Test engineer

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A test engineer is a professional who determines how to create a process that would best test a particular product in manufacturing and related disciplines, in order to assure that the product meets applicable specifications. Test engineers are also responsible for determining the best way a test can be performed in order to achieve adequate test coverage. Often test engineers also serve as a liaison between manufacturing, design engineering, sales engineering and marketing communities as well.

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Test engineer expertises

Test engineers can have different expertise, which depends on what test process they are more familiar with (although many test engineers have full familiarity from the PCB level processes like ICT, JTAG, and AXI) to PCBA and system level processes like board functional test (BFT or FT), burn-in test, system level test (ST). Some of the processes used in manufacturing [1] where a test engineer is needed are:

Early project involvement from design phase

Ideally, a test engineer's involvement with a product begins with the very early stages of the engineering design process, i.e. the requirements engineering stage and the design engineering stage. Depending on the culture of the firm, these early stages could involve a Product Requirements Document (PRD) and Marketing Requirements Document (MRD)—some of the earliest work done during a new product introduction (NPI).

By working with or as part of the NPI group, a test engineer ensures that a product is designed for both testability and manufacturability. In other words, to make sure that the product can be readily tested and built.

The following are some general rules to ensure testability and manufacturability of a product:

By following the general rules above, test engineers minimize future surprises (like adding extra components, re-layout of the boards, etc.) which drives up costs and development delays of the final product.

Working with cross platform teams, hardware and software team

Often people take shortcuts to be able to deliver final products. Because of these shortcuts, the product's manufacturability and testability becomes complicated (inability to read and write information, creating deviation from the process, etc.) which impacts the manufacturing complexity of a product. Because of this complexity, bottlenecks in the manufacturing and delivery schedule delays are introduced.

With this in mind, test engineers always get involved in the following reviews as well:

Yield maintenance

Products' yield plays a very important part during their lifespan. [2] There are usually three stages for a product, engineering, initial production (IP) and full production (FP).

In addition, yields will show if another process needs to be introduced (e.g., because processes already used cannot capture certain test errors). Yields can also decide if an existing test process can be trimmed down (step-wise or time-wise) or even eliminated. E.g., if the ESS errors can be captured during the 3rd hour, test time can be cut down from a normal 24 hours down to maybe 4. Or if a process consistently yields 100% during a 15-month period, teams can get together and decide to eliminate that process at all.

Test automation

Test automation refers to the automation of the process to test a product through the use of machines. Depending on the product, the machines that we are referring to could mean a combination of Automatic Test Equipment (ATE), handler, interface board, and test program that drives the ATE, as with the case of the IC chip testing.

Test automation is a big part of a test engineer's job.

The whole intention of automating the test is as follows:

Overall, this drives manufacturing reliability [3] and quality at the end of the line making sure that all units shipped out to customers are well tested, stressed, filtered out of any errors, and configured properly. [4]

Defining standard test documents

Following are some of the documents that the test engineers maintain or define:

Contract manufacturer

A contract manufacturer (CM) also provides a test engineer for their customers. The function of these test engineers varies depending on the level of support they provide for their customers: providing "interactive and first level of defense"-only support or providing partial or ground-up solutions.

Providing interactive and first level-of-defense support

Providing "interactive and first level-of-defense"-only support is the usual job of the CM TE. Here are some typical job functions for a CM test engineer:

Because of their close involvement with the test line, they monitor the products going through the line and inspect the failed boards to decide if it really failed or if the failure was just caused by some improper test setup. Some examples of these false failures are:

Providing partial or ground up solutions

There is a small number of companies who prefer to outsource their test engineering work to their corresponding CM. In that case, the CM TEs will be in charge of providing the test automation solution, test fixture design, yield gathering plus the usual interactive and first level of defense for their customers.

Of course, outsourcing test solutions to the CM has its pros and cons.

Some of the advantages are:

Some of the disadvantages are:

Because it is hard to find a test engineer who knows every aspect of testing methodology (from PCB tests like ICT, JTAG test, flying probe test, and X-Ray test to PCBA test which includes writing test automation from functional test to FQA test among others), companies usually outsource part of the development of this missing test piece to their CM. For example, if none of the in-house TEs know much about ICT fixtures, they will ask their CM to develop the ICT test solutions for them instead.

See also

Related Research Articles

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<span class="mw-page-title-main">Product lifecycle</span> Duration of processing of products from inception, to engineering, design & manufacture

In industry, product lifecycle management (PLM) is the process of managing the entire lifecycle of a product from its inception through the engineering, design and manufacture, as well as the service and disposal of manufactured products. PLM integrates people, data, processes, and business systems and provides a product information backbone for companies and their extended enterprises.

JTAG is an industry standard for verifying designs and testing printed circuit boards after manufacture.

A design engineer is an engineer focused on the engineering design process in any of the various engineering disciplines and design disciplines like Human-Computer Interaction. Design engineers tend to work on products and systems that involve adapting and using complex scientific and mathematical techniques. The emphasis tends to be on utilizing engineering physics and other applied sciences to develop solutions for society.

<span class="mw-page-title-main">Depaneling</span>

Depaneling is a process step in high-volume electronics assembly production. In order to increase the throughput of printed circuit board (PCB) manufacturing and surface mount (SMT) lines, PCBs are often designed so that they consist of many smaller individual PCBs that will be used in the final product. This PCB cluster is called a panel or multiblock. The large panel is broken up or "depaneled" as a certain step in the process - depending on the product, it may happen right after SMT process, after in-circuit test (ICT), after soldering of through-hole elements, or even right before the final assembly of the PCBA into the enclosure.

<span class="mw-page-title-main">Automatic test equipment</span> Apparatus used in hardware testing that carries out a series of tests automatically

Automatic test equipment or automated test equipment (ATE) is any apparatus that performs tests on a device, known as the device under test (DUT), equipment under test (EUT) or unit under test (UUT), using automation to quickly perform measurements and evaluate the test results. An ATE can be a simple computer-controlled digital multimeter, or a complicated system containing dozens of complex test instruments capable of automatically testing and diagnosing faults in sophisticated electronic packaged parts or on wafer testing, including system on chips and integrated circuits.

<span class="mw-page-title-main">Boundary scan</span>

Boundary scan is a method for testing interconnects on printed circuit boards or sub-blocks inside an integrated circuit. Boundary scan is also widely used as a debugging method to watch integrated circuit pin states, measure voltage, or analyze sub-blocks inside an integrated circuit.

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Design for testing or design for testability (DFT) consists of IC design techniques that add testability features to a hardware product design. The added features make it easier to develop and apply manufacturing tests to the designed hardware. The purpose of manufacturing tests is to validate that the product hardware contains no manufacturing defects that could adversely affect the product's correct functioning.

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<span class="mw-page-title-main">Integrated circuit design</span> Engineering process for electronic hardware

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<span class="mw-page-title-main">Design for manufacturability</span> Designing products to facilitate manufacturing

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Design Closure is a part of the digital electronic design automation workflow by which an integrated circuit design is modified from its initial description to meet a growing list of design constraints and objectives.

An engineering change order (ECO), also called an engineering change notice (ECN), engineering change (EC), or engineering release notice(ERN), is an artifact used to implement changes to components or end products. The ECO is utilized to control and coordinate changes to product designs that evolve over time.

Automated optical inspection (AOI) is an automated visual inspection of printed circuit board (PCB) manufacture where a camera autonomously scans the device under test for both catastrophic failure and quality defects. It is commonly used in the manufacturing process because it is a non-contact test method. It is implemented at many stages through the manufacturing process including bare board inspection, solder paste inspection (SPI), pre-reflow and post-re-flow as well as other stages.

Engineer to order is a production approach characterized by:

  1. Engineering activities need to be added to product lead time.
  2. Upon receipt of a customer order, the order engineering requirements and specifications are not known in detail. There is a substantial amount of design and engineering analysis required.

In-circuit testing (ICT) is an example of white box testing where an electrical probe tests a populated printed circuit board (PCB), checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assembly was correctly fabricated. It may be performed with a "bed of nails" test fixture and specialist test equipment, or with a fixtureless in-circuit test setup.

In the manufacture of electronic printed circuit boards, flying probes are used for testing both bare circuit boards and boards loaded with components. Flying probes were introduced in the late 1980’s. Flying probes can be found in many manufacturing and assembly operations. A flying probe tester uses one or more test probes to make contact with the circuit board under test; the probes are moved from place to place on the circuit board to carry out tests of multiple conductors or components. Flying probe testers are an alternative to bed of nails testers, which use multiple contacts to simultaneously contact the board and which rely on electrical switching to carry out measurements.

References

  1. "威尼斯欢乐娱人城2299-首页". www.tcdmsecurity.com. Archived from the original on September 25, 2008.
  2. "Silicon Test and Yield Analysis - White Papers". Archived from the original on 2011-07-20.
  3. "中国电子制造 EMAsia-China.com". Emasiamag.com. Archived from the original on 2012-02-17. Retrieved 2014-01-25.
  4. "Cost-Benefit Analysis of Test Automation". StickyMinds. 2000-11-17. Retrieved 2014-01-25.