JPH0236306A - Warp quantity measuring method for printed circuit board - Google Patents

Abstract

PURPOSE:To measure the warp quantity of the circuit board by measuring the distances between measurement points arranged on the printed circuit board at constant intervals and a distance measuring means and processing data on them. CONSTITUTION:The printed circuit board 1 is mounted on an X-Y table 7 and single or plural distance measuring means 8 are installed on the substrate 1. Then the table 7 is moved in an X and a Y direction to move the means 8 onto all the measurement points 4 arrayed on the substrate 1 at the constant intervals, the distances are measured, and the data on them are inputted to the storage device of an arithmetic unit. Here, an electronic component 2 is mounted on the board 1 and a fitting hole 3 is bored, so there is data which has a large variation quantity and varies abruptly as compared with data on adjacent measurement points 4, but the arithmetic unit discards the data like this and interpolates data which has a small variation quantity and varies smoothly and data at a standard measurement point to obtain a curve indicating the entire warp quantity of the board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the amount of warpage of a printed circuit board on which electronic components are mounted.

[Summary of the invention]

The present invention measures the distance between measurement points arranged at regular intervals on the printed circuit board and the distance detection means using a distance detection means provided at a position corresponding to a printed circuit board on which electronic components are mounted, and uses the distance detection means to measure the distance between measurement points arranged at regular intervals on the printed circuit board and the distance detection means. In this method, the amount of warpage of the printed circuit board at each measurement point is measured by inputting the data into the storage means of the arithmetic device and processing each input data by the arithmetic device.

[Conventional technology]

Conventionally, the laser soldering device shown in FIG. Devices such as the chip component mounting inspection device shown in FIG. 5 are used in the manufacturing process of electronic devices.

Since both of the above-mentioned devices use optical equipment such as a laser 9 and a camera 10, it is necessary to focus on an object such as the electronic component 2 on the top surface of the printed circuit board 1.

In general, the printed circuit board 1 on which the electronic component 2 is mounted is subjected to various heating processes such as flow soldering and reflow oven for soldering, and after the heating process the cylinder 6 is warped as shown in FIG. 7. A downward curvature as shown in FIG. 2 occurs, and if this amount of curvature exceeds a certain value, a problem as described below will occur.

(1) In the case of the laser soldering device shown in Figure 4,
The spot of the laser 9 is no longer focused on the soldering point of the electronic component 2 on the printed circuit board 1, and the heating temperature decreases, resulting in defective soldering. Also, laser 9
Since it is irradiated obliquely from above, the spot of the laser 9 is shifted from the heating point on the printed circuit board 1.

(2) In the case of the chip component mounting inspection device shown in FIG. 5, since the camera 10 becomes out of focus, the quality of the input image of the chip component 2 on the printed circuit board 1 deteriorates, and the chip mounting state is inspected. An error occurs in the judgment.

[Problem to be solved by the invention]

In the past, various efforts have been made to prevent warping of printed circuit boards due to heating.
According to Japanese Patent No. 0662, a warpage straightening device is provided in the printed circuit board cooling process of a flow solder for automatically soldering printed circuit boards to prevent warping of the printed circuit board due to heating. Also, for example, JP-A-59-2949
According to Publication No. 2, in the process of attaching leaded components to the front surface and attaching chip components to the back side of a printed circuit board that has gone through a flow mite process, warped printed circuit boards or printed circuit boards that occur during the chip attachment process are removed. A backup bin is provided to prevent or correct warping of the circuit board.

However, with the prior art, it is possible to prevent or correct warpage in the case of a downwardly warped printed circuit board as shown in FIG. 7, but it is not possible to prevent or correct warpage in the case of an upwardly warped printed circuit board as shown in FIG. Since correction is impossible, it is not possible to eliminate the above-mentioned problems with a warped printed circuit board.

[Means to try to solve the problem]

Therefore, in order to solve the above-mentioned problems, the present invention does not prevent or correct the warpage that occurs during the heating process of the printed circuit board, but measures the amount of warpage of the printed circuit board where the warp has occurred, and according to the amount of warpage. In the laser soldering process, in order to automatically adjust the focus of the laser or camera of the chip component mounting inspection device, the laser soldering is performed at regular intervals on the printed circuit board using a distance detection means provided on the top of the printed circuit board on which electronic components are mounted. The distance between the placed measurement point and the distance detection means is measured, the data is input into the storage means of the calculation device, each input data is processed by the calculation device, and the data between adjacent measurement points is Calculate the amount of change in , import only data that has a small amount of change and that changes smoothly into the arithmetic device, discard data that has a large amount of change and change rapidly, and import the truncated data into the arithmetic device. This is a method of measuring the amount of warpage of the circuit board on the printed circuit board 1 at each measurement point by supplementing with data.

[Effect]

The present invention adopts the method for measuring the amount of warpage of a printed circuit board as described above, and automatically adjusts the focus of the laser or camera of a laser soldering device or a chip component mounting inspection device according to the amount of warpage of the printed circuit board. You can always maintain the best focus.

〔Example〕

FIG. 1 is a perspective view illustrating a method for measuring the amount of warpage of a printed circuit board 1 according to an embodiment of the present invention, and FIG. 2 shows the arrangement of measurement points 4 for measuring the amount of warpage on the printed circuit board 1. The plan view and FIG. 3 are schematic diagrams showing the measured values at each measurement point 4 of the present invention and the amount of warpage of the printed circuit board 1, which is data processed by an arithmetic device based on the measured values.

In FIG. 1, a printed circuit board 41i, 1 with electronic components 2 mounted thereon is placed on an X-Y table 7, and one or more distance measuring means 8 are provided on the top of the printed circuit board 1.
will be installed. For example, a laser displacement sensor is used as the distance measuring means 8, and whether it is single or plural,
By moving the table 7 in the X direction,
The distance measuring means 8 can be moved above all the measuring points 4 of the printed circuit board 1 as shown in FIG. is measured and the data is input into the storage means of the arithmetic unit.

An electronic component 2 is mounted on a printed circuit board 1.
Further, holes 3 are provided to be used for attaching the printed circuit board 1 to a device mount or the like, or for other purposes. When the electronic component 2 and the hole 3 come to the position of the measurement point 4, the data of the distance from the distance measuring means 8 to the surface of the printed circuit board 1 corresponding to the position of each measurement point 4 is shown in the schematic diagram of FIG. Solid line 5 in the figure
It can be obtained in the form shown. In FIGS. 2 and 3, when the measurement point 4 located at the end of the printed circuit board 1 and where no electronic component 2 is mounted is taken as the reference measurement point 4a, and the data of the reference measurement point 4a is taken as the solid line 5a, The data when the electronic component 2 is present at the measurement point 4 becomes a solid line 5b, which is smaller than the solid line 5a of the data at the reference measurement point 4a. Conversely, the data when the hole 3 is present at the measurement point 4 becomes a solid line 5c, which is larger than the solid line 5a of the data at the reference measurement point 4a. Furthermore, when there is no electronic component 2 or hole 3, and there is only warpage of the printed circuit board 1, the data at the measurement point 4 becomes a solid line 5d.

The arithmetic device performs arithmetic processing on the data of each measurement point 4 inputted to the storage means, and determines whether the amount of change is large compared to the data of adjacent measurement points 4 as shown by solid lines 5b and 5c in FIG. Data that changed rapidly is discarded, and the data at measurement point 4 where the data was discarded is supplemented with data that changes smoothly and with a small amount of change as shown by solid line 5d, and data shown as solid line 5a obtained from reference measurement point 4a. 3, a printed circuit board 1 as shown by the curve of dotted line 6 in FIG.
A total warpage of 49 is obtained. Based on the data of the amount of warpage of the printed circuit board 1 shown by the curve of the dotted line 6, the laser soldering shown in FIG.
The focus of the lens 10 of the chip component mounting inspection apparatus shown in the figure is automatically adjusted to always maintain the best focus state.

As the distance measuring means 8 of the present invention, in addition to the laser displacement sensor described in the embodiment, an ultrasonic sensor, an optical sensor, an electrostatic sensor, etc. can also be used, and any distance measuring means 8 can be used in the same way. results.

automatically adjusts the focus of the camera according to the amount of warpage of the printed circuit board, and by always setting the best focus, the following effects can be obtained.

(1) In the case of laser soldering equipment, the laser spot focuses on the soldering point of electronic components on the printed circuit board, and soldering is performed at the optimal heating temperature. Furthermore, even if the laser is irradiated obliquely from above, the laser spot will not deviate from the heating point on the printed circuit board, and high-quality electronic devices can be produced.

(2) In the case of a chip component mounting inspection device, since the camera is focused, the quality of the input image of the chip component on the printed circuit board does not deteriorate, and the inspection judgment of the chip mounting state becomes accurate.

〔Effect of the invention〕

The present invention employs the method for measuring the amount of warpage of a printed circuit board as described above.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating a method for measuring the amount of warpage of a printed circuit board according to an embodiment of the present invention, and FIG. 2 is an arrangement of measurement points on the printed circuit board for measuring the amount of warpage of a printed circuit board of the present invention. FIG. 3 is a schematic diagram showing the measured values at each measurement point of the present invention and the amount of warpage of a printed circuit board processed by a calculation device based on the measured values. FIG. Laser soldering is a perspective view of the equipment, Figure 5 is a perspective view of the chip component mounting inspection equipment, Figure 6 is a side view showing the upwardly warped state of the printed circuit board, and Figure 7 is the right warped state of the printed circuit board. FIG. 1... Printed circuit board 2... Electronic component 3... Hole 4... Measurement point 5... Solid line 6... Dotted line 7... .. Figure 4 Hole 3 2 Electronic parts 7 X-Y tape 2 Diagram 5 of the Ibaraki Keizozu? 42 is a walking person. 11th page of Ebaku Figure 6 ＼ Separately reversed image (state, 1usu ■ 7U figure M7 figure

Claims (1)

[Claims] Distance detecting means is provided at a position corresponding to a printed circuit board on which electronic components are mounted, and the distance detecting means measures the distance between measurement points arranged at regular intervals on the printed circuit board and the distance detecting means. , the data is input to a storage means of a calculation device, each data input to the storage device is processed by the calculation device, and the amount of change in data between adjacent measurement points among the data of the measurement points is calculated. Only data that changes smoothly and with a small amount of change is taken into the arithmetic unit, data that has a large amount of change and changes rapidly is discarded, and the truncated data is supplemented with data that has a small amount of change taken into the arithmetic unit. A method for measuring the amount of warpage of the printed circuit board at each measurement point.