Rj45 male pcb connector circuit board
The quality and reliability evaluation of PCB products generally adopts the PCB or test sample used by the whole machine for the following project inspection and testing, and then is evaluated.Appearance check.
Use visual or magnifying glass to check the surface of products (raw and auxiliary materials, PCB, etc.) for abnormal appearance, such as scars, colors, contaminants, residues, obvious open circuit and short circuit, etc.
With the development of high density and refinement, AOI (automatic optical inspection machine) must be used to check the appearance of products, and even SEM (scanning electron microscopy) should be used to check and measure the micro-corrosion of copper foil surface, the oxidation treatment of inner surface, and the roughness of bore hole wall.
Microscopic section surface examination.
The metallographic microscope was used to observe whether there was any abnormality or size, such as the roughness of the hole wall, the decontamination of the hole wall, the thickness distribution and defects of the plating layer, the position and structure of the interlayer and the conditions after various aging tests.
Tool microscope, coordinate measuring instrument or all kinds of measuring tools were used to measure and evaluate the shape, hole longitude, hole position, wire width and distance, welding plate size, position relation and flatness (warping degree, deformation) of the surface.
Electrical performance testing.
Used in a variety of electrical test equipment, used for loop (line) "tong", "broken" (or "open", "short" road) test, conductor resistance (/ guide hole inner conductor connection), insulation resistance measurements (loop and loop, etc.) between layer and layer test, the electrical resistance (wires, guide hole or plated through hole) test and the voltage resistance (surface layer, between layer and layer) of the test.
Mechanical performance testing.
The peeling strength of copper foil, the peeling strength of copper plating layer (adhesion), the tensile strength, ductility, bending resistance, bending resistance, the adhesion and hardness of resistance welding agent and marking mark were tested by various test devices and tools.
Aging (lifetime reliability) test.
Various test devices are used for testing and evaluation of high and low temperature cycling resistance, heat shock resistance (gas/liquid phase, such as floating welding test), temperature and humidity cycling resistance, interconnect stress test (IST), etc.
Test and evaluation of flame resistance, solvent resistance, cleanliness, weldability, heat resistance of welding (reflux, reflux, reflux, etc.
In recent years, due to the rapid development of electronic products towards high-speed signal transmission, digitization and multi-functionalization, significant changes and progresses and diversities have taken place in the general environment and installation technology of substrate and PCB products.Therefore, the conditions and methods of testing and evaluation must be adjusted and changed accordingly.Such as fine graphics (or fine line width/span) and tiny electrode (connection plate) of bonding strength and insulating properties tests, the characteristics of thin laminated impedance control and measurement, resistance transference test, the high frequency characteristics (high frequency characteristic of substrate or gigahertz band, copper foil processing layer of insulation resistance, etc.) of the test and evaluation, the use of resonant solder heat resistance (bond strength) of the test conditions and evaluation, etc.
It is also worth noting that as the production cycle of PCB products is significantly shortened, it is increasingly important to shorten the test and evaluation time and reduce the cost of test and evaluation when carrying out reliability evaluation.Therefore, it is urgent to develop new test methods or to speed up test methods and evaluation.
The above conditions and methods of testing and evaluation will select related projects for testing and evaluation in the process of PCB production, final product and product aging (service life).
Universal needle bed testing.The grid matrix needle bed structure is tested, and each grid node is provided with gold - plated spring
Needle and spring pin holder. One end of the spring pin holder is in a circular groove so that the hard pin in the test fixture can be pushed into contact.The other end is connected to the switch circuit card.It is required that the contact pressure between the tip and the panel test point is greater than 259 grams to ensure good contact.
The grid node size has been increased by 2.The 54mm trend is 1.27mm, 0.635mm, 0.50mm, even as small as 0.30mm. The fault rate is high and has reached the limit.
Special needle bed test.Connect the test points according to the PCB with the switch circuit card, which saves the test needle bed with grid arrangement, but the special test fixture must be made.
The problem of testing limit and damage test point caused by high density also exists.
No jig test moving probe (flying pin) test.
It tested the "on" and "off" of each grid separately by two - sided moving probes (multiple pairs).Because it is tested in series, it is slower than the "parallel" test of the needle bed, but it can test the high-density PCB board.Such as BGA and mu-bga, even a small pitch of 0.30mm is adequate.But there is also the problem of bruising test point.
Universal no fixture test (UFT).The test head is staggered in an array to form a double-density test substrate.Such a high density ensures that the PCB can be tested by more than two test heads in any direction on the test platform.This test head density can be up to 11,600 test heads per square inch.At present, this method is not widely used.
Electron beam testing.This is to collect secondary emission electrons to distinguish charging and non-charging test points, so as to judge "open" and "short" roads.The steps are as follows:
Charging a test disk at a node of N network (that is, charging to a certain voltage value on N network);
Other nodes of the network are detected by the electron beam. If the node cannot test the secondary emission electron, the network is open.
At the same time, the node of N+1 network is tested. If the secondary emission electron is tested, the short circuit between N+1 network and N network is formed.
Ion beam testing.Photoelectric or laser beam testing.
In conclusion, the quality of PCB products is produced, or rather produced by quality control in the production process.PCB products are produced through many processes. Therefore, the quality of PCB products is the result of the comprehensive production quality of each production process.That is to say, the quality of PCB products is mainly determined by the worst production process, equipment and operators, which fully demonstrates the importance of PCB products in the production process.