Why Rapid Prototyping?
Withstanding the trend of outsourcing and focusing on IP provision, Micram runs two complementary business units - Rapid!Prototyping and Test&Measurement - into the spectrum of services. Key objective of these business units is to bring better products to market faster, by supporting the product development cycle during the time consuming period from first silicon to production release.
While designers spend lot of time and effort on performance optimization of the ASIC, chip assembly and interconnect take a back seat. That's a pity, since the entire awesome chip performance must propagate through the interconnects and relies on the assembly. This is why Micram design methodology considers interconnect and assembly by adequate simulation models already during concept and design. In addition, Rapid!Prototyping and Test&Measurement are working hand in hand to provide those models and validate design performance. This in-house combination of Rapid!Prototyping, Test&Measurement and design services, yields short optimization cycles because board and chip designers are working hand in hand on site. Depending on the requirements, turnaround times below five days including RF layout design are standard.
Micram's Rapid!Prototyping is understood as interconnect technology at the interface between the high-performance chip and surrounding application. In particular, this can be just a simple PCB board with a standard package but also a high-speed MCM (Multi-Chip-Module) with multiple chips operating at 100 Gbit/s.
Rapid!Prototyping services are e.g. applied for production of
- Prototype assemblies,
- Evaluation boards,
- Golden devices,
- Test fixtures for parameter extraction,
- Deembedding and reference structures,
- Test and measurement accessories (e.g. amplifiers, frequency dividers...),
which are used for evaluation, characterization, parameter extraction and root cause of failure analysis. A short overview on technical details and some Rapid!Prototyping examples can be found on the following pages.
Micram's Rapid!Prototyping is offered in conjunction with any MICRAM turnkey ASIC development as well as a separate complementary customer service. For more information on Rapid!Prototyping, please contact your Micram sales representative.
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Rapid!Prototyping features
- Soft substrates for high-speed, high-density applications:
- PTFE/Polymer based,
- bandwidth over 100 GHz,
- dielectric constants of 2.2 ... 10.8,
- arbitrarily shaped substrates,
- plated through holes,
- edge metallization,
- fine pitch resolution with 2 mil lines/spaces.
- Thermal mounting for power densities up to 1 W/mm2.
- Fine pitch Al, Au wire bonding.
- Broadband high-speed board/substrate design utilizing verified library elements.
- Module and subassembly manufacturing.
- Lead time for standard applications below 1 week.
- Board repair and chip replacement service.
Soft Substrate Material Benefits
- High performance multi substrate carriers for high bandwidth even in conjunction with high I/O count.
- Arbitrary substrate shapes and apertures, even 3D plane shapes are possible.
- Fast optimized standard processes for mask generation, drilling, etching and plating.
- Process suitable for multilayer applications.
- Minimum line width/spacing 50 microns for standard production.
- Bandwidth >100 GHz with low dispersion (epsr=2.2).
Connecting the Chip
- Conventional ultrasonic wedge bonding applying 25 / 17.5 micron aluminum or gold bond wires.
- Fine pitch bonding (80 microns).
- Recess chip assembly.
- Short and flat bond wires for minimum inductance.
- Tight tolerance chip mounting: Minimum Chip-Substrate gap < 150 microns.
- Minimum bond wire length < 400 microns.
- Electrically isolated, thermally conductive chip mounting with e.g. 2 K/W for 10 mm2 chip size.
- Reusable submount saves cost and time.
Process Options
- Standard wet etch process with optimized properties yields:
- fast processing,
- line width and spacing below 50 microns,
- well defined rectangular line shapes,
- line impedance control.
- Edge metallization with arbitrary shapes yields high performance ground contacts to the substrate backside (e.g. in the substrate recess for the chip insert):
- excellent common mode noise performance for low ground bounce,
- excellent RF performance supported by short current return path,
- high I/O density, no additional Vcc lines required.
- Recess chip assembly yields:
- low bond inductance by short, flat bond wires,
- low inductance, high current contact plane by edge metallization surrounding the chip.
- High power, thermally enhanced conductive/isolated chip assembly ensures:
- highest chip performance by low junction temperatures,
- thermal control by direct access of chip backside.
Assembly and Board Design
Rapid manufacturing alone is not enough to yield Rapid!Prototyping, but needs to be supported by rapid, first-time-right design. However, successful design of microwave circuit modules is a lot more than what is commonly thought of as just designing some 50 Ohm lines. MICRAM designers are developing and using physical, element based Spice/Spectre© simulation models for
- chip (pad, cavity, substrate),
- bond wires (including coupling),
- transmission lines (line end, coupling, radiation, arbitrary shapes, skin effect),
- RF connectors,
- RF components (Bias-Tee, blocking-C, ...),
to account for any effect degrading overall device performance. All models are valid for even, odd and conversion modes.
While numerous designs have amassed a profound know-how on appropriate line types, transition types, etc., for a majority of requirements, one outstanding advantage of MICRAM Rapid!Prototyping service using soft substrates is its fast turnaround time. If necessary, various test structures can be manufactured and characterized in-house via MICRAM Test&Measurement service, parallel to the actual design, to support the latter. Needless to say that full electromagnetic simulation of microwave circuits, using state-of-the-art simulators is supported by MICRAM's service, too.
And what about ceramics ?
There are different reasons why customers sometimes prefer use of microwave circuits built on ceramics or glass type materials such as aluminum oxide, aluminum nitride or sapphire. The latter of course at the expense of increased manufacturing times, as corresponding manufacturers typically need at least 3 weeks. Even in this situation MICRAM Rapid!Prototyping services can help customers to cut down turnaround times as much as possible. First of all, MICRAM engineers are familiar with these types of material, too. Through numerous designs also in this material systems appropriate microwave circuit structures are well known and proved and, hence, design time is minimized. On the other hand, MICRAM has already established contacts to manufacturers, preventing significant time delay, e.g. due to wrong or inappropriate data format or misunderstandings.
Examples
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