JPH1021404A - Circuit pattern read and input device for printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely read the line width of a circuit pattern on a printed wiring board by receiving transmission light passing through the printed wiring board from a light source and outputting a circuit pattern picture data in an image sensor and detecting the transmission light and controlling the light emission of the light source in an optical sensor. SOLUTION: The image sensor 2 receives transmission light passing through the printed wiring board P from the light source 1 and reads the form of the circuit pattern Y. The optical sensor 5 senses the light quantity and the optical spectrum of transmission light passing through the printed wiring board P from the light source 1 and sends a control signal to an inventor control circuit 4. Namely, the optical sensor 5 detects the difference of transmission light from the printed wiring board P by the difference of the material of a board Pa as the difference of light quantity and the optical spectrum, feeds back it to the inventor control circuit 4, controls the inventor 3 and adjusts the light source 1 so that a prescribed condition is obtained for the image sensor 2 even if the material of the substrate Pa changes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit pattern formed by optically reading a circuit pattern on a printed wiring board in order to find a wiring defect of a circuit formed on the substrate of the printed wiring board by inspecting the appearance of the wiring. The present invention relates to an apparatus for obtaining image data (image electric signal).

[0002]

2. Description of the Related Art In general, the main defects in a circuit pattern of a printed wiring board include a disconnection defect, a short-circuit defect, a thin defect, and a fat defect. That is, as shown in FIG. 2, a part of the circuit pattern Y formed on the substrate of the printed wiring board P includes a disconnection defect Q1, a short-circuit defect Q2, and a thin defect Q3.
Or, a fat defect Q4 may occur. Thin defect Q3
Is a state where the line width is abnormally thinner than the allowable thinning specification allowed for the normal design line width W, and the fat defect Q4 is the allowable line width W for the normal design line width W. In this state, the line width has become abnormally thicker than the allowable thickening specification.
The thin defect Q3 and the fat defect Q4 are serious defects that have not yet resulted in a disconnection defect or a short-circuit defect, but are likely to be in a disconnection state or a short-circuit condition.

In order to find such a defect in a circuit pattern, an appearance inspection of the circuit pattern is indispensable. As the appearance inspection, a circuit pattern inspection by image recognition using a computer is frequently used. .
That is, the circuit pattern Y on the printed wiring board P is
(Charge Coupled Device) Read by a camera, input this as circuit pattern image data to a CPU (Central Processing Unit of a computer), compare it with image data of a normal circuit pattern stored in advance, The presence or absence of a defect in the circuit pattern Y is inspected. Then, light is emitted from the back of the printed wiring board P to
The CCD camera receives the transmitted light transmitted through the CCD camera, and since the amount of light and the light spectrum of the transmitted light are different between the portion where the circuit pattern Y exists and the portion where the circuit pattern Y does not exist, the circuit pattern Y is read by the CCD camera and the CPU outputs the circuit pattern image data. Is used. On the other hand, as the substrate of the printed wiring board P, substrates of various materials such as a phenol resin substrate, an epoxy resin substrate, and a polyimide resin substrate are used depending on the application.

[0004]

In such a conventional circuit pattern reading and input device for a printed wiring board, since the light transmittance varies depending on the material of the substrate of the printed wiring board, light is transmitted from the back surface of the printed wiring board. Even if the light emitted from the light source emits the same light, the amount of light and the light spectrum transmitted through the printed wiring board change depending on the material of the substrate. As a result, the threshold of the operating voltage of the CCD (threshold) is obtained.
Therefore, even if the actual line width of the circuit pattern on the printed wiring board is the same, the line width of the circuit pattern read by the CCD differs depending on the material of the substrate, and the line width of the circuit pattern image read by the CCD May be recognized as being thinner or thicker than the correct line width. An object of the present invention is to allow a line width of a circuit pattern on a printed wiring board to be correctly read by a CCD even if the material of the substrate of the printed wiring board is changed.

[0005]

In order to solve the above-mentioned problems, a circuit pattern reading and input device for a printed wiring board according to the present invention comprises: a light source for irradiating a printed wiring board on which a circuit pattern is formed from a back surface; An image sensor that receives the transmitted light transmitted through the printed wiring board from the light source and reads the circuit pattern on the printed wiring board and outputs circuit pattern image data, and an optical sensor that detects this transmitted light are provided. This optical sensor detects the difference in transmitted light from the printed wiring board due to the difference in the material of the board as the difference in the amount of transmitted light and the spectrum of the transmitted light.Based on this detection signal, even if the material of the board is different, the image sensor The light emission of the light source is controlled so that the light reception becomes constant.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of a circuit pattern reading and input device for a printed wiring board according to the present invention, a light source for irradiating the back surface of a printed wiring board on which a circuit pattern is formed, and a light source for transmitting the printed wiring board from the light source. An image sensor that receives the transmitted light, reads the circuit pattern of the printed wiring board and outputs circuit pattern image data, and an optical sensor that detects the transmitted light and controls the light emission of the light source. With reference to FIG. 1, one specific embodiment of a circuit pattern reading and input device for a printed wiring board according to the present invention will be described. P is a printed wiring board, and a circuit pattern Y is formed on the surface of the substrate Pa. Reference numeral 1 denotes a light source, which is a surface light source composed of a horizontally long fluorescent lamp so as to obtain a parallel light beam. Then, the light source 1 irradiates the back surface of the printed wiring board P. Reference numeral 2 denotes an image sensor composed of a CCD.
In this case, the shape of the circuit pattern Y is read by receiving the transmitted light transmitted therethrough. Reference numeral 3 denotes an inverter, and 4 denotes an inverter control circuit, which emits light from the light source 1 by changing the pulse lighting timing of the light source 1 by a PWM method (pulse width modulation method). Dimming the light. Reference numeral 5 denotes an optical sensor which senses the amount of light and the optical spectrum of light transmitted from the light source 1 through the printed wiring board P and sends a control signal to the inverter control circuit 4. In the circuit pattern reading and input device for a printed wiring board, a difference in transmitted light from the printed wiring board P due to a difference in the material of the substrate Pa is detected by the optical sensor 5 as a difference in light amount or light spectrum, and this is detected by an inverter. The inverter 3 is controlled by feeding back to the control circuit 4, and the light source 1 is adjusted so that the image sensor (CCD) 2 can receive light under certain conditions even when the material of the substrate Pa changes.

The surface of the printed wiring board P (the surface on which the circuit pattern is formed) is irradiated with light from a light source, and the reflected light is received by the image sensor 2 so that the circuit pattern Y
In the method of reading the circuit pattern Y, irregular reflection occurs at the corners of the circuit pattern Y, and the circuit pattern Y may not be correctly read, for example, the accuracy of the image is reduced or the image is captured as an image having dimensions different from the actual product. Therefore, in order to accurately read the circuit pattern Y, a method is employed in which light is emitted from the back surface of the printed wiring board P, and the transmitted light is received by the image sensor 2 to read the circuit pattern Y.

[0008]

As the substrate Pa of the printed wiring board P, substrates of various materials such as a paper-based phenol resin substrate, a glass-fabric-based epoxy resin substrate, and a glass-fabric-based polyimide resin substrate are generally used. . And the substrate P
Since the light transmittance differs depending on the material of the substrate a, even if the light emission from the light source 1 is the same, the light amount and the light spectrum of the light transmitted through the printed wiring board P vary depending on the material of the substrate Pa. As a result, the image sensor (CC
D) Due to the threshold of the operating voltage of 2, even if the line width W of the circuit pattern Y is the same, the pulse width Wp of the output pulse 6 of the image sensor 2 generated corresponding to this line width W May vary depending on the material of the substrate Pa, and the line width of the circuit pattern image read by the imager 2 may be recognized as being thinner or thicker than the actual correct line width. In the device for reading and inputting a circuit pattern of a printed circuit board, the difference in transmitted light from the printed circuit board P due to the difference in the material of the substrate Pa is detected by the optical sensor 5 as the difference in the amount of light or the light spectrum. The inverter 3 is controlled by feeding it back to the inverter control circuit 4 so that the image sensor 2 can receive light under a certain condition even if the material of the substrate Pa changes. Since the first dimming, even if the material of the substrate Pa various changes can correctly recognize the shape and dimensions of the circuit pattern Y by the image sensor 2.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for reading and inputting a circuit pattern of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of a printed wiring board.

[Explanation of symbols]

 Reference Signs List 1 light source 2 image sensor (CCD) 3 inverter 4 inverter control circuit 5 optical sensor 6 output pulse Wp output pulse width P printed wiring board Pa board Y circuit pattern Q1 disconnection defect Q2 short circuit defect Q3 thin defect Q4 fat defect

Claims (4)

[Claims] 1. A light source for irradiating a back surface of a printed wiring board on which a circuit pattern is formed, and a light transmitted through the printed wiring board from the light source is received to read the circuit pattern and output circuit pattern image data. A circuit pattern reading and input device for a printed wiring board, comprising: an image sensor; and an optical sensor that detects the transmitted light and controls light emission of the light source. 2. A light source for irradiating a back surface of a printed wiring board having a circuit pattern formed on a front surface, a light transmitted through the printed wiring board from the light source, the circuit pattern being read, and circuit pattern image data being read. An image sensor for outputting, an optical sensor for detecting the transmitted light, an inverter for controlling electric power to the light source, and an inverter control circuit for controlling the operation of the inverter based on a detection signal of the optical sensor. A circuit pattern reading and input device for a printed wiring board. 3. The printed circuit board circuit pattern input device according to claim 1, further comprising an optical sensor for detecting the amount of transmitted light. 4. The apparatus according to claim 1, further comprising an optical sensor for detecting an optical spectrum of transmitted light.