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Quality check of components – How?

Pick and place component handler

Pick and place component handler

40 years of experience

This year it is exactly forty years ago DELTA Microelectronics started our electrical testing of IC components.

Back in 1976 it all started when DELTA was hired to verify the quality of electrical components that were intended for the F-16 Fighting Falcons purchased by the Danish government from Lockheed Martin.

Over these four decades DELTA’s experience has vastly expanded. Today, we develop high quality electrical test programs for application specific chips for multi-international companies.

Advanced machinery

A typical electrical test solution from DELTA includes a tester, a customised test program and customised hardware interfaces to wafers, chips or components (the DUT – Device Under Test).

The hardware interface to test wafers is called a probecard. When you test components it is called a loadboard.

Nearly all our test equipment is supplied by Advantest (former Agilent/Verigy). Such testers are called Very Large Scale Integration testers i.e. VLSI testers. Investment in a tester amounts to around USD 1 million. DELTA’s test facilities include five VLSI test systems and one more is coming up in 2016.

The testers have different specialties such as wireless, mixed signal, digital and light.

It is DELTA’s strategy to invest in test systems from one vendor only. In that way, we always have back-up testers. Furthermore, the test systems can be used for either production or development of new test programs.

Customer’s requirements

When a customer approaches DELTA with a request for test, we evaluate the type of device to be tested. It can be analog, wireless, mixed signal or even very complex digital devices. Our testers must be able to create the appropriate stimuli and measure the response.

The requirements to the customised hardware that connects the tester and the DUT depend on the device functionality and packaging.

Operating with high frequency wireless components it is crucial to conclude whether the tester measures the DUT or the hardware. This issue is solved by thorough debugging. The customised test hardware is owned by the customer and accounts for 20-33% of the total cost for the test solution.

The hardware can be rather complex. Below there is a close-up view of an advanced probecard for wafer test.

Close-up of advanced probecard

Close-up of advanced probecard

The actual test solution is developed together with the customer either according to DELTA’s test templates and experience or according to the customer’s test specification.

First step is to define a test sequence which will provide good test coverage. DELTA is often hired to work out a bullet proof test specification together with the customer. Thus we do not end up in a situation where certain tests cannot be implemented.

DELTA’s test knowledge is – due to our 40 years’ history – a valuable input to our customers.

What kind of tests is typically performed?

A standard test solution will implement a sequence of tests according to the below guideline:

  • Connectivity test
  • Device connection tests: Leakage, power supply, driver capabilities and other DC- parameters
  • Digital tests: Test vectors for design database in imported to clock driven digital test sequence
  • Analog tests: Set-up and measurements
  • Wireless tests: Transmission, receiving

With the above tests implemented in the test solution, DELTA is able to check the quality against expectations.

What is good quality?

Some people believe that a test set-up is used to build quality into the components. This is not the case. The quality of a component is determined by the supply chain: Design quality, wafer quality, packaging quality, etc.

The purpose of the test is to check whether a component’s electrical parameters comply with the specification. The component specification ensures that a certain quality level is met.

Test during various stages of the device life cycle

Most customers make use of the test program in various phases of a component’s life.

During prototype evaluation, the test solution is used to characterise the electrical parameters of the device. The electrical parameters are measured over a pre-defined temperature range. The output data will demonstrate stability of the device.

The test solution is used under ramp to production to test corner lots and to qualify the reliability of the device. Devices are electrically tested before and after exposure to relevant stimuli. Changes in parameters are examined in order to conclude whether the device has the expected quality level and reliability needed for the application.

The last phase is the actual production in which the devices are tested at one or more temperatures and sorted in good and bad.

High through-put minimises costs

Often, it makes sense not to focus on test price per hour but on the test price per device.

Some test facilities test one device at a time, others can carry out the so-called multi-site test i.e. testing 16, 32, 64 or more devices in parallel thus minimising the overall test time significantly.

Therefore, focus on the test price per device instead of test price per hour. Throughput iswhat matters.

What can DELTA offer?

Beginning 2016, DELTA has five testers in operation and we have one more on its way in. All are equipped with component handlers or 8″ or 12″ wafer probers.

DELTA has been operative since 1976 and has as such one of Europe’s most experienced test facilities. Test development, production test, qualification and failure analysis are carried out in the same test facility providing a very high quality of test solutions.

Our skilled team of 10 experienced developers ensures the best test solution for your device. Together, they represent more than 115 man years’ experience.

You are most welcome to visit our test facility. We shall be very happy to give you a guided tour around our premises. You can also visit our test facility virtually by watching our video.

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