JPH03109800A - Pattern matching of screen mask - Google Patents

Abstract

PURPOSE:To apply paste solder to an ideal position on a land by detecting a midpoint of two lands and a midpoint of two patterns to make these two midpoints coincide with each other. CONSTITUTION:A midpoint of a line of two lands (a) formed on a board 24 and a midpoint of a line connecting two pattern holes (b) corresponding to two lands (a) formed on a screen mask 33 are detected by a camera. Then, the board 24 is transferred relatively to the screen mask 33 by driving an XY table so as to make two midpoints to coincide each other. Thereby, the pattern holes (b) of the screen mask 33 are correctly matched with the lands (a) of the board 24 in order to apply paste solder to an ideal position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for pattern matching a screen mask, and more specifically, a method for optimally matching pattern holes formed in a screen mask to lands formed on a substrate. Concerning a method for doing so.

(Prior art) Electronic components such as IC chips and capacitor chips are manufactured by applying paste solder onto lands (electrodes) formed on a substrate using a screen printer, and then applying the electrode portions of the electronic components onto the paste solder. It will land and be glued. In this case, if the paste solder is deviated from the land, the electronic component cannot be properly bonded, so the paste solder must be applied accurately to a predetermined position on the land.

FIG. 6(a) shows the ideal application position of the paste solder 100. The paste solder 100 is smaller than the land 101, and is placed on one side of the land 101 (in this example, to the right). It is applied by Therefore, in this state,
The centroids Gl and G2 of both do not match.

By the way, pattern matching is generally performed by detecting the centroids of two objects to be matched with each other using a camera and matching the centroids with the centroids. However, when this 41m pattern matching method is used, the paste solder 100 is applied to the center of the land 101, as shown in FIG. It shifts considerably.

FIG. 7 shows a conventional means for solving the above problem, in which the screen mask 102 has a pattern hole 103 for applying paste solder, and a diagonal hole far away from the printing area 105. Two small holes 104 and 104 for pattern matching are formed in the. This device uses a camera to detect the positions of the small holes 104, 104, aligns the small holes 104, 104 with matching marks formed on the board (not shown), and applies solder paste. It has become.

(Problem to be Solved by the Invention) If the small holes 104 and 104 are formed in a separate process from the pattern hole 103, the relative positional accuracy of both 103 and 104 will be disturbed, so both 103 and 104 are etched. They must be formed together in the same process by other means. Therefore, although this conventional method can be applied when forming a new screen mask, it cannot be applied to an existing screen mask in which pattern holes have already been formed.

Therefore, the present invention provides a method for performing ideal pattern matching as shown in FIG. 6(a) without forming special matching means such as the above-mentioned small holes on a screen mask or a substrate. The purpose is to provide

(Means for Solving the Problems) In the present invention, as shown in FIG. 6(a), centroids Gl and G2 of individual lands and paste solder are not matched, but
The midpoint of two lands and the 2 corresponding to these two lands.
The midpoints of the cream solders were created with an eye to matching. To this end, the present invention uses a camera to detect the midpoint of a line connecting two lands formed on a substrate, and also connects two pattern holes corresponding to the two lands formed on a screen mask. The midpoint of the line is detected by a camera, and the XY child table is driven to move the substrate relative to the screen mask in order to match the two midpoints.

(Function) In the above configuration, paste solder is applied to the ideal position on the land by detecting the midpoints of the two lands and the midpoints of the two pattern holes and matching these two midpoints. do.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 4 and FIG. 5 are a perspective view and a front view of a screen printing machine. It consists of a screen device 3 provided in the.

The XYZ table device 1 has an X table 5. It is constructed by stacking an X-table 6, a rotary table 7°, and an X-table 8. The X table 5 is placed on an X direction rail 11 provided on the base plate 4 via a slider 12, and is reciprocated in the X direction by a motor MX and a feed screw 13.

The X table 6 is placed on a Y direction rail 15 provided on the X table 5 via a slider 16.
It reciprocates in the Y direction by motor MY and feed screw 17.

The rotary table 7 has its corner section
It is rotatably placed on a table 6. Further, a motor Mθ2 feed screw 19 is provided on the Y chief fluro. 20 is a nut screwed onto the feed screw 19; 21;
is a roller that is attached to the tip of the arm 22 extending from the rotary table 7 and that fits into the NAND portion 20 .

Therefore, when the motor Mθ is driven and the nut portion 20 slides along the feed screw 19, the rotary table 7
Rotate horizontally around .

The Z table 8 is attached to an actuator MZ consisting of a cylinder provided at the center of the rotary table 7. 23 is a guide rod portion. 24 is a substrate positioned on the Z table 8, and is a reference point Jl for observing positional deviation.

K1 is provided. Reference numeral 25 denotes a mask observation camera, which is integrally attached to the side of the Y table 6.

The board observation device 2 is configured by attaching a board observation camera 31 to a support 30, and observes the reference points Jl, Kl of the board 24 that has moved below the camera 31 from above.

The screen device 3 includes a mask 33 supported by a frame 32 and a mask 33 driven by a drive device (not shown).
It consists of a squeegee 34 that slides on the mask 33, and a reference point J2 is provided on the mask 33.

FIG. 1 is a plan view of the group vi24, in which the land portion A
A large number of 1 to AN are formed. Each land part A1-A
N is formed by arranging in parallel a plurality of lands (electrodes) a to which many leads of electronic components are grounded. This land a is precisely formed by etching means using a conductive material such as copper foil.

FIG. 2 is a plan view of the screen mask 33,
A large number of pattern holes B1 to BN are formed. The pattern hole portions Bl-BN correspond to the land portions A1 to AN, respectively, and each pattern hole portion B1 to B
Patterned holes corresponding to the respective lands a are formed in N. The pattern holes are smaller than the lands a, and by matching each pattern hole to the land a and sliding the squeegee 34, paste solder is applied onto each land a.

This screen printing machine is constructed as described above, and its operation will be explained next.

The motor MX is driven to move the camera 25 below the mask 33 (see the broken line in Figure 5), and then the motors MX, MY
By driving the camera 25 in the XY force directions, the two reference points J2. Observe 2. Next, drive the motor MX to move the board 24 below the camera 31, and then drive the motors MX and MY to move the board 24 in the XY force direction.
Observe the two reference points Jl and Kl (see the dashed line in Figure 5).

Next, mask 330 reference point J2. The reference point Jl of the substrate 24 with respect to 2.

The positional deviation of K1 in the xyθ directions is calculated. Such calculations, control of each motor, etc. are performed by a control device such as a computer.

Next, the reference point J1 of the board 24. 1 to the reference point J2 of the mask 33. 2, each motor MX, MY, M
The substrate 24 is moved directly below the mask 33 by driving θ. Next, the actuator MZ is driven to raise the substrate 24 and press it against the lower surface of the mask 33, and then the squeegee 34
to print cream solder on the circuit pattern of the board 240 (see the chain line in FIG. 5). Once you have finished printing,
The substrate 24 returns to its original position and is transported to the next process by a conveyor (not shown).

Next, the pattern matching method will be explained with reference to FIG.

As a mark for matching, for example, the land area Al
, AN and pattern hole portions Bl and BN are selected. This selection is arbitrary, but in order to improve the matching accuracy, especially in the θ direction (rotation direction), it is necessary to select lands AI that are diagonally located and far apart from each other, as in this embodiment. , AN and pattern hole B1. It is desirable to select BN.

Now, while operating the XY child table 6 and moving the group vi24 in the XY force direction, select the land portion A selected above.
t, two lands a11.t, AN, respectively. a19.
a21. A27 is observed with the camera 31. The selection of these lands is arbitrary, but for the same reason as mentioned above, lands a11 and a are located diagonally and apart from each other.
19. a21. It is desirable to select a27. Then the respective centroids Gll, Gl9, G21 . G27 is detected, and each centroid G11. G19 and G21. Line Nl connecting G27.

Find the midpoints Ql and Q2 of N2.

Similarly, while moving the turtle 25 in the XY force direction, each land al of the screen mask 33 is
l, a19. a21. Pattern hole bl corresponding to a27
l, b19. Observe b21b27 and find each centroid gll
, g19°g21. g27 and the lines connecting them nl, n
2 midpoints q1 and q2 are detected.

As explained with reference to FIG. 6(b), land a
If the centroid G of the pattern hole matches the centroid g of the pattern hole, the solder paste cannot be printed at the ideal position shown in FIG. 6(a). However, as is clear from FIG. 3, the above midpoint Ql.

By matching Q2 with the midpoints q1 and q2, the pattern hole can be ideally matched to the land a, and paste solder can be applied to the ideal position shown in FIG. 6(a).

The present invention has been made by paying attention to the fact that the land a and the pattern hole have such a unique matching characteristic.

Therefore, each midpoint Q1. XY child table to match Q2 with each midpoint q1, q2.

6 to move the substrate 24 directly below the screen mask 33, the solder paste can be applied to the ideal position. In Fig. 3, M is the midpoint Q above.
This is a line connecting l, ql and the midpoint Q2°q2, from which positional deviation in the θ direction is detected. Further, in the above embodiment, the group F
Although the midpoints Q1 to q2 are matched by moving 24 and 24 in the XY force direction, the screen mask 33 or both 24 and 24 may be moved in the XY force direction for matching.

By the way, once paste solder is applied to a predetermined number of boards 24 using the screen mask 33, this screen mask 33 is removed from the printing machine and stored in a separate storage, etc., and a new screen mask is printed. It is set on a machine and prints on a different type of substrate.

At a later date, when the same type of substrate 24 is to be printed again using the screen mask 33, the screen mask 33 is taken out of the storage and set in the printing machine. However, in this case, you may accidentally set another screen mask on the printing machine, or you may set screen mask 1 in the wrong front/back or left/right orientation, and if you print without noticing this error, , resulting in the production of defective products. Therefore, means for preventing such mistakes will be explained below.

As mentioned above, the land a11 of the substrate 24 observed with the camera 31. a19. a21. Centroid Gll of a27, G19
．． G21. The coordinates of G27 and the pattern holes bll, b19, b21 . observed with the camera 25. b27 centroid gll,
g19. Set the coordinates of g21 and g27 to this board 2.
4 and is registered in the computer as a unique feature point of this screen mask 33. That is, the centroids Gll to G
A substrate 24 on which lands all to a27 having 27 are present.
The screen mask used for centroids gll to g2
The computer is made to remember that there is a pattern hole having a number 7. If you do this, you can avoid accidentally centsing another screen mask, or screen mask 3.
If the direction of 3 is set incorrectly, the above centroid Gll
Since the centroid gll~g27 corresponding to ~G27 is not observed, the operator can be alerted to this fact by emitting an alarm sound or light using an alarm device.

Note that the feature point is not limited to the above-mentioned centroid, but may be any feature as long as it can be observed with a camera and is unique to the substrate or screen mask.

Further, although the number of feature points is arbitrary, erroneous determination can be more reliably prevented by increasing the number to a certain extent.

(Effects of the Invention) As explained above, the present invention uses a camera to detect the midpoint of a line connecting two lands formed on a substrate, and detects the midpoint of a line connecting two lands formed on a screen mask, and detects the midpoint of a line connecting two lands formed on a screen mask. A camera detects the midpoint of the line connecting the two pattern holes, and in order to match the two midpoints, the XY child table is driven to move the board relative to the screen mask. So, make sure to match the pattern holes of the screen mask to the lands of the board correctly.
Paste solder can be applied to ideal locations. In particular, this method has the advantage that it does not require any special modifications to the screen mask or substrate, and can be applied to existing screen masks as is.

[BRIEF DESCRIPTION OF THE DRAWINGS] The figures show an embodiment of the present invention, in which Fig. 1 is a plan view of a screen mask, Fig. 2 is a plan view of a substrate, and Fig. 3 is a plan view of the main part under observation. 4 is a perspective view of the screen printing machine, FIG. 5 is a front view of the same, FIGS. 6(a) and (b) are plan views of the land and paste solder, and FIG. 7 is a plan view of a conventional screen mask. It is a diagram. 33...Screen mask 25.31...Camera 24...Substrate 5.6...XY child table...Land b...Pattern hole Ql, Q2. ql, q2...midpoint

Claims (1)

[Claims] A camera detects the midpoint of a line connecting two lands formed on the substrate, and a camera detects the midpoint of a line connecting two pattern holes corresponding to the two lands formed on the screen mask. A pattern matching method for a screen mask, characterized in that the substrate is moved relative to the screen mask by driving an XY table in order to detect and match the two midpoints.