CN102183206B - Line width measuring method for line on printed circuit board (PCB) - Google Patents

Abstract

The invention discloses a line width measuring method for a line on a printed circuit board (PCB). The method comprises the following steps of: (1) determining direction of a line to be measured on the PCB to be measured and determining a movable region of a pixel wide template on the PCB to be measured; (2) translating the pixel wide template based on a step h in the direction perpendicular to the line to be measured, and calculating an edge detection function every time the pixel wide template moves a step h to obtain four maximum peak values, wherein A and B are two adjacent regions on the line to be measured; gray values of the regions A and B are shown in the specification; nA and nB are numbers of pixels at the regions A and B; SA and SB are gray variances of the regions A and B; and e is a normal number; (3) finding positions corresponding to four maximum peak values from an original drawing corresponding to the PCB to be measured so as to obtain an upper line and a lower line for line width of the line to be measured, wherein vertical distance between the upper line and the lower line is the line width. By the method, the size of the line width of the line on the PCB is automatically and precisely measured, and the measuring accuracy is high.

Description

The line width measuring method of circuit on a kind of pcb board

Technical field

The present invention relates to the circuit on a kind of pcb board, specifically the measuring method of the live width of circuit on a kind of pcb board.

Background technology

In the pcb board production run, it mainly is for the live width of operation circuit size that the live width of circuit disposed thereon is measured, and meets the electrical specification requirement to guarantee line impedance.

Along with the development of technology, the circuit on the pcb board is more and more thinner, and dense degree is more and more higher, and live width/line-spacing is by having dropped to below the 4 mil mil/4 mil mil more than the former 5 mil mil/5 mil mil.PCB manufacturing enterprise measures such as hundred times of mirrors by traditional manual detection method, and personal error is larger, can not satisfy client's precision and efficient requirement.Thereby occurred being used for the wire width measuring instrument that wiring board detects, this system carries out analyzing and processing by picture or the video of collected by camera target, obtains the actual information of detected target, have accurately, at a high speed, the characteristics of good reproducibility.Existing wire width measuring instrument system mainly obtains up and down line position information of live width by the cutting apart of image, edge extracting in conjunction with methods such as eye recognitions, and its precision generally can reach 1 pixel under fixed multiplying power, can reach 0.5 pixel by processing.All improved much although compare precision and efficient with the manual detection method, for some clients, still can not meet the demands.

Summary of the invention

The technical problem to be solved in the present invention provides the line width measuring method of circuit on a kind of pcb board, and measuring accuracy is high.

In order to solve the problems of the technologies described above, the present invention takes following technical scheme:

The line width measuring method of circuit on a kind of pcb board may further comprise the steps:

(1) determine test line direction on the pcb board to be measured, and the moving area of the wide template of definite pixel on pcb board to be measured;

(2) make the wide template of pixel along with the perpendicular direction of test line with step-length h translation, step-length h of every movement is the edge calculation detection function:

$T(A,B)=\frac{|\stackrel{\‾}{A}-\stackrel{\‾}{B}|}{\sqrt{\frac{s_A}{n_A}+\frac{s_B}{n_B}+e}},$ Draw four peak-peaks,

Wherein, A, B are two adjacent areas on the test line,

Be the gray-scale value in A, B zone, n _A, n _BBe the number of pixels in A, B zone, s _A, s _BBe the gray variance in A, B zone, e is a normal number;

(3) find four positions that peak-peak is corresponding in former figure corresponding to pcb board to be measured, draw reaching the standard grade and rolling off the production line of test line live width, the vertical range between reaching the standard grade and rolling off the production line namely is live width.

Described step (1) is to the original image of pcb board to be measured carries out image segmentation, obtains the circuit edge, test line direction and the wide template of pixel are obtained in edge screening and Hough hough conversion moving area.

Step-length h in the described step (2) is 0.1～1.2 pixel.

Measuring accuracy of the present invention is high, and measuring accuracy can reach 0.1 pixel under fixed multiplying power, only can reach 0.5 pixel and compares with existing, greatly improved precision, and the duplicate measurements precision can satisfy each level client's requirement in 1 pixel.

Description of drawings

The numerical value synoptic diagram that accompanying drawing 1 produces for the wide template translation of pixel back edge detection function among the present invention; Accompanying drawing 2 for the peak value that screens in the accompanying drawing 1 in the circuit original image, depict with tested line parallel after the synoptic diagram of line; Accompanying drawing 3 is the cross sectional representation of circuit in the accompanying drawing 2.

Embodiment

For the ease of those skilled in the art's understanding, the invention will be further described below in conjunction with drawings and Examples.

The present invention has disclosed the line width measuring method of circuit on a kind of pcb board, may further comprise the steps: (1) determines the test line direction on the pcb board to be measured, and the moving area of the wide template of definite pixel on pcb board to be measured; (2) make the wide template of pixel along with the perpendicular direction of test line with step-length h translation, step-length h of every movement is the edge calculation detection function:

$T(A,B)=\frac{|\stackrel{\‾}{A}-\stackrel{\‾}{B}|}{\sqrt{\frac{s_A}{n_A}+\frac{s_B}{n_B}+e}},$ Draw four peak-peaks,

Wherein, A, B are two adjacent areas on the test line,

Be the gray-scale value in A, B zone, n _A, n _BBe the number of pixels in A, B zone, s _A, s _BBe the gray variance in A, B zone, e is a normal number, and this constant is used for adjusting the sensitivity of functional value; (3) find four positions that peak-peak is corresponding in former figure corresponding to pcb board to be measured, draw reaching the standard grade and rolling off the production line of test line live width, the vertical range between reaching the standard grade and rolling off the production line namely is live width.Obtain the direction of test line in step (1), by the moving area that the original image to pcb board to be measured carries out image segmentation, obtains the circuit edge, test line direction and the wide template of pixel are obtained in edge screening and Hough hough conversion.In order to obtain comparatively accurate data, the step-length h that adopts during the wide template of translation pixel is 0.1～1.2 pixel.

Shown in accompanying drawing 1,2, during concrete the measurement, the wide template of pixel is being carried out translation take 1 pixel as step-length with the perpendicular line segment of test line direction, step-length of every translation is namely calculated by edge indicator function, until move to the edge of circuit, from the data that obtain, choose the peak value of four maximums.In order to obtain more accurate peak value, at the peak value place of four maximums that obtain, again take step-length as the wide template of 0.1 pixel translation pixel, near the wide template of translation pixel each peak value, further peak-peak is chosen in refinement, and then obtains more accurate four peak-peaks.In the corresponding original image of pcb board, find out four corresponding particular locations of peak-peak, the line that each peak value place does and circuit balances each other then obtains four lines, and the vertical range J between two inner lines is upper live width, article two, the vertical range K between outermost line is lower live width, as shown in Figure 3, be the cross-sectional view of accompanying drawing 2, be similar to trapezoidal, upper live width J is this trapezoidal upper base, and lower live width K is this trapezoidal going to the bottom.The measuring method that adopts the present invention to disclose, measuring accuracy is high, measuring accuracy can reach 0.1 pixel under fixed multiplying power, and existing measuring system measuring accuracy under fixed multiplying power can only reach 1 pixel, and the precision of method duplicate measurements of the present invention can be controlled in 1 pixel, according to client's different requirements, measure accordingly, can satisfy each level client's accuracy requirement.

The wide template of pixel can adopt the template that 6 pixels are wide or 4 pixels are wide.In addition, hough is transformed to existing technology, itself is not innovation of the present invention place, it is not done detailed giving unnecessary details at this.

Claims (2)

1. the line width measuring method of circuit on the pcb board may further comprise the steps:

(1) determines test line direction on the pcb board to be measured, to the moving area that the original image on this pcb board to be measured carries out image segmentation, obtains the circuit edge, test line direction and the wide template of pixel are obtained in edge screening and Hough hough conversion;

(2) make the wide template of pixel along with the perpendicular direction of test line with step-length h translation, step-length h of every movement is the edge calculation detection function:

$T(A,B)=\frac{|\stackrel{\‾}{A}-\stackrel{\‾}{B}|}{\sqrt{\frac{s_A}{n_A}+\frac{s_B}{n_B}+e}},$ Draw four peak-peaks,

Wherein, A, B are two adjacent areas on the test line, Be the gray-scale value in A, B zone, n _A, n _BBe the number of pixels in A, B zone, s _A, s _BBe the gray variance in A, B zone, e is a normal number;

(3) find four positions that peak-peak is corresponding in former figure corresponding to pcb board to be measured, draw reaching the standard grade and rolling off the production line of test line live width, the vertical range between reaching the standard grade and rolling off the production line namely is live width.

2. the line width measuring method of circuit on the pcb board according to claim 1, it is characterized in that: the step-length h in the described step (2) is 0.1～1.2 pixel.

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