PCB And PCBA Testing- Why Is Important And Necessary
Printed circuit boards are commonly used in a variety of electronic devices and technologies, making them very valuable devices. PCB is the core of the effective operation of electronic equipment. To ensure that the entire device is running as planned, it is critical to thoroughly test them. If the printed circuit board has defects or manufacturing problems, it may cause the final product to malfunction and cause inconvenience. In these cases, the manufacturer must recall the device and spend more time and resources to resolve the failure.
Design for Manufacturing (DFM)
DFM is the process of arranging PCB layout techniques to alleviate problems that may arise during PCB fabrication and PCB assembly required to fabricate electronic systems.
Design for Assembly (DFA)
The goal of the assembly design is to determine how to design the product to make assembly the most cost effective. Assembly Design (DFA) involves reducing material inputs, capital indirect costs, and labor reduction. Focus on the application of standards to reduce production costs and shorten product development cycles.
Design for Test (DFT)
When designing a new product, consider the complexity of supporting a long product lifecycle that includes components that are nearing the end of life or may be outdated. Inventory availability and backup purchases are some of the variables that experienced electronic contract manufacturers will consider when building customer raw material supply chains.
Many PCB manufacturers prefer to use an online test (ICT) using ICT. The online test (ICT) method is a common strategy for providing fault diagnosis at the component level. Manufacturers can effectively test individual components and their electronic characteristics.
Traditional ICTs require a "nail bed" fixture. These luminaires must be designed to accommodate the board. Use the nail bed test fixture to access multiple test points on the bottom of the PCB. With sufficient access points, ICT can transmit test signals to and from the PCB at high speed to perform component and circuit evaluation. ICT offers OEM customers the following benefits: ICT covers 100% testing to detect all power and ground shorts. ICT testing can enhance testing and eliminate customer commissioning requirements These luminaires are often expensive. ICT is best when used in most stable, high-volume production terminal tests. It is cost effective and helps identify PCB issues before integrating the PCB into larger units. ICT is a very accurate test process.
Flying Probe Test
The flying probe test, also known as the Fixtureless In-Circuit Test (FICT) , is another type of ICT. Flying probes do not require custom fixtures, eliminating the need for additional fixtures. FICT uses a test-based move-based test pin (flying pin).
The flying probe test checks the same things as traditional ICT, but has the advantage of lower cost and the ability to test both sides of the PCB. In the event of a defect or problem, the FICT system only needs to be reprogrammed to generate new parts without defects. In contrast, ICT may require a brand new fixture.
Programming guides flying probes to run tests to pinpoint highly specific areas and nodes. This level of accuracy is suitable for small boards and boards with high density components.
Automated Test Equipment (ATE)
The testing phase is usually a thorough phase and requires a lot of attention to detail. The circuit board contains a variety of complex components. These may include capacitors, resistors, transistors, diodes and fuses. These are the main components that need to be tested for any irregularities and signs of failure.
Automated Test Equipment (ATE) performs a Manufacturing Defect Analysis (MDA). This test verifies each component on the PCB and verifies the passive control measurements, the direction of the diodes and transistors, and the supply voltage. It also looks for open circuits and short circuits. Testing can include basic functional process verification and checking for "no vector" testing of PCB pins. Analog and digital measurements can be tested.
Automatic Optical Inspection (AOI)
PCB design is becoming more complex and components are getting smaller and smaller. Today, the human eye's ability is mostly insufficient to achieve reliable quality control. In addition, almost all applications now require a zero defect strategy. All of these factors require the requirements of a detection system with a high performance camera module. This automated optical inspection (AOI) machine allows operators to perform non-contact testing of bare boards and assembled printed circuit boards (PCBs) at various stages of PCB assembly.
Such AOI units are typically composed of an operating system to enable programming of measurement and comparison functions.
Solder Paste Inspection System (SPI)
Solder paste deposition is a key process for board assembly operations using SMT technology. Solder paste printing is a complex process and many factors can improve its accuracy, including the composition and rheology of the slurry, the type of stencil and squeegee used, and the process conditions used to lay the slurry. Since solder paste printing is an important process, it is important to test and verify the quantity and height of the printed solder paste because the dispersion of the micron can result in a late short or open circuit.
SPI devices are used in printed circuit board manufacturing to monitor and control one of the most critical steps affecting the quality of printed circuit boards. The SPI system measures the height and volume of the pads before component application and solder melting, and if used properly, can reduce the incidence of solder-related defects to a statistically insignificant amount. The key to SPI measurement is the accuracy of height measurement because it is directly related to solder volume and defects. The importance of accurate height measurement in SPI is that accurate solder height detection not only contributes to the quality of the finished product, but also reduces the inspection time required, thereby positively affecting productivity and thus reducing manufacturing costs.
Automatic X-ray inspection (AXI) is a technology based on the same principles as automatic optical inspection (AOI). It uses X-rays as a light source rather than visible light to automatically inspect features that are usually hidden outside the field of view. Increasingly, ICs and BGAs are used where the connections are under the chip and are invisible, making ordinary optical inspection impossible. Since the connections are located below the chip package, it is more desirable to ensure that the manufacturing process properly accommodates these chips. In addition, chips using BGA packages tend to be larger chips with many connections. Therefore, all connections must be made correct. To meet these growing and complex demands, X-ray inspection systems are beginning to appear to inspect, test and measure the underlying layers of PCBs and under the solder joints.
In addition, X-ray inspection systems are used wherever defects are detected by non-destructive means. It is used in a wide range of applications, including various department and inspection tasks, from material testing of cracks and air inclusions to foreign object inclusions and shape deviations. In the electronics industry, the increased use of miniature housings and the trend to move components within electronic components requires high quality inspections to capture hidden defects in a cost effective and deterministic manner.
Functional Test (FCT)
Functional testing (FCT) is used as the final manufacturing step. It provides a pass/fail determination of the finished PCB prior to shipment. The purpose of the FCT is to verify that the product hardware is free from defects that would otherwise adversely affect the normal operation of the product in the system application.
A functional tester is typically connected to the PCB under test through its edge connector or test probe point. This test simulates the final electrical environment in which the PCB will be used.