JP3364307B2 - Inspection method of solder joint - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a solder joint portion of an electronic component soldered to a board.

[0002]

2. Description of the Related Art In recent years, inspection devices for solder joints of electronic parts have become important as ICs with a narrow pitch, ICs with a small solder fillet, and the like have increased. A conventional technique is disclosed in, for example, Japanese Patent Laid-Open No. 2-287150.

A conventional solder joint inspection device will be described below with reference to the drawings. FIG. 4 shows a conventional solder joint inspection device. In FIG. 4, 1 is a continuous wave oscillating means for irradiating a portion to be inspected such as a continuous wave laser of a single wavelength mode such as argon, 2 is a light modulating means for intermittently irradiating light, and 3 is a piezo element. , A conversion means for receiving a signal such as a sound generated by the change of the solder joint portion and converting it into an electric signal, 4 is an arithmetic processing unit for receiving the signal from the conversion means 3 and performing arithmetic processing, 5 is an electronic component soldered The substrate 6 is an electronic component. FIG. 5 shows the operation principle (a) and the inspection output example (b) of the conventional solder joint inspection device.
(c) is shown.

In the above-mentioned conventional example, the light to be inspected is irradiated with the light whose intensity is modulated by the continuous wave oscillating means 1 for irradiating the inspected portion and the light modulating means 2 for intermittently irradiating the light. At this time, the electrode of the inspected part undergoes thermal expansion and contraction due to the change of the light intensity as shown in FIG. 5A, and acoustic vibration of the inspected part is obtained. The arithmetic processing unit 4 which receives the electric signal from the conversion means 3 which receives the acoustic vibration of the portion to be inspected and converts the electric signal into the electric signal operates to judge the quality of the soldered portion. When not soldered, a remarkable amplitude output is produced at the resonance point of the electrode as shown in FIG. 5 (b). When soldered, a flat amplitude output is obtained as shown in FIG. 5 (c).

[0005]

However, in the above-mentioned structure, there is a problem that it takes time to inspect because each light spot is inspected. For example, when inspecting all the pins of a 100-pin electronic component, it takes about 5 seconds per pin considering the vibration response time and frequency range.
An inspection time of about 8 minutes is required for each part.

The present invention solves the above-mentioned problems of the prior art. By simultaneously inspecting the joint portion between the substrate and the electronic component, the joint state between the electrode of the electronic component and the substrate can be inspected in a short inspection time. The purpose is to provide an inspection method that

[0007]

Means for Solving the Problems To this end, in the inspection method for inspecting the bonding state of the solder joint soldered electronic components on a substrate of the present invention, the laser over light <br/> irradiating the inspected portion of the substrate and the bonding portion of the electronic component, Leh
The joint heat is vibrated by the heat of the laser light, and the irradiation light to the inspected part and the reflected light from the inspected part interfere with each other, and the interference light is detected by the photodetector.
In receiving and computation processing signals from the light detecting element that,
Further, as the light detecting element Ru undergoing interference Wataruhikari, CCD (CHARG
e Co up led Device), PSD (Position Sensitive Detec)
tor), it is obtained as a photodiode is used.

[0008]

According to the above construction, the light from the laser light source is radiated to the inspected portion in a one-dimensional or two-dimensional manner, and the intensity of the light is changed. When the electrode of the inspected part undergoes thermal expansion and contraction due to the change of light intensity and the electrode is not soldered, the electrode resonates because the light is modulated at the natural vibration frequency of the electrode. , Vibrates with a large vibration amplitude. Also,
When the electrodes are soldered, there is no large vibration because the natural vibration frequencies are different. A one-dimensional or two-dimensional photodetecting element that interferes the irradiation light to the inspected portion and the reflected light from the inspected portion and receives the interference light, and an arithmetic process that performs arithmetic processing by receiving a signal from the photodetecting element A large number of electrodes in the soldered portion are simultaneously inspected by means to judge whether they are good or bad.

[0009]

Embodiments will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a solder joint inspection device according to a first embodiment of the present invention. In FIG. 1, 10 is a laser light source, 11 is a cylindrical lens that is an optical system for expanding the laser light source 10 one-dimensionally, 12 is an acousto-optical conversion element for applying intensity and frequency modulation to light, and 13 is a measured object. , 14 is a lens for focusing light on the measurement object 13,
15 is the irradiation position of the object to be measured 13, 16 is a beam splitter for generating interference light, 17 is a reflecting mirror for producing reference light, 18 is a light receiving element for interference light, 19 is a converter, and 20 is an output voltage. is there.

The operation of the first embodiment will be described. First, the laser light emitted from the laser light source 10 is one-dimensionally stretched by the cylindrical lens 11, and the acousto-optic conversion element 12 subjects the light to intensity and frequency modulation. This light passes through a lens 14 for condensing the light on the object to be measured 13, is radiated to the irradiation position 15 of the object to be measured 13 in a one-dimensional manner, and passes through the lens 14 again to generate a beam of interference light. Return to Splitter 16. The beam splitter 16 interferes with this light and the reference light from the reflecting mirror 17,
The light receiving element 18 receives the interference light, and the converter 19 obtains the one-dimensional vibration velocity information of the object to be measured 13 from the incident light and outputs the output voltage.
I am taking it out as 20.

The above structure and operation are the same as those of the heterodyne type laser Doppler vibrometer except that the light is one-dimensional.

FIG. 2 shows the structure of a solder joint inspection apparatus according to the second embodiment of the present invention. Further, those having the same effects as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 2, reference numeral 21 is a semiconductor one-dimensional or two-dimensional light emitting laser, and 22 is a photocurrent modulation power source for modulating semiconductor laser light.

The difference between the second embodiment and the first embodiment will now be described. In the first embodiment, the portion constituted by the laser light source 10 and the cylindrical lens 11 is a one-dimensional or two-dimensional light emitting laser 21, and the acousto-optic conversion element 12 that modulates the intensity and frequency of light is a photocurrent modulation power source 22. The part that modulates the semiconductor laser light is different, and other operations are the same. From this, the structure is simplified by using the laser of linear emission or planar emission instead of converting the point laser into linear or planar emission.

Further, FIG. 3 shows a solder joint inspection device according to the first embodiment. (A) The light receiving element is a CCD for one pixel output, and (b) the light receiving element is a PSD for each output of A and B, ( c) The light receiving element shows an example of the output of the photodiode. The difference in output when the light receiving element 18 is a CCD, a PSD, or a photodiode will be described with reference to FIG.

According to the present invention, since the laser light is radiated in a wide range in one dimension or two dimensions, a light interference state is created on the CCD. Since the electrode of the object 13 to be soldered is vibrated, the frequency of interference is different from that of other portions. By capturing this image information a plurality of times and checking the change in illuminance, it is possible to identify the presence or absence of a soldering failure and the location of the failure. Further, when the CCD is the PSD, the output of the PSD can be separately measured and calculated to determine the presence or absence of a defect, and it is possible to roughly specify the defective portion. Furthermore, when the CCD is used as a photodiode, from the change in the amplitude output from the photodiode,
Several defective points can be detected at the same time, and the inspection time can be shortened.

[0016]

As described above, according to the present invention,
By using the one-dimensional or two-dimensional laser beam and utilizing the thermal vibration phenomenon of the solder joint, the solder joint can be inspected in a shorter time than the conventional inspection method. It is possible to achieve automation and high-quality production.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a solder joint inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a solder joint inspection device according to a second embodiment of the present invention.

FIG. 3 is an inspection output of the solder joint inspection device in the first embodiment (a) the light receiving element is a CCD, (b) the light receiving element is a PSD,
(c) A diagram showing an example in which the light receiving element is a photodiode.

FIG. 4 is a block diagram showing a configuration of a conventional solder joint inspection device.

5A and 5B are diagrams showing an operation principle (a) and an example of inspection output (b) of a conventional solder joint inspection device, and (c) a case where soldering is performed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Continuous light oscillation means, 2 ... Optical modulation means, 3 ... Conversion means, 4 ... Arithmetic processing device, 5 ... Substrate, 6 ... Electronic component, 10 ... Laser light source, 11 ... Cylindrical lens, 12 ... Acousto-optic conversion element , 13 ... Measured object, 14 ... Lens, 15 ... Irradiation position, 16 ... Beam splitter, 17
... Reflecting mirror, 18 ... Light receiving element, 19 ... Converter, 20 ... Output voltage, 21 ... One-dimensional or two-dimensional emitting laser, 22
… Photocurrent modulation power supply.

Continuation of front page (51) Int.Cl. ⁷ identification code FI H05K 3/34 512 G01B 11/24 D (72) Inventor Masanori Yasutake 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-287150 (JP, A) JP-A-4-81654 (JP, A) JP-A-4-163935 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G01B 17/00-17/08 G01B 11/00-11/30 102 B23R 1/00 G01N 21/84-21/958 H05R 3/32-3/34 512

Claims (4)

(57) [Claims] 1. A test method for inspecting the bonding state of the solder joint soldered electronic components on a substrate, the laser over
Light is applied to the inspected portion of the joint portion of the substrate and the electronic component , the joint portion is vibrated by the heat of the laser light, and the irradiation light to the inspected portion and the reflected light from the inspected portion interfere with each other. is allowed, the interference light received by the light detecting element, the solder joint inspection methods, wherein the benzalkonium be arithmetic processing signals from the light detection element. Wherein as the light detecting element Ru undergoing interference Wataruhikari, CC
The method for inspecting a solder joint according to claim 1 , wherein D is used . As 3. A light detecting elements Ru interfered light, PS
Method of inspecting a solder joint according to claim 1 Symbol mounting characterized by using D. As wherein the light detecting element Ru interfered light, follower
Method of inspecting a solder joint according to claim 1 Symbol mounting is characterized by using a preparative diode.