JPH11284400A - Method for detecting floating of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether a portion to be soldered is soldered in a recessed or projected form or not soldered, by successively detecting how the portion to be soldered is soldered and how an electronic component is mounted and determining whether the soldering state and the mounting state are acceptable or not based on the irregularly reflected light of a beam reflected from the portion to be soldered. SOLUTION: A beam B is injected from a movable galvanometer 3 onto a portion to be soldered of a chip component to be mounted. Light-receiving elements are provided on the four inner side surfaces of light-receiving means 9. When the portion to be soldered is soldered normally, the reflected light is dispersed in four directions uniformly. When the portion to be soldered is soldered with one end thereof floating, the amount of light received varies from one side surface to another. A processing unit 10 has a comparative reference value regarding the dispersion of the amounts of light received by the four side surfaces when the chip component is mounted normally, and compares one dispersion value with another. When the dispersion value of light irregularly reflected by the elements on the four side surfaces is out of the reference value range, it is determined that the chip component is mounted defectively due to some soldered portion(s) floating. Since the shape of a soldered portion is recessed or projected, it is determined that the portion to be soldered is soldered normally when reflected light is received, and it is determined that the portion to be soldered is not soldered when no light is received.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining whether or not an electronic component such as a resistor chip, a capacitor chip, or an integrated circuit mounted on a printed wiring board is mounted in a floating state with respect to a pad and is in a mounting failure state. The present invention relates to a method for detecting a floating electronic component.

[0002]

2. Description of the Related Art Conventional means for detecting the soldering state of chip components mounted on a printed wiring board are disclosed in Japanese Utility Model Publication No. 7-29483 filed by the present applicant and Japanese Patent Laid-Open No.
There is an apparatus proposed in Japanese Patent Application Publication No. 0-051194. Less than,
This device will be described with reference to FIGS.

FIG. 3 is a perspective view showing an optical system, 1 is a laser light source such as a He-Ne laser gun for emitting laser light, and 2 is a laser light source 1 for squeezing a laser beam sufficiently. This is an expander for temporarily expanding a beam to be formed into a parallel beam having a diameter of about 5 mm.

A beam spot 3 is swept in a direction crossing the longitudinal direction of an electronic component, for example, a chip component C mounted on a printed circuit board P for inspection, which is removably mounted on an XY stage T. A galvanometer having a Y-axis rotating mirror 3a for scanning a beam so as to scan the beam and a X-axis rotating mirror 3b for scanning the beam so that a beam spot is swept in the longitudinal direction of the chip component C. The beam is scanned within a solid angle based on the movable range of 3a and 3b.

[0005] Each of the mirrors 3a and 3b is servo-controlled by a signal of a built-in encoder. At this time, the position of the beam B irradiated on the printed board P is determined by the encoder signal.

Reference numeral 4 denotes a condensing lens for condensing a beam scanned by the galvanometer 3 on a printed wiring board P via a mirror 5 and a half mirror 6. Reference numeral 7 denotes a beam from a beam irradiation hole 9a of a light receiving means 9 to be described later. A light receiving element for receiving the reflected light from the solder surface coming out from above;
a lens for condensing the reflected light coming out from the light receiving element 7 on the light receiving element 7.

The light receiving means 9 is formed in a box shape having an open lower surface, and a beam irradiation hole 9a for passing a beam reflected from the half mirror 6 is formed in the center of the upper surface. A light receiving element divided into a plurality of stages in the vertical direction is attached to the side surface.

Next, the control system will be described with reference to the block diagram of FIG. The same reference numerals as those described above denote the same members, and a description thereof will be omitted. Reference numeral 10 denotes a processing device, and an operation unit 1
An output is sent to an XY stage control unit 15 and a galvano drive circuit 14b, which will be described later, based on the data input from 2 to irradiate and sweep the beam over a predetermined range. Then, the soldering state and the like of the electronic component are determined. Reference numeral 11 denotes a monitor such as a CRT for displaying the inspection result by the beam, 12 denotes an operation unit such as a keyboard, a floppy disk driver, a CD-ROM driver, and 13 denotes a printer for printing the inspection result by the beam.

Reference numeral 14 denotes a servo control unit, which comprises a servo control circuit 14a for driving and controlling the galvanometer 3 and a galvanometer driving circuit 14b. Reference numeral 15 denotes an XY stage control unit that controls the XY stage T, drives the XY stage T based on the position coordinates output from the processing device 10, and moves the printed circuit board P to a predetermined position. Things.

That is, a two-dimensional coordinate system in the X direction and the Y direction is set in the printed circuit board installation portion of the XY stage T, which is not shown, and the two-dimensional coordinate system output from the processing device 10 The XY stage T is driven so that the point coincides with a fixed point such as the initial setting position of the beam spot.

Next, the operation will be described with reference to FIG. First, before starting the inspection, inspection data such as a board name for identifying the type of the printed wiring board P is registered in a storage device (not shown) or the like beforehand. When the inspection is performed, the printed wiring board P is moved to the XY stage. When the device is placed on the T and a board name or the like is input from the operation unit 12, an inspection is automatically performed based on inspection data such as position information of an inspection location recorded in advance.

Then, one printed wiring board P is sent onto the XY stage T by a conveyor or the like, and is stopped and locked at a predetermined position by a stopper. In this state, the XY stage T
Is controlled so that the chip component C mounted on the printed wiring board P is located directly below the beam irradiation hole 9a in the light receiving means 9.

Next, when the position information for irradiating the beam is output from the processing device 10 to the servo control circuit 14a, the servo control circuit 14a outputs the X direction control signal and the Y direction control signal output to the galvano drive circuit 14b. Is corrected and output by the encoder output of the galvanometer 3, and the galvanometer 3 is driven to correct by the galvanometer driving circuit 14b, and the scanning direction of the beam B is determined.

Then, the processing unit 10 controls each unit and calculates based on the input signal, thereby forming the beam B in FIG.
The sweep is performed from left to right only for the soldered portion of the chip component C mounted on the printed wiring board P shown in (a) and (b). By this sweep, in the case of FIG. 5A, the reflected light is applied to the light receiving element on the left side of the light receiving means 9 in the counterclockwise direction, and in the case of FIG. Light is emitted clockwise to the light receiving element. Note that P in FIG.
₁ is a pad, C ₁ is an electrode.

The analog signal from the light receiving means 9 which has received the reflected light is sent to the processing device 10 and is converted into a digital signal internally. In the case of the reflected light moving in the counterclockwise direction, the solder surface is If it is concave, and if it moves clockwise, it is determined to be convex.

In the above description, the method of forming the solder surface on the left side of the chip component C is described, but the same inspection is performed on the right side of the chip component C.
In this case, the light receiving element on the right side of the light receiving means 9 receives the reflected light, the concave solder shape when the clockwise reflected light is received, and the concave solder shape when the counterclockwise reflected light is received. Judge as a convex solder shape.

By the way, the conventional concave solder shape obtained as a result of the reflected light as described above is good,
The convex solder shape was determined to be defective. But,
Regardless of the mounting method of the flow solder and the reflow solder for mounting the chip component C on the printed wiring board P, there is a problem that the shape of the solder is difficult to be uniform for the following reasons.

That is, in the case of flow soldering, it is difficult to form a systematically uniform solder shape, and in the case of reflow soldering, solder printing is performed based on the solder amount of a typical component. Therefore, a concave-shaped solder and a convex-shaped solder are generated.

However, even in the case of a convex solder shape, when there is a large amount of solder, there is no problem in terms of solder strength in terms of component mounting strength. There has been an increasing demand for judging that the product is good.

[0020]

Therefore, regardless of the shape of the solder, that is, even if the shape of the solder is concave or convex, if the criterion is relaxed so as to be judged as a good product, FIG. As shown in the drawing, even in the defective mounting state where the chip component C is floating, it is difficult to determine the floating from the solder shape, and this floating state is overlooked, and a problem that a good product is determined is generated. did.

An object of the present invention is to solve the above-described problems. The object of the present invention is to irradiate a beam to soldering surfaces at both ends of an electronic component and to reflect light (specular reflection) from the soldering surface. ) Is detected by the light receiving position of the light receiving means, the electronic component itself is irradiated with a beam, and the reflected light (irregular reflection) from the electronic component is detected by the light receiving balance of the light receiving means to obtain the solder shape and the electronic component. It is an object of the present invention to provide a method for detecting the floating of an electronic component in which the floating of the electronic component is determined.

[0022]

SUMMARY OF THE INVENTION The object of the present invention is to detect the floating of an electronic component by irradiating a beam to a soldering surface of the electronic component mounted on a printed wiring board. In the detection method, the reflected light is received by the light receiving means to detect the mounting state of the electronic component, and the position of the reflected light from the soldered portion of the beam is detected by the light receiving position of the light receiving means to determine the soldering state. Determination, and irregularly reflected light of the beam from the electronic component itself is detected by the light receiving balance of the light receiving means to determine the quality of the mounting state, and that the two determinations are continuously performed. Features.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for detecting floating of an electronic component according to the present invention will be described with reference to the flowchart of FIG.
A case in which a beam is applied to the chip component will be described. Since the optical system and the block diagram are the same as those in the conventional example, the description is omitted, but the operation of the processing device 10 is the same as the operation in the flowchart of FIG.

First, the chip component C mounted on the printed wiring board P by the XY stage T is controlled so as to be directly below the beam irradiation hole 9a in the light receiving means 9. In this state, the beam B is irradiated toward the chip component C while irradiating the beam B to the solder part of one electrode of the chip component C by the galvanometer 3.

Then, the reflected light from the soldered portion is received by the light receiving means 9, and it is monitored whether the reflected light is received in the clockwise or counterclockwise direction (step S1). If the reflected light is received, the process proceeds to the next step S2 since the solder shape is concave or convex, but if no reflected light in any of the above directions is received, it is in the unsoldered state. (Step S2).

Next, the beam B is output by the galvanometer 3.
Is further moved so that the beam B is controlled to be directly above the chip component C. Then, the amounts of light received by the light receiving elements on the four inner side surfaces of the light receiving means 9 at this time are added for each side surface (step S3).

Since the upper surface of the chip component C is rough, the beam B applied to the upper surface is irregularly reflected. However, when the soldering state is normal as shown in FIG.
The reflected light is dispersed in four directions on average, and FIG.
When one of them is floating, the light receiving elements on the four sides do not receive the average amount of light, and the light receiving elements in the direction in which the chip component C is tilted receive a particularly large amount of light. The amount of received light varies.

Therefore, a comparison reference value relating to the variance of the amount of light received by the light receiving elements on the four sides in the normal component mounting state is set in the processing apparatus 10 in advance, and the variance value obtained by the following equation is compared.

(Equation 1) Here, x _{1 to} x ₄ are the amounts of light received by the light receiving elements on the four side surfaces in the light receiving means 9.

Then, it is monitored whether or not the scattered value of the irregularly reflected light by the light receiving elements on the four sides is within the range of the comparison reference value (step S4). It is determined that _{one of} C is floating from the pad P1, and it is determined that the mounting failure is caused by the floating of the chip component (step S5).

Next, when it is determined in step S4 that there is no floating, similarly to the determination in step S1, the chip component C is irradiated with the beam B to the solder part of the other electrode of the chip component C by the galvanometer 3.
The beam B is moved in a direction away from the beam B.

Then, the reflected light from the soldered portion is received by the light receiving means 9, and it is monitored whether the reflected light is received in a clockwise direction or a counterclockwise direction (step S6). When the reflected light is received, since the solder shape is concave or convex, it is determined that the soldering state is normal and there is no lifting of the chip component C, and the mounting state of the component is good (step S7). . If the reflected light in any of the above directions is not received, it is determined that the soldering is not completed, that is, it is in an unsoldered state (step S8).

In the above-described embodiment, the case where a chip component is used as an electronic component has been described. However, the present invention can be applied to general electronic components mounted via leads.

[0033]

As described above, according to the present invention, whether the soldering state is concave soldering or convex soldering depends on where the reflected light of the beam applied to the soldering portion of the electronic component is received by the light receiving means. Or whether it is not soldered, and irradiates the beam to the electronic component itself,
Since the amount of reflected light received from the electronic component itself is determined to be within the range of the comparison reference value in the preset dispersion, the floating of the electronic component is determined.
Even if it is determined that the solder is good in the state of the delicate convex solder, it is possible to prevent the erroneous determination by the floating determination of the electronic component.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an operation of an electronic component floating detection method and apparatus according to the present invention.

FIG. 2 is a side view showing a normal soldering state and a floating state of the electronic component.

FIG. 3 is a perspective view of a conventional optical system for performing a soldering inspection.

FIG. 4 is a block diagram illustrating a configuration of the entire apparatus.

FIG. 5A is a side view showing reflected light in a concave solder state;
(B) is a side view showing reflected light in a convex solder state.

FIG. 6 is a side view of one of the electronic components in a floating state.

[Explanation of symbols]

 P Printed wiring board C Chip component B Beam 9 Light receiving means

Claims (1)

[Claims] 1. A detection method for irradiating a beam onto a soldering surface of an electronic component mounted on a printed wiring board and receiving reflected light thereof by a light receiving means to detect a mounting state of the electronic component. The position of the reflected light from the attachment part is detected by the light receiving position of the light receiving means to determine the soldering state, and the irregularly reflected light of the beam from the electronic component itself is detected by the light receiving balance of the light receiving means to determine the mounting state. A method for detecting the floating of an electronic component, the method further comprising: determining whether or not the electronic component is good or not, and performing the two determinations continuously.