Peace of mind is priceless

TTI 1Buying qualified components for military or high reliability applications can be a headache. TTI’s director of industry marketing Europe, defence, aerospace and space, Lee Thompson, resolves some common queries.

Why are special parts required for military and hi-rel applications?
The majority of standard parts are not of a high enough performance or quality standard for use in harsh environments. Factors such as extremes of shock, vibration and temperature, extended life cycles, possible attack by gases and liquids, all require components designed to work ultra-reliably under specific and often demanding conditions.

Why not just use MIL-STD parts?
The US defence standard, known as MIL-STD, is the most widely used standard governing high-performance parts. A huge variety of electronic components including active, passive, e-mech, interconnect, hybrid and even sub-systems, are covered by different MIL-STDs. Each one governs the manufacture and testing of the parts in question, however, MIL-STD numbers are associated with a specific component. Developing MIL-STDs for new parts is a long process and once the standard is developed, it can be costly to get a part listed. MIL -STD parts therefore tend to be older technology components.

What alternatives are there?
There are a couple of options. COTS+ is a development based on commercial off-the-shelf parts. It addresses the disparity between needing a lower cost, more easily available device and one which is fully-approved to meet harsh environment use. COTS+ programs start with an enhanced part, often an automotive grade device with an elevated operational temperature range, then add specific tests as necessary for an application.
Alternatively, Defense Supply Center, Columbus qualification is another way to address this issue. In many ways it is similar to MIL-STD, including being administrated by the same United States Department of Defense, Defense Logistics Agency site. Even more than that, DSCC approvals often reference MIL-STDs for testing and procedure. Where they differ is that they are more flexible and quicker to implement. In this way designers get to work with the latest technologies rather than having to wait for the standards to catch up.

What is JOSCAR?
JOSCAR, the Joint Supply Chain Accreditation Register, is a new accreditation system for the aerospace, defence and security sectors. The system was established following an initiative led by ADS Group, which is the trade organisation for companies in the UK aerospace, defence, security and space markets. It addresses the need for companies working in demanding sectors to manage their supply chain in respect to export controls. It ensures and demonstrates that companies have the correct procedures and processes in place.

How can TTI help?
TTI is JOSCAR registered. The company is also AS 9100 A and C approved, relating to warehousing and value added assembly and sales respectively. TTI also holds a number of other international and company-specific approvals required by the defence and aerospace markets.

In fact, TTI works with a number of suppliers that offer parts for high reliability applications. We urge designers to look beyond the MIL-STD portfolio to see whether a COTS+ device or a component carrying DSCC approval might offer the performance they need. To help customers through the maze of parts approvals, TTI has produced a brochure illustrating simply to what level a component is approved.