CN1318839C - Automatic optical detecting system for blemish assembly on printed circuit board - Google Patents

Automatic optical detecting system for blemish assembly on printed circuit board Download PDF

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Publication number
CN1318839C
CN1318839C CNB021538298A CN02153829A CN1318839C CN 1318839 C CN1318839 C CN 1318839C CN B021538298 A CNB021538298 A CN B021538298A CN 02153829 A CN02153829 A CN 02153829A CN 1318839 C CN1318839 C CN 1318839C
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pcb
image
flaw
assembly
printed circuit
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CNB021538298A
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Chinese (zh)
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CN1504742A (en
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彭德保
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威光机械工程股份有限公司
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Abstract

The present invention relates to an automatic optical detection system of flaw components on a printed circuit board, which comprises three units of operating system architecture, actual practice identification, classification detection, etc. The system architecture unit establishes software architecture, hardware architecture, and an automatic positioning printed circuit board by the hardware architecture, retrieves images to a computer, and establishes the data of a standard package, a virtual image reference moulding board, a standard detection board, an on-line detection program, a component flaw, etc. by the software architecture, which can supply for establishing component standard detection value and relevant environmental parameters during the off-line operation, and supply for detecting component flaw states on the printed circuit board during the production on-line operation; the actual practice identification unit utilizes a figure comparison method or a normalization related coefficient method to carry out the operation of identification and calibration; the classification detection unit carries out classification calculation for the components on the printed circuit board carried out identification and calibration so as to accurately detect and obtain the flaw components comprising short item, deflection, polarity reverse, bridge connection, too big or too small soldering quantity, etc.

Description

The automatic optical detection method of flaw assembly on the printed circuit board (PCB)

Technical field

The automatic optical detecting system of flaw assembly on a kind of printed circuit board (PCB) of the present invention, be specially adapted on the assembly line of printed circuit board (PCB), too much or very little wait the designed detection system of flaw phenomenon in order to detect common or expected assembly Short Item, crooked, the pole reversal, bridge joint, soldering amount.

Background technology

In the streets, no matter be printed circuit board (PCB) (Printed Circuit Board, abbreviation PCB), surface mount design (Surface Mounting Design, be called for short SMD) or surface mount processing procedure (SurfaceMounting Technology, abbreviation SMT) machines of usefulness, its product commercialization degree is all quite high.With regard to the machines with surface mount design (SMD) usefulness, but the test item of each product is roughly the same, and the difference of product then is speed and some specific function (for example the stereoscopic vision at solder joint detects).Now inciting somebody to action at present in the streets, the detection board characteristic of surface mount design (SMD) usefulness is summarized as follows:

1. test item: surface mount design (SMD) in the streets detects, and has developed one not very short period, and therefore to so far, various boards institute can not have too big variation by test item; Coherent detection project at components comprises: Short Item, crooked, gravestone, polarity, displacement etc.The relevant test item of solder joint comprises: WU is too much, WU is very few, bridge joint, WU hole, the perk of WU pin etc.In addition on the IC text-recognition, tend to use optical characteristics to confirm (Optical Characteristic Verification, be called for short OCV) but not traditional optical characteristic identification (Optical Characteristic Recognition, be called for short OCR), on the one hand may be because the degree of fragmentation of literal as a result of laser beam marking is too high, the printed words of IC mint-mark all are expected results on the other hand, as long as therefore can judge the mint-mark correctness.

2. travel mechanism: in the streets surface mount design (SMD) is with twin shaft microscope carrier (X-YTable) design that detects on the board, its mode is variation quite, such as design load charge-coupled device (Charge CoupledDevice is arranged, be called for short CCD, or title image vision device) with the mobile person of light source, or the mobile person of design (calculated) load printed circuit board (PCB) (PCB) arranged, also have load Charged Coupled Device (CCD) along X-axis move and simultaneously load printed circuit board (PCB) (PCB) along the moving person of y-axis shift, if but then move based on printed circuit board (PCB) (PCB) with the detection board that speed is attached most importance to.

3. capture mechanism: in the streets in order to strengthen surface mount design (SMD) sensing range with pick-up unit, the resolution that detects the charge-coupled device (CCD) of usefulness also constantly promotes.Numeral rolls up with the application of colored charge-coupled device (CCD) in addition; Color information has to a certain degree lifting to detecting effect, and the obtained image quality of digital charge-coupled device (CCD) just than analog be good, also have the dealer to be known as the digital focus function of its product, can make testing result not be subjected to the influence of component height.

4. light source: in the streets the dealer have light-source system is considered as trade secret and light sources with whole the wrapping of charge-coupled device (CCD), but very simple detection board that uses white annular daylight lamp arranged also.Light emitting diode (Light Emitting Diode, LED) light source has become the optimal selection of more detection board because stable, but form of light source then has annular, square, matrix to cooperate many kinds such as refracting telescope to change.Most light sources that detect board are fundamental purpose with even illumination, and less seeing switched Different Light to obtain how various image information person.

Aspect the machines of the surface mount design (SMD) of using visible light, developing direction is detecting general contingent fault phenomenon, and requires higher speed and lower False Rate.And the SMD vision-based detection can't use the algorithm of too complex, but suitably uses with general rudimentary algorithm commonly used.

And know in the streets dealer and products thereof the function (as shown in Table 1) of the existing SMT of manufacturing machines, generally acknowledge that wherein the automatic optical detecting system (being called for short AOI) of Israel's design is that the whole world is the strongest:

Manufacturer Product function Orbotech (the high agency of Israel's skill) (each measuring ability project is asked for an interview the 4th page of explanation) ■ function (a.b.c.d.e.f.h.i.) ■ 5 or 13 CCD, the X of xenon flash lamp optical ring illumination ■ assembly, the positional accuracy of Y and θ is measured, and assembly is misplaced (OCV), empty weldering, short circuit, the IC pin sticks up empty weldering, the paste solder printing shortcoming of bubble (wave-soldering) ■ 2D: tin is not molten, tin point planarization, lack tin, tin cream is stained to scatter, space, the bad crack of printing precision 2.5D paste solder printing shortcoming: paste solder printing THICKNESS CONTROL standard TERADYNE (U.S.) ■ function (a.b.d.g.f.h.)

5 CCD of ■, led light source ■ plug-in unit pin flaw Sony (Japanese Jian Taifeng, the woods electricity world) ■ appearance inspection machine (Solder Paste Inspection Machine) high de-agglomeration energy. check at a high speed; Resolution ratio: vertical 29um * horizontal 24um ■ utilizes image that the upside illumination obtains and horizontal side illumination to obtain image and does calculation, detects the printing state of tin cream on the substrate Omron (Ri Benwenhui agency) ■ function (a.d.f.) ■ OCR: once can read 32 characters, need not to login character code storehouse ■ rosin joint, ball bonding HIROX (the high agency of Japanese Supreme Being's bodyguard) ■ 3D rotation inspection system (the QC laboratory is used) Samsung (Korea S letter black horse, put down into the agency) ■ PCB detects MVP (Mei Guo Xi agate agency) ■ AOI/ automated optical part inspection machine CYBEROPTICS (agency of U.S. thunder section) ■ function (a.b.c.d.e.f.g.h.i.) ■ OCV Agilent (Dublin, Ireland Tai Wangang builds the agency) ■ function (a.c.d.e.f.g.h.) ■ OCR, OCV ■ 2D tin detect: tin is thick, position, tin amount De Lv (Tianwan businessman) ■ is anti-white for ■ function (a.b.c.d.e.f.g.h.), the golden finger surface blemish, the surperficial scratch ■ plate of pcb board is curved, plate sticks up, software automatic revisal ■ special light sources and CCD Camera compensate function automatically Utechzone Co., Ltd (Tianwan businessman) The naked version of ■ PCB detects, BGA detects Changyu Xinye Co., Ltd ■ LED brightness and wavelength detect Guwei Electronic Industry Co., Ltd ■ detects the assembling circuit version The prompt semiconductor science and technology in east ■ checks that PCB, BGA flaw ■ check TFT LCD face version flaw

Burger scientific ﹠ technical corporation ■ PCB surface blemish detects, BGA detects the disconnected pin detection system ■ micron order Precision Position Location System of ■ IC Triumphant man of virtue and ability Science and Technology Co., Ltd. (Tianwan businessman) ■ IN-LINE vision testing machine, PCB test macro The functional item symbol description that table is right: (e.) (a.) (f.) (b.) (g.) pin displacement of mistake (wrong) of Xi Qiao (solder bridge) of Short Item (part missing) of polarity (polarity)/bending (leads floating/bend) (c.) crooked (misalignment) (h.) tin very few/too much (solder lack/excess) (d.) (i.) seam quality (joint quality) of gravestone (tombstone)

Table one: dealer of manufacturing SMT machines and products thereof function ratio

Summary of the invention

The automatic optical detecting system automatic optical detecting system that the purpose of this invention is to provide flaw assembly on a kind of printed circuit board (PCB) (is called for short AOI,) be the software architecture starting stage of the present invention with the conventional art difference in system architecture, novel and distinguished three-layer type framework have promptly been cooked up, comprise A program (A-Prog.), B program (B-Prog.) and c program (C-Prog.), this three-tier architecture has bigger use elasticity, and all can distinguish independent execution, its major advantage is described below:

1.A program (A-Prog.): be to supply with the design end to set up the standard package database, can increase standard package newly or revise the detected parameters of having set up standard package in the database.By this, the component database guardian of design end can set detectable flaw kind to this standard package, and selects detection method at various flaw kinds.Simultaneously, high because printed circuit board (PCB) (PCB) is gone up the repeatability of assembly, so each assembly only need set up the standard package database that standard picture is stored in A program (A-Prog.), and just reusable afterwards, save the training activity duration.

2.B program (B-Prog.): be supply with sell or use side in the component blocks selection operation mode of suitable intuition, finish the setting of detection components position and test item, and can set up the detection data of this standard detection plate at each different order, carry out the detection of printed circuit board (PCB) (PCB) by the gross for trace routine on the line.

3.C program (C-Prog.): be to supply with use side on production line, to operate, in the time of particularly often will changing the printed circuit board (PCB) (PCB) of single different configurations of production (layout), c program (C-Prog.) as long as call out the detection data that this printed circuit board (PCB) (PCB) is finished in B program (B-Prog.), just can detect when changing list immediately by the gross.

The present invention can comply with the variation of industry, comprising:

1. at components; Because manufacture of semiconductor is constantly improved, the volume of assembly is also more and more littler, and the assembly of PCB storing density also improves simultaneously, and the present invention can be accompanied by the lifting of CCD resolution, and is overcome.There is the part assembly to use also can the arrange in pairs or groups detection technique (as X-ray) of tool penetrability or the stereoscopic vision scheme of many camera lenses of the encapsulation technology (as BGA etc.) of new development, the present invention to solve in addition.

2. in the PCB industry: the at present main developing direction of the present invention is for detecting products such as the motherboard that uses among the PC, interface card, if this series products future development is to saturated dead state, then detecting gordian technique, still to can be applicable to many other be on the emerging product of framework, as mobile phone, PDA etc. with PCB.

3. in wafer package industry: bearing of trend of the present invention is the detectability of small scale more, with high-rate lens and the capture of line style scan-type video camera, cooperate the full-fledged algorithm of leading portion, can shorten the whole development time-histories, set up the detection board that is fit to wafer package industry (BGA, wire bonding) fast.

In addition, developing goal of the present invention is that expectation can replace the artificial visual detection, and strengthens the quality and the speed of detection.And can an automatic optical detecting system successful, and most important key component is the exploitation of detection algorithm.The purpose of detection algorithm is the test item at different assemblies, extracts representative feature pointer value and set suitable judgement rule from detected image, detects to judge whether target is non-defective unit or defective products.And good detection algorithm except need have good detection effect, also to pursue minimum calculation complexity; The low more then computing velocity of complexity is fast more, and this algorithm also greatly improves in industrial practicality.Detection algorithm used in the present invention, it is the module diagnostic of observing earlier in the detected image, with succinct algorithm applied in any combination in addition, manage characteristics of image is quantified as pointer value, after detected image (comprising non-defective unit and the defective products) experiment via some, determine the judgement rule of non-defective unit/defective products again.

In order clearly to obtain the characteristics of image of assembly, also must there be suitable light-source system to assist capture.The function of light-source system not only provides enough illuminations to obtain image, more will further can highlight the feature of assembly.The kind of light-source system is very various, even the light source of single kind also can have the variation of many forms; The AOI system needs the light-source system that can cooperate various detection algorithms, just good detection effect can be arranged.The present invention will design a cover suitable detection algorithm and the available program control light-source system of collocation mutually simultaneously, be applicable to the detection board that detects every different assembly flaws to develop.

Range of application of the present invention and field include:

(1) the accurate running fix of .CCD

(2). the automatic collocation control of detection algorithm and light-source system

(3) every Defect Detection of last assembly of .PCB such as pellet resistance (Resistor), flaky electric capacity (Capacitor), small-sized outer pin (SOP) and quad-flat-pack integrated circuit (QFP), listed as table two:

(not having this defective in the part table processing procedure of space takes place)

Table two: be that the present invention can detect assembly kind and the defective item thereof on the PCB

The present invention is described in detail below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the hardware structure synoptic diagram of detection system of the present invention;

Fig. 2 is the software architecture synoptic diagram of detection system of the present invention;

Fig. 3 is the present invention sets up the A program of standard package in software architecture a process flow diagram;

Fig. 4 is the B1 program flow diagram of the present invention's reference template of setting up the virtual CCD of PCB in software architecture;

Fig. 5 is the present invention sets up the B program that detects the PCB data in software architecture a process flow diagram;

Fig. 6 is the process flow diagram that detects on the software architecture center line of the present invention with c program;

Fig. 7 is a D program flow diagram of inspecting the PCB flaw data in the software architecture of the present invention;

Fig. 8 is positioning flow figure automatically on the line in the practice identification of the present invention;

Fig. 9 is with the synoptic diagram of off-line virtual reference template image in the practice identification of the present invention;

Figure 10 is the process concept figure of established standards eigenwert in the detection method of the present invention;

Figure 11 is the orthograph of IC pin bridge joint flaw of the present invention;

Figure 12 is element orthogonal projection result figure of the present invention.

Embodiment

The present invention has developed the automatic optical detecting system that is applicable to flaw assembly on the PCB assembly line, be recognized as the design consideration emphasis with common on the production line or expected flaw practice, now will be described as follows one by one respectively with Unit three such as detection system framework, practice identification and classification and Detection methods:

(1), detection system architectural elements:

The detection system architecture design is divided into the design of hardware structure and software architecture control, will implement partly to inquire into off-line operation and on line operation two respectively, wherein:

This off-line operation; Being meant that detection system is as the criterion not influence Production Line power, under cost is considered, is that operating environment can be supplied with required information with a PC only; And be major function with standard detection value and the relevant environment parameter of setting up assembly, so be called training (Training) operation again.

This on line operation; Being meant that detection system is as the criterion with quality control on the supplement production line, is major function with the flaw state that detects testing component, so be called detection (Inspection) operation again.

This hardware structure (as shown in Figure 1); Include a twin shaft microscope carrier 10 (X-Y Table), be load chart visual organ 11 (CCD) and LED ring-shaped light source 12 (Ring LED Light), and move to printed circuit board (PCB) 16 (PCB) the storing position of user's appointment by driving governor 13 (Driver Controller) control; Wherein,

This image vision device 11 (CCD) is capture usefulness, and (Frame Grabber) transfers the analog image signal to the digital picture signal via capturing images card 14.

This LED ring-shaped light source 12 (Ring LED Light): be to control via digital conversion analog signal controller 15 (Digital/Analog Converter), according to different test item demands, suitable light illumination mode is provided, can be by the multiple combination of light sources of program control generation.

Above-mentioned driving governor 13, capturing images card (14 and digital conversion analog signal controller 15 all can see through a personal computer 17 and be controlled as job platform.

According to above-mentioned hardware structure, when off-line training step, standard printed circuit board (PCB) is to load with manual mode to detect microscope carrier; Detection-phase on line finishes when a PCB detects, and the signal of changing PCB can be assigned by system, stops all and detects action, until changing a PCB to be measured, continues to assign and detects instruction, begins then to detect.

This software architecture (as shown in Figure 2); Be in the PCB detection system, set up in the actions such as a standard package and a PCB data of foundation detection, consider the off-line operation of practice identification, for not making off-line training action influence the operation of production line, the operation of software off-line operation is assisted and improved to the notion that the present invention designs virtual CCD (Virtual CCD).Comprise:

I, set up the A program (A-Prog.) of standard package: major function is set up standard package database (A01 to A05) for the design end is provided, and can increase standard package newly or revise the detected parameters of having set up standard package in the database.

The guardian of the component database of design end, can be at above-mentioned standard package database [(A01 to A05], * .cop), the flaw kind 21 of established standards assembly, select suitable detection algorithm 22 at various flaw kinds, foundation obtains the image document 23 of standard package, and data stream (as shown in Figure 3) such as desired parameters 24 when set up detecting, and uses storage standard assembly data 2 (* .cop) (being the standard package eigenwert).

II, set up the B1 program (B1-Prog) of the virtual CCD data of PCB B10 (as Fig. 2): major function stores whole Standard PC B information for setting up one, reference template (Reference Template) the data B15 that is set up with the notion of virtual CCD, comprise and set PCB information B11, the mobile twin shaft microscope carrier 10 of setting to the data of fixed position B12, the data of selection image combination method B13 etc., the image B 14 of institute's combination can be supplied with the action (as shown in Figure 4) of off-line operation procedure simulation real CCD acquisition image.

III, set up to detect the B program [as Fig. 2, (B-Prog.)] of PCB data: major function is trained data B20 for setting up a standard detection plate data B2 and output, for selling or use side detects by the gross with trace routine on the line.The user can be from above-mentioned standard package database (A01 to A05) the testing component B21 on the choice criteria check-out console and read virtual CCD data B10 (as shown in Figure 2), and set up automatic navigation data B23 and foundation or choice criteria assembly B24, select component detection item B 22 simultaneously, and mobile twin shaft microscope carrier record component position B25 (as shown in Figure 5).The PCB that can be conveniently new order be produced of B program adjusts test item fast by this.

The c program that detects on IV, the line is [as Fig. 2, (C-Prog.)]: major function is to utilize training data B20 (* .trn) archives (as Fig. 5) of B program, carry out the check of PCB C10 to be measured by the gross, obtain every PCB testing result data C11 (* .inp) and flaw data C12, C15 (* .fut).

In addition referring to shown in Figure 6, can further learn the implementing procedure of c program, comprise and read above-mentioned training data B20 earlier, and loading PCB C10 to be measured by the gross, make each PCB locate C16 automatically, then PCB to be measured is detected C17, so that read above-mentioned every PCB testing result data C11 (* .inp) and flaw data C12 (* .fut).

V, inspect the D program of PCB flaw data [as Fig. 2, (D-Prog)]: major function is to utilize the D program to point out flaw place (D0) flaw Shared-with data C12 of every PCB that above-mentioned c program produces, comprise flaw module position D01 and flaw classification D02, for repairing (as shown in Figure 7).

In Fig. 7, as seen know when carrying out the D program, can read above-mentioned virtual CCD data B10 and read the archives of flaw data C12, and in graphoscope 18, disclose flaw module position D01 and flaw classification D02 on each PCB.

(2), practice identification unit:

In the above-mentioned software architecture of the present invention, consider location and the virtual CCD of the off-line institute reference template of foundation respectively automatically of PCB on the production line, both all adopt figure comparison Pattern Matching method or regular correlation coefficient process (Normalized correlation coefficient), are described as follows:

(I) PCB of (On-Line) locatees automatically on the line;

Be when detecting every PCB on line, to force PCB can't all arrive correct location because of influenced by the conveyor external factor, its subsequent detection operation may be therefore influenced and cause misjudgment, so design this method for automatically positioning at every turn.

Use PCB to be automatically positioned on opportunity and the flow process (as shown in Figure 8) that detects operation on off-line training operation and the line, be described as follows now:

[a]. utilize the B program when Standard PC B is set up in off-line training operation (Training), first frame choosing record PCB location feature B3, and record PCB goes up the feature relevant position B4 of assembly.(B4 includes the position of image with respect to twin shaft microscope carrier 10 to this feature relevant position, and location feature B3 is with respect to the position of image.

[b]. before utilizing c program to detect every PCB, can be according to the previous location feature B3 that sets, automatically calculating causes X-axis or (reaching) Y-axis side-play amount of twin shaft microscope carrier 10 because of conveyor or detent mechanism, and when mobile twin shaft microscope carrier 10, carry out revisal calibration location at X or (reaching) Y-axis side-play amount of this PCB.

Above-mentioned X or (reaching) Y-axis side-play amount are among the location feature B3 by the B program, utilize figure comparison (Pattern Matching) method to search C2, find out the possible position on PCB to be measured, and comparison position coordinate C3, promptly be that the feature relevant position B4 of record when making the possible position on the PCB to be measured with off-line training operation (Training) compares; When skew took place, both measuress of dispersion were the side-play amount of X or (reaching) Y-axis, should revise CCD position C4 this moment to correct place, were beneficial to mobile CCD C5 to PCB top and detected C17.

(II) the virtual CCD with off-line (Off-Line) sets up the PCB reference template;

That virtual CCD is provided as is undistorted, with the reference template B15 of the identical enlargement ratio of real CCD.The CCD enlargement ratio is 640 * 480/23 * 17 (pixel (pixels)/mm2), PCB (23 * 20cm among the present invention 2) about 6400 * 6300 pixels of all images (pixels).Virtual CCD function is the emulation real CCD, makes it can set up whole PCB reference template B15.Virtual CCD is B1 program generation (as shown in Figure 4) at present in the present invention, B program and D program off-line operation software use.The image of the reference template B15 that virtual CCD set up produces, no matter twin shaft microscope carrier 10 is handled summary step following (as shown in Figure 7) in X-axis or Y-axis motion:

(a) CCD on the twin shaft microscope carrier is moved fixed range 40, first image before produce moving with move after second image; This fixed range 40 is about 1/3 (overlapping region of expection) of image length and width.

(b) only fixing the use with a kind of light source in same CCD position as the judgment processing image.

(c) doubling of the image zone 43 is the zone of numerical analysis.

(d) obtain the overlapping region 43 of first image 41 and second image 42 via computing, excision from second image 42.

Desire excision superimposed images, the present invention utilizes the identification masterplate of first overlapping region 43 on the image 41 for figure comparison (Pattern Matching) method, and searches similar area on second image 42, to excise from second image 42.

(3), classification and Detection unit:

The classification and Detection method can be described as the flaw sorting algorithm again in the present invention, mainly is to be divided into that (or claiming to detect) operation two large divisions carries out on off-line (or claim training) operation and the line.

When off-line operation, be earlier by acquisition standard package eigenwert 50 in the standard package data of A program, and setting detection block 51, being beneficial on line operation tested 52 o'clock, relatively or the associated eigenvalue of comparison standard package and testing component, and 5 (as shown in figure 10) of module diagnostic value that will be qualified storage.

1. the Short Item of electric capacity, crooked detection transaction module;

Be electric capacity Short Item on PCB when getting its gray scale image, present two kinds of situations: when (A) PCB went up the electric capacity Short Item, module position did not contain circuit and 2PCB when going up the electric capacity Short Item, and the assembly vertical centred position contains circuit and passes through.Electric capacity is present in the standard package on the PCB.

In practice detected, the assembly on the PCB was to allow the situation of skew slightly, is not flaw, used Pattern Matching method to obtain the position of correct assembly so the present invention intends the phase one, and subordinate phase reintroduces algorithm and judges whether Short Item (or wrong part).

The phase one-figure comparison (Pattern Matching) method-obtain position of correct assembly.Fair receipts (Acceptance) threshold setting of figure comparison method there is no certain standard, so the present invention intends adopting earlier lower fair receipts (Acceptance) threshold value, the result who makes figure compare method comprises (A) correct assembly, the erroneous judgement of (B) Short Item reaches situations such as (C) wrong part erroneous judgement, carries out category filter with standard package and the feature difference of judging block by accident again.Subordinate phase reintroduces algorithm and judges whether Short Item of electric capacity.For convenience of description, be black patch ratio (Black Percentage) method with what call in the following text.

Whether subordinate phase-black patch ratio (Black Percentage) method-judge electric capacity Short Item.This method is intended utilizing suitable light illumination, causes feature of electric capacity own and printed circuit board (PCB) (PCB) to go up the difference of Short Item or wrong part characteristics of image.The similar assembly that the figure comparison is found is an example, observe the shade of gray distribution plan (as shown in Table 3) of assembly block, contain a dotted line in the table three, can obviously tell, the shade of gray distribution plan of standard package 01 does not contain any pixel (pixel) pixel in the dotted line left side, and all the other gray-scale distribution figure for erroneous judgement assembly 02,03,04 then contain the image pixel in the dotted line left side.

Table three: erroneous judgement assembly and standard package shade of gray distribution graph

2. bridge joint (short circuit) detects transaction module;

Bridge joint flaw phenomenon only comes across on the assembly with IC pin, is quad-flat-pack integrated circuit (QFP) the IC pin enlarged drawing that the bridge joint flaw is arranged as figure 13.

Consider on the practice because of detecting tin pin regional extent, may since during the off-line training operation artificial frame Selected Inspection survey PCB skew or assembly puzzlement of skew slightly in tolerance slightly in tolerance when detecting operation on regional hour offset, the line; Incorrect action has just taken place when surveying the zone as if the frame Selected Inspection, and subsequent algorithm can cause the result that can't correctly judge detection because of detecting the skew of starting point and judgement check point position.

The present invention intends solving the problem of location in the mode of IC pin in the searching and detecting zone, and follow-up image projection (Image Projection) method that cooperates again detects, and method is described as follows:

(A) enlarge surveyed area (Inflate region): owing to detect the number of IC pin, set during for the off-line training operation, need to see through manual type and inform the surveyed area position, for avoiding the skew of human factor, when the user determines the surveyed area position, not change the center of surveyed area, strengthen former surveyed area size.

(B) speckle search (Find Stripe): present chequered with black and white speckle feature after the IC pin binaryzation, and the action that positions with speckle search method (Find Stripe method).Because have the situation of hiding backplane circuit between the IC pin, circuit can be subjected to the effect of altitude of both sides IC pin, cause the light source lightness that is received to reduce, so can use the binaryzation mode to be eliminated; But in the part IC pin row, also may contain the backplane circuit line as first IC pin side, the notable feature that be to keep the IC pin, do not intend with binarization method will elimination fully, the light source lightness of accepting because of first IC pin is than being height through the backplane circuit between the IC pin.

Consider the practice identification, speckle search (Find Stripe) method will with " Hei-Bai-Hei " alternate speckle mark, the position that estimates about second IC pin appearance in enlarging surveyed area (Inflate region) is the starting point in speckle search (Find Stripe) comparison zone, hunt out the position of correct second IC pin, a position location of IC pin of winning can be pushed away by known IC pin width, and correct surveyed area can be tried to achieve.

(C) image projection (Image Projection) method; Its algorithm is as follows:

(a) zone is surveyed in the frame Selected Inspection;

(b) image binaryzation is handled;

(c) the image orthogonal projection is handled, and obtains shade of gray accumulative total;

(d) numerical analysis: set and detect starting point, the spacing of IC pin, the width of IC pin, IC pin number then can calculate IC pin tram, if the aggregate-value of binaryzation shade of gray is too high between the IC pin, judges that then bridge joint flaw (as shown in figure 11) takes place at this place.

3. the pole reversal detects transaction module;

The present invention is with in the PCB assembly of inquiring into (comprising SOP and QFP), and polarity represents to be divided into strip polarity and poroid polarity.Pole reversal phenomenon there is no the external form flaw and takes place on assembly, mainly put position-reversed because of assembly and cause the assembly function forfeiture, so can indicate polar orientation with mark on the assembly, and can utilize this mark to find out the position of polarity.This section illustrates the detection model of strip polarity and the detection model of poroid polarity respectively.

(A) strip polarity detection model;

Mainly comprised two kinds of information of assembly sequence number and assembly polarity in the testing component body, utilized binary conversion treatment earlier this information and background separation.Because the assembly sequence number is identical with the GTG degree of polarity, therefore need further to separate this two category information; The position of all strip polarity marks, it all is end in component body, therefore according to this characteristic relevant with the position, elder generation is with the position of detection block assignment component body, image in the detection block is handled with orthography, obtained the result of Figure 12, the numerical data that the two dimensional image data can be converted to one-dimension array is handled in orthogonal projection, further utilize this numeric data to get its peaked position, can learn the position of polarity bar on assembly.

(B) poroid polarity detection model;

Most of QFP assemblies are all represented the polarity position with the circular hole of depression, and the degree of its polarity circular hole depression and pore size can change to some extent along with the QFP assembly of different model.

The irradiation of polarity aperture lateral light, white ring-like aperture can appear in circular, therefore the present invention intends utilizing the formed reflection characteristic of this sidelight, and uses the form facture (Morphology) in the Flame Image Process to strengthen required ring of light information, further judges the position in polarity hole.Method is described below:

(a) binary conversion treatment: for polarity detected, the information that need obtain from image was having or not of polarity circular hole, and therefore a gray scale image can utilize the mode of binaryzation that unwanted GTG value is removed earlier.Through after the binaryzation, can be a little with ring-like aperture and background separation, but still have partial noise to mix wherein, must further handle computing and eliminate noise with form.

(b) form is handled: in the application that form is handled, our standing suitable matrix of meter and use specific operation method on pending figure to eliminate or to strengthen some signal.The present invention intends adopting image to corrode (Erosion) operation method and eliminates noise, strengthens signal with image expansion (Dilation) operation method.The most of ring-like aperture signal of reservation that so can be successful, and eliminate overriding noise.

(c) particle disposal: because QFP component body smooth surface, when the sidelight capture, have only the polarity hole site of depression reflective phenomenon can occur, the present invention intends using particle disposal (Blob process) to calculate shared pixel (pixel) number of white point particle in its image, be particle area (Blob Area), whether the foundation of polarity hole appearance is arranged as surveyed area.

(d) numerical analysis: the particle area can be used as the parameter values for detection of standard component, yet the ring-like aperture area of this particle area after handling, has still comprised the noise that does not remove fully.Therefore design in the parameter values for detection that circular hole polarity detects, should be with flexible strategy on the total grain surface product after calculating, with the shared particle area of filtering noise, the setting of flexible strategy value then must could determine by further experiment.When to be measured particle area that obtains after treatment less than parameter values for detection, then just decidable its be the flaw situation of the pole reversal.

4. the detection model of soldering amount;

QFP assembly on the PCB in the SMT processing procedure, may produce the tin amount too much, tin amount secondary flaw very little.Go up the normal tin welding spot of QFP tin amount in PCB, get its gray scale image.Its detection method brief description is as follows:

(A) establish tin pin space D, tin pin width W, the method for utilizing image to cut will comprise the QFP assembly that N props up the tin pin, be starting point with S, and every (D+W) * i, (0≤i<N, i ∈ integer) promptly cuts out the tin welding spot image.

(B) the tin welding spot image that utilizes above-mentioned (A) item to be cut out calculates following parameter value.

Make U iBe the shade of gray mean value of tin welding spot under the lighting environment of upper strata, (0≤i<N, i ∈ integer)

L iBe the shade of gray mean value of tin welding spot under lower floor's lighting environment, (0≤i<N, i ∈ integer)

μ 1 : Σ i = 0 N - 1 U i / N μ 2 : Σ i = 0 N - 1 L i / N

v 1 : ( Σ i = 0 N - 1 U i 2 / N ) - μ 1 2 v 2 : ( Σ i = 0 N - 1 L i 2 / N ) - μ 2 2

(C) utilize the levels light source, calculate tin welding spot shade of gray mean value, use again in the visual processes classification (Classfication) with normal tin amount, tin amount too much and the tin amount very little tin welding spot separate out.

Now it is as follows to set forth application example of the present invention again:

The detection system of the present invention's development has been considered the demand on the actual production line, program design comprises three-layer type framework (A, B and c program), virtual CCD (B1 program) and testing result report output (D program), this example is framework and aforesaid detection method according to this, with a PCB example complete description native system operating process, this example is desired detection components and is comprised pellet resistance, flaky electric capacity and quad-flat-pack integrated circuit (QFP) totally 78 assemblies.

(A) set up the A program (A-Prog.) of standard package: at first in the A program, set up the standard package database, step for the standard package that CCD is moved to desire and detect after, frame selects the standard package image, and set each component detection project with and detection algorithm.

(B) set up the B1 program (B1-Prog.) of the virtual CCD data of PCB: set the long 225mm of PCB, wide 230mm and the required displacement of CCD photographic images (shown in the B1-Prog operation screen of Figure 34) herein, CCD can take the subimage of PCB automatically in regular turn during execution, and all subimages are combined into one whole complete Standard PC B information, to set up reference template (Reference Template), for the action of off-line operation procedure simulation real CCD acquisition image.In conjunction with the complete PCB image of finishing.

(C) set up the B program (B-Prog.) that detects the PCB data: utilize the images off-line of B1-Prog institute combination to browse PCB, frame selects the position of assembly on PCB, when selecting, sensing range can be strengthened a little so that search module position by frame, in the standard package database that A-Prog finished, choose corresponding standard package, and choose the project that desire detects.

(D) c program of trace routine (C-Prog.) on the line: the standard detection version information paper that utilizes B-Prog to produce, carry out the check of PCB to be measured by the gross, and the detection data of every PCB of output and flaw information.

(E) inspect the D program (D-Prog.) of PCB flaw data: the flaw Shared-with information of utilizing C-Prog to produce, indicate the position and the flaw classification of flaw assembly.。

Automatic optical detecting system provided by the present invention (AOI) possesses following advantage is arranged:

1. quality consistency: machine is because of artificial factor, as the state of mind, lazy, carelessness, tired etc., causes quality standard inconsistent, dispatches from the factory and allow the bad product of quality reach a standard.

2. raising judgement: the sky weldering of some defective such as SMT, Xi Qiao, tin sweat(ing) etc., naked eyes and can't finding out really, the AOI system is not only short detection time, has than high sense for this type of flaw, and can not omit to some extent.

3. real time reaction: AOI cooperates the function of statistical process control (SPC), and the relevant information of the defective products collected of feedback is found the processing procedure problem in real time and adjusted tool parameters, to safeguard processing procedure stability, the minimizing loss that defective products caused fast.

4. reduce casual injury: the AOI system is the non-contact detection system, can reduce or eliminate the chance of hand contact product, to avoid the injury to product such as static, the lines of the hand.

In sum, the development of the automatic optical detecting system of flaw assembly (AOI) on the printed circuit board (PCB) of the present invention, not only can reduce production costs, improve detection speed and reduce False Rate, and can accomplish the level of one hundred percent inspection, the consistance of its efficient, usefulness and quality is much better than traditional manual detection, and in the present situation, client also is considered as AOI the basic demand of product quality gradually, therefore domestic industry is if will increase product competitiveness, and development AOI and quick the importing are believed the trend of being inevitable.

Claims (10)

1. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) is characterized in that:
(1) set up the A program of standard package database: after image vision device CCD was moved to the standard package that desire detects, the frame choosing is acquisition standard package image also, and sets the test item and the detection algorithm thereof of each assembly;
(2) set up the B1 program of the virtual image visual organ CCD data of printing board PCB: the information of setting printing board PCB, comprise length, width and the required displacement of image vision device CCD photographic images, image vision device CCD takes the subimage of PCB automatically in regular turn during execution, and all subimages are combined into a complete standard printed circuit board PCB information, setting up reference template, and in conjunction with the complete printing board PCB image of finishing;
(3) set up the B program that detects the printing board PCB data: utilize the images off-line of above institute combination to browse printing board PCB, frame selects the position of assembly on printing board PCB, from above-mentioned standard package database, choose corresponding standard package, and choose the project that desire detects;
(4) carry out the c program that detects on the line: utilize the standard detection plate information paper that is produced, carry out the detection of printing board PCB to be measured by the gross, and produce detection data and the flaw information of every PCB;
(5) inspect the D program of printing board PCB flaw data: utilize the flaw information that is produced to indicate the position and the flaw classification of flaw assembly;
Wherein, described method has adopted the automatic optical detecting system that comprises system architecture unit, practice discrimination unit and classification and Detection unit, this system architecture unit is provided with hardware structure and software architecture, when off-line operation and on line operation, carry out practice identification and classification and Detection for the user, described off-line operation is standard detection value and a relevant environment parameter of setting up testing component on the printed circuit board (PCB), and described on line operation is to carry out the flaw state that detects testing component on the printed circuit board (PCB).
2. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1, but wherein the standard package database of this A program is set the flaw kind of examination criteria assembly for the user.
3. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1 wherein is the flaw kind by the established standards assembly and select suitable detection algorithm to obtain the standard package image document.
4. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1, wherein this B1 program setting moves the range data of twin shaft microscope carrier to the fixed position.
5. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1, wherein this B1 program is being carried out the practice identification when setting up reference template for off-line operation, and the B1 program is set the data of selecting the image combination in the following manner:
(a) the image vision device on the twin shaft microscope carrier is moved fixed range, first image before produce moving with move after second image;
(b) only fixing the use with a kind of LED ring-shaped light source in same image vision device position as the foundation of judging image;
(c) doubling of the image zone is the zone of numerical analysis;
(d) obtain the overlapping region of first image and second image via computing, from second image, excise.
6. as the automatic optical detection method of flaw assembly on the printed circuit board (PCB) as described in the claim 6, wherein this fixed range is 1/3 of image length and width.
7. as the automatic optical detection method of flaw assembly on the printed circuit board (PCB) as described in the claim 6, wherein when the excision superimposed images, utilize the identification template of first overlapping region on the image, and on second image, search similar area, to excise from second image for figure comparison method.
8. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1, wherein this B program is when on line operation selects to read required standard package data to be measured, be in the practice identification unit, to adopt figure comparison method, the location feature of elder generation's frame choosing record printing board PCB, and the feature relevant position of assembly on the record printing board PCB, hunt out the X-axis or the Y-axis side-play amount of twin shaft microscope carrier thus, perhaps X-axis and Y-axis side-play amount, can this side-play amount of revisal during for mobile twin shaft microscope carrier, in order to the calibration location and set up the automatic locator data of printed circuit board (PCB).
9. as the automatic optical detection method of flaw assembly on the printed circuit board (PCB) as described in the claim 10, the feature relevant position of assembly on this printed circuit board (PCB) wherein includes image with respect to the position of twin shaft microscope carrier and the location feature position with respect to image.
10. the automatic optical detection method of flaw assembly on the printed circuit board (PCB) according to claim 1, wherein this B program can read the virtual CCD data of B1 program.
CNB021538298A 2002-11-28 2002-11-28 Automatic optical detecting system for blemish assembly on printed circuit board CN1318839C (en)

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