Why the PCB testing is necessary
Testing is a primary requirement in the PCB assembly industry. When you don’t properly test, it means the entire printed circuit board comes to you flawed in various ways.
Testing avoids errors, and problems may have overlooked during the production stage. It is possible to cause failure and defects in the field. So as to reduce the chance of failure and maintain customer satisfaction, it is important to undertake the PCB through testing procedures. Note that the producers are implemented to make sure that the PCB and the components are fully functioning. The following are some of the advantages of PCB testing;
Bug identification: The main advantage of PCB testing is that it assists in identifying problems in PCBs. If the issue lies in manufacturability, functionality, or elsewhere, PCB testing is able to identify what is a PCB design so that designers can regulate as a result.
Time savings: PCB testing serves as an early stage to help save time in the long run. The testing also allows designers to identify major issues during the prototyping stage. In the testing process enables designers to govern the root cause of each problem posed quickly and easily. It also leads to early decisions if to make adjustments so that they can move on with production at a faster rate as well as manage production time.
Cost reduction: PCB testing plays a key role in reducing wasteful production of faulty products by applying prototypes and small-scale assemblies to test the products. When testing is done early in the design process, it helps the designers to prevent wasteful full-scale assemblies of faulty PCBs. It also serves to ensure that the design is as flawless as possible before it goes into production. This step helps to reduce production costs meaningfully.
What is being tested
Lamination-This component determines the lifespan of a PCB. Thus need to test keenly and in detail. When not tested can cause issues in the final functionality of aboard. Testers focus on looking at the laminate’s resistance so as to peel by force or use heat.
Copper plating-tester test the quality of copper used to laminate the board so as to provide conductivity. They analyze the tensile strength and elongation in detail.
Solderability- here tested does analyze the wetting or how well a surface accepts liquid solder. This is essential because it determines the functionality of PCB because it ensures that the components can be attached firmly to the board.
Cleanliness– this means the ability of the PCB to resist environmental factors like humidity and corrosion. It includes analyzing PCBS before and after undergoing thorough the various environmental conditions.
Solderability: Solderability testing to the material is essential for a functioning PCB as it ensures that components can be attached firmly to the board. The most commonly analyzed factor is wetting, or how well a surface accepts liquid solder.
Environment: Many PCBs operate in humid environments, so a common test for PCBs is for water absorption. In these types of tests, the PCB is weighed before and after being put in a humid environment, and any significant weight change results in a failing grade.
Electrical-testing the PCB conductivity so as to enable electric currents with minimal leakage.
Hole wall quality– it is another very important component to test so as to ensure the hole walls would not crack or delaminate as the PCB undergoes into the field. This component is analyzed in an environment with cycling and quickly changing temperatures to see how well they react to thermal stress.
Testing Methods of Printed Circuit Board
There is no specified method to use and perfectly test PCBs fully. Thus many factors should take into consideration when making a decision on which method to use. The key to this is to focus on the correct testing procedures, reliability, and the cost of testing.
There are various methods to use in PCB testing and designing to optimize the assembly process.
In-Circuit check (ICT)
Many PCB makers favor using one style of in-circuit testing (ICT) or another. Using ICT, a manufacturer will with efficiency check individual elements and their electronic characteristics.
Traditional ICT needs a “bed of nails” fixture. These fixtures should bear a style section to suit the circuit card. The fixtures generally come back at a nice expense. ICT shines best once used for end-of-line testing of largely stable, high volume productions. Once the assembly doesn’t justify the value, makers should generally pass a number of the fixture prices on to customers.
Fixtureless In-Circuit check (FICT) / Flying Probe check
A flying probe check, conjointly called fixtureless in-circuit testing (FICT), is another style of ICT. Flying probe eliminates the requirement for custom fixtures that eliminates more fixture prices. FICT uses check pins that move supported programming (flying probes).
However, it has the advantage of cost accounting less and, therefore, the ability to check either side of a PCB. If a defect or downside shows up, the FICT system solely needs reprogramming to provide a brand new piece while not the defect? In contrast, and ICT will need a wholly new fixture.
Programming guides the flying probes, which make it attainable to run tests that pinpoint extremely specific areas and nodes. That level of accuracy works well with smaller boards and boards with high-density elements.
Functional Circuit check
Functional tests area unit dead to certify that the electronic equipment functions in keeping with style specifications. Testing is often performed mistreatment DUT (device below test) connectors or a BON (bed of nails) fixture. A pogo pin device, a setup wont to establish a short-lived association between 2 computer circuit boards, is employed to conduct testing. The number of pogo pins, sometimes required for a practical check fixture, is considerably but associate ICT fixture.
Boundary Scan Testing
The boundary scan could be a methodology for testing wire lines on computer circuit boards. Boundary-scan is additionally wide used as a debugging methodology to look at computer circuit pin states, live voltage, or associate analyze sub-blocks within a computer circuit.
Design for producing (DFM)
DFM is that the method of composition a PCB layout topology to mitigate issues that would probably arise throughout the PCB fabrication and PCB assembly processes needed to manufacture the electronic system.
Design for Assembly (DFA)
The goal of style for assembly is to work out a way to style a product such assembly happens most cost-effectively. The style for assembly (DFA) thinks about with a discount of fabric inputs, capital overhead prices, and reduction of labor. There’s attention to the applying of standards to scale back production prices and to shorten the merchandise development cycle time.
Design for check (DFT)
The price of testing a completed computer circuit board wills quantity to the maximum amount as half-hour of the full cost of the merchandise. By coming up with a product optimized for check coverage and, therefore, the ability to isolate faults quickly for each PCB producing errors and part failures, design-for-test (DFT) becomes terribly pregnant to style for profit.
Design for offer Chain (DSC)
When coming up with new merchandise, the complexness of supporting long product life cycles containing elements nearing the tip of life or in danger of changing into obsolete ought to be a thought. Stock convenience associated alternate sourcing area unit a number of the variables an experienced physical science contract manufacturer can contemplate once fitting a customer’s offer chain for raw materials.
What tools are used to perform PCB testing
There are two key tools one can use to test if the PCB is functioning as intended. They are;
A multimeter is incredibly helpful for measuring voltages and resistance within a circuit.
Multimeter electrical / electronic measurement tool
Oscilloscopes and logic analyzers are helpful for visualizing voltage changes within a circuit to ascertain if a circuit is behaving properly. Sadly these are terribly costly and are commonly too expensive for many hobby electronic enthusiasts. There’s an alternative that is to use the Arduino, your computer, and a little touch bit of circuitry to produce a basic operating oscilloscope/logic analyzer. This can be one thing I’ll want presently to feature to my very own electronic check tools.
The cost of PCB testing
One way to realize cost justification is to try and do a cost and advantages analysis supported every type of test. Once the amount is proscribed from a couple of boards to perhaps fifty or so, an honest PCB testing answer might be flying probe, whereas if the amount is higher, typically speaking, in-circuit test (ICT) may be a sensible choice.
The cost of producing ICT fixtures ranges from many thousand to over $50,000, and justification is demanded to create these greenback outlays. That’s once the number of product shipments factors in. If an EMS supplier is shipping fifty to a hundred boards a month to an aftermarket, for instance, and it’s determined that the product’s lifecycle is predicted to be a minimum of 2 years or additional, then the value of this high-ticket ICT fixture might be amortized over that point amount. Keeping all alternative incidental prices in mind, the marginal cost of the fixture per board provided is comparatively tiny.
On the opposite hand, if monthly shipments in terms of the range of PCBs ar comparatively massive say 250 to three hundred boards per cargo, then amortization wouldn’t even take two years. Hence, the complete value of producing such a rich ICT fixture might be amortized in but a year. Therefore, amortization depends on ICT fixture producing value and also the range of shipments scheduled for AN extended period.
At Moko Technology, we understand the testing process fully, and our products are well tested. We have been offering services more than 17 years now and using a team of seasoned manufacturing engineers and associates. Thus we have established a name for ourselves in the PCB assembly industry in China.