CN101936708B - Method for positioning and detecting QFP (Quad Flat Package) chip - Google Patents

Abstract

The invention relates to a method for positioning and detecting a QFP (Quad Flat Package) chip, comprising the following steps of: a collecting and pretreating an image of the QFP chip; b extracting four extreme points of coordinate axes x and y on the contour of the QFP chip to generate a extreme quadrangle; c calculating the coarse deflection angle of the QFP chip according to the extreme quadrangle on the contour of the QFP chip; and d determining four straight lines according to the coarse deflection angle and the four extreme points, fitting edge points into four straight lines by adopting a least square method after extracting the edge point of the tail end in the length direction of a pin at each side according to the set threshold value, and finally accurately calculating the deflection angle and the central coordinate of the QFP chip, thereby accomplishing the positioning and detection of the QFP chip. The invention improves the positioning and detecting precision and speed of the QFP chip and can accurately and efficiently accomplish the positioning and detection of the QFP chip on a high-speed chip mounter.

Description

The position finding and detection method of QFP chip

Technical field

The invention belongs to the detection range of electronic devices and components, especially a kind of position finding and detection method based on COMPUTER DETECTION QFP chip.

Background technology

Along with the development of electronics manufacturing, the development of surface patch technology is more and more faster, and wherein the bearing accuracy of paster components and parts and speed are the important indicators that influences the chip mounter performance.Computer based electronic devices and components localization method has high speed, high precision and intelligentized characteristics; The flexibility and the automaticity of producing have not only been increased; And improved the intelligent and versatility of producing greatly, thereby the high-performance chip mounter all adopts the Computer Vision Detection technology to improve the paster efficient of chip mounter.

The computer vision localization method of electronic devices and components comprises template matching method and centroid method etc. in traditional chip mounter; Wherein the bearing accuracy of template matching method is higher, but complex algorithm, and the speed of images match is slower; Though and latter's locating speed is fast, bearing accuracy is not high.Do not have a kind of general calculation machine vision localization detection method all obtaining comparatively ideal effect aspect detection speed and the precision at present yet, thereby select targetedly to the characteristics of components and parts itself that position finding and detection method is a kind of comparatively scheme of reality for use.The QFP chip is the most common electronic devices and components; Owing to there is one section bending in the QFP chip pin; And the gray scale of QFP chip pin corresponding region is inconsistent in the image that obtains; Make in the QFP chip image after profile extracts that the phenomenon of QFP chip pin fracture occurs, the detection of QFP chip position and the defective of pin are brought very big difficulty to analysis simultaneously; And the method for utilizing directional expansion to repair pin detects the QFP chip, often is discontented with full border application requirements because of long, inefficiency consuming time.Therefore, the chip mounter Computer Vision Detection System presses for the position finding and detection method of a kind of high speed, high-precision QFP chip.

Summary of the invention

The objective of the invention is: the position finding and detection method that the QFP chip that a kind of locating speed is fast, bearing accuracy is high is provided.

In order to achieve the above object, technical scheme of the present invention is: a kind of position finding and detection method of QFP chip, and its step comprises:

A, step 1 are the IMAQ and the image pre-service of QFP chip:

Gather the image of QFP chip with video camera and image pick-up card, and send into computing machine to the image of the QFP chip that collects and carry out the image pre-service, obtain the image (m * n) of the pretreated QFP chip of image;

B, step 2 are structure limit quadrilateral:

(m * n) carry out area dividing promptly is divided into left field [0, m/4] and right side area [3m/4 by the x coordinate with the image of the pretreated QFP chip of image in the step 1; M-1]; Be divided into upper-side area [0, n/4] and underside area [3n/4, n-1] by the y coordinate; Above-mentioned four zones are designated as area I, area I I, area I II and area I V respectively, in area I and area I I, extract the x coordinate minimum point L (X of the profile of QFP chip then respectively _Min, Y _L) and maximum of points R (X _Max, Y _R), in area I II and area I V, extract the y coordinate minimum point U (X of the profile of QFP chip respectively _U, Y _Min) and maximum of points B (X _B, Y _Max), four extreme points are connected in turn by the order of U → R → B → L generates limit quadrilateral URBL;

C, step 3 are for calculating the rough deflection angle θ of QFP chip:

(c ₁), when the QFP chip does not deflect, go out limit quadrilateral U according to method construct in the step 2 ₀R ₀B ₀L ₀,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₀R ₀B ₀L ₀In limit U ₀R ₀Deflection angle θ with the x coordinate axis ₀, if the QFP chip is of a size of

, the first last pin of QFP chip homonymy is w along the ultimate range between the Width outermost edges of pin, then ${\mathrm{\θ}}_0=\mathrm{Arctg}\frac{l-w}{2l+w};$

(c2), when the QFP chip deflects, go out limit quadrilateral U according to method construct in the step 2 ₁R ₁B ₁L ₁,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₁R ₁B ₁L ₁In limit U ₁R ₁Angle with the x coordinate axis

Calculate the rough deflection angle θ=θ of QFP chip thus ₁-θ ₀

D, step 4 are had a few by the terminal edge line of each pin that extracts four sides in the image of the pretreated QFP chip of image in step 1; And all points that extract are carried out match; Obtain four straight-line equations; And calculate the accurate deflection angle θ ' and the centre coordinate (X, Y) of QFP chip by straight-line equation, thereby accomplish the detection and localization of QFP chip;

In the position finding and detection method of above-mentioned QFP chip, four straight-line equations in the said step 4 are according to limit quadrilateral U in the step 3 ₁R ₁B ₁L ₁Four extreme point U ₁, R ₁, B ₁, L ₁Confirm that with the rough deflection angle θ of QFP chip promptly four straight-line equations are respectively:

The upside straight line $L_{U_1}:$ $y=k_{U_1}(x-X_{U_1})+Y_{\mathrm{Min}},$

The downside straight line $L_{B_1}:$ $y=k_{B_1}(x-X_{B_1})+Y_{\mathrm{Max}},$

The left side straight line $L_{L_1}:$ $y=k_{L_1}(x-X_{\mathrm{Min}})+{\mathrm{<figure-callout\; id="1"\; label="Y\; L"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">Y</figure-callout>}}_{L_{}},$

The right side straight line $L_{R_1}:$ $y=k_{R_1}(x-X_{\mathrm{Max}})+Y_{R_1};$

Wherein, ${\mathrm{<figure-callout\; id="1"\; label="k\; U"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{U_{}}={\mathrm{<figure-callout\; id="1"\; label="k\; B"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{B_{}}=\mathrm{Tan}\mathrm{\&theta;},$ ${\mathrm{<figure-callout\; id="1"\; label="k\; R"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{R_{}}={\mathrm{<figure-callout\; id="1"\; label="k\; L"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{L_{}}=-1/\left(\mathrm{Tan}\mathrm{\&theta;}\right),$ And setting threshold δ if the point of QFP chip pin stub area arrives the distance of one's respective area straight line less than δ, then is stored in this point in the set on computers, forms the set omega of the terminal point of four QFP chip pins respectively _i(i=1,2,3,4),

, opposite side slope equal relation reciprocal each other according to the adjacent both sides of rectangle slope obtain set omega _iThe quadratic sum of each point fitting a straight line distance to the corresponding region is in (i=1,2,3,4):

$D=\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{(y_{1j}-{\mathrm{kx}}_{1j}-b_{U_1})}^2+\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{(x_{2j}+{\mathrm{ky}}_{2j}-b_{R_1})}^2+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}{(y_{3j}-{\mathrm{kx}}_{3j}-b_{B_1})}^2+\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}{(x_{4j}+{\mathrm{ky}}_{4j}-b_{L_1})}^2$

According to least square method; Can get D to k; The partial derivative of

equals zero respectively, and the intercept

of trying to achieve slope k and every limit correspondence thus finally obtains four straight-line equations of match;

In the position finding and detection method of above-mentioned QFP chip, (X is the intersection point of finding the solution four straight lines earlier with accurate deflection angle θ ' Y), and the coordinate that obtains intersection point then is respectively (X to calculate the centre coordinate of QFP chip according to four straight-line equations in the said step 4 ₁, Y ₁), (X ₂, Y ₂), (X ₃, Y ₃), (X ₄, Y ₄), and the position coordinates of calculating the QFP chip according to four intersection points is following:

θ '=arctan (k).

In the position finding and detection method of above-mentioned QFP chip; Also comprise whether detect the QFP pin of chip has deflection and fracture after the said step 4; Be about to the QFP chip and rotate counterclockwise θ ',, generating straight line apart from the terminal inboard pin length of pin 1/3 position along the length direction of pin respectively to the pin of four sides of QFP chip; The profile of statistics pin and the logarithm of this straight-line intersection on rectilinear direction; The logarithm of the intersection point of gained is the number of pin, calculates the interval S of two adjacent leads of homonymy in the QFP chip four side pins then, and compares through the standard pin width of computing machine with adjacent leads interval S of calculating and QFP chip; Differentiate pin and whether have deflection and fracture, thereby accomplish the SHAPE DETECTION of QFP chip.

In the position finding and detection method of above-mentioned QFP chip, the image pre-service of said step 1 comprises that the profile of filtering, threshold segmentation and QFP chip strengthens.

Compared with prior art, the good effect that the present invention had is:

(1) locating speed is fast: the conventional positioning method adopts the method for template matches; Not only method is complicated; And can not satisfy the chip mounter requirement simultaneously aspect coupling accuracy and the positioning accuracy; And the position finding and detection method of the QFP chip that the present invention proposes not only detection method is simple; And by constructing the coarse positioning of limit quadrangle realization chip; Significantly reduce detection time, can realize the quick location of QFP chip;

(2) position detection accuracy is high: the present invention is behind structure limit quadrilateral, and the match of carrying out four straight lines when adopting least square method has fully guaranteed bearing accuracy, under the prerequisite that guarantees detection speed, can reach the higher detection precision again;

(3) wide adaptability: different with general localization method; The detection method that the present invention proposes proposes position finding and detection method to the features of shape of QFP chip itself; This method also can be promoted in the detection and localization of other chips, makes corresponding method for detecting position according to its features of shape.

Description of drawings

Fig. 1 is the process flow diagram of the position finding and detection method of QFP chip;

Fig. 2 carries out pretreated image for the image to the QFP chip that collects;

Fig. 3 is for carrying out the synoptic diagram of area dividing to the image of the pretreated QFP chip of image among Fig. 2;

Fig. 4 extracts the tetragonal synoptic diagram of limit when not deflecting for the QFP chip;

When deflecting for the QFP chip, extracts Fig. 5 the tetragonal synoptic diagram of limit;

Fig. 6 is for carrying out the synoptic diagram of fitting a straight line to the image of the pretreated QFP chip of image;

The synoptic diagram that Fig. 7 detects for the QFP chip form.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed description.

A kind of position finding and detection method of QFP chip, its step comprises:

A, step 1 are the IMAQ and the image pre-service of QFP chip:

Gather the image of QFP chip with high-speed camera and image pick-up card; And send into computing machine to the image of the QFP chip that collects and carry out the image pre-service; Obtain the image (m * n) of the pretreated QFP chip of image; Wherein, the image pre-service comprises that the profile of filtering, threshold segmentation and QFP chip strengthens;

B, step 2 are structure limit quadrilateral:

(m * n) carry out area dividing promptly is divided into left field [0, m/4] and right side area [3m/4 by the x coordinate with the image of the pretreated QFP chip of image in the step 1; M-1], be divided into upper-side area [0, n/4] and underside area [3n/4 by the y coordinate; N-1]; Above-mentioned four zones are designated as area I, area I I, area I II and area I V respectively, detect the minimum point U of y coordinate axis then at area I II, detect the maximum point R of x coordinate axis at area I I; At the maximum point B of area I V detection y coordinate axis, detect the minimum point L of x coordinate axis in area I;

To the U point, when a plurality of y occurring _MinDuring the pixel of value, get the point of the minimum of x value wherein; To the R point, when a plurality of x occurring _MaxDuring the pixel of value, get the point of the minimum of y value wherein; To the L point, when a plurality of y occurring _MaxDuring the pixel of value, get the point of the maximum of x value wherein; To the B point, when a plurality of x occurring _MinDuring the pixel of value, get the point of the maximum of y value wherein;

In area I and area I I, extract the x coordinate minimum point L (X of the profile of QFP chip then respectively _Min, Y _L) and maximum of points R (X _Max, Y _Min), in area I II and area I V, extract the y coordinate minimum point U (X of the profile of QFP chip respectively _U, Y _Min) and maximum of points B (X _B, Y _Max), four extreme points are connected in turn by the order of L → B → U → R generates limit quadrilateral URBL;

In the position finding and detection method of QFP chip of the present invention, according to image processing method the normal upper left corner coordinate system that adopts, be positive number along the direction of X axle arrow coordinate, the direction of y axle arrow coordinate.

C, step 3 are for calculating the rough deflection angle θ of QFP chip:

(c ₁), when the QFP chip does not deflect, go out limit quadrilateral U according to method construct in the step 2 ₀R ₀B ₀L ₀,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₀R ₀B ₀L ₀In limit U ₀R ₀Deflection angle θ with the x coordinate axis ₀, if the QFP chip is of a size of

, the first last pin of QFP chip homonymy is w along the ultimate range between the Width outermost edges of pin, then ${\mathrm{\&theta;}}_0=\mathrm{Arctg}\frac{l-w}{2l+w};$

(c2), when the OFP chip deflects, go out limit quadrilateral U according to method construct in the step 2 ₁R ₁B ₁L ₁,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₁R ₁B ₁L ₁In limit U ₁R ₁Angle with the x coordinate axis

Calculate the rough deflection angle θ=θ of QFP chip thus ₁-θ ₀

D, step 4 are had a few by the terminal edge line of each pin that extracts four sides in the image of pretreated QFP chip in step 1; And all points that extract are carried out match; Obtain four straight-line equations, and by straight-line equation calculate the QFP chip deflection angle θ and centre coordinate (X, Y); Thereby accomplish the detection and localization of QFP chip, four straight-line equations in the said step 4 are to shake according to limit quadrilateral U in the step 3 ₁R ₁B ₁L ₁Four extreme point U ₁, R ₁, B ₁, L ₁Confirm that with the rough deflection angle θ of QFP chip promptly four straight-line equations are respectively:

The upside straight line $L_{U_1}:$ $y=k_{U_1}(x-X_{U_1})+Y_{\mathrm{Min}},$

The downside straight line $L_{B_1}:$ $y=k_{B_1}(x-X_{B_1})+Y_{\mathrm{Max}},$

The left side straight line $L_{L_1}:$ $y=k_{L_1}(x-X_{\mathrm{Min}})+{\mathrm{<figure-callout\; id="1"\; label="Y\; L"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">Y</figure-callout>}}_{L_{}},$

The right side straight line $L_{R_1}:$ $y=k_{R_1}(x-X_{\mathrm{Max}})+Y_{R_1};$

Wherein, ${\mathrm{<figure-callout\; id="1"\; label="k\; U"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{U_{}}={\mathrm{<figure-callout\; id="1"\; label="k\; B"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{B_{}}=\mathrm{Tan}\mathrm{\&theta;},$ ${\mathrm{<figure-callout\; id="1"\; label="k\; R"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{R_{}}={\mathrm{<figure-callout\; id="1"\; label="k\; L"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">k</figure-callout>}}_{L_{}}=-1/\left(\mathrm{Tan}\mathrm{\&theta;}\right),$ And setting threshold δ if the point of QFP chip pin stub area arrives the distance of one's respective area straight line less than δ, then is stored in this point in the set on computers, forms the set omega of the terminal point of four QFP chip pins respectively _i(i=1,2,3,4),

, opposite side slope equal relation reciprocal each other according to the adjacent both sides of rectangle slope obtain set omega _iThe quadratic sum of each point fitting a straight line distance to the corresponding region is in (i=1,2,3,4):

$D=\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{(y_{1j}-{\mathrm{kx}}_{1j}-b_{U_1})}^2+\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{(x_{2j}+{\mathrm{ky}}_{2j}-b_{R_1})}^2+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}{(y_{3j}-{\mathrm{kx}}_{3j}-b_{B_1})}^2+\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}{(x_{4j}+{\mathrm{ky}}_{4j}-b_{L_1})}^2$

According to least square method; Can get D to k; The partial derivative of

equals zero respectively, obtains following system of equations:

, opposite side slope equal relation reciprocal each other according to the adjacent both sides of rectangle slope obtain set omega _iThe quadratic sum of each point fitting a straight line distance to the corresponding region is in (i=1,2,3,4):

$D=\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{(y_{1j}-{\mathrm{kx}}_{1j}-b_{U_1})}^2+\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{(x_{2j}+{\mathrm{ky}}_{2j}-b_{R_1})}^2+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}{(y_{3j}-{\mathrm{kx}}_{3j}-b_{B_1})}^2+\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}{(x_{4j}+{\mathrm{ky}}_{4j}-b_{L_1})}^2$

According to least square method; Can get D to k; The partial derivative of

equals zero respectively, obtains following system of equations:

$\left\{\begin{array}{c}k(\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{x}_{1j}^2+\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{y}_{2j}^2+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}{x}_{3j}^2+\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}{y}_{4j}^2)-(\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{x}_{1j}(y_{1j}-b_{U_1})-\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{x}_{2j}(y_{2j}-b_{R_1})+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}{x}_{3j}(y_{3j}-b_{B_1})-\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}{x}_{4j}(y_{4j}-b_{L_1}))=0\\ {\mathrm{<figure-callout\; id="1"\; label="b\; U"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">b</figure-callout>}}_{U_{}}+\underset{j=1}{\overset{n_1}{\mathrm{\&Sigma;}}}({\mathrm{kx}}_{1j}-y_{1j})=0\\ b_{R_1}-\underset{j=1}{\overset{n_2}{\mathrm{\&Sigma;}}}(x_{2j}+{\mathrm{ky}}_{2j})=0\\ {\mathrm{<figure-callout\; id="1"\; label="b\; B"\; filenames="HSA00000229277500021.png,HSA00000229277500022.png"\; state="\{\{state\}\}">b</figure-callout>}}_{B_{}}+\underset{j=1}{\overset{n_3}{\mathrm{\&Sigma;}}}({\mathrm{kx}}_{3j}-y_{3j})=0\\ b_{L_1}-\underset{j=1}{\overset{n_4}{\mathrm{\&Sigma;}}}(x_{4j}+{\mathrm{ky}}_{4j})=0\end{array}\right.$

Find the solution the value that draws the corresponding intercept

in slope k and every limit behind the above-mentioned equation respectively, finally can get the equation of four straight lines of match;

(X is the intersection point of finding the solution four straight lines earlier with accurate deflection angle θ ' Y), and the coordinate that obtains intersection point then is respectively (X to calculate the centre coordinate of QFP chip according to four straight-line equations in the said step 4 ₁, Y ₁), (X ₂, Y ₂), (X ₃, Y ₃), (X ₄, Y ₄), and the position coordinates of calculating the QFP chip according to four intersection points is following: $X=\left(\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}{X}_i\right)/4,$ $Y=\left(\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}{Y}_i\right)/4,$ θ '=arctan (k);

Comprise also after the e, said step 4 whether detect the QFP pin of chip has deflection and fracture; Be about to the QFP chip and rotate counterclockwise θ '; Be directed against the pin of four sides of QFP chip respectively; Length direction along pin is generating straight line apart from the terminal inboard pin length of pin 1/3 position, the profile of statistics pin and the logarithm of this straight-line intersection on rectilinear direction, and the logarithm of the intersection point of gained is the number of pin; Calculate the interval S of two adjacent leads of homonymy in the QFP chip four side pins then; And compare through the standard pin width of computing machine with adjacent leads interval S of calculating and QFP chip, differentiate pin and whether have deflection and fracture, thereby accomplish the SHAPE DETECTION of QFP chip.

The position finding and detection method of QFP of the present invention simply, not only locating speed is fast, and precision is high.

Claims (3)

1. the position finding and detection method of a QFP chip, it is characterized in that: its step comprises:

A, step 1 are the IMAQ and the image pre-service of QFP chip:

Gather the image of QFP chip with video camera and image pick-up card, and send into computing machine to the image of the QFP chip that collects and carry out the image pre-service, obtain the image (m * n) of the pretreated QFP chip of image;

B, step 2 are structure limit quadrilateral:

(m * n) carry out area dividing promptly is divided into left field [0, m/4] and right side area [3m/4 by the x coordinate with the image of the pretreated QFP chip of image in the step 1; M-1]; Be divided into upper-side area [0, n/4] and underside area [3n/4, n-1] by the y coordinate; Above-mentioned four zones are designated as area I, regional II, area I II and regional IV respectively, in area I and regional II, extract the x coordinate minimum point L (X of the profile of QFP chip then respectively _Min, Y _L) and maximum of points R (X _Max, Y _R), in area I II and regional IV, extract the y coordinate minimum point U (X of the profile of QFP chip respectively _U, Y _Min) and maximum of points B (X _B, Y _Max), four extreme points are connected in turn by the order of U → R → B → L generates limit quadrilateral URBL;

C, step 3 are for calculating the rough deflection angle θ of QFP chip:

(c ₁), when the QFP chip does not deflect, go out limit quadrilateral U according to method construct in the step 2 ₀R ₀B ₀L ₀,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₀R ₀B ₀L ₀In limit U ₀R ₀Deflection angle θ with the x coordinate axis ₀, if the QFP chip is of a size of

The first last pin of QFP chip homonymy is w along the ultimate range between the Width outermost edges of pin, then

(c ₂), when the QFP chip deflects, go out limit quadrilateral U according to method construct in the step 2 ₁R ₁B ₁L ₁,, calculate the limit quadrilateral U of formation according to the geometric position of QFP pin of chip ₁R ₁B ₁L ₁In limit U ₁R ₁Angle with the x coordinate axis

Calculate the rough deflection angle θ=θ of QFP chip thus ₁-θ ₀

D, step 4 are had a few by the terminal edge line of each pin that extracts four sides in the image of the pretreated QFP chip of image in step 1; And all points that extract are carried out match; Obtain four straight-line equations; And calculate the accurate deflection angle θ ' and the centre coordinate (X, Y) of QFP chip by straight-line equation, thereby accomplish the detection and localization of QFP chip;

Four straight-line equations in the said step 4 are according to limit quadrilateral U in the step 3 ₁R ₁B ₁L ₁Four extreme point U ₁, R ₁, B ₁, L ₁Confirm that with the rough deflection angle θ of QFP chip promptly four straight-line equations are respectively:

The upper line?

Lower line?

Left straight?

Right side of the line?

Wherein,

And setting threshold δ if the point of QFP chip pin stub area arrives the distance of one's respective area straight line less than δ, then is stored in this point in the set on computers, forms the set omega of the terminal point of four QFP chip pins respectively _i(i=1,2,3,4),

, opposite side slope equal relation reciprocal each other according to the adjacent both sides of rectangle slope obtain set omega _iThe quadratic sum of each point fitting a straight line distance to the corresponding region is in (i=1,2,3,4):

According to least square method; Can get D to k; The partial derivative of

equals zero respectively, and the intercept

of trying to achieve slope k and every limit correspondence thus finally obtains four straight-line equations of match;

(X is the intersection point of finding the solution four straight lines earlier with accurate deflection angle θ ' Y), and the coordinate that obtains intersection point then is respectively (X to calculate the centre coordinate of QFP chip according to four straight-line equations in the said step 4 ₁, Y ₁), (X ₂, Y ₂), (X ₃, Y ₃), (X ₄, Y ₄), and the position coordinates of calculating the QFP chip according to four intersection points is following:

θ '=arctan (k).

2. the position finding and detection method of QFP chip according to claim 1; It is characterized in that: also comprise whether detect the QFP pin of chip has deflection and fracture after the said step 4; Be about to the QFP chip and rotate counterclockwise θ ',, generating straight line apart from the terminal inboard pin length of pin 1/3 position along the length direction of pin respectively to the pin of four sides of QFP chip; The profile of statistics pin and the logarithm of this straight-line intersection on rectilinear direction; The logarithm of the intersection point of gained is the number of pin, calculates the interval S of two adjacent leads of homonymy in the QFP chip four side pins then, and compares through the standard pin width of computing machine with adjacent leads interval S of calculating and QFP chip; Differentiate pin and whether have deflection and fracture, thereby accomplish the SHAPE DETECTION of QFP chip.

3. the position finding and detection method of QFP chip according to claim 1 is characterized in that: the image pre-service of said step 1 comprises that the profile of filtering, threshold segmentation and QFP chip strengthens.

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