Hybrid Microcircuits

Contract electronics manufacture

Something like three quarters of the hybrid microcircuits market is still captive to the OEMs, people like Thales and BAE, and now GE Aviation. Over time the outsource trend is going to increase, and we're seeing some acceleration now.

Operating as a solutions provider C-MAC builds to a specification, rather than building a customer-designed part, and the resulting module or subsystem then goes into a tier one manufacturer's product. Markets are military, aerospace, medical and industrial.

C-MAC was bought out of EMS firm Solectron last year by private investors. The new freedom and financial backing has enabled the company to develop markets for its products which it was previously unable to explore, since many potential customers were Solectron's competitors.

They have an established track record [in design] but what they haven't done, particularly when owned by Solectron, is go out and sell.

www.cmac.com/mt

Chip-on-board hybrid microcicuits.

Most electronic components are assembled on standard FR4 type Printed Circuit Boards (PCBs). These can be either with through hole or surface mount devices (SMD).

This is not always the best solution especially if you are looking to have a small footprint, want to protect your intellectual property (IP) or have critical circuitry.

A Hybrid circuit is normally built on a ceramic substrate with component interconnects made using a conductive paste. These connections are made using various printing processes (thick and thin film). By using other resistive pastes low tolerance resistors can be created negating the use of chip or SMD parts. This helps to reduce the number of components used.

Standard SMD components can be soldered to the substrate although this is not the most space efficient method. The preferred route is to use bare die components. These are attached to the substrate and connected using bond wires in the same manner as standard electronics package assembly.

The substrate can be encapsulated with a ceramic lid if required or mounted in a shielding metal can. If not encapsulated any bare die would need to be ‘glob’ topped to prevent damage.

It is often the case where a combination of die and SMD components are required on the same substrate. Note that not all packaged parts are available in bare die format.

If cost is a prime consideration it may be beneficial to consider a Chip-On-Board solution. This is often using glob topped die on standard FR4 along with other SMD components.