JPH0571902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is an automatic inspection device for mounted printed circuit boards, and in particular, uses a narrowly focused beam, such as a laser beam, to inspect mounted printed circuit boards due to soldering defects. The present invention relates to an automatic inspection device for mounted printed circuit boards that is capable of quickly and automatically detecting the presence or absence of bridges depending on the board using a non-contact method.

[Conventional technology]

Previously, assembled printed circuit boards were inspected primarily by visual inspection by inspectors, but this was slow and the inspection results often varied.

On the other hand, in recent years, the assembly work of printed circuit boards has been greatly automated, consolidated, and speeded up through the development of automatic component insertion robots and automatic solder baths. Along with this, attempts have been made to automate the inspection of printed circuit boards, and several mounted printed circuit board automatic inspection apparatuses have been proposed.

However, in all of them, pins are set up in the same number of holes as the component mounting holes on the printed circuit board, and the solder side of the printed circuit board on which the components are mounted is pressed against the pins. It used a contact inspection method to detect the presence or absence of attachment defects.

Especially recently, in combination with a microcomputer, the conduction state between all pins is memorized for a correctly mounted printed circuit board with no defective parts, and the degree of agreement between this and the detected mounted printed circuit board is detected to detect whether it is good or defective. This has led to the development of devices that significantly shorten inspection time.

[Problem that the invention seeks to solve]

All of the conventional automatic inspection devices for mounted printed circuit boards mentioned above check for continuity by bringing the pins installed in the inspection device into contact with the solder surface of the printed circuit board to be inspected, and their essence is a contact method. For some reason, it had the following problems.

(a) Since the same number of pins as the component mounting holes on the printed circuit board are used, poor contact between the solder surface and the pins is likely to occur.

(b) It is necessary to set the pins according to the component mounting hole positions on the printed circuit board, so when inspecting many types of printed circuit boards, it is necessary to reset the pins each time according to the component mounting hole position on each printed circuit board. be.

(c) Since pins are used, the distance between the component mounting holes that can be inspected on the printed circuit board is limited by the diameter of the pins.
For example, it is impossible to inspect recent Shrink ICs that have narrow mounting hole positions.

(d) Since the continuity test is conducted using pins, even if there is no solder on the solder surface, if the feet of the staff are in contact with the solder surface, the product is determined to be good, and as a result, the printed circuit board that may cause a failure later can be detected. It will be missed.

These problems basically cannot be solved as long as the contact method is used.

[Means for solving problems]

The present invention solves the above-mentioned problems of the conventional mounted printed circuit board automatic inspection apparatus, and is capable of reliably and quickly detecting bridges formed due to soldering defects. (a) Beam generation that generates a beam 11 that is focused narrower than the width of the bridge to be detected and projected perpendicularly to the solder side of the mounted printed circuit board 12; and (b) forming a wave-like path in at least a portion of the component mounting portion of the mounted printed circuit board 12 at a predetermined location without passing through other component mounting portions or printed wiring patterns. (d) sweep control means 21 for sweeping the beam 1 from the mounted printed circuit board 12 through a path including;
and inspection means having a bridge detection device 19 for detecting the presence or absence of bridges formed by poor soldering based on the reflected light 11R of No. 1.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4. In the following example, the component mounting section mounts the component through the component mounting hole, and along with the bridge formed on the mounted bridge board due to poor soldering, the component is mounted in the component mounting hole of the printed circuit board. An embodiment will be described in which an opening (hole) generated in a component mounting hole due to poor soldering at the time of soldering is also detected.

FIG. 1 is a block diagram illustrating the configuration of a mounted printed circuit board automatic inspection apparatus according to an embodiment of the present invention, FIG. FIG. 4 is an explanatory diagram of operating waveforms when a linear beam sweeping method is used in the same embodiment, and FIG. 4 is an explanatory diagram of operating waveforms when a beam sweeping method using a wavy path is used in the same embodiment.

(A) Structure of the Embodiment In Figs. 1 to 4, 10 is a beam generating means, which is used to generate bridges and holes formed in component mounting holes due to poor soldering on the mounted printed circuit board. ) is generated that is narrow enough to detect the beam 11.

Since bridges can be reliably detected along with openings, the beam 11 projected onto the printed circuit board 12
The diameter of the bridge is narrower than the width of the bridge, for example, about 200 μm. A beam as narrow as this can be generated by, for example, a known laser beam generator.

This beam generating means 10 is equipped with an optical sweeping means such as a scanner capable of sweeping a beam perpendicular to the solder side of the mounted bridge board 12, and straight lines between component holes are used to detect bridges and openings. The configuration allows wave-like sweeping to be performed by applying vibrations perpendicular to the sweeping direction to the beam.

Reference numeral 12 denotes a mounted printed circuit board (hereinafter referred to as "printed circuit board 12"), on which components are mounted by soldering onto wiring patterns formed on the surface thereof. 13 is a wiring pattern printed on the printed circuit board 12, 13A, 13B
etc. indicate some of them.

Reference numeral 14 denotes a component mounting hole, in which a component is mounted by soldering as a component mounting portion (hereinafter simply referred to as "component hole 14"). 14A, 14B, etc. indicate individual component holes 14. Reference numeral 15 indicates mounted components, one of which is illustrated.

16 is a passing light receiver, and the printed circuit board 1
The beam 11T that has passed through the aperture formed at 2 is received. Reference numeral 17 denotes an aperture detection device, which receives the output of the passing light receiver 16 and detects the presence or absence of an aperture.

18 is a reflected light receiver, and the printed circuit board 1
The beam 11R reflected from the wiring pattern 13 on the wiring pattern 2 is received.

Reference numeral 19 denotes a bridge detection device, which receives the output of the reflected light receiver 18 and detects the presence or absence of a bridge. Reference numeral 20 denotes a bridge, which is formed when a portion not connected by the wiring pattern 13 is short-circuited by solder due to poor soldering.

21 is a sweep control means, and the printed circuit board 1
2 or by driving the beam generating means 10, the beam 11 is controlled to sweep the surface of the printed circuit board 12 in a predetermined sweeping manner. This sweep control means 21 includes, for example, various types of known X,
It can be configured using a Y drive device.

(B) Operation of the embodiment during linear sweep Next, the operation of the device shown in Fig. 1, that is, the operation of detecting holes and bridges caused by poor soldering, begins with the detection of holes and bridges between each component hole. The operation of linearly sweeping will be explained with reference to FIGS. 1 to 3.

Beam 1 projected from beam generating means 10
1, the sweep control means 21 sweeps the surface of the printed circuit board 12 in a single stroke across each component hole 14, as shown in FIG.

Bridging is generally more likely to occur between component holes that are located close to each other, but the locations of component holes where there is a risk of bridging can be identified when creating a printed wiring pattern or by performing a process after creating a printed circuit board. This can be determined through tests, etc.

Therefore, if you want to detect the presence or absence of bridges,
It is necessary to sweep the beam 11 so that it always passes between holes in closely spaced parts to be inspected. To do this, it is necessary to select a sweep so that the beam 11 sweeps between each component hole in such an order that the beam 11 always passes through one component hole and then the other component hole between the component holes to be inspected. is necessary.

In this manner, when sweeping between the component holes, the sweep is made in a predetermined order so that the component holes to be inspected for the presence or absence of bridges are successively passed through. For example, in FIG. 2, when inspecting the presence or absence of bridges between and and and also inspecting the presence or absence of openings occurring in each component hole 14, the beam 11 is
It is swept in the order of →→→→→→→→→.

At this time, the important orders for bridge inspection are → (the order in which the component hole must be passed after the component hole, and the same applies hereafter), →, →, and →. Therefore, these orders must be followed, but other orders may be changed. Also, the above and
For example, between , , and ,
Of course, the order may be reversed, such as → and →.

In this way, the beam 11 is
The hole position coordinates of each component hole required to sweep the surface of 2 in a predetermined sweep method are, for example,
It can be obtained by reading from an NC (numerical control) tape (not shown) during fabrication of a printed circuit board. Further, information such as the order in which each component hole 14 is inspected and between which component hole positions the bridge inspection is to be performed can be formed by adding them as attributes to the component hole position coordinates obtained from the NC tape.

The sweep control means 21 automatically performs a predetermined linear sweep on the beam 11 as illustrated in FIG. 2 by driving and controlling the beam generation means 10 based on the sweep control information created in this way. have it done.

Hereinafter, the operation of detecting the presence or absence of openings and bridges using the above-mentioned linear sweep method will be described.

(a) Detection of openings (holes) Holes are holes that occur on the solder surface due to poor soldering when the component 15 is mounted in the component hole 14 of the printed circuit board 12.
4 to form a hole penetrating the printed circuit board 12.

Therefore, if such an opening exists in the part hole 14 of the printed circuit board 12, the beam 11 will pass through this opening in FIG. The light is then received.

The light opening detection device 17 receives the light reception output of the passing light receiver 16 and the swept component position information from the sweep control means 21, and detects whether or not an opening exists in each swept component hole portion.

(b) Bridge detection Component holes 14A and 1 for detecting the presence or absence of bridges
4B, the beam 11 is moved in a straight line (including a curved line) as shown in FIG. 3C. This sweep path passes beam 1 between component holes 14A and 14B.
When moving forward, make sure that it does not pass through other component holes or wiring patterns.

Then, if there is no bridge between the component holes 14A and 14B, there will be almost no reflected beam between them, and in the wiring patterns 13A and 13B, the solder surface on the copper foil of the wiring pattern will There is strong beam reflection.

Therefore, in the absence of a bridge, the light receiving output of the reflected light receiver 18 is large at the wiring patterns 14A and 14B, and is at an extremely low level in the middle, as shown in FIG. 3A.

On the other hand, if a bridge 20 as shown in FIG.
And beam reflected light of the same level as the 13B portion is generated.

Therefore, if bridge 20 exists,
As shown in FIG. 3B, the output of the reflected light receiver 18 at the bridge 20 is approximately the same as the output from the wiring patterns 13A and 13B.

The bridge detection device 19 includes a reflected light receiver 18
1 and the component hole position information for bridge detection from the sweep control means 21.
The presence or absence of a bridge is detected from the change in the received light output level of the reflected light receiver 18 while sweeping between 4A and 14B.

(c) Operation of the embodiment during wavy sweep Next, referring to FIG. 4, we will explain the operation when detecting bridging by sweeping a beam between component holes using the wavy sweep method that passes through a wavy path. do.

The bridge 20 moves the beam 11 in a straight line between the component holes 14A and 14B as shown in FIG. 4C.
If it is formed off the path of S, then Fig. 4A
As shown in , there is a region (DC) where there is no beam reflected light between the component holes 14A and 14B even though a bridge actually exists, so the light reception output of the reflected light receiver 18 is in this region.
It decreases greatly in the DC part. Therefore, the third
The presence or absence of such a bridge cannot be detected by the sweep method that moves linearly between the component holes 14A and 14B as shown in the figure. FIG. 4 shows a wave-like sweep method that can detect the presence or absence of bridges even in such cases.

In this wave-like sweep method, between the component holes 14 and 14B to be inspected for the presence or absence of bridges,
As shown in FIG. 4C, a sweeping method is used in which the waveform is swept in a waveform of 11W.

This wavy sweep method can be obtained by applying vibrations perpendicular to the direction of movement to the beam in the portion between the holes of the component where bridge inspection is performed in the linear sweep method shown in FIG. Specifically, based on the sweep control information from the sweep control means 21, for example, the scanner section of the beam generation means 10 can easily cause the beam 11 to vibrate in the perpendicular direction.

When such a wavy sweep method is used, even if the bridge 20 is formed out of a straight line, the wavy peak of the wavy beam 11W can sweep the bridge 20.
Reflected light from 0 is obtained. Therefore, the light receiving output of the reflected light receiver 18 has a continuous pulse-like waveform between the component holes 14A and 14B, as shown in FIG. 4B. Therefore, in this wave-like sweep method, the amplitude of the wave-like path is selected such that bridges formed out of a straight line can be reliably detected.

The bridge detection device 19 includes a reflected light receiver 18
1 and the component hole position information for bridge detection from the sweep control means 21.
The presence or absence of a bridge is detected based on the presence or absence of a pulse-like waveform output in a predetermined section DT in the central portion between 4A and 14B. Predetermined section DT in the center
The size of is selected to match the spacing between holes in each component for detecting the presence or absence of bridges.

If this wavy sweep method is used in conjunction with only those parts of the component holes to be inspected for bridges where the bridges tend to deviate from the straight line, the entire hole and bridge inspection can be carried out quickly. Even when this wave-like sweep method is used, the wave-like beam 11W is prevented from passing through other component holes or wiring pattern portions on the way, as in the case of the linear sweep method.

In the bridge inspection described above, it is automatically determined whether to use the linear sweep method or the wavy sweep method as the sweep method.

In other words, the locations of component holes where there is a risk of curved bridges can be determined by predicting the shape of the printed wiring pattern, soldering method, etc. when creating the printed wiring pattern, or by testing after creating the printed circuit board. Since this information can be known, the respective sweep methods can be determined in correspondence to the holes of each part to be inspected for bridges.

The information on the sweep method determined in this way, that is, the information on whether to adopt the linear sweep method or the wavy sweep method as the sweep method for bridge inspection, is also obtained from the parts holes obtained using the NC tape, etc. mentioned above. Added as an attribute to the location coordinates.

Based on this attribute information read together with the position coordinates of the component hole, it is automatically determined whether the beam sweep up to the component hole to be swept next is to be performed in a linear sweep method or in a wavy sweep method.

Although a laser beam is suitable as the beam 11 used in the present invention, the present invention is not limited thereto.

〔Effect of the invention〕

In the present invention, as described above, bridges are detected by using a beam and its passing light and reflected light without using the pin contact method, so that the following advantages can be obtained.

(a) Since the test is performed without contacting the printed circuit board, there are no malfunctions such as poor contact. In addition, inspection can be performed without affecting the mounted elements of the printed circuit board at all.

(b) Since the beam can be focused narrowly, inspection is possible even if the distance between the component mounting areas of the printed circuit board is narrow. Therefore, it is possible to inspect not only shrink-link ICs that cannot be tested using the pin contact method, but also those with extremely narrow leg spacing, such as recent flat package ICs.

(c) Since the presence or absence of bridges is detected using a narrowed beam, even minute bridges can be reliably detected.

(d) Since the inspection is performed by sweeping the beam, the inspection time can be shorter than the pin contact method.

(e) Furthermore, since the beam is swept along a wavy path, bridges that are not on a straight line can be detected easily and reliably.

(f) When inspecting a new printed circuit board, it is sufficient to add the order of sweep of each component mounting area read with NC tape, etc., the position information for bridge inspection, and the information on the sweep method as attributes, so the pin stand Compared to the conventional method of repair, the amount of pre-work and time can be significantly reduced.

(g) Since the position information of the component mounting area including the above-mentioned attributes can be stored, by preparing a memory that stores the above-mentioned information about many printed circuit boards, it is possible to inspect different printed circuit boards with simple switching. can. This is extremely advantageous when testing multiple types of printed circuit boards.

[Brief explanation of the drawing]

Fig. 1 is a block diagram illustrating the configuration of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the beam sweep method in the same embodiment, and Fig. 3 is a case using the linear beam sweep method in the same embodiment. FIG. 4 is an explanatory diagram of operational waveforms when the wavy path beam sweeping method in the same embodiment is used. 10... Beam generating means, 11... Beam, 1
2...Mounted printed circuit board (printed circuit board), 1
3... Wiring pattern, 14... Component mounting part (component mounting hole or component hole), 15... Component, 16... Passing light receiver, 17... Opening detection device, 18... Reflected light receiver, 19... bridge detection device, 20...
...Bridge, 21...Sweep control means.

Claims (1)

[Scope of Claims] 1. Beam generating means 10 that generates a beam 11 that is narrower than the width of the bridge to be detected and that is projected perpendicularly to the solder side of the mounted printed circuit board 12; A sweep that sweeps between the component mounting sections for detecting bridges on the printed circuit board 12 at a predetermined location without passing through other component mounting sections or printed wiring pattern sections, and through a route that includes a wavy route at least in part. a control means 21; and the beam 11 from the mounted printed circuit board 12.
an inspection means having a bridge detection device 19 for detecting the presence or absence of bridges formed due to soldering defects based on the reflected light 11R of the mounted printed circuit board.