JPS59202048A - Inspection of connection state for electronic components - Google Patents

Abstract

PURPOSE:To inspect the connection state of electronic components to a printed circuit board at a high accuracy by irradiating a lead of electronic components with an energy beam to detect infrared rays radiated from a conductor pattern. CONSTITUTION:A part 5 of a lead 4 of electronic components 6 carried on substrate 1 is irradiated with an energy beam 7 such as laser beam to observe changes in the time of an infrared rays 8 radiated from a pattern 2. When the connection is normal, as the quantity of heat applied is consumed to raise the temperature of a solder 3, the rising of the infrared rays 8 is slow with time while when it is defective, that is quick because of a quick heat conduction to the pattern 2. Thus, the connection state of electronic components 6 to the substrate 1 can be inspected at a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the mounting of electronic components on a printed circuit board, and more particularly to an inspection method for inspecting the quality of the connection between the electronic components and the printed circuit board.

[Background of the invention]

Figure 1 and Figure 2 show the conventional method for inspecting the connection status of electronic components to printed circuit boards.
1411 and 2 are plan views.

A conductor pattern 2 is formed on a printed circuit board 1, a molten metal layer such as solder 3 is placed on this pattern 2, an electronic component 6 is mounted on this printed circuit board 1, and leads 4 are connected to the pattern through the solder 3. Connect to 2. One of the conventional inspection methods for inspecting the connection state of the electronic component 6 connected to the printed circuit board 1 in this way is to apply energy such as a laser beam to a part of the lead 4, for example, a flat part as shown by 9. Infrared rays 8 emitted from lead 4 by irradiating beam 7
This was to inspect the quality of the connection of the electronic section 8B by observing the The amount of heat possessed by the energy beam 7 irradiated onto the lead 4 instantaneously raises the temperature of the irradiated portion 9 of the lead 4, and also heat-immerses the pattern 2 through the solder 6.
Fru. At this time, the temperature of the lead 4 changes when the lead 4 is normally connected to the pattern 2 as shown in Figure 1, and when the lead 4 is not sufficiently connected to the pattern 2 as shown in Figure 4. are different. In other words, if the lead 4 is connected normally, the temperature of the lead 4 will drop, but if the lead 4 is not connected properly, the temperature of the lead 4 will drop.
The temperature decrease tends to be relatively slow. Therefore, if you observe the change in the infrared rays emitted from the lead 4 over 80 hours, you can determine whether the lead 4 connection is good or bad. However, in this method, if the heat conducted by the lead 4vc in the direction of the solder 6 is slow, the temperature of the lead 4 tends to decrease slowly. There was a problem that there were few. In addition, the shape of the lead 4 is not necessarily flat due to variations in the molding state, etc., so the infrared rays emitted from the lead 4 are emitted in random directions, and the intensity of the infrared rays detected by the infrared heat sensor varies. This drawback makes it difficult to measure the connection state of the leads 4 with high accuracy.

[Purpose of the invention]

An object of the present invention is to provide a method for accurately inspecting the connection state of electronic components to a printed circuit board.

[Summary of the invention]

The present invention is characterized by a method for inspecting the connection state of an electronic component, which irradiates the lead of the electronic component with an energy beam and detects infrared rays emitted from a conductor pattern to which the lead is connected.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to Figure 6 of the spear and Figure 4 of the fang. Figures 6 and 4 are side views of the electronic component 6 mounted on the printed circuit board 1, which are comparable to Figures 1 and 2 of the conventional method. ]-Figure 6 shows a case where the electronic component 6 is connected normally, and figure 4 shows a case where the connection is poor. The energy beam 7 is an energy beam such as a laser beam irradiated onto the lead 4, and the infrared ray 8 is infrared ray radiated from the pattern 2. The method of irradiating the energy beam 7 and the method of sensing the infrared rays 8 are basically the same as the conventional method.

To explain the method of this embodiment, a part of the lead 4, for example the part shown by 5, is irradiated with an energy beam 7,
Observe the change in infrared rays emitted from pattern 2 over 80 hours. Alternatively, the portion indicated by 9 on the lead 4 may be irradiated with the energy beam 7. As shown in Figure 3, in a normal case, the amount of heat applied relatively increases the temperature of the band 3, so the time change in the infrared ray 80 intensity rises slowly. In addition, as shown in Figure 24, in the case of a defect, pattern 2
Since the heat conduction to the infrared rays 8 is fast, the rise of the infrared rays 8 is fast.

In carrying out the present invention, it is necessary to accurately irradiate the energy beam 7 onto the lead 4.

For example, set the aperture limit of energy beam 7 to 80.
μm, and assuming that the positioning error of the energy beam 7 generation source with respect to the printed circuit board 1 or the positioning error of the printed circuit board 1 with respect to the engineering energy beam 7 generation source is ±50 μm, in order for the energy beam 7 to be positioned on the lead 4, ( 80/2+50)μm×2mi180μm
, f, that is, the width of the lead 4 is required to be 0.28 or more.

Energy beam 7 to one lead 4 or the next lead 4
When moving the source of the ball, it is desirable to use an NC control method in which the amount of movement is specified in advance using data and this data is used to drive a servo motor to move the ball screw.

Furthermore, as a method for sensing the temperature change in pattern 2, that is, the change in infrared rays 8, by using a non-contact type measurement method using an infrared heat sensor, accurate measurement can be performed without causing any thermal effect on the object. By configuring this sensor integrally with the energy beam 7 source, the relative position with the energy beam 7 source becomes constant, ensuring positioning accuracy comparable to the positioning accuracy of the energy beam 7 source described above. can do.

As can be seen from the description of this embodiment, the present invention is a method of detecting infrared rays emitted from a conductor pattern 2, and since the upper surface of the pattern 2 has a relatively constant planar shape,
There is little variation in the intensity of infrared rays detected by infrared heat detectors.

〔Effect of the invention〕

According to the present invention, the connection state of an electronic component to a printed circuit board can be accurately inspected.

[Brief explanation of the drawing]

Fig. 1 is a side view of the printed circuit board 1 on which electronic components 6 are mounted, showing a conventional connection state inspection method, Fig. 2 is a plan view of the same as Fig. 1, and Fig. 1 is a plan view of the same as Fig. 1 of the present invention. A side view showing the inspection method of one embodiment and showing a normal connection state, No. 4
The figure is a side view showing the same inspection method as the third figure and showing a defective connection state. 1...Printed circuit board 2...Pattern 3...Solder 4...Lead 7...Energy beam 8...Infrared ray agent Masu filler High 8 Akira Daihayabusa 7 Figure Rod Z Figure Sheep 3 figure Doutouni

Claims (1)

[Claims] An inspection method for inspecting the connection state of leads of electronic components connected to conductor patterns on a board, characterized by irradiating the leads with an energy beam and detecting infrared radiation emitted from the conductor patterns. A method for inspecting the connection status of electronic components.