How do OSAT providers produce high-reliability electronics for extreme temperature applications?

6 December 2023

by Adele Pliscott, SiP Packaging Engineer, Filtronic

Not all OSAT providers are the same

Many semiconductor suppliers and electronics companies work with outsourced semiconductor assembly and testing (OSAT) partners to manufacture specialist devices for specific industries. But not all OSAT companies are the same. When you need to provide control and monitoring devices for the most challenging high-temperature applications, you need to choose an OSAT partner that can consistently deliver high-reliability hybrid products for the harshest environments.

Some of these challenging applications include control and power modules located close to engines in aircraft, or sensors used in the oil and gas sector to monitor drilling operations. In all of these applications, high reliability is the primary requirement. Not every OSAT provider can deliver the hermetic hybrid electronic products required for such high-performance applications.

High-temperature applications demand a different approach 

Standard hybrid assemblies for applications below 150°C have been manufactured for many years using well-understood material sets. For temperature ranges above 150°C, however, specialist expertise is required to achieve the performance and reliability levels required.

It’s important to recognise that high reliability at high temperatures is linked to the way products are processed, not just their design. Specialist high-reliability OSAT partners take designs and schematics provided by clients – which are generally based on PCBs – and reconfigure them to create compact hybrid solutions with form, fit and function, designed for high-reliability, long-life performance.

So what differentiates an OSAT provider capable of delivering high-reliability hybrid electronics from a standard OSAT company?

– Materials selection

A key factor in achieving high reliability is the selection of materials. Most standard hybrid modules are built using epoxies as an adhesive for the components. However, the resins used in epoxies decompose with temperature and time, leading to outgassing from the module and ultimately the corrosion and mechanical breakdown of the electronics within.

To overcome this problem in higher temperature applications, material sets need to be selected for low outgassing, high structural strength and greater control of intermetallic interactions. This means choosing metal layers for the substrate that match the components and material you’re adhering to.

– Component selection

Alongside material selection, selecting the right components is the next critical step to ensure maximum product life. It’s important to avoid mismatches in coefficients of thermal expansion (CTE) between the joining materials and the selected components. CTE mismatches are the primary cause of most electronic failures within modules. To mitigate these stresses, specialist knowledge is required to select the appropriate joining materials.

– Precision manufacturing

Achieving extremely high reliability also requires precision manufacturing in a controlled environment. Order quantities for these complex modules tend to be small, but the costs are relatively high. To maximise accuracy and consistency in every module, component placement needs to be extremely precise. OSAT partners capable of manufacturing hybrid electronics for high-temperature applications will use fully automated dispense and component placement machinery, and implement rigorous visual and manufacturing processes.

Producing robust hermetic hybrid electronics means working beyond the current military standards. Manufacturing and testing components to perform at high temperatures means effectively working to bespoke standards, enabling products to be tailored to perform reliably in the most challenging conditions.

– Test

Depending on the functionality of the hybrid module some level of expertise and engineering capability is required to develop, maintain, and deliver robust end-of-line product test. The OSAT supply of optical modules, power modules or high-frequency RF hybrids requires a high level of subject matter expertise and access to state-of-the-art test equipment. Choosing a supplier with a strong track record in the technology is vital for a full turnkey OSAT solution.

Traceability and accountability

Filtronic leverages its in-house Manufacturing Execution System (MES) software to track every aspect of the manufacturing process including materials, components, and labour.  Filtronic’s cloud-based software provides real-time data capture and analysis of multiple indicators at each step in the manufacturing process. Filtronic tracks production efficiency and other valuable KPIs. The MES also enables tracking of individual components or assemblies using bar codes which triggers the next station to prepare for assembly downstream. Filtronic’s MES is an essential tool for our production planners to identify where each unit or lot is within the manufacturing cycle, what materials are needed, and when.

Hybrid electronics for extreme applications

Very few OSAT providers have the in-house knowledge and experience to design, manufacture and test high-reliability electronics to such exacting standards. At Filtronic, we specialise in developing bespoke and customised electronics for specific clients and applications.

We have a track record of delivering reliable, high-performance components for the aerospace, defence and space sectors. That means we have the process knowledge, materials expertise and manufacturing capabilities to deliver high-reliability components with the necessary properties to perform consistently in extreme environments.

If you are looking for an OSAT partner for a challenging application like Oil & Gas or Aerospace, or if you are looking for a market leading RF OSAT partner, contact the specialists at Filtronic who can offer the expertise and advice you need.

Find out more about Filtronic’s capabilities:

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