February 01, 2022 16 min read
Nina Bibikova
Writer
Andrey Solovev
Chief Technology Officer, PhD in Physics and Mathematics
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The importance of electronics cannot be overemphasized. Our comfortable and stable existence to some extent depends on its reliability. In that regard, electronics testing gradually comes to the foreground. This article initiates a series of publications devoted to electronic device testing. Being a hardware and software development company, we attach importance to this process and are good at figuring testing methods out.
Even carefully designed and well-made electronics are vulnerable to failure. Defects have to be identified before a device’s mass production, ideally at the development stage.
That is why it is so important to ensure adequate testing of electronics components, especially printed circuit board (PCB) testing.
Testing is a very important part of the PCB design process. When PCB testing continues throughout the production cycle, it helps to achieve economies and prevents or minimizes problems at the “end-of-the-pipeline” phase.
Before and during the manufacture of PCBs, a lot of designers’ efforts go into quality control and PCB testing. They have to be sure that a lot of indicators, such as current capacity, performance and impedance are within appropriate values, and the PCB has no short circuits, open or faulty solder joints.
There are many quality verifications to ensure high-quality designs are suitable for production at scale. Thus, Integra Sources’ designers first emphasize printed circuit board assemblies (PCBA’s) testing. Only then can they install PCBAs in a system and make a system-level test.
During manufacture and assembly, specialists conduct a series of printed circuit board tests. PCB board testing aims to rate its yield and quality, and make sure the design was not damaged during assembly. These PCB checks are usually run on prototypes or small batches. They examine boards for probable electrical short circuits, imperfect solder joints, and test their functionality.
Various PCB analysis methods can be used for testing bare boards and assembled ones. Here are the foremost used approaches. They aim to check the manufacturing process of a PCB and the quality of a PCBa.
Manual visual inspection (MVI) used to be one of the earliest PCB testing methods for inspecting electronic circuits. It allows one to find out those visible shortcomings which can be done right on a PCB assembly jig:
Human errors and growing PCB complexity make this method less effective in large batch production. Nevertheless, it is commonly used in PCB design and prototyping.
Integra Sources specialists conduct a scrupulous MVI check for all PCBs they are dealing with. Our vendors are highly reliable, and the quality of parts we use is very good, so the number of situations when we have discovered flaws could be counted on one hand. Thus, working on one of our projects, we eliminated a defect of assembly - diodes have been placed incorrectly.
We always check new printed circuit boards before working with them, thus cutting off even slight flaws at an early stage.
Automated Optical Inspection (AOI) is the next level of MVI and a manufacturing test for large scale production.
AOI compares the images of your circuit test board taken by a single 2D or two 3 D cameras to the image of an example.
This electronic testing equipment can be installed at the end of the production process, taking into consideration different manufacturing assembly methods. An AOI machine can be useful as
It can also be combined with other methods of PCB checking, such as
AOI circuit board testing can help with a relatively large scale of production but is not suitable for work with prototype design.
Automated X-ray Inspection (AXI) is a unique circuit board tester. By using X-rays, AXI creates 2D or 3D images of the hidden solder joints such as on Ball Grid Arrays (BGA) or Quad Flat No-leads (QFN) packages.
As one of the PCB testing services, it can be helpful
The contractors that Integra Sources is dealing with make mandatory AXI tests to check the soldering and the absence of defects in the boards.
In-circuit testing (ICT), aka a “bed of nails,”- is a highly reliable and advanced type of PCBa component testing for large production lots nowadays. Due to the fact that it is a rather expensive printed circuit board testing technology, the in-circuit component test fits best for the concluding testing of high-scale products with the final version of the design.
How to test a circuit board for a short and opens, check its component orientation, resistance, and capacitance in the most accurate way? An ICT PCB test turns on and checks each part individually and makes a thorough component level testing. It provides more than 90% fault coverage. Equipment, used for electronic parts testing, is completely automated.
This electronics component tester uses fixed sensor points, “nails”, placed according to the PCB design. Their task is to check the solder joints’ integrity. ICT sensor probes link up with the board via relevant circuit board test points. They make sure that the connection is not damaged.
Customized testing jigs or test fixtures for PCB can be performed for large or follow-up batches to provide cost-effective and prompt production lot testing. These printed circuit board testers can be
PCB testing jig is great for
In some cases, our clients ask to check components with the help of the PCB test fixture for automatic voltage measurement in PCB control points.
Flying probe electronics testing (FPT) is a less expensive type of ICT as it doesn’t need a test jig for PCB. FPT can adjust to a new PCBa easily but provides testing not so quickly as ICT.
Unlike the ICT, flying probe circuit board testing equipment uses for connection of:
Test needles use a software-controlled program for testing electrical components. This is one of the circuit board testing methods most suitable for
Introduced in the late 1980s, this flexible PCBa tester has become popular among electrical component manufacturers.
Time Domain Reflectometry (TDR) is electrical equipment for testing networks by measuring the reflections that appear from a signal going through a transmission environment. TDR is used as a PCB tester to find faults in high-frequency boards.
The Resistivity of Solvent Extract (ROSE) Testing – is one of the easiest and most reliable circuit board testing procedures in PCB and PCBa manufacturing. It can effectively analyze and identify any faults and significant surface residues remaining from manufacturing processes.
Integra Sources cooperates with responsible PCB manufacturers whom we trust to conduct mandatory tests. Nevertheless, based on the specific requests and needs of our clients, we can request additional checks or protocols of testing, for example, a protocol of manual board testing (as a rule, this is the measurement of voltages at the control points of the board).
Other noteworthy methods are Stress Tests. They may be required to estimate the maximum allowable PCB limits within which it will remain functional and structurally intact. These tests don’t need to be used for all boards and very rarely on prototypes.
Design prototypes, as well as boards for large batch production, can be tested with Burn-in testing. This test is performed on the upper limits of PCB operating conditions such as temperature (257°F, or 125°C), frequency, or voltage to provide comprehensive information about the product’s reliability.
Stress tests belong to the HALT/HASS group of methods (Highly Accelerated Life Testing/Highly Accelerated Stress Screening) and are conducted according to HALT/HASS testing guidelines. These methods target the elimination of the identified shortcomings and to ensure product quality at the stage of development (HALT) or production (HASS). They are commonly used for
The PCB Functional Test (FCT) checks that the correct electronics are working. These tests are used at the end of the manufacturing process, verifying a PCB’s functionality and its performance to specifications. Due to the design complexity and individual testing needs, PCBa functional testing can be either simple confirmation that the product will power up or a more complex investigation. A thorough production testing can be conducted according to requirements, protocols, or standards and includes software testing.
Functional testing is a must-have during small-batch manufacturing or prototyping when you need to be sure of the functionality of every PCB.
Preparation of functional testing has become a long and painstaking task due to the increasing complexity of devices.
By pre-production testing component elements of assemblies, manufacturers make it much easier.
Peel PCB tests measure the force needed to peel off a laminate in a PCB stack after it has been created and fully cured.
Solder pot and float tests determine the level of thermal stress a PCB plated through-hole (PTH) and via barrel can resist and their solderability.
Integra Sources design team carries out different types of FCT throughout each project. Our clients can be completely confident that both software and hardware involved in the project undergo complete testing to exclude even the slightest defects.
Thanks to well-organized quality control in production, we get boards without defects in 99.9% of cases. In a single case when the Bluetooth module’s contacts were not properly soldered, our specialists eliminated it on the spot.
You can entrust the testing of printed circuit boards to a specialized laboratory with various component testing equipment, and the ability to do PCB lab tests not only in the field of electronics but if needed, in physical and chemical fields for a comprehensive study of PCB’s safety and performance.
Labs are usually equipped with different electronic component testers, such as
An important aspect of the design of printed circuit boards is their compliance with certain standards and specifications.
These standards define some criteria that must be carried out on a designed board. You can read more about this in our article on PCB certification.
Instead of physical tests of real boards, PCB pre-production simulation instruments can be used for calculating the electrical characteristics of the board. The choice of simulation is justified
PCB manufacturing expenses can be rather high, but so is the cost of possible PCB failure. Simulation allows designers to stay within a budget.
Any part of the printed circuit board can be analyzed. Simulation models can be used both for analog devices and for digital electronic components testing. PCB simulation software applies mathematical models to predict board operation.
Let us highlight some aspects and tools of this process.
Simulation Program with Integrated Circuit Emphasis (SPICE) is one of the most popular simulation tools used in PCB design testing.
Designers use SPICE applications for front-end engineering. These packages can perform different types of analyses, from the basic to the complicated. Each of them can help specialists to get useful data, for example, facts connected with component tolerances and sensitivities.
Various business SPICE applications may contain different attributes, but they all have the same basic procedure for PCB analysis.
Input/Output simulation has become a key element of digital system design at present. If problems connected with signal integrity are determined at the beginning of the design cycle, a developer can reduce the number of board fixes, and therefore, reduce the new PCB’s time of release.
SPICE simulators are commonly used in PCB design, but they have some minuses.
Input/Output Buffer Information Specification (IBIS) for simulation of the integrated circuits’ input/output buffers is an alternative to SPICE simulation. Intel’s invention provides information about digital electronic components’ functionality and can be used during PCB development.
The advantage of IBIS models is that they can be applied to devices that haven’t got complete prototypes due to secrecy, complexity, or other reasons. IBIS was developed to provide consumers with precise IO buffer models without risking their intellectual property. So, the great advantage is that it can be a free electronic product testing, as IBIS models for many devices are available over the net. The same electronic testing board may be used for the simulation of different constructors’ devices.
PCB design cannot be done without high-quality testing, especially when the complexity of products is increasing constantly. Choosing the appropriate test combination is usually a task of the PCB manufacturer, but very often outsourcing companies, which value their reputation and customers, conduct comprehensive PCB and PCBa tests. Electronic components testing can not only ensure the safety and reliability of the circuit board but in the long run, save time and money and increase the level of customer confidence by identifying and preventing potential defects before mass production.
Although Integra Sources relies on the experience and responsible attitude of our PCB vendors, we have highly skilled staff who constantly run various tests throughout the whole design process. We conduct both hardware and software-related tests and continue to stay in touch with clients after project completion.
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