and cracks within optically opaque structures and components such as chip capacitors, chip resistors, circuit board traces, discrete semiconductor devices, integrated circuits (ICs), and other electronic components.
This SAM is capable of:
- Scanning JEDEC trays or a 300mm wafer,
- Water recirculation and optional inline temperature control,
- Digital Image Analysis (DIA)™ using advanced algorithms to quantify the acoustic data to set accurate, automatic, accept/reject criteria,
- Virtual Rescanning Mode (VRM)™ that stores comprehensive data and enables performing a complete analysis of a sample, even when it is no longer available.
Shear testing machine
XYZTEC Condor Sigma is a bond tester that offers an unique multiple load cell cartridge for measuring all kinds of horizontally and vertically tested bonds, using pull, peel, push or shear methods; either destructive or non-destructive. The key point is the automatic selection of the pull or shear tool and corresponding measurement sensor by software. Typical applications include wire pull testing using a hook, solder ball pull testing using tweezers, gold wire ball shear, solder ball shear, die shear testing as well as full automatic testing.
To investigate the thermomechanical stress present in the materials and interfaces, a new Raman confocal microscope coupled to a laser source and spectrometer is used. The Raman spectrometer can be used for the investigation of inter- and intra-molecular charge and energy transfer, fast coherent and incoherent dynamics, and nonlinear optical response in complex systems like molecular crystals, molecular aggregates, metal and semiconductor nanoparticles. Optical properties will be detected also for properly synthetized nanostructured materials, like core-shells, spherical nanoparticles and metallic substrates.
3. Prognostic of remaining useful life
Environmental Test Chamber
Currently under development is an Environmental Test Chamber (ETC). The ETC is not only able to stress components by temperature cycling or by vibration testing but to combine this test to try to replicate field conditions more realistically. Additionally, the atmosphere in the test camper will be controllable, humidity and noxious gases can be added.
The primary application for the ETC will be the testing of cameras- and LiDAR-Sensors. The state of the sensors will be monitored during accelerated aging. The generated date will help to develop physics based and data driven models.
In its secondary application the ETC is supposed to test non optical electrical components in simultaneously run tests.