Reliability is the Most Important Consideration with Compatibles
What do you expect from an optical transceiver? Great design? Functionality? High quality? Yes, you would expect that and more from your transceiver – but if it lacks reliability in any way, it is essentially useless to you. There are many companies that make fully functional optical transceivers, but not many that give you the reliability that you need. Reliability is the most important consideration as it reflects not just a device’s ability to perform in most conditions, but also whether you can depend on it to function normally without having to worry about the risks of failure.
So, the so-called carrier class products, for example, are needed to work for 15 to 20 years at a time. Clearly, you cannot test a product and see if it will indeed last for so long, which is why we use techniques such as accelerated ageing and statistical analysis. This can help hasten the process, but still, the tests can take more than 6 months. Reliability is all the more important in data centres and telecom equipment. That’s because the entire digital age is built upon these systems – if your data centres fail and if your telecom equipment does not function as it should, that can lead to massive financial losses as so many business systems such as utilities, banking, transportation and education are so dependent on the infrastructure.
Testing Reliability as Part of an Integrated System
In order to create a really effective process to test reliability, an optical transceiver manufacturer should have an entire team working on everything from the product concept to manufacturing and support. The process of testing reliability is a part of an integrated system, which means only a company which uses an organic end to end methodology, can succeed at this. Reliability in this case comes from several different disciplines – electronics, mechanics and material science.
There are several different parameters involved in this, such as humidity, temperature, mechanical and electrical stresses and corrosion. The tests fall into two different categories – environmental and mechanical, and involve testing the capability of the product to tolerate extremely difficult operational conditions and its physical resilience against pressure.
The reliability test plans are according to a set of standards defined by the IEC or Telcordia. The crucial factors here are the test procedure, which should be defined as clearly as possible so that the tests can be repeated again and again; the sample size, and most importantly, the criteria to determine whether the tests have passed or failed. All the devices or equipment parts used in the transceiver should be independently qualified and the internal interconnects should be verified. Specific attention should be given to areas where you could have high mechanical stress.
The mechanical tests consist of vibration, drop and shock tests done on the standalone equipment, as well as on its use on various platforms. This should take into consideration factors such as de-mating cycles, optical and electrical mating and de-mating cycles, ESD, EMC and operational vibration, in order to ensure that the process is reliable both in the internal and external day-to-day conditions. The goal is to keep dead on arrival parts to a minimum.
The environmental tests consist of alterations done to the humidity, temperature and other external conditions. This will involve thermal shocks, applying heat and humidity separately or damp heating, temperature cycling and testing the equipment at high temperatures. Increasing the temperature can be used to accelerate the process and shorten the test duration. This would make it possible to estimate the wear out mortality and infant mortality of the product. It is also essential to involve manufacturers in the whole lifecycle of the product development, from the design and conceptualisation onwards. This way the costs can be kept low to a great extent.
Ensuring Reliability should be the responsibility of everyone involved in different stages of the product development cycle. This depends on the integrity of the various components, the quality of the materials and the operating conditions under which the manufacturing is done. The quality of the workmanship can make all the difference to the reliability. The construction of the product should be carefully monitored at every stage. Reliability testing should not be just about getting through a checklist – it should be a part of the mindset within the company.
Just using the right processes cannot ensure reliability. Reliability should be something that is embedded within the company and should be a part of the basic building blocks of the organization. If not for this, the products can work well; but it wouldn’t be possible to absolutely guarantee the reliability.