JP3832062B2 - Cream solder appearance inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the appearance inspection method of the cream solder for soldering electronic components.
[0002]
[Prior art]
Cream solder for soldering electronic components to the substrate is printed on the substrate by a screen printing apparatus. The screen printing apparatus prints cream solder on the electrode of the circuit pattern of the substrate through a pattern hole formed in a large number of holes in the screen mask by overlaying the screen mask on the substrate and sliding the squeegee on the screen mask. Is.
[0003]
However, when cream solder is printed on a substrate by a screen printing apparatus, defects such as chipping, sagging, and shortage are likely to occur in the cream solder. Therefore, the appearance inspection of the cream solder printed on the substrate is performed.
[0004]
Conventionally, the appearance inspection of cream solder has been performed as follows. That is, after the cream solder is printed on the substrate using the screen mask, the substrate is taken out from the screen printing apparatus and set in the appearance inspection apparatus. Then, the position and size data of the cream solder is read by the optical element by the appearance inspection device. In the memory provided in the appearance inspection apparatus, a quality determination reference value is registered in advance as reference data, and the quality of the cream solder appearance is determined by comparing the data with the reference data.
[0005]
[Problems to be solved by the invention]
However, in the conventional method described above, data registered in the memory in advance is used as absolute reference data, and the read data is compared with the reference data to make a pass / fail judgment. Therefore, the reference data itself does not match the actual situation. In such a case, there is a problem that it is easy to mistakenly judge a good product as a defective product.
[0006]
Accordingly, the present invention aims at providing the appearance inspection method of the cream solder can be carried out precisely with reference cream solder visual inspection printed on the substrate to the state of the setup well, and the screen mask.
[0008]
[Means for Solving the Problems]
The cream solder appearance inspection apparatus of the present invention includes a screen mask positioning portion, a substrate positioning portion provided at the same plane position as the screen mask positioning portion, and a screen mask pattern hole positioned in each positioning portion. And an optical element for reading the cream solder printed on the substrate with the screen mask, and a moving means for moving the optical element in the horizontal direction, and the cream solder is positioned on the positioning portion before printing on the substrate . reading an image of the screen mask by the optical element, the center of gravity position and length and width of the pattern holes calculates the read image an image processing to the control unit, and a step of registering the data in the memory, the screen the substrate cream solder is printed through the pattern holes of the mask is positioned on the positioning unit, the A step you calculate the gravity center position and the length and width of the cream solder by reading an image of solder paste by the control unit by Manabu element, the cream solder of the data printed on the data and the board of pattern holes of the screen mask by comparing comprises a step of determining in determining means the quality of the cream solder appearance.
[0009]
According to the present invention having the above configuration, an image of a substrate on which a screen mask and cream solder are printed by a common optical element at the same plane position is obtained, and the pattern hole and cream solder data obtained thereby are compared. Since the appearance of the cream solder is judged as good or bad, the quality of the appearance of the cream solder printed on the substrate can be accurately judged according to the current state of the pattern holes of the screen mask actually used.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of an appearance inspection apparatus for cream solder according to an embodiment of the present invention, FIG. 2 is a perspective view showing an internal structure of the appearance inspection apparatus for cream solder, and FIG. 3 is an appearance inspection apparatus for the cream solder. 4 is a block diagram of the appearance inspection apparatus for the cream solder, FIG. 5 (a) is a plan view of the pattern hole of the screen mask, and FIG. 5 (b) is the cream solder printed on the substrate. FIG. 6 is a flowchart of the appearance inspection of the cream solder appearance inspection apparatus.
[0011]
In FIG. 1, a screen mask loading / unloading opening 2 and a substrate loading / unloading opening 3 are opened on the side surface of the main body case 1.
[0012]
In FIG. 2, the screen mask 4 is held by a mask holder 5 and a large number of pattern holes 6 are opened. Further, circuit pattern electrodes 8 are formed on the substrate 7, and cream solder is printed on these electrodes 8 through the pattern holes 6.
[0013]
A pair of left and right guide rails 10 are provided inside the opening 2, and the screen mask 4 is positioned on the guide rails 10. That is, the guide rail 10 serves as a positioning portion for the screen mask 4. A pair of left and right conveyors 11 is provided below the guide rail 10, and the substrate 7 is positioned on the conveyor 11. The conveyor 11 serves as a positioning portion for the substrate 7. The screen mask 4 and the substrate 7 are positioned at the same plane position, so that the appearance can be recognized by a common optical element (described later).
[0014]
2 and 3, reference numeral 13 denotes an optical element for reading an image, which includes a line sensor, a CCD camera, and the like. A nut 14 is coupled to the optical element 13, and a horizontal feed screw 15 is screwed into the nut 14. The feed screw 15 is driven to rotate by a motor 16. The feed screw 15 and the motor 16 are means for moving the optical element 13. Reference numeral 17 denotes a guide rail for the optical element 13. The optical element 13 moves horizontally above the screen mask 4 positioned on the guide rail 10 along the feed screw 15 (see the arrow in FIG. 3), and registers the read image data in the memory 21 (described later). . Further, the substrate 7 on which the cream solder is printed with the screen mask 4 is positioned on the conveyor 11, the optical element 13 is moved along the feed screw 15 above the substrate 7, and the read image data is registered in the memory.
[0015]
In FIG. 4, an optical element 13, a motor 16, a memory 21, a comparison unit 22, and the like are connected to a control unit (CPU) 20.
[0016]
This cream solder appearance inspection apparatus is configured as described above. Next, a cream solder appearance inspection method will be described with reference to the flowchart of FIG. First, the screen mask 4 is positioned on the guide rail 10 (step 1). Next, as shown in FIG. 3, the optical element 13 is moved above the screen mask 4, and the image of the screen mask 4 before the cream solder is printed on the substrate 7 is read (step 2). The read image data is registered in the memory 21 and processed by the control unit 20 (step 3).
[0017]
FIG. 5A shows the contents of this image processing. In this image processing, the center of gravity G (x, y) of the pattern hole 6 in the reference coordinate system (X, Y), the length L and the width W, and preferably the round shapes R1, R2 and the opening area S are controlled. Calculated in part 20. These data are registered in the memory 21. More preferably, auxiliary data such as the thickness of the screen mask 4 is also registered separately.
[0018]
Next, the screen mask 4 is removed from the guide rail 10, and the screen mask 4 is used to print cream solder on the substrate 7 by a screen printing apparatus (not shown) (step 4). Next, the board 7 on which the cream solder is printed is carried onto the conveyor 11 and positioned (step 5). Next, the image of cream solder is read by the optical element 13, and the data is registered in the memory 21 (step 6). Next, as in the case of Step 3, in addition to the center of gravity position G ′ (x ′, y ′), the length L ′, and the width W ′ of the cream solder shown in FIG. 5B, the round shapes R1 ′ and R2 ′ And the printing area S ′ is calculated by the control unit 20 (step 7). Desirably, a laser displacement meter may be provided above the substrate 7, and the height of the cream solder may be measured together with laser light.
[0019]
Next, the pattern hole 6 data and the cream solder data are compared by the comparison means 22 to determine whether or not the difference between the two is within an allowable range (step 8). If yes, screen printing is continued (step 9), and if no, the operator is notified and screen printing is stopped (step 10).
[0021]
【The invention's effect】
The present invention obtains an image of a substrate on which a screen mask and cream solder are printed by a common optical element at the same plane position, and compares the pattern hole and cream solder data obtained thereby to determine the appearance of the cream solder. since so as to determine the quality, it can be accurately carried out with reference to the present state of good determination of the cream solder printing.
[Brief description of the drawings]
FIG. 1 is a perspective view of a cream solder appearance inspection apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing an internal structure of the cream solder appearance inspection apparatus according to an embodiment of the present invention. FIG. 4 is a partial side view of a cream solder appearance inspection apparatus according to an embodiment of the present invention. FIG. 4 is a block diagram of a cream solder appearance inspection apparatus according to an embodiment of the present invention. Plan view of pattern hole of screen mask of embodiment (b) Plan view of cream solder printed on substrate of embodiment of the present invention FIG. 6 Visual inspection of cream solder of embodiment of the present invention Flow chart of appearance inspection of equipment
4 Screen mask 6 Pattern hole 7 Substrate 8 Electrode 9 Cream solder 10 Guide rail 11 Conveyor 13 Optical element 14 Nut 15 Feed screw 16 Motor 20 Control unit 21 Memory 22 Comparison means

Claims (1)

Positioning part of screen mask, positioning part of substrate provided at the same plane position as positioning part of screen mask, pattern hole of screen mask positioned in each positioning part, and cream printed on substrate with this screen mask An optical element for reading the solder, and a moving means for moving the optical element in the horizontal direction,
Before printing a cream solder on a substrate, the image of the positioned screen mask the positioning portion read by the optical element, the center of gravity position and length and pattern holes the read image an image processing to the control unit the width was calculated, and the step of registering the data in the memory, the substrate cream solder is printed through the pattern holes in the screen mask is positioned at the positioning portion, cream solder reads an image of solder paste by the optical element determining a step you calculate center of gravity position and control the length and width portion, the data and quality as compared to the cream solder appearance cream solder of the data printed on the substrate of the pattern holes of the screen mask of cream solder appearance inspection method which comprises the step of determining by a means.

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