PCB test method summary
Publisher: Administrator Date：2020-04-24
With automated test equipment becoming an integral part of the electronic assembly process, DFT (design for test) includes not only traditional hardware usage knowledge, but also knowledge of test equipment diagnostic capabilities. Testable design is not a single person's business. It is the work of a team composed of representatives from the Design Engineering Department, Side Test Engineering Department, Manufacturing Department, and Procurement Department. The design project must specify the functional products and their error requirements. The side test project must provide a strategy with the lowest cost, the least rework, and the highest possible first-pass pass rate (FPY, fast-passyield). The manufacturing department and quality department must provide input for production costs. What has been done in similar products in the past. What has not been done, and the design for the most productive improvement (DFV. Design for volume). The procurement department must provide available components. Especially reliability information. When purchasing components for on-board side-testing hardware, the testing department and the purchasing department must work together to ensure that these components are available and easy to implement. The test system is usually used as a sensor to collect historical data to achieve process improvement. This is the goal of the quality team. So these functions should be completed before any nodes are selected.
1. Parameters Before formulating the test environment policy. Preparation and understanding are critical. The parameters that influence the side test strategy include:
①Accessibility. The full access and large side test W disk is the monthly standard for designing circuit boards. Unfortunately, most design engineers believe that the accessibility of test points is a printed circuit board! PCB (PCB) less important thing.
② Board size. The design size is smaller. It mainly solves the "extra" board space of the test Yepan. When it is impossible to use the simple diagnosis of in-circuit tester (ICT), the product must be debugged by the design engineer. The situation will be another matter. If full access is not available. Test options are limited. The performance loss in high-speed design may highlight some of the functions of the castanets, but it can gradually reduce the impact on product testability.
③ Board size, number of nodes: When the size of the physical board cannot be tested in any existing equipment. This problem can be solved by increasing the budget on new equipment or using external test facilities. . When the number of nodes is larger than the existing one and the CT problem is more difficult to solve. The DFT team must understand the test methods that will allow the manufacturing department to use a small amount of time and money to produce good products. Embedded self-test, boundary scan (BS, boundary scan) and function block test can do this. Diagnosis must support the unit under test (UUT, unit under test), which can only be done through an in-depth understanding of the test methods used, existing test equipment and capabilities, and the frequency of failures in the manufacturing environment.
The DFP Rule Mountain understands the manufacturing environment, process and functional testing requirements and is enforced by the team of engineers. In the actual environment and manufacturing process It requires communication between design, computer-aided design (CAD) and side test. This repetitive work is prone to human error and is often overlooked due to the time-to-market pressure of product I. Now Industrial II has started to use automatic "manufacturability analyzers" to evaluate CAD files using DFC rules. When used by contract manufacturers (CM. Contract manufacturer), multiple sets of rules can be classified. Rule continuity and error-free product evaluation are the advantages of this method.