RF Solutions for harsh environments.

Linwave Technology has a unique range of products working in high reliability applications around the world. These range from the depths of Naval submarines and elevations of high-altitude avionics, to Road and Marine navigation safety; communication via satellite; and enabling latest medical therapies.

Most of Linwave products are designed for applications that are regarded as harsh in some degree – this can relate to the environmental aspects of the end application, or the rigour of testing and approval needed for a high reliability medical application.

To ensure compliance Linwave utilise a series of internal and externally managed screening tests.

Internal vibration facility is maintained for use on our smaller mass product requirements, incorporating Digital Vibration Controller system DVC-4 supporting Random and sinewave vibration waveforms schedules. Classical shock testing can be completed with single or multiple shock cycles to simulate high level performance or shipping conditions.

Harsh Environment Design Proving

Temperature cycling is conducted in accordance with MIL-STD-883G Method 1010 reference, with typical profiles ranging from -55/+85C to -65 / +300C which is conducted with 10min dwell time and up to 10 cycles.

In process stabilisation bake and burn in of product is utilised where appropriate or mandated. Stabilisation bakes are deployed to store the product at an elevated temperature without electrical stress as a screening or stabilisation phase of production. These can vary in standard duration from 168 hrs at 125 C to 8 hours at 170C. The burn in process screens for active performance degradation revealed by time and stress failure modes.

Linwave products designed for harsh environments can be leak tested to fine or gross levels. Mechanical sealing methods vary depending on the application, internal components selected, environment and seal level required ranging from a basic gasket hylomar process to a laser seal. With each sealing process cleanliness is paramount and the use of the correct evacuation bake out and dry nitrogen back-fill process to ensure the elimination of moisture to the required level, ensuring longevity of service life. We supplement our internal processes with use of accredited external test facility, allowing us a suite of test conditions such as:

• Humidity MIL-STD 883 Method 1004
• Temperature cycling MIL-STD 883 method 1010
• Fine leak MIL-STD 883 Method 10014
• Gross Leak MIL-STD 883 Method 1014
• Altitude MIL-STD 883 Method 1001
• Acceleration MIL-STD 883 Method 1013
• Mechanical shock MIL-STD 883 Method 2002
• Vibration MIL-STD 883 Method 2007
• PIND Test MIL-STD 883 Method 2020
• Burn in MIL-STD 883 Method 1015
• Salt Fog MIL-STD 883 Method 1009

One of the key aspects of custom module design is the choice of environmental protection for the application. Selection of the package or enclosure is the primary consideration for ease of interfacing with the system but also protection to ensure long term service life.

Hermetic sealing is an airtight seal preventing contaminants entering the package. Level of sealing can be selected to prevent, moisture, dust, or other particle ingress.

Linwave employ 3D CAD packages to allow solid-model generation and data sharing with stakeholders enabling good system integration and a collaborative design approach with customers. Our standard packages are Altium and Solidworks with output in step format for use in various other third-party tools.

Designs are selected to take account of environmental conditions such as temperature, altitude, vibration, shock, pressure, humidity as well as mandated controls such as hazardous materials, general safety, and EMC/EMI directives. Specific applications such as airborne incur specific standards such as the DO-160 Environmental conditions and test procedures for airborne equipment.

The selection of a custom module allows the user to benefit from the flexibility to modify the shape and size of the product to allow for optimum interfacing, rather than build a system around several set blocks of standard supplier units.

Based on the wide scope of applications we support; our range of packing solutions is considerable; typically selected by collaboration with the system architect on the needs of the application.

About Design of Housings and Hermetic enclosures

Airborne electronics has seen a migration to VPX interface standard, this allows data intensive interfaces that can run at speeds up to 10Gbit/s. The standard evolved from Vita standards group that have collaborated to deliver PCI card and VMEbus standards. Linwave have adapted their hermetic module enclosures to interface with VPX effectively allowing optimised systems interfacing via backplanes. High vibration environments are covered by Vita 46 key alignment. Coaxial interfaces for microwave frequencies are available thro’ locking SMP or suitable sub miniature connectors. At microwave frequencies we can integrate alternate interfaces such as Waveguide for minimised loss and fibre interface for data capacity.

Defence applications can be supported by Mean Time Between Failure (MTBF) reliability calculations to MIL-HDBK217.

Some examples of die enclosures are QFN and Kovar based.

QFN (quad flat no lead) packages allow the mounting of multiple die level components, with associated tuning and biasing in an air cavity package that can be sealed and presented for standard solder mounting. This enables the user to optimise performance, shrink combined size and realise the benefits of simplified handling. Specifications for packaged RF semiconductors are generally stated with wide tolerance or as typical performance as standard, so the user benefits from specific tightening of performance management in their area of concern.

Based on the frequency of application specialized packaging solutions using kovar with laser or compression welded seals can provide coverage of frequencies up to 100 GHz with high specification, low-level leak rates.

For high frequency two terminal devices Linwave specialise in the supply of millimetre wave diodes for waveguide mounting that are sealed in an inert environment. Packages are available to waveguide mount by screw in or press fit methods. These packages offer low parasitic capacitance and good thermal contact, the products are found in high frequency Gunn oscillators utilising high fundamental frequency of operation.

Within the supply chain – Linwave specialise in supporting Tier 2 Integrated sub systems, Tier 3 Modules, and chip level components. We define our customers typically as Original equipment manufacturers for mission systems or wider product solutions.

Linwave’s success is based on a core focus on RF and Microwave based design requirements. Senior staff have decades of experience in RF from the early days of Microwave in the UK in the 1980s, working across multiple wide-ranging markets from Defence, Avionics to Medical, Telecoms and Space.

Investment in industry leading software allows us to move efficiency from concept to prototyping and production. Most custom solutions projects are driven to produce indicative hardware solutions at the earliest point of the process to allow higher level system evaluation and feedback for benefits optimisation.

About RF & Microwave design and manufacturing capability

Established relationships with our suppliers allow us to combine the needs of fast turn machining, electronic components, rf and circuit manufacture. Internally multi-functional teams work thro from line up schematics to circuit layout and hardware design.

The cornerstone of our RF design concepts is Microwave Office design suite, allowing us to model solutions to high frequencies. Simulation of both active and passive discrete device models with linear and nonlinear cct simulation. Amplifier bandwidth and linearity can be assessed against target line ups, combining these with filters and switches for complex integration assessment.

RF design considerations are managed through key areas of activity, planning, design, output review, validation, and verification. As modern systems continue to merge the gap between RF and digital domains, Linwave continue to integrate the RF concepts with digital control and embedded software, as necessary.

Key enclosure considerations are managed using 3D solid models, allowing interactive collaboration with internal and customer stakeholders for any trade-offs and optimisation.

RF Design schematics are transferred to circuit layouts using Altium, the use of design rule criteria ensures that the cct solutions are maintained within industry standard manufacturing constraints.

Cct analysis with spice and microwave office

Thermal evaluation

Risk and de-rating

In many microwave assembly solutions there is a requirement for some form of embedded digital control. Linwave implements interfaces to its products ranging from minimal RS232 to fully integrated communication protocols such as Ethernet or CanBus. These enable a much greater degree of functionality with the module becoming a mini system on its own. Many Linwave products routinely implement these complex customer requirements.

As the complexity of the embedded firmware increases, the requirement to interface and control it increases as well. To complement the embedded functionality, Windows GUIs are typically developed either for in-house use or customer driven requirements. GUIs can range from simple tick box sheets to fully featured system controllers.

Linwave also creates its own custom ATE programs and scripts to work seamlessly with embedded firmware to generate efficient and cost-effective test strategies.

About Integration of Embedded software

Our software is thoroughly tested to ensure a robust and stable platform for your requirements. The modular nature of the software allows later expansion of the code to match a customer’s increasing demands and reduces code duplication between applications. Typical applications of our Embedded Software includes:

• RF detector linearisation
• Monitor and control functions over RF and fibre-optic links
• Antenna pan and tilt control
• Advanced control of RF electronic counter-measures
• Industrial instrumentation
• Low speed AFSK modems
• SPI/I2C chip initialisation and control
• Environmental monitoring and control
• USB, RS-232/422/485, ethernet and fibre communications
• CANBUS
• High speed multi-band synthesizer control
• Web-enabled devices (HTTP/Telnet/FTP)
• Thermal management systems
• Serial language/code translation

Linwave Technology offers custom MMIC solutions. Linwave has the ability to package MMIC devices that are currently only available as die hence making a much wider range of components available. This service is available to MMIC manufacturers or to end users who only have access to SMT manufacturing.

Linwave utilizes its skills and experience to characterize and test the packaged MMIC to ensure optimum performance. Linwave Technology can fully characterize packaged devices to 50GHz. The in-house expertise is used to optimize parameters such as gain flatness, output power and input/output matches.

For demanding applications Linwave can offer packages that control the surface finish. This provides solutions to combat tin whisker and gold embrittlement issues sometimes found in military applications. The use of the latest liquid crystal polymer LCP packaging processes allows for excellent broadband performance from these QFN packages. Complementing this QFN assembly capability, a wide range of other suitably packaged parts can also be hermetically sealed.

About Custom MMIC Hybrid solutions

Obsolescence Solutions –Linwave offer a service to package obsolete die and the capability to package modern equivalents to replace obsolete packaged devices.

Die level integration skills allow Linwave to provide multi-chip and multi-function solutions in small surface mount compatible solutions building from bare die.

This technology approach allows size weight and power saving (SWaP-C) on new designs for high reliability and harsh environment electronics.

• Chip scaled packages.
• QFN
• Ceramic
• Kovar
• Products
• Limiter LNA
• Amplifier – Phase shifter
• Amp – Filter
• VCO- Buffer amp

Linwave Technology has the following assembly and test capabilities:

• Thermosonic, epoxy and eutectic die mount capability
• Ball, wedge and tape bond capability down to 7.5µm wire size
• Specialize in GaAs die assembly
• Hermetic sealing capability using eutectic or projection welding techniques.
• Epoxy encapsulation (Glob top) option
• Circuit and die singulation capability.
• DC test and characterization capability
• RF test, measurement and characterization capability up to 94GHz
• Thermal resistance test capability

Supply of custom solutions benefits from an efficient new product introduction process, enabling Linwave to follow a structured path that starts with a launch review to capture the key requirements and ensure they are in line with expectations. Design and contractual parameters are confirmed and recorded. At this point key risks to managed are initially defined.

As the design continues information is gathered for a provisional Design review which categorises a summary of deliverables, analyses performance via functional block diagram and completes an initial compliance review.

On successful completion of this gate the design would continue and move towards a Critical design review. At this phase full components list will be defined, test plan and document sets would be established. If needed a qualification plan would be defined and data reviewed.

About New Product Introduction (NPI) Process Management

This stage would release component purchase on successful completion and the project would progress to the Manufacturing readiness review. At this stage Final release test and build documents are available and test related jigs and fixtures, ATE etc defined.

A final design review would detail analysis of the performance achieved and document the qualification and production test plans

Post-delivery project completion review would then be undertaken to document pricing analysis, performance updates and record lessons learned for future use.

Obsolescence occurs when the original equipment manufacturer is unable or un-willing to supply the product or service further.

Obsolescence issues are becoming more common in the RF world due to both the rapidly advancing nature of semiconductor processing driving changes to fabrication methods and production capacity, and the ongoing mergers and acquisition activity in the market-place leading to a wholesale review of the profitability of semiconductor product portfolios.

Linwave offer a service for pro-active management of long install life products by ongoing assessment of the supply chain component availability. These services use component availability software and supplier management to monitor status over the product life-cycle.

Linwave design strategy is not retire our products from the market – but we are limited by the availability of supplier components.

About Obsolescence Re-engineering and management

Linwave offer the following services that may assist in obsolescence management.

Product re-engineering and specification development.

Product failure investigation, de-lid and fault investigation.

Provision of die level engineered solutions for on-circuit retrofit.

Linwave can respond to fast turn requirements using our internal pcb router for fast turn cct evaluation. Once RF performance needs are established we have a sub-contract partnerships that can supply metalwork to our CAD designs in days, combined with fast turn pcb for RF and electronic ccts. Boards can be assembled internally or via one of fast turn sub-con partners where needed.

Often the speed of solution is based on effective collaboration at the front end of the request and by agreeing the methodology needed to meet the timescale, cost and quality of the prototype required.

Linwave offers an ATE programming service. Our significant experience of programming RF test and automation applications allows us to offer our customers value-added product integration and production test solutions.

We have written ATE modules to support most of the popular RF and microwave test equipment manufacturers products, including Agilent/HP, Rhode & Schwarz, RDL, Fluke, Philips, IFR, TTI, Gigatronics, Tektronix, LeCroy and ESS.

Our software is thoroughly tested to ensure a robust and stable platform for your requirements. The modular nature of our software allows for later expansion to match a customer’s evolving demands and reduces code duplication across products.

A fully automated test procedure offers a number of distinct advantages compared to manual testing:

• Reduced test time
• Improved productivity
• Reduced configuration and testing errors
• Improved outgoing product quality
• Continuous statistical monitoring

About Automated Testing & Programming Capability

Our ATE service can simply be used to automate a few tedious production tests or provide a complete production test suite. Some of the features that can be incorporated into an ATE test system include:

• Real time data gathering and processing
• Real time statistical process control (SPC)
• Automated yield analysis
• Automatic Pass/Fail criteria
• Automated failure analysis
• Automatic WIP control
• Generation of final sign off paperwork
• Stop after a predetermined number of consecutive fails
• Automatic prompting of calibration
• Result sharing over a computer network
• Store module test data into embedded characterization memory

Graphical User Interfaces can be provided for customer test interfacing or for product field implementation. These can vary from the test implementation support for system integration to full user interface for end customer testing.

Linwave also provide supporting test jigs and equipment to ensure most efficient system integration of the product.

Linwave have supported numerous projects operating at excess of 77GHz.

W band applications require the ability to work with bare die and understand the limitations of small wavelengths.

Applications at these higher frequencies are growing beyond early space exploration, automotive collision avoidance and missile guidance as more components appear. High data rate comms bands are used at 70 and 80GHz for satellite communication.

Supporting our higher frequency Gunn Diode and Transceiver products test and assy facilities extend to 100GHz.