Printed circuit board pcb and its non-destructive testing method and device

Abstract

The present invention discloses a printed circuit board (PCB) and a method and device of a lossless test thereof. The surface solder resist of the PCB is a solder resist formed by solvent-based ink solidification, a raised silk-screen ring is arranged at the position of a line to be tested at the surface solder resist, the silk-screen ring is formed by the non-solvent based ink solidification, and the inner circle of the silk-screen ring corresponds to the line to be tested and arrangement prohibit zones distributed at two sides of the line to be tested. The method comprises the following steps: adding a solder resist ink solvent in the silk-screen ring, and dissolving the solidified solder resist ink in the silk-screen ring; contacting an access test pen with the line to be tested in the silk-screen ring after the solder resist ink at the PCB surface in the silk-screen ring is dissolved to liquid state, and obtaining signals to be tested. Compared to test points generally employed in the prior art, the printed circuit board (PCB) and the method and device of the lossless test thereof can greatly reduce occupation area of test points, avoid PCB appearance damaging caused by striking off surface solder resist by using a scraper blade, and circularly perform repeat test without PCB appearance damaging.

Description

technical field [0001] The invention relates to the field of PCB signal testing, in particular to a PCB and a non-destructive testing method and device thereof. Background technique [0002] With the rapid development and popularization of smart electronic consumer products, and the development of smart electronic products towards thinner and higher density, the layout density of components in smart electronic consumer products, especially smart phone products, is also increasing. PCB (Printed Circuit Board , printed circuit board) wiring is becoming more and more dense, and the signal rate of the line on the PCB is getting higher and higher. This leads to the need to test numerous signals during the hardware testing phase. [0003] The existing PCB hardware signal testing methods mainly adopt the following two methods: [0004] A. During PCB design, reserve test points on the circuit that needs to be tested in the later stage. During the later test, touch the test point w...

AI Technical Summary

Problems solved by technology

[0007] 1. Nowadays, the circuits of smart electronic consumer products are complex, the PCB layout area is very tight, and the test points generally have a large area

It will take up valuable layout area on the PCB, and as the number of signals to be tested increases, it is unrealistic to add test points for each signal

[0008] 2. If the test point itself is not on the PCB trace signal, the test signal needs to pull a section of trace to the test point, thereby introducing the stub effect. For high-speed signals, it will cause signal reflection, distortion, and cause signal The decline in quality, or even cause the system not to work

[0009] 3. If the test point itself is on the PCB trace signal, the diameter of the test point is much wider than the trace, which will cause a sudden change in the impedance of the trace, and the parasitic capacitance of the test point itself is also large, which will cause signal reflection, ringing and other distortions. Cause the signal quality to drop, even cause the system not to work

[0010] 4. Increase PCB cost, because the surface treatment process of test points generally requires gold plating treatment, too many test points will lead to an increase in PCB cost, thereby increasing the cost of the whole machine

[0012] 1. When the engineer scrapes off the surface of the PCB with a scraper or other mechanical methods, the position of the tested line cannot be accurately determined because the line is covered by the solder mask.

[0013] 2. It is easy to scratch and break the circuit, resulting in the scrapping of the PCB as a whole

[0014] 3. When scraping off the solder mask, the line under test is easily scraped thin, and the change in the thickness of the PCB line will affect the DC resistance and characteristic impedance of the line.

The solder mask on the line is scraped off, and the environment of the PCB trace changes, which will also lead to a change in the characteristic impedance of the trace; these will cause signal distortion, cause a decrease in signal quality, and even cause the system to fail to work

[0015] 4. It is a destructive test. After the test is completed, the appearance of the PCB is severely damaged, and it cannot be shipped as a normal product, resulting in an increase in the cost of the entire product project.

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