JP2006295036A - Inspection method of printed circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve inspection problem in which in a method of inspecting a printed circuit up to now, a checking error is never avoided in visual inspection because a reflection of blue component is strong even if regular black light is used, therefore, a test piece becomes very difficult to see. <P>SOLUTION: In an inspection method of the printed circuit, a light having a wavelength of invisible region is irradiated; the light is ultraviolet rays; the ultraviolet rays have a wavelength of region not containing the blue component; the light is irradiated from upper, lower, and side hoop directions, an irradiation of the light is performed by combining a source of luminescence and optical system elements such as lens, prism, and mirror; and the irradiation of the light is performed by switching two or more wavelengths different from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention makes it possible to surely check the disconnection, crack, touch, poor connection, existence of unnecessary elements, etc. in the printed wiring board, in particular, the printed wiring board in the single board state before the multilayer construction by visual inspection of the inspector. The present invention relates to an inspection method for printed wiring boards.

  Conventionally, the inspection of a printed wiring board in a single plate state has been mainly performed by an inspector's visual inspection. This inspection method is performed by irradiating the printed wiring boards, which are sequentially conveyed one by one by a conveying means such as a belt conveyor, with white light from the white LED to brighten the entire printed wiring board. After that, it is common to irradiate red or yellow light to improve accuracy and reconfirm.

  However, in the method described above, there are many parts that depend on the proficiency level of the inspector, and it is not possible to clearly see the defective part at a glance, and a check mistake often occurs.

  For this reason, the printed wiring board is irradiated with a black light after the light irradiation by the white LED, but in this case, the ultraviolet ray emitted from the normal black light contains a lot of blue components. Therefore, the blue component is strongly reflected, and it becomes difficult for the inspector to see various elements of the printed wiring board.

In addition, a method of using a laser beam having a plurality of wavelengths is also disclosed for the inspection of a printed wiring board. In this case, various device elements such as a polygon mirror, a spectroscope, a photodetector, and an arithmetic unit are also disclosed. Is required, and in particular, it is specified for inspection and measurement of shape defects at the height position of the mounted electronic component.
JP 2003-97924 A

  The problem to be solved by the present invention is that, in the conventional method for inspecting a printed wiring board, a check mistake is unavoidable for visual inspection. The reflection is so strong that it becomes very difficult to see.

  In order to solve the above-mentioned problems, the printed wiring board inspection method according to the present invention is characterized by irradiating light having a wavelength in an invisible region, and the above-described light is ultraviolet light. Ultraviolet rays have a wavelength in a region not containing a blue component.

  The printed wiring board inspection method according to the present invention is characterized in that the above-mentioned light is irradiated from above, below, and the lateral direction, and the above-mentioned light irradiation is performed by an optical source such as a light source, a lens, a prism, a mirror, It is characterized in that system elements are combined, and the above-described light irradiation is characterized by switching between two or more different wavelengths.

  The printed wiring board inspection method according to the present invention is configured as described above. For this reason, when using ultraviolet rays with a wavelength that does not contain a blue component, and irradiating them, defective parts such as disconnections, cracks, touches, etc. can be clearly revealed. Can be grasped, and check mistakes can be completely prevented.

  Further, by performing this irradiation from the upper, lower and side peripheral surfaces, a three-dimensional check can be performed, so that a defective portion in a hidden portion is not overlooked. Furthermore, by switching and irradiating ultraviolet rays having a plurality of wavelengths, it is possible to visually compare the emergence of defective portions at each wavelength, and it is also possible to find the defective portions in a flash manner.

  For the printed circuit board in a single plate state that is being conveyed, a light emitter (element) that emits ultraviolet light of a wavelength that does not contain a blue component is arranged at a plurality of locations on the upper, lower and side peripheral surfaces, This is realized by providing a light emitter (element) that emits ultraviolet rays having other commonly used wavelengths.

  Next, a preferred embodiment of the present invention will be described. The printed wiring board, which is an object in a single plate state, is sequentially conveyed at an appropriate interval by a conveying means such as a belt conveyor, and stops for a predetermined time in front of the inspector.

  It is desirable that the peripheral area where the printed wiring board to be inspected is stopped be as dark as possible with the illumination blocked. In addition, light emitting elements that emit ultraviolet light having a wavelength (340 nm to 408 nm) that does not include a blue component are fixedly disposed at positions above and below the stop position and on the side peripheral surface of the stopped printed wiring board. Keep it.

  In addition, it is possible to provide a general ultraviolet light emitting element in parallel with the light emitting element that emits ultraviolet light having a wavelength not including the blue component, and this is achieved by using a single light emitting element. It can also be set as the apparatus which switches.

  In this state, when the printed wiring board that has been transported and stopped is irradiated with ultraviolet rays of a wavelength that does not contain a blue component, either sequentially or simultaneously, the defective part that is in an abnormal state, particularly by keeping the surroundings dark. Appears more clearly than in normal cases. That is, the defective part is expressed with a clear difference.

  This phenomenon can be compared with the state immediately before it is irradiated with UV light of a wavelength that does not contain a blue component, and it can be compared with the momentary time difference when general UV light is irradiated and the situation is still unknown. It can be grasped like a flash. That is, it is similar to performing irradiation by removing a blue component from general ultraviolet rays, and instantaneously cancels reflection of the blue component.

As described above, the present invention is mainly characterized by irradiating the target printed wiring board with ultraviolet rays not containing a blue component, and the normal state is stored in the memory of the computer and conveyed. Compared with the whole printed circuit board, it becomes clearer by adding a mark or the like. Therefore, instead of using a printed wiring board as an object, it can be used to check the authenticity of printed materials such as banknotes, cards, gift certificates, tickets, lotteries, etc. A wide range of applications can be implemented. In particular, it works better for authenticating Chinese 100-yuan banknotes.

Claims (6)

  A method for inspecting a printed wiring board, comprising irradiating light having a wavelength in an invisible region.   2. The printed wiring board inspection method according to claim 1, wherein the light is ultraviolet light.   The printed wiring board inspection method according to claim 2, wherein the ultraviolet ray has a wavelength in a region not including a blue component.   4. The printed wiring board inspection method according to claim 1, wherein the above-mentioned light is irradiated from above, below, and a lateral direction.   5. The printed wiring board according to claim 1, wherein the light irradiation is performed by combining a light emitting source and an optical system element such as a lens, a prism, and a mirror. Inspection method. 6. The printed wiring board inspection method according to claim 1, wherein the light irradiation is performed by switching between two or more different wavelengths. .