JPS62133341A - Inspecting device for soldered part - Google Patents

Abstract

PURPOSE:To inspect defects such as lead floating, a shift in lead position, and solder bridging at a soldered part automatically by detecting the self-vibration of a lead due to air jet injection by using laser speckle. CONSTITUTION:An XY table 13 is positioned at an inspection position firstly under the command of a table control circuit 20 and a galvanomirror 11 is set at a specific position under the command of a galvanomirror 15. Then, an air jet is injected to a parts lead 1 from an air nozzle 2 under the command of a jet control circuit 16. A fluorescence waveform and speckle waveforms before and after the jet injection are inputted to a speckle and fluorescence sensor control circuit 17 and a speckle defect decision part 19 decides a lead floating defect. Further, the mirror 11 is driven under the command of the circuit 15 during the decision period to rotate, and a fluorescent image from a linear sensor 8 for fluorescence detection is inputted to the circuit 17 in synchronism with the rotation, so that a fluorescence defect decision part 18 decides a lead position shift and a solder bridging defect on the basis of the detected fluorescent image.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an inspection device for soldering parts, and in particular, to reliable inspection of lead floating, solder bridging, and lead misalignment defects in high-density flat package components. The present invention relates to a soldering part inspection device suitable for high inspection.

[Background of the invention]

Figure 5 shows the soldered portion of the flat cage-shaped component to be inspected. The soldering portion has a structure in which a wiring pattern 23 formed on a substrate 12 and a component lead 1 provided on a component 24 such as an LSI are joined. Defects in the soldered portion include those shown in FIG.

FIG. 6(a) shows a lead floating defect where the wiring pattern 23 and the component lead 1 are not bonded, FIG. 6(b) shows a lead misalignment defect where the component lead 1 is bonded to the wiring butter/23 with a misalignment. FIG. 6(c) shows a solder bridge defect in which the adjacent soldered portion is attached to the solder bridge 29. Since defects in these soldered parts are difficult to visually inspect, there is a strong need for automated inspection. but,
There is a problem that automatic inspection is difficult.

Conventionally, there are four methods for visually inspecting soldered parts, as described below.

The first method is to excite the vibrator at a frequency of 60H2 to 200KH2 by bringing it into contact with the soldered part, and detect the state of vibration at that time with a vibration detector. Defects are determined based on the condition (US Pat. No. 4,218,922).

The second method is to bring the vibrator into contact with the soldered part, which will span 20H2~IME2'' and 150KH2~65
Excite the soldering part by changing it at 0KH2t,
By detecting the magnitude of vibration at this time with a vibration detector, the frequency response of the soldered part is measured, and defects are determined based on this frequency response (U.S. Pat. No. 4,287,7
66).

The third method is called speckle vibration detection method.
Automatic vibration is generated in a floating lead by air injection, and the vibration is detected and determined as a defect using speckles generated by a laser irradiated on the lead (Japanese Patent Laid-Open No. 60-85363).

The fourth method is a fluorescent detection method developed for pattern inspection of printed circuit boards. In this method, short wavelength light is irradiated onto the object to be inspected, and only the fluorescence emitted from the base material is captured as a silhouette image of the detection pattern for pattern inspection (Japanese Patent Laid-Open No. 59-252344).

Among these methods, the first and second methods perform vibration excitation and vibration detection in a contact type, and therefore the test speed is slow and there is a possibility that a problem may arise in test reliability. Also, 1st. 2nd and 3rd
The method described above has the disadvantage that it can only detect lead floating defects, and the fourth method can only detect lead position deviations, solder position deviations, and solder bridge defects.

[Purpose of the invention]

An object of the present invention is to provide a soldering part inspection device that can automatically inspect lead floating defects, lead misalignment defects, and solder bridging defects in soldering parts.

[Summary of the invention]

In order to achieve the above object, the present invention integrates a mechanism that uses laser speckles to detect the automatic vibration of a reed caused by gas jet injection, and a mechanism that detects fluorescence generated from an object to be inspected by irradiating short wavelength light. Combined with this, a soldering part inspection device is constructed.

However, lead floating defects and lead misalignment defects,
Solder bridge defects can be automatically detected at the same time.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram of the inspection apparatus, which consists of an inspection head and a control section. The inspection head of the inspection device is an LSI
An air nozzle 2 that injects a turbulent air jet to indirectly give vibration to a component lead 1 such as, an Ar laser 3 that generates a short wavelength laser beam, and a lead that covers one side by converting the laser beam into a slit shape. Illumination optical system 4 for illuminating
, an imaging lens 5 for forming an image of speckles and fluorescent light on detection sensors 8 and 10, a dichroic mirror 6 for separating a fluorescent component and a speckle component in the detection light, and a fluorescent component and speckle component. dichroic mirror 7 that separates the components (wavelength characteristics are different from dichroic mirror 6)
, a linear sensor 8 for detecting fluorescent components, a cylindrical lens 9 for defocusing speckles to increase vibration detection sensitivity, a linear sensor 10 for detecting speckles, and a linear sensor 8 for detecting speckles. It consists of a galvanometer mirror 11 for scanning a one-dimensional fluorescent image into a two-dimensional image.

The control unit 22 of the inspection device includes an XY table 13 for positioning the printed circuit board 12 on which the component lead 1 to be inspected is mounted relative to the detection head, a galvano mirror drive circuit 14 for controlling the galvano mirror 11, and a galvano mirror drive circuit 14 for controlling the galvano mirror 11. A fluorescence sensor control circuit 15 that drives the IJ near sensor 8 for fluorescence detection in synchronization with the drive and captures the fluorescence image, and a jet flow control circuit 16 that controls the air jet from the air nozzle 2 in synchronization with the jet. Speckle detection linear sensor 10
and a speckle/fluorescence sensor control circuit 1 that drives the linear sensor 8 for fluorescence detection to capture speckle and fluorescence waveforms.
7, a fluorescent defect determination unit 18 that analyzes the detected fluorescent image to determine lead position misalignment and solder bridge defects, and a speckle defect that determines lead floating defects from the detected speckles and fluorescent waveforms. Judgment unit 19 and XY table 13
It consists of a table control circuit 20 that drives the table, and an overall control section 21 that controls the entire control.

In this embodiment configured as described above, the overall operation is performed as follows.

Inspection is performed by repeating positioning of the inspection target and detection judgment as described below. First, the XY table 16 is positioned at an inspection position by a command from the table control circuit 20, and the galvano mirror 11 is set at a predetermined position by a command from the galvano mirror control circuit 15. Next, a jet of air is injected onto the component lead 1 from the air nozzle 2 according to a command from the jet flow control circuit 16 . In synchronization with this jet, the fluorescence waveform and the speckle waveforms before and during jet injection are input to the speckle/fluorescence sensor control circuit 17, and speckle defects are determined based on the detected waveforms. In section 19, a floating lead defect is determined as will be described later. Also, during this judgment period, the galvano mirror 11 is driven by a command from the galvano mirror control circuit 15 to rotate the mirror 11, and in synchronization with this, the fluorescent image from the linear sensor 8 for detecting fluorescent light is illuminated. The sensor control circuit 15 receives the data, and based on the detected fluorescent image, the fluorescent defect determining section 18 determines lead position deviation and solder bridge defects as will be described later.

Defect determination is performed by a speckle defect determination section 19 and a fluorescence defect determination section 18. First, the speckle defect determination section 19
This section describes the defect determination performed in . As previously mentioned,
There are three types of waveforms taken into the speckle fluorescence sensor control circuit 17 as shown in FIG. FIG. 2(a) shows a fluorescence waveform, where the component lead 1 and the wiring pattern 23 are dark, and the substrate 12 is bright because it is an organic material that emits fluorescence. FIG. 2(b) shows a speckle waveform before air jet injection, and speckles from each component lead are detected as having severe irregularities. Figure 2 (c) shows the speckle waveform during air jet injection, and the speckle 25 from the good reed has almost the same waveform as the waveform before injection, and from the floating reed of the type where the reed automatically vibrates with a large amplitude. The speckle 26 is a smooth waveform with less unevenness compared to the waveform before injection, and the speckle 27 from a floating reed of a type where the reed hardly vibrates automatically has a more severe unevenness than the waveform before injection. Although there is almost no change in the waveform, the position of the unevenness has changed.

First, the maximum value f, , 8 and the minimum value fsin are determined from the fluorescence waveform, and the binarization threshold f'th is calculated using the following equation.

f'th = a (f, .-fsin) +fsi
n, 0. −, ,,, (1) where a, o(
The locations of the component lead 1 and the wiring pattern 23 (hereinafter abbreviated as the lead pattern section) are detected by binarizing with the calculated threshold value f'tb, which is a constant of 1, and the detected locations are sequentially expressed as Pl: Cx 1+x1
], P2: CX2*X2) ・” -Pn: C
X, , *Xn].

Number p1 of this lead pattern part. p2. p and l correspond to component lead numbers when there is no solder bridge defect. If there is a solder bridge defect, it will be detected by the fluorescence defect determination described in the next section, so here it is considered that it corresponds to the component lead number.

For each lead pattern portion corresponding to this lead number, the following operations are performed on the speckle waveforms before and during air jet injection to determine lead floating defects.

The unevenness is emphasized by taking the second derivative of the speckle waveform g+(x) before injection and the speckle waveform g2(x) during injection,
gl(X), g2(X) (denotes the second derivative g"(
x)=-g(x-m)+2g(x)g(x+m
): Calculate the cross-correlation ψ of (using the arm length of mVi differential 1 or 2), and consider a defect if ψ1 is smaller than a predetermined threshold ψth. The cross-correlation is calculated using the following formula.

Here, Σ is the sum up to (x,, xi).

Next, the defect determination performed by the fluorescent defect determination section 18 will be described. The detected fluorescent image is shown in FIG.

The fluorescent image is dark at the component lead 1 and wiring pattern 23 (lead pattern portion) and bright at the board 12. Furthermore, the lead misalignment defect 28 is caused by the protrusion amount S! of the component lead 1 from the wiring pattern 23! is larger than a predetermined tolerance value S, and a solder bridge defect 29 is a short-circuit between adjacent wiring patterns due to solder. Binarize this fluorescent image,
The inspection range y, to yo is projected in the y direction. The projected waveform is designated as h(x) and is shown in FIG. The projected waveform is binarized using a predetermined threshold hth, the width W of the lead pattern part (1=1.2...on) is calculated, and this is the predetermined protrusion tolerance SL and pattern width. A defect that is larger than the sum of W and smaller than the pattern pitch Wth2 is determined to be a lead misalignment defect, and a defect that is larger than Wth2 is determined to be a solder bridge defect.

According to this embodiment, speckles in the lead pattern portion are identified using fluorescence information, so weak speckles generated from the substrate are submerged in noise and the correlation value decreases. Misjudgment of lead floating defects can be reduced.

〔Effect of the invention〕

According to the present invention, speckle detection and fluorescence detection can be realized with a single head, and devices for detecting lead floating, lead misalignment, and solder bridge defects are integrated, so defects that should be detected with a single device. It has the effect of automatically inspecting everything.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a solder inspection device according to an embodiment of the present invention, FIG. 2(a) is a fluorescence waveform diagram, FIG. 2(b) is a speckle waveform diagram before air jet injection, and FIG. Figure 2 (0) is a speckle waveform diagram during air jet injection, Figure 3 is a fluorescence image diagram, and Figure 4 is a diagram of a fluorescence image.
The figure is a projected waveform diagram, Figure 5 is a perspective view of the solder parts of a flat package type component, and Figure 6 - Hibori #≠ Fermentation is an explanatory diagram of lead floating defects, lead misalignment defects, and solder bridging defects, respectively. . 1... Parts lead. 2... Air nozzle 3... Laser. 4...Irradiation optical system. 5... Imaging lens. 6.7...Dichroic mirror. 8...Linear sensor for fluorescence detection. 10...Linear sensor for speckle detection. 11... Galvano mirror 2 12... Printed circuit board 13... XY table. 22...Control unit. 23...Wiring pattern. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A first mechanism that uses laser speckles to detect automatic vibration of a reed caused by gas jet injection, and a second mechanism that detects fluorescence generated from an object to be inspected by irradiating short wavelength light. What is claimed is: 1. A soldering part inspection apparatus characterized in that the illumination light source of both mechanisms and the imaging lens of the detection optical system are made common to each other. 2. The soldering part inspection device according to claim 1, wherein the first mechanism includes an air nozzle that injects an air jet onto the leads, a laser light source that irradiates the leads with a laser beam, and an irradiation optical system. A soldering part inspection device comprising an imaging lens, a defocusing cylindrical lens, and a speckle detection sensor. 3. In the soldering part inspection apparatus according to claim 1, the second mechanism includes a light source that irradiates short wavelength light, an irradiation optical system, an imaging lens, and wavelength-separates fluorescent components. A soldering part inspection device comprising a dichroic mirror, a linear sensor for image detection, and a galvanometer mirror. 4. The soldered part inspection apparatus according to claim 1, wherein the light source is an Ar laser.