Company expands hybrid microcircuit capabilities

by BI Technologies

BI Technologies used their hybrid microcircuit assembly technology to hermetically package a single bare Integrated Circuit (I.C.) chip (die) and screen it to the military specifications.

Designers and manufacturers of military and aerospace electronic systems require the highest reliability grades from component suppliers.

Unfortunately, many IC manufacturers have reduced their offerings for military level components, choosing instead to focus on commercial grade product in plastic molded packages.

One of our customers asked if we could use our hybrid microcircuit assembly technology to hermetically package a single bare Integrated Circuit (I.C.) chip (die) and screen it to the military specifications.

BI Technologies proceeded to support this need and we have since made this a regular offering to the market. Because many I.C. manufacturers just want to supply die in molded packages, customers who require military level components have had few options in the past.

While IC manufacturers often offer components with an extended operating temperature range, very few offer a version screened to military standards as well because of the extensive equipment, additional skilled labor and military certifications required.

The military mandates that their systems suppliers begin using Commercial Off The Shelf (C.O.T.S.) technology to reduce cost and keep up with new technologies in electronic components.

Components screened to military standards are often required by military, aerospace and other high-end applications such as space hardware. By placing the manufacturer’s die into hermetic packages, DIP packages (Dual In-line Packages) and flat packs, we are able to enhance the reliability of the components for harsh environments.

Not Just Off The Shelf
Around 1995, the military mandated that their systems suppliers begin using Commercial Off The Shelf (C.O.T.S.) technology to reduce cost and keep up with new technologies in electronic components. It has subsequently become very common with most of the military system suppliers.

This allows them to adapt commercial parts to the military environment. Many of these C.O.T.S. based systems require modification to withstand military, space or field conditions. Also, instead of designing and building custom electronic systems - such as hybrid microcircuits - from scratch, many military vendors began using the building block approach.

These C.O.T.S. parts are then tested to military specifications, also known as up-screening. The benefits are lower costs and reduced nonrecurring engineering (NRE). The problem occurs when these parts must meet the harsh environments of a battlefield or space.

Full military screened components must meet ambient temperatures of -55ºC to +125ºC and be immune to humidity, ambient gases, vibration and other harsh conditions.

Full military screened components must meet ambient temperatures of -55ºC to +125ºC and be immune to humidity, ambient gases, vibration and other harsh conditions.

That generally means the package must be hermetic and tested to make sure they can withstand these conditions. When this is done the components are then known as M.O.T.S. (Military Off the Shelf) and are not really just off the shelf.

In the military context, M.O.T.S. refers to a product that is developed or customized by a commercial or military vendor to respond to specific military requirements. Because a M.O.T.S. product is adapted for a specific purpose, it can be purchased and used immediately, without further testing. The process to become a M.O.T.S. component, as you will see, is arduous.

Meeting The Standards
Our packaged die service includes assembling, sealing, and screening the packages to the military standards and specifications such as MIL-STD-883 or MIL-PRF-38534, respectively.

This assembly is virtually the same as assembling hybrid microcircuits for the military. The difference is in how many devices are inside the packages. In the case of a microcircuit there are many components, active and passive, and circuitry on a substrate or directly on the package, i.e., there is an entire system in a single package.

This is typically done where weight and size are an issue.  In the case of packaged die there is typically only one active component. Both follow the same flow through the factory and both are built to the same high standards. This finished military qualified component will then be placed in the next level assembly.

Typical front-end military microcircuits assembly process flows include the following: kitting the components and packages, mounting and cure of the die on a substrate or directly in the package, wire-bond, preseal electrical testing at room temperature, preseal visual inspection, a vacuum bake out and seal.

In the case of packaged die the standard choice is a solder seal DIP package. Accommodating Customer Source Inspection provides further added value.

Back-end processes, i.e. the up-screening of the component, may include a stabilization bake step, temperature cycling (to stress the component in order to find early failures), centrifuge testing (to see if the die remains attached to the package), P.I.N.D. (particle impact noise detection) testing (in order to check for loose particles in the package), burn-in under power at temperature (again to catch early failures), marking, final electrical testing (to make sure that after all the exposure to harsh treatment, the part still functions), and leak testing (to insure that the part is still hermetic).

BI Technologies also supports quality provisions such as serialized package marking, component traceability and any in-line quality conformance requirements.

Sometimes we use customer supplied test fixtures when available, but if necessary we can design and produce the test boxes and burn-in boards required to comply with the customer’s Source Control Drawing (SCD). 

By offering hermetically packaged industry standard die and up-screening the units to meet military specifications, we have expanded the service offerings of our hybrid microcircuit product line.