The SPPDG assembly facility is incorporated into two separate clean rooms, with interconnecting doors: 1) a dual-bay, 1500 square foot, Class 100 clean room for microelectronics prototype assembly, inspection, rework, and failure analysis; and 2) one half of a five-bay 2300 square foot Class 10 clean room; both of these facilities are sufficiently clean that critical tasks such as thin film spin coating, mask alignment and exposure for photolithography can be supported, and bare wafers and integrated circuits can be processed "in the open" for long periods without significant contamination by airborne particles. The two photos immediately below depict the two bays of the 1500 square foot Class 100 clean room.
North bay of SPPDG Class 100 clean room. Left hand side: X-ray fluorescence spectrometer, two manual die bonders, manual wire bonder, hot gas rework station, manual flip chip bonder. Right hand side: wafer dicing saw, wafer tape expander, wafer scriber, general inspection microscope, wide-field measurement microscope, high magnification measurement microscope, lead-forming station.
bay of SPPDG Class 100 clean room. Left hand side: SST Ultra-high vacuum package sealer, R&D condensation soldering system, Thermodyne 30400 furnace , MCS LF-5 plasma oven, Ecomet 3 grinder polisher, Isomet 2000 precision saw Logitech LP50 wafer thinner. Right hand side: Rofin laser welding system, SET FC150 die and flip chip bonder, X-Tek X-ray inspection system.
The photo below illustrates our five-bay 2300 square foot Class 10 facility; the rightmost two bays of this clean room are dedicated to the same range of assembly equipment as in the two photos immediately above, including wire bonding, wafer bumping, and surface mount (lead free) printed circuit board assembly. The entire room is sufficiently clean that it did not prove necessary to install a partition to separate the assembly from the test functions.
2300 square foot Class 10 facility: right two bays: production-rated Palomar Model 3500 automatic pick-and-place component assembly machine, two Palomar wedge bonders, Royce wire pull/shear testers, Palomar ball bonder, Essemtec Semi-automatic Stencil printer, high magnification measurement microscope.
The SPPDG assembly laboratory provides a collage of capabilities in first and second level packaging.
First Level Packaging
The assembly laboratory provides prototype high-end first level packaging capability. Specifically, an integrated circuit (IC) wafer from 3" to 6" in diameter (larger diameter wafers can be handled if pre-sawn into quarters) can be thinned from its nominal 50 mil thickness down to as little as 2 mils (as required by the systems application), and then scribed or sawed into individual IC die. These die can be attached "face up" into single chip packages or multichip modules (MCMs) using eutectic solder reflow or epoxy die attachment methods (first Figure below), or attached "face down" using flip chip die attachment methods (second Figure below). For "face up" mounting, the power, ground and signal pins on the die can be connected to the IC package or MCM utilizing automatic wire bonding (both wedge and ball types). For "face down" mounting, the bare die can be "bumped" with gold balls in our facility to facilitate attachment. The flip chip attachment of bare die onto an interposer ball grid array (BGA) board or multichip module (MCM) substrate can be accomplished through either thermo-compression, thermo-sonic bonding or eutectic solder with better than 5 micron overlay accuracy in both X- and Y- dimensions.
Our laboratory can also provide very precise chip placement over a 6” x 6” area with better than 1 micron accuracy. To complement this packaging capability, the laboratory can also provide hermetic packaging of integrated circuit components.
IC and capacitor die attach in ceramic chip carrier.
Photomicrograph of flip chip die on liquid crystal polymer (LCP) printed circuit board material for 80 Gbps circuit demonstration.
Second Level Packaging
For second level packaging capability, the laboratory is equipped to handle various prototype printed circuit board assemblies. Surface mount attachment of packaged discretes, ICs, connectors, BGA devices, etc., is performed utilizing either an automated or manual pick and place machine with better than 12 micron X and Y overlay accuracy. Leaded and lead-free solders along with epoxies can be dispensed automatically or manually on those same machines or with a manual screen printer. Reflow is executed with a 5-zone combination IR and convection reflow belt oven. A substrate degreaser is also available.
The laboratory also has X-ray inspection capability for flip chip and BGA mechanical inspection. To address the processing of "reduction of hazardous substances" (ROHS) lead-free components, the laboratory also has X-ray fluorescence (XRF) capability for surface finish and BGA solder ball material characterization to determine proper solder reflow processes.
Sampling of Assembly Tool Set
Finetech Pico flip chip bonder (See first Figure below)
Karl Suss FC-150 flip chip bonder (See second Figure below)
Palomar Model 3500 automatic pick-and-place component assembly machine
X-Tek Hawk X-ray inspection system
Oxford XGT-1000WR XRF
Palomar 2460-V ball bonder & 2470-V wedge bonder
LPKF printed circuit board prototype unit (See third Figure below)
Finetech pico bonder A4V flip chip attach system.
SET (formerly Karl Suss) FC-150 flip-chip precision die alignment, placement, and bonding, with 1-3 micron overlay accuracy and up to 50 kg of force.
Rapid Prototyping Capability
Our laboratory supports several types of rapid prototyping capabilities, including: 1) the ability to create simple but fully functional printed wiring boards, that allow us to assemble functional electronic subsystems using electronic components from our laboratory stock of supplies; 2) the ability to fabricate rapid-turnaround electronic packages and cases for small circuit boards; and 3) the ability to fabricate three-dimensional structures rapidly that we can “hold in our hands” to acquire a sense for structural size and to visualize thermal aspects of such structures.
To satisfy the rapid turnaround circuit board capability, we employ a LPKF Protomat S62 advanced circuit board router. Starting with a piece of copper-clad double-sided organic circuit board stock, we can use the unit’s vertical end mill to remove metal from the cladding layer such that the power and ground planes, and the signal traces, are defined. Using the appropriate computer-aided design (CAD) tools, we design the circuit board, and then drive the circuit board router directly from the CAD file. In this manner we can transition from an initial concept, through circuit board layout, to a final unpopulated board, in a few hours. This approach is not a substitute for a multilayer board, but a number of quick-turn prototype projects have been found amenable to this initial approach.
EXAMPLE OF TOOL CAPABILITY
LPKF Protomat S62 advanced circuit board router.
To achieve the ability to rapidly construct a variety of fully functional electronic packages and other three-dimensional structures both in metal and various plastics, we have a high precision micromachining capability, based upon a Datron M7 HP Excelsior EX high-speed multi-tool system. The system is capable of machining soft metals (aluminum, copper, brass), plastics, and engraving steel, with a positional accuracy of 0.02 mils (0.5 microns) and a repeatability of 0.04 mils (1 micron) utilizing the 60,000 rpm liquid cooled spindle. The system specification is driven primarily by the temperature of the machine, which is 0.1 mil (2.5 microns) per degree Fahrenheit. The work envelope is 20" x 25" x 9.5” with a 18” x 12” vacuum plate for easy component mounting and support. The Datron system can accept input from standard CAD and CAM software formats generated by industry-leading software packages such as SolidWorks (CAD) and MasterCAM (CAM).
Datron M7 HP Excelsior EX high-speed high-precision milling machine.
To achieve the capability to create dimensionally accurate three-dimensional structures, the laboratory is equipped with a Z corporation Zprinter® 650 3D printer. The printer is capable of constructing a demonstration (mock-up) component with dimensions less than 10” x 15” x 8” (254 x 381 x 203 mm) on each side respectively. The resolution of the unit is 3.5 mils, utilizing specially formulated gypsum (plaster of Paris) with an epoxy binder. The color overlay (e.g., to illustrate thermal profiles directly on the structure) is created using 5 Hewlett Packard (HP) ink jet printer cartridges capable of generating 24-bit color models. Here again, the Zprinter 650 can accept input from standard CAD and CAM software formats generated by industry leading software packages such as SolidWorks (CAD) and MasterCAM (CAM). Driven by the appropriate CAD programs, we can generate mockup models of a variety of structures within a few hours.
Z corporation Zprinter® 650 3D printer.
Rework and Failure Analysis
Rework and failure analysis can be performed for all assembly processes (for example see Figure immediately below), in some cases on bare substrates and bare die by utilizing the following capabilities:
YAG laser system
Hot gas rework station
Wire bond pull, IC die shear, and ball shear tester
Inspection microscopes (3.2X to 1000X magnification) with oblique viewing and X Y Z micro measurement capability
Hitachi Model S-4700 Scanning Electron Microscope with energy dispersive analysis capability (see the second Figure below)
A photography room located immediately adjacent to the clean room facilities
A flip chip C4 BGA package cross section viewed with a scanning electron microscope at 1000x magnification.
Hitachi S-4700 scanning electron microscope (SEM) with energy-dispersive spectometry (EDS) used to photograph surfaces of wafers and die and cross-sections of die, coupons, and boards (magnification range: 20-500 K).