JPH04140650A - Apparatus for inspecting printed circuit board - Google Patents

Abstract

PURPOSE:To efficiently determine whether soldering is good or defective in a short time by detecting rises in temperature of all soldered parts by image data and comparing the image data with stored image data of a good product. CONSTITUTION:A laser generator 4 applies laser light by a control signal of an interface unit 9. An infrared camera 5 measures temperature of a soldered part 7, makes distribution of the temperature into a visual signal, and an image processing circuit 8 converts the visual signal obtained by the camera 5 into a digital signal and also calculates data of an image data storage unit 11. The soldered part 7 to which the laser light from the generator 4 has been applied generates heat to emit infrared rays while the camera 5 converts the emission amount into a visual signal and sends it to the circuit 8. The circuit 8 converts the visual signal into a digital signal and stores in the storage unit 11, and by logic calculation with the data to be inspected and stored data of a good product, it is possible to efficiently determine whether soldering is good or defective in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a printed board inspection device that efficiently determines the quality of soldering on a printed board.

(Prior Art) The density, capacity, and size of printed circuit boards have been rapidly increased, and as a result, components have been made smaller and surface mounting technology has come into wide use.

Against the background of such industrial demands, miniaturization of soldering for connecting printed wiring boards and electronic components is being carried out. However, solder connection techniques produce manufacturing defects such as solder bridges and blowholes. However, the main method of detecting solder defects is through visual inspection by humans, and as soldering points become smaller, it is becoming impossible to inspect soldered areas by human visual inspection. .

Furthermore, as an alternative to visual inspection, an inspection device using a laser as shown in FIG. 4 has been developed. This principle is to irradiate the soldering part 7 with a laser, detect the temperature rise that occurs on the irradiated surface with the infrared detector 21, and measure the time it takes for the temperature to rise to a certain level to determine whether the soldering is good or bad.

(Problems to be Solved by the Invention) However, conventional inspection methods have problems in that it takes time to determine pass/fail, and the content of one determination is unclear.

That is, in the conventional inspection method, the time required to inspect one point is about 1.00 m5, and as the number of points increases, it takes more time. In addition, since pass/fail judgment is made based on whether or not the temperature rise of the laser irradiated surface is observed within a certain period of time, the details of the defect are not clear, and the temperature rise time may vary due to oversoldering or undersoldering. There were problems with measurement accuracy, as the product was judged to be defective even when the product was in poor condition.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a printed board inspection device that can efficiently determine the quality of soldering in a short time and can also determine defective states.

[Structure of the invention]

(Means and Effects for Solving the Problems) In order to achieve the above object, the present invention irradiates a laser beam onto a soldered part of a printed circuit board on which a large number of electronic components are mounted by soldering, thereby increasing the temperature of the soldered part. A device for determining the quality of soldered parts from scratch includes means for sequentially scanning and irradiating a large number of soldered parts with laser light, an infrared camera for detecting temperature rises in all soldered parts using image data, and This printed board inspection device is equipped with an image processing means that compares with pre-stored image data of non-defective products to determine defective locations and defective states of soldered parts.

(Example) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment according to the invention.

1 is a computer that performs command 9 judgment, processing 9 display, and data input/output of the soldering inspection device; 2 outputs a position control signal to the XY child table structure 3 based on the position data received from the computer 1; XY child table gobe. 4 is a laser generator that irradiates laser light according to a control signal from the interface section 9; Reference numeral 6 denotes a laser light adjustment lens that adjusts the focus of the laser light emitted from the laser generator in the soldering inspection section 7. 5 is an infrared camera that measures the temperature of the soldering inspection section 7 and converts the temperature distribution state into a video signal. 8
An image processing circuit converts the video signal obtained by the infrared camera 5 into a digital signal, calculates data in the image data storage section 11, and determines the quality of soldering. 1
1 consists of three parts: a test data storage section that stores unprocessed data obtained by digitizing video signals, a non-defective data storage section that stores standard values for soldering pass/fail judgments, and a comparison data storage section that stores pass/fail judgment results. An image data storage unit consisting of. 9
Reference numeral 1 denotes an interface unit which performs the functions of sending commands to the laser generator 4 and control commands to the image processing circuit 8, receiving processing results, and sending a soldering quality determination result to the computer 1 according to the commands of the computer 1. 10 is a display device that visualizes the data of the image processing circuit 8.

The computer 1 reads soldering part position data for which inspection is to be started from the inspection information storage 12 and outputs it to the XY child table controller 2. The XY child table control unit 2 controls the XY child table structure 3 and moves it based on the soldering part position data so that the irradiation surface of the laser beam irradiated from the laser generator 4 focuses on the soldering inspection part 7. . When the movement to the specified position is completed, the computer 1 issues a start signal to the laser generator 4 via the interface section 9 to start laser irradiation. The laser generator receives the command and emits laser light for the specified time. The laser beam is adjusted so as to pass through a laser beam adjustment lens 6 and be focused by a reflecting mirror 13. The reflector drive unit 14 changes the angle of the reflector 13 according to the control signal from the interface unit 9, and can change the laser beam irradiation point without moving the XY child table structure 3. 7 locations can be heated simultaneously by repeating high-speed scanning. The soldering inspection section 7 irradiated with the laser light generates heat and emits infrared rays. The amount of radiation depends on the intensity of the laser beam, the irradiation time, and the heat capacity of the irradiated surface. If the intensity and irradiation time of the laser beam are constant, it is possible to determine the quality of soldering by measuring the amount of infrared radiation, which is determined by the heat capacity determined by the electronic component and the soldering state. Infrared camera 5
The amount of infrared radiation from the soldering inspection section is converted into a video signal and sent to the image processing circuit 8.

The image processing circuit 8 converts the video signal sent from the infrared camera 5 into a digital signal and stores it in the image data storage section 11.
Stored in the data area under test. Furthermore, the image processing circuit 8
calculates comparison data by performing a logical operation on this test data and previously stored non-defective data that serves as a standard for determining the quality of soldering, and analyzes this comparison data to determine the quality of soldering. Then, the pass/fail determination result is sent to the computer 1 through the interface circuit 9.

Further, the display device 10 displays an image of the soldering part and the contents of the abnormal value. Soldering inspection is carried out by this function.

FIG. 2 is a diagram specifically showing the soldering inspection section 7.
This is an example in which a square chip resistor 7a is attached to a pad 7c of a printed circuit board 7b with solder 7d.

The temperature distribution of the soldered part after laser irradiation is also shown below. Arrows A and H indicate the irradiation position of the laser beam. The A side is an example of a lack of solder, and the B side is an example of an excess of solder. In this case, the A side has a small heat capacity at the irradiation point and a high temperature peak TA, and the B side has a large heat capacity and a low temperature peak TB. The temperature peak work is within the specified range (T
When L<T<TH>, the inspection department is judged to have good soldering, and the others are judged to be defective.

Figure 3(a) shows the lead 16 of sop type ICl3.
This is an example of inspecting the state in which the pad 7c of the printed circuit board 7b is soldered.

Section C in the figure shows a defective IC lead 16a that is open.

The illustrated area is an example of a solder bridge defect. When the solder joint 7d on the insertion pad 7C is irradiated with laser light in this state, image data as shown in FIG. 3(b) is detected and stored in the image data storage section 11.

This image data is compared with the image data of a non-defective item shown in FIG. 3(c), which is stored separately in the image data storage unit 11, and is determined to have a 0 copy as shown in FIG. 3(d) by exclusive OR processing. Image data is obtained in which only the abnormal portion of portion D is extracted.

This makes it possible to easily determine abnormalities in the soldered portion. Furthermore, the image data in FIG. 3(e) is obtained from the AND of the image data in FIG. 3(b) and (d), and the image data in FIG. 3(d) is
It can be determined that part 0, where the abnormal data disappears, is defective due to unsoldering, and part D, which remains, is defective due to solder bridging.

〔Effect of the invention〕

According to the present invention, a large number of solder joints are sequentially scanned with laser light, the temperature rise is detected by an infrared camera, and the images are processed all at once, thereby shortening the inspection time. It is possible to identify the location and type of soldering defects and the shape of the solder joint surface. It is possible to obtain a printed board inspection device that can efficiently determine the quality of soldering.

[Brief explanation of drawings]

Figure 1 is a block diagram of one embodiment of the present invention, Figures 2 and 3 are diagrams for explaining the process of extracting soldering defects according to the above embodiment, and Figure 4 is an explanatory diagram of the prior art. be. 1...Calculator 2...XY child table control section 3...XY child table structure section 4...Laser generator 6...Laser light adjustment lens 7...Soldering inspection section 8... Image processing circuit 9
...Interface section 10...Display device 11.
...Image data storage unit Engineering 2...Inspection information storage 13
...Reflector 14...Reflector drive unit 5
...Infrared camera

Claims (1)

[Claims] A device that irradiates laser light onto the soldered parts of a printed circuit board on which many electronic components are soldered, and determines the quality of the soldered parts based on the temperature rise.
A means to sequentially scan and irradiate a large number of soldered parts with laser light, an infrared camera that detects the temperature rise of all soldered parts using image data, and a comparison of the above image data with pre-stored image data of non-defective products. 1. A printed board inspection device comprising image processing means for determining defective locations and defective states of soldered parts.