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Testable design of pcb board

2019-11-12 22:12:46 Juding Circuit Technology 290

The basic concept of testable design of pcb board The testability design of product is one of the main contents of product manufacturability, and it is also one of the important contents that must be considered in electronic product design. The testability design of the product means that when designing the product, it should consider how to test the performance and processing quality of the product in the simplest way, or try to test its performance and quality according to the specified method.


        For electronic products, online testing and functional testing are required for mass production. For the design of pcb boards, the feasibility and convenience of circuit testing and development of production testing equipment should be considered. The testability design of a good product can simplify the preparation of inspection and final product inspection in the production process, improve test efficiency, reduce test cost, and easily find defects and failures of the product, thus ensuring product quality stability and reliability. Sex. The testability design of a bad product not only increases the time and cost of testing, but even the quality and reliability of the product cannot be guaranteed due to the difficulty of testing.


1: Testability of pcb design:

The testability of the pcb design is the same as the designability of the pcb. The testability design of the pcb board also belongs to the technical design of the printed board. It also includes the testability of the printed board manufacturing and the finished printed board (light board). Sex. The testability of the printed board assembly is two parts. The test methods and requirements of the two parts are completely different. For pcb designers, it is necessary to understand the performance and test methods that need to be tested on the printed board, as well as the installation test requirements and test methods of the printed board assembly.


The test methods and performance requirements for the finished printed board (light board) can be found by uniformly checking the standards of the relevant printed boards. For the test of printed circuit board assemblies, it is necessary to consider all the characteristics according to the characteristics and requirements of the circuit and structure. When laying out and wiring, appropriate measures should be taken to set the test points reasonably, or to decompose the test in the installation process.


With the miniaturization of electronic products, the pitch of components is getting smaller and smaller, the installation density is getting larger and larger, and the number of circuit nodes available for testing is becoming less and less, so the difficulty of online testing of printed board assemblies is becoming more and more difficult. The bigger. Therefore, the design should take into account the electrical conditions and physical and mechanical conditions of the testability of the printed board, as well as the use of appropriate mechanical and electronic equipment.


2: pcb light board test:

The pcb light board test is an important means to ensure the quality of the printed boards of the components to be installed, and is also an important part to ensure the quality of the printed board assembly and reduce the loss of repair, rework and waste. The electronics industry at home and abroad attaches great importance to testing the performance of printed boards and has developed many testing standards and methods. The main testing items are standard specifications for appearance inspection, mechanical performance testing, electrical performance testing, and physical and chemical performance testing, as long as reliability and environmental adaptability testing are required.


There are many test items for printed board, but there are fewer restrictions on design. Appearance testing requires little testability design. Appearance inspection generally refers to inspection by visual inspection or appropriate optical instruments on the finished printed board, mainly to check the appearance quality of the manufacturing.


The electrical performance test is most affected by the layout and layout of the pcb design, including test items such as withstand voltage, insulation resistance, characteristic impedance, and circuit continuity, and the test point design should meet the test requirements. The circuit continuity test has the greatest relationship with the testability design. This test is a key test to ensure the quality of the printed board. It requires 100% logic continuity test for each printed board.


When designing the printed board, the matching between the test probe and the physical size of the test circuit that may be used during the test should be considered to avoid the error or test of the test due to the position and size error of the measured point on the printed board. The problem of poor repeatability. For destructive mechanical, physical, and chemical performance tests, test panels or attached test panels that are sampled or designed from the same batch of products are generally used, tested and evaluated according to standards, and should be familiar with test panels and attached tests during design. Board design, as well as test requirements and methods.


3: Testing of printed board assemblies

The test of the printed board assembly refers to the electrical and physical testing of the printed board after the component is mounted, and the detection method is much more complicated than the light board inspection of the printed board. The testability of the pcb assembly needs to be reviewed by technicians such as the manufacture, installation and testing of the printed board before the design begins. The review involves the visibility of the circuit pattern, the mounting density, the test operation method, and the test area. Division, special test requirements and test specifications. The testable design of the assembly includes system testability issues and should be reviewed for the system's testability functional requirements.


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