CN-121977428-A - Method for measuring printed circuit board

CN121977428ACN 121977428 ACN121977428 ACN 121977428ACN-121977428-A

Abstract

The invention discloses a measuring method of a printed circuit board. The method for measuring the printed circuit board comprises the following steps of obtaining a capacitance value corresponding to one of a plurality of ideal printed circuit boards to establish standard value data, defining a plate between two conductive assemblies as a measuring object by two conductive assemblies at a selected interval on the printed circuit board to be measured, applying a test signal to the two conductive assemblies to generate a capacitance value, establishing a relative capacitance pointer according to the normalized capacitance value and the standard value data, and outputting the thickness of the measuring object according to the relative capacitance pointer.

Inventors

JIA YONGLIN
XIAO YUJIN
WANG LIANG
CHEN MEIJIA

Assignees

健鼎（无锡）电子有限公司

Dates

Publication Date: 20260505
Application Date: 20260331

Claims (6)

1. A method of measuring a printed circuit board, the method comprising the steps of: Obtaining capacitance value corresponding to one of a plurality of ideal printed circuit boards to establish standard numerical value data; Two conductive components with selected intervals on a printed circuit board to be tested are used for defining a plate between the two conductive components as a measuring object; Applying a test signal to both of the conductive elements to generate a capacitance value; establishing a relative capacitance indicator from the normalized capacitance value and the normalized value data, and And outputting the thickness of the measuring object according to the relative capacitance pointer.
2. The method for measuring a printed circuit board according to claim 1, further comprising the steps of: Capacitance measurement is carried out by a plurality of ideal printed circuit boards so as to obtain a standard capacitance value set; Calculating an average value and a standard deviation of the standard capacitance value set; Defining a normal fluctuation range of the standard numerical data according to the average value plus or minus three standard deviations, and And when the capacitance value falls outside the normal fluctuation range, judging that the measured object has abnormality at the position between the two conductive components.
3. The method for measuring a printed circuit board according to claim 1, further comprising the steps of: dividing the surface of the printed circuit board to be tested to establish a plurality of matrix areas; Measuring two adjacent measuring points in a first area in the matrix areas to obtain a first capacitance value and a second capacitance value; Measuring two adjacent measuring points in a second area in the matrix areas to obtain a third capacitance value and a fourth capacitance value; Obtaining a first local feature ratio in the first region according to the ratio of the first capacitance value to the second capacitance value, and Obtaining a second local feature ratio in the second region according to the ratio of the third capacitance value to the fourth capacitance value; Dividing the first local feature ratio with the second local feature ratio to obtain a thickness difference ratio; Outputting a relative thickness distribution profile between the first region and the second region according to the thickness difference ratio.
4. The method for measuring a printed circuit board according to claim 1, further comprising the steps of: dividing the surface of the printed circuit board to be tested to establish a plurality of matrix areas; identifying a particular region of differential capacitance measurement having minimal to zero variance among a plurality of the matrix regions; setting the specific area as a global zero-state calibration standard of the printed circuit board to be tested; And eliminating crosstalk of parasitic capacitance by using the global zero-state calibration standard.
5. The method according to claim 1, wherein the two conductive members are two alignment targets on the printed circuit board to be tested, respectively, and areas of the two alignment targets are different from each other.
6. The method of claim 1, wherein the two conductive members are two external conductive sheets, respectively, and the two external conductive sheets are disposed on opposite sides of the printed circuit board to be measured, respectively.

Description

Method for measuring printed circuit board Technical Field The present invention relates to a measuring method, and more particularly to a measuring method for a printed circuit board. Background In the current printed circuit board process, in order to monitor the lamination quality and the thickness variation of the dielectric layer, a special test structure is often designed inside the printed circuit board, and the thickness variation is reversely pushed by measuring the capacitance between the inner conductors. However, the existing measurement method of the printed circuit board must additionally reserve the space of the test structure in the design time of the circuit board, not only increases the design complexity, but also limits the measurement range between the internal conductors, so that the solder mask layer or the surface dielectric structure located outside the conductors can only participate in the fringe electric field, and the thickness of the solder mask layer or the surface dielectric structure cannot be accurately measured, and further it is difficult to quickly reflect the integral structure and the surface dielectric change of the printed circuit board in the mass production stage on the premise of not changing the design and not damaging the board. Accordingly, the present inventors considered that the above-mentioned drawbacks could be improved, and have intensively studied and combined with the application of scientific principles, and finally have proposed an invention which is reasonable in design and effectively improves the above-mentioned drawbacks. Disclosure of Invention The invention aims to provide a measuring method of a printed circuit board aiming at the defects of the prior art. The embodiment of the invention discloses a measurement method of a printed circuit board, which comprises the following steps of obtaining a capacitance value corresponding to one of a plurality of ideal printed circuit boards to establish standard value data, defining a plate between two conductive assemblies as a measurement object by two conductive assemblies at a selected interval on the printed circuit board to be measured, applying a test signal to the two conductive assemblies to generate a capacitance value, establishing a relative capacitance pointer according to the normalized capacitance value and the standard value data, and outputting the thickness of the measurement object according to the relative capacitance pointer. Preferably, the measurement method of the printed circuit board further comprises the steps of carrying out capacitance measurement by a plurality of ideal printed circuit boards to obtain a standard capacitance value set, calculating an average value and a standard deviation of the standard capacitance value set, defining a normal fluctuation range of the standard value data according to the average value plus and minus three standard deviations, and judging that the measured object has abnormality at a position between two conductive components when the capacitance value is out of the normal fluctuation range. Preferably, the method for measuring the printed circuit board further comprises the steps of dividing the surface of the printed circuit board to be measured to establish a plurality of matrix areas, measuring two adjacent measuring points in a first area of the matrix areas to obtain a first capacitance value and a second capacitance value, measuring two adjacent measuring points in a second area of the matrix areas to obtain a third capacitance value and a fourth capacitance value, obtaining a first local feature ratio in the first area according to the ratio of the first capacitance value to the second capacitance value, obtaining a second local feature ratio in the second area according to the ratio of the third capacitance value to the fourth capacitance value, dividing the first local feature ratio by the second local feature ratio to obtain a thickness difference ratio, and outputting a relative thickness distribution profile between the first area and the second area according to the thickness difference ratio. Preferably, the method for measuring the printed circuit board further comprises the steps of dividing the surface of the printed circuit board to be measured to establish a plurality of matrix areas, identifying a specific area with minimum difference to zero difference in differential capacitance measurement in the plurality of matrix areas, setting the specific area as a global zero state calibration standard of the printed circuit board to be measured, and eliminating crosstalk of parasitic capacitance by using the global zero state calibration standard. Preferably, the two conductive components are two alignment targets on the printed circuit board to be tested, and the areas of the two alignment targets are different from each other. Preferably, the two conductive components are two external conductive sheets respectively, and the two