OrCAD® is used to capture schematics and then perform board layouts. Multiple routing layers can be
accomplished. With the use of design rules, the board can be checked for errors before fabrication.
SolidWorks® is a three-dimensional Computer Aided Design (CAD) software suite that allows the APEI, Inc. packaging team to
design, develop, and analyze our systems in a single application environment. With SolidWorks®, sophisticated and complex systems can be
outlined, optimized, and improved quickly in a digital environment without requring the expensive and time consuming process of building and
testing physical prototypes and design revisions. Capabilities include solid part and assembly modeling (including multiple part
configurations in a single file), physical analysis and validation (stress and displacement), and a powerful thermal analysis tool capable of
performing both Finite Element Analysis (FEA) and Computation Fluid Dynamic (CFD) transient or steady-state studies.
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Matlab® is a matrix based numerical computing software suite that allows APEI engineers to perform complex mathematical
operations rapidly. Matlab® has its own programming language well suited for setting up iterative equation solving, and a power array of
solution graphing capabilities. This is used frequently for initial thermal designs in order to optimize certain features (layer
thicknesses, part spacing, etc.) before spending the time to construct the 3D geometry for analysis.
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Saber has been used to model and simulate theoretical new power topologies and control schemes applicable to modular converters. The simulation results have been validated through experimental results in the lab.
APEI, Inc.’s wet processing lab is a Class 1,000 facility devoted to the fabrication
of both high and low power prototype substrates. As a completely self-contained
process, APEI engineers can rapidly design and fabricate a layout in the fraction
of the time it would take elsewhere. A dry film photolithographic process is employed,
during which a photosensitive film is deposited on a substrate such as direct bond
copper (DBC), direct bond aluminum (DBA), or similar metalized dielectric assembly.
The film is then masked, exposed, developed, etched, and stripped, resulting in
a fully patterned electronic substrate. Post processing capabilities (such as nickel
and gold plating) are also performed in this facility.
Single and multi-layer ceramic substrates are fabricated at the nearby low temperature
co-fired ceramic (LTCC) Class 10,000 facility operated by HiDEC. Ceramic substrates
offer numerous material properties and characteristics which are well suited for
high-temperature and high-frequency environments. Elements such as integrated passives
(inductors, transformers, capacitors, resistors, etc.) can be implemented from a
wide variety of screen-printable pastes.
Left: 10 layer LTCC substrate for high-temperature gate driver. Right:DBC Layout
Examples of wire bonding performed in APEI’s assembly lab
APEI’s current device interconnect capabilities include fine gauge wire and
ribbon bonding used for analog, digital, and RF electronics and large gauge wire and ribbon bonding used for high
power or high current devices. The fine gauge wire bonding is performed on a K&S 4523 AD with wire diameters ranging
from 0.7 mil to 3 mil and ribbon dimension as small as 0.4 by 0.8 mil. The large gauge interconnects are made using
an Orthodyne power bonder and includes wire diameters from 3 mils to 20 mils and ribbon up to 40 by 2 mils.
Eutectic die bonding with Cammax die bonder
APEI, Inc. employs a number of processes for bare die and component attaches (including oven, box furnace,
conveyor oven, and vacuum furnace operations) depending on the particular requirements of the joining system.
Standard (eutectic solder, epoxy, etc.) and exotic (specialized epoxies, transient liquid phase bonding,
sintering) solid state diffusion techniques are used in order to create strong and reliable bonds. Capabilities include processing
temperatures up to 1100°C in a number of oxidizing, inert, or fluxing atmospheres. Specialized fixtures and
reflow profiles are tailored by APEI engineers for specific processes and systems.
APEI has access to an array of failure analysis equipment. In house capabilities include an environmental lab with several
furnaces for long term temperature exposure testing and a Keyence VHX-600 high resolution (54 megapixels) digital microscope
used for visual inspection up to 1000X magnification. Through its partnerships with the University of Arkansas’s High
Density Electronics Center (HiDEC), Materials and Manufacturing Research Laboratories (MMRL) , and Arkansas Analytical
Laboratory, APEI has access to scanning acoustic microscopes used for non destructive analysis, sectioning and polishing
equipment used for metallography, scanning electron microscopes used for visual inspection up to 100,000X magnification,
electron dispersion spectroscopy (EDX) for elemental analysis, and x-ray diffraction used for microstructure analysis.
This equipment allows APEI to identify problems such as intermetallic growth, voids in solder under devices, metal layer
delamination, and contamination introduced during processing.
Left: SAM of die attach voiding on a thyristor. Right: 3D image capture from Keyence microscope.
SEM of Ultrasonic 3-mil gold bonds before and after thermal cycling from -55 °C to 300 °C |
Cross section of packaged SiC device |