JPH04100849U - height adjustment device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to constantly optimize the off-contact distance of an off-contact printing machine, and in the same way, it is also possible to automatically adjust the height of a component mounting machine that mounts electronic components on a workpiece. Do it like this. [Structure] A height adjustment device for an off-contact printing machine that mounts a printed matter on a metal mask placed opposite the workpiece at a small distance, and slides a squeegee on the mask to print the printed matter on the workpiece. , a mask moving unit that mechanically presses a part of the mask to contact the workpiece; and an optical system that measures the amount of displacement of the mask when the mask comes into contact with the workpiece due to a moving operation by the mask moving unit. It is equipped with a type displacement meter and a lifting mechanism that lifts and lowers the workpiece so that the amount of displacement becomes a predetermined set value, and the off-contact distance is always kept constant.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a height adjustment device applied to off-contact printing machines or component mounting machines. related.

0002

[Conventional technology]

Off-contact printing that can print cream solder on the component mounting area of a printed circuit board The machine uses a combination metal mask with the structure shown in Figure 4. The same figure 11 is a rectangular plate frame, 12 is a resin elastic film attached to the plate frame, and 13 is the elastic film. It is a metal mask with a printed pattern attached to cover the opening in the center of the sexual membrane. (a is the bonded part).

This metal mask 13 is arranged at a predetermined off-contact distance _D1 from a workpiece 14 (for example, a printed circuit board) as shown in FIG. 5(a), and a printed matter is placed on it as shown in FIG. (Cream solder) 16 lumps are installed. Then, as shown in FIG. 5(c), the inclined squeegee 15 is lowered onto the mask 13, and when the squeegee 15 is slid from one end of the mask 13 to the other end, the printed matter passes through the opening of the mask 13. A printed material having a predetermined mask opening shape and mask thickness is printed (transferred to workpiece 14). In this case, the portions of the mask 13 before and after printing that are not in contact with the squeegee 15 are separated from the workpiece 14 due to the elasticity of the mask 13 and the elastic film 12.

0004 In addition, the component mounter also handles surface mount mounts picked up by the component mounting head 51 as shown in FIG. The part 52 of the pipe is lowered a predetermined distance and pressed onto the cream solder 16 on the workpiece 14. The end of the workpiece 14 is supported by the carrier 53, and the lower surface is exposed from below. It is supported by a backup pin (or backup plate) 54.

[0005]

[Problem to be solved by the invention] In the above-mentioned off-contact printing machine, it is important that the mask 13 and the workpiece 14 come into close contact with each other during printing, and that they quickly separate to a predetermined off-contact distance D ₁ after printing. . In order to easily realize this, the above-mentioned combination mask having elasticity is used. However, in reality, there are the following problems.

[0006] (1) If the off-contact distance is too large, the cream solder periphery will become fuzzy. Solder may spill onto non-printing areas of the workpiece, reducing resolution and causing solder blots. This may cause stains or smudges. Figure 6 is an explanatory diagram of this, where (a) is when printing and (b) is separated. It's time. If the off-contact distance d is large as shown in Figure (b), the mask 13 will return. The printing speed V is also large, and as a result, as shown in (c), the print on the workpiece 14 after mask removal is Fuzz may appear around the solder 16, or the part may fall onto the workpiece 14. do.

[0007] (2) If the off-contact distance is too small, the metal mass will be removed when the squeegee slides after printing. Cream solder bleeds onto the workpiece due to misalignment between the mark and the workpiece. Figure 7 is In this explanatory diagram, (a) is the time of printing, and (b) is the time of separation. As shown in the same figure (b), If the contact distance is small, a misalignment will occur between the mask 13 and the workpiece 14 during separation. However, as shown in (c), the solder 16 bleeds onto the workpiece 14 after the workpiece is removed.

[0008] (3) Off-contact distance adjustment is often done with screws, so for example, adjust the distance to 1mm. Fine precision control such as ±0.1mm is difficult.

[0009] (4) When the width of the printing area changes, the weight of the metal mask itself also changes. Another bullet Since the tension of the metal film also differs from one to another, even the same printing machine can print a combination metal mass. You must readjust the off-contact distance each time you change the distance.

0010 (5) The off-contact distance is determined by soldering on the metal mask 13 as shown in Figure 5(a). D without the₁and D when the solder 16 is mounted as shown in Fig. 5(b). ₂ , and the solder weight changes as printing is repeated (for example, 50 (from 0g to 250g), so it is not constant. Therefore, the distance is D in Fig. 5(a).₁Adjust with Even if D in Fig. 5(b)₂Even if you make adjustments, it is difficult to optimize it in one go.

[0011] Similarly, the problem with component mounting machines is their adaptability to variations in warpage of the workpiece 14. Ru. In Fig. 9, the work 14 (in this case, a printed circuit board) is as shown in Fig. 9(a). If the workpiece 14 is aligned downward, it will come into contact with the backup pin 54 and the workpiece 14 will be flat. There is no problem because it becomes

0012 However, if the workpiece 14 is tilted upward as shown in the same figure (b), the backup will occur. Since the correction using the pin 54 is not effective, lower the head 51 by the same distance as in (a). In this case, the part 52 tends to be pushed into the workpiece 14. As a result, the parts Misalignment (horizontal direction) may occur, or the cream solder 16 may be crushed and soldered. This causes ridges to form.

[0013] This invention constantly optimizes the off-contact distance of such off-contact printing machines. The height of the component mounting machine that mounts electronic components on the workpiece in the same way The purpose is to allow adjustments to be made automatically.

[0014]

[Means to solve the problem]

This invention prints on a metal mask placed opposite the workpiece at a small distance. Load the object and slide the squeegee over the mask to print the printed material on the workpiece. In the height adjustment device of an off-contact printing press, a part of the mask is mechanically pressed. an off-contact distance moving section that presses the workpiece into contact with the workpiece; an optical variable that measures the amount of displacement of the mask when it comes into contact with the workpiece; position meter, and a lifting mechanism that lifts and lowers the workpiece so that the amount of displacement becomes a predetermined set value. The first feature is that it is equipped with a An optical displacement sensor is attached to the component mounting head to be lowered, and the workpiece obtained by the sensor is The first step is to optimally set the descending distance of the head for each workpiece based on the distance information to the workpiece. 2.

[0015]

[Effect]

According to a first feature of the invention, the off-contact distance is adjusted frequently (e.g. This is done once per swivel of the squeegee), so even if the amount of printed material loaded changes, the It is possible to keep the off-contact distance constant, and it is also possible to maintain a constant off-contact distance, and to avoid resetting during initial settings and mask conversion. No settings are required.

[0016] According to the second feature of the present invention, even if there is distortion in the workpiece on which the component is mounted, Since the height of the component mounting head is adjusted (adjustment of the amount of descent) in anticipation of the can be prevented from occurring.

[0017]

【Example】

FIG. 1 is a block diagram of an off-contact printing machine showing an embodiment of the present invention. In the figure, The plate frame 11, elastic membrane 12, and metal mask 13 are the same combination metal as shown in Fig. 4. A mask 10 is configured. The workpiece 14 facing this mask is driven by a pulse motor 21 The workpiece is placed on a base 22 of a workpiece lifting mechanism 20 that moves up and down. On the other hand, printed matter The squeegee 15 that presses the squeegee 16 is the base 3 of the squeegee drive mechanism 30 above the mask. It is attached to 1.

[0018] A part of this squeegee drive mechanism 30 has a metal plate that pushes out the shaft 32 using air pressure. an off-contact distance checking pneumatic actuator 33 that presses the screen 13; An optical displacement meter 34 for measuring the distance to the metal mask 13 is provided.

[0019] Measurement of the off-contact distance according to the present invention is performed immediately before printing using the following procedure. First of all, a Push out the shaft 32 of the actuator 33 to press the metal mask 13 onto the workpiece 14. Let's go. Then, the amount of mask displacement at this time is measured using an optical variable device such as an LED or laser reflection type. It is measured with a position meter 34 and its output is input to a comparator 41. Memory 42 is desired in advance. The comparator 41 is an optical type. The actual displacement measured by the displacement meter 34 is compared with the set value. Then, set value and actual The difference from the actual displacement becomes the control amount (correction value) of the pulse motor 21 and is fed back. be done. The pulse motor 21 receives the output (with polarity) of the comparator 41 and rotates forward or reverse. The base 22 is raised and lowered so that the output of the comparator 41 becomes zero.

[0020] After this, the squeegee 15 is slid to print on the workpiece 14. and then another When printing on the workpiece 14, immediately before printing, the off-contact Readjust the distance. Therefore, the weight of the solder 16 may change or the mask 13 may be replaced. However, the distance is always kept constant. Note that the measurement and adjustment of this distance is done while maintaining the plate frame 11. It may also be carried out using a holder (not shown).

[0021] FIG. 2 is a configuration diagram of a component mounting machine according to the present invention. The component mounting head 51 is Z, θ The height Z and rotation angle θ are adjusted by being supported by the unit 55, and the Z, θ unit The shaft 55 is supported by an X, Y unit 56 and its position within the horizontal plane XY is adjusted.

[0022] The role of this component mounting head is to pick up components, position components, and move components. movement (transportation), mounting of parts on the workpiece, and confirmation of the parts mounting position (X, Y, Z, θ). Knowledge is the main thing.

[0023] Among these, the component mounting position is recognized using a pattern recognition camera 57 installed in parallel. conduct. That is, the target pattern is captured in the visible range of the camera 57, and the image is The amount of deviation is determined by comparing it with a virtual pattern with no deviation, and this amount of deviation is calculated as the amount of part movement. Please provide feedback and make corrections.

[0024] This feedback function can only correct the horizontal directions X, Y, and θ; The vertical direction Z cannot be modified. The embodiment of FIG. 2 makes this possible, An optical displacement sensor 58 similar to the embodiment shown in FIG. 1 is attached to the Z and θ unit 55. Ru. This sensor 58 is also a reflective type using an LED or laser as a light source. The distance to the workpiece 14 is measured.

[0025] Then, if the actual measured distance differs from the descending distance of the head 51, it will be corrected. A Z, θ unit 55 adjusts the amount of movement in the Z direction. As a result, Fig. 9(b) Even if the workpiece 14 is along the upper side as shown in the figure, the above-mentioned component mounting error will not occur. stomach.

The height adjustment (descent amount adjustment) described above can also be performed using the camera 57 for pattern recognition. FIG. 3 is an explanatory diagram of this, and (a) shows a case where the distance from the camera 57 to the workpiece 14 matches the focal length of the camera 57. In this case, since the reflectance of the conductor 14a within the visible range of the camera 57 is high and the reflectance of the surrounding base material is low, the recognized image becomes a pattern having a white portion 59a with a diameter d ₁ .

On the other hand, when the distance between the camera 57 and the workpiece 14 is shorter than the focal length as shown in FIG. 3(b), the diameter d ₂ of the white portion 59b of the recognized image is larger than d ₁ . Also, when the distance between the camera 57 and the workpiece 14 is longer than the focal length as shown in (c), the diameter d ₃ of the white portion 59c of the recognized image is larger than d ₁ .

[0028] Therefore, when the component mounting head 51 and the workpiece 14 are at an appropriate distance, the If the relationship between the camera 57 and the workpiece 14 is set as shown in FIG. 3(a), the optical The height of the head 51 can be adjusted to the optimum value without using the displacement sensor 58.

[0029] However, there is also an advantage of using the sensor 58 and camera 57 together. That is sensor 5 If you adjust the height first with step 8, the focus matching rate of the camera 57 that performs pattern recognition will be better. This is the point. In addition, pattern recognition involves binarizing the target pattern into black and white, and This is done by comparing the center of gravity position of the reference pattern with the center of gravity position of the reference pattern to find the deviation. The deviation is added to the component mounting position to correct the mounting position.

[0030]

[Effect of the idea]

As described above, according to the present invention, the off-contact distance of the off-contact printing machine is The distance can be constantly optimized, and electronic components can be mounted on the workpiece in the same way. The height of the component mounting machine can also be adjusted automatically.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of distance adjustment using a pattern recognition camera.

FIG. 4 is a configuration diagram of a combination metal mask.

FIG. 5 is an explanatory diagram of off-contact printing.

FIG. 6 is an explanatory diagram of fuzzing and falling.

FIG. 7 is an explanatory diagram of bleeding.

FIG. 8 is an explanatory diagram of a defect.

FIG. 9 is an explanatory diagram of a conventional component mounting machine.

[Explanation of symbols]

10 Combination metal mask 14 Work 15 Squeegee 20 Work lifting mechanism 30 Squeegee sliding mechanism 33 Off-contact distance check section 34 Optical displacement meter 41 Comparator 51 Component mounting head 58 Optical displacement sensor

Claims (2)

[Scope of utility model registration request] [Claim 1] Height of an off-contact printing machine that mounts a printed matter on a metal mask placed opposite the workpiece at a small distance, and prints the printed matter on the workpiece by sliding a squeegee on the mask. In the adjustment device, a mask moving unit mechanically presses a part of the mask to contact the workpiece, and a displacement amount of the mask is measured when the mask comes into contact with the workpiece through a moving operation by the mask moving unit. 1. A height adjustment device comprising: an optical displacement meter that moves the workpiece; and a lifting mechanism that moves the workpiece up and down so that the amount of displacement becomes a predetermined set value. [Claim 2] An optical displacement sensor is attached to the component mounting head that descends while holding the component to be mounted on the workpiece, and the descending distance of the head is determined for each workpiece based on the distance information to the workpiece obtained by the sensor. A height adjustment device for a component mounting machine that is characterized by optimal settings.