JPH09201943A - Device for spreading solder and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grasp the amount of creamy solder on a screen mask more precisely than by visual observation, reduce the amount of scatter in observations by workers and consequently materialize the secure prevention of the spreading work under the starved creamy solder from occurring by a method wherein human elements in solder spreading work are made small. SOLUTION: A solder spreading device 17 is equipped with a screen mask 18, squeegees 22 and 24 and the sensors of the amount of solder 26 and 35. The screen mask 18 is arranged on a printed-wiring board 11 and has spreading holes 21 at the places corresponding to the lands 15 of the wiring board 11. The squeegees 22 and 24 are provided slidably on the screen mask 18 so as to move the creamy solder 16 on the mask 18 under the state being rolled by the sliding in order to spread the solder through the spreading holes 21 on the lands 15. The sensors of the amount of solder 26 and 36 are respectively arranged to this sides of the sliding directions of the squeegees 22 and 24 so as to detect the heights of the creamy solder 16, which decrease as the slidings of the squeegees 22 and 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for applying cream solder to a land of a printed wiring board.

[0002]

2. Description of the Related Art A printed wiring board on which electronic parts are mounted is constructed by forming a wiring pattern on the surface of the substrate. When mounting an electronic component, cream solder is applied to the land of the wiring pattern according to a method such as a screen printing method, and the electrode of the electronic component is placed on the cream solder. The printed wiring board on which the electronic components are mounted in this manner is heat-treated and then cooled. Then, the cream solder is melted and solidified, and the electrode of the electronic component is soldered to the land.

In order to securely mount the electronic component on the printed wiring board, it is important to surely apply an appropriate amount of cream solder on the land. For this reason, various techniques relating to the application of cream solder have been conventionally proposed (see, for example, Japanese Patent Laid-Open No. 6-6023).

When cream solder is applied to a large number of printed wiring boards of the same type by one screen mask, in the technique of the above publication, application holes are formed on the printed wiring board before the cream solder is applied. Arrange the screen mask that has. The cream solder is put into the end of the screen mask, and the squeegee is slid from the end on the screen mask to the opposite end. The cream solder is pushed by a squeegee and moves with rotation (while rolling). A part of the cream solder enters the coating hole during this movement and fills the coating hole. This filling reduces the amount of cream solder on the screen mask. When the squeegee slides to the end of the screen mask, the mask and the printed wiring board are separated. Then, the cream solder escapes from the application hole and remains on the land. In this way, the cream solder is applied to the land. Next, the printed wiring board is replaced, a squeegee different from the one described above is slid in the opposite direction, and the cream solder remaining on the screen mask is moved while rolling to be supplied to the application hole. By alternately sliding a pair of squeegees in this way, cream solder is applied onto the lands of a large number of printed wiring boards.

[0005]

However, as described above, each time a pair of squeegees slides alternately and cream solder is supplied to the application hole, the amount of cream solder remaining on the screen mask decreases. Go on. When the amount of cream solder falls below a predetermined amount due to this decrease, the cream solder is less likely to roll and slips on the screen mask. Then, the application holes may not be filled with the cream solder, and the land may not be applied with the cream solder in a sufficient amount and may be faint. To prevent such problems, the operator visually monitors the amount of cream solder,
It is possible to prevent the application work from being continued with the shortage of the solder. However, the amount of cream solder visually recognized may vary from worker to worker due to differences in experience and the like. Therefore, this technique is not sufficient as a measure for preventing the above-mentioned problems.

The present invention has been made in view of the above-mentioned circumstances, and its object is to reduce the amount of cream solder on a screen mask more accurately than in the case of visual observation by reducing the human factors in the solder application work. Therefore, it is possible to reliably prevent the application work from being performed in a state where the cream solder is insufficient in order to reduce variations among workers.

[0007]

In order to achieve the above object, a first invention according to claim 1 is to arrange a coating hole on a printed wiring board and to form a coating hole at a location corresponding to a land of the printed wiring board. A screen mask having, and slidably provided on the screen mask, the sliding while moving the cream solder on the screen mask while rolling, a squeegee for applying on the land from the application hole, A solder amount detector, which is disposed on the front side in the sliding direction of the squeegee and detects the amount of cream solder on the screen mask, which decreases as the squeegee slides.

In the first aspect of the invention, the cream solder on the screen mask is pushed by the sliding movement of the squeegee. The cream solder moves while rolling and fills the application holes. Each time the cream solder is filled in the application hole, the amount of cream solder on the screen mask decreases. The amount of this cream solder is detected by a solder amount detector arranged on the front side in the sliding direction of the squeegee. Therefore, as compared with the case where the amount of solder is visually checked by the operator, it is possible to reduce human factors in the solder application work and avoid the problem that the cream solder is applied in a state of being insufficient.

A second invention according to claim 2 is the first invention.
The solder amount detector in the invention comprises a plurality of electrodes arranged in a state of being separated from each other along a direction intersecting the sliding direction of the squeegee, and depending on whether or not each electrode is in contact with the cream solder. The amount of cream solder is detected at a plurality of points in the intersecting direction.

According to the second aspect of the invention, the amount of cream solder is detected by the contact of many electrodes of the solder amount detector with the same solder. These electrodes are arranged along a direction intersecting the sliding direction of the squeegee in a state of being separated from each other. Therefore, even if the amount of cream solder is different for each of a large number of points along the intersecting direction, the amount is accurately detected. Therefore, human factors are further reduced as compared with the first invention. It can also be applied to printed wiring boards where the number and size of lands differ depending on the part.

According to a third aspect of the present invention, cream solder is put on a screen mask having coating holes,
A method in which the squeegee is slid on the screen mask to move the cream solder while rolling the squeegee, and the cream solder is applied to the land of the printed wiring board arranged under the screen mask from the application hole. In, the amount of cream solder on the screen mask is detected by a solder amount detector, and when the detected value becomes smaller than a predetermined value, the cream solder is prompted to be put on the screen mask. .

According to the third invention, the cream solder is put on the screen mask when the cream solder is applied. The squeegee is slid on the screen mask. The cream solder pushed by the squeegee moves while rolling. The solder is applied to the land of the printed wiring board from the application of the screen mask. The amount of cream solder on the screen mask is detected by a solder amount detector. Therefore, as compared with the case where the amount of solder is grasped visually by the operator, the human factors in the solder application work are reduced. Then, when the detected value of the solder amount detector becomes smaller than a predetermined value, the introduction of cream solder is prompted. For this reason, the worker can grasp the timing of charging the cream solder without monitoring the detection value of the solder amount detector.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the first to third inventions will be described below. As shown in FIG. 1, the printed wiring board 11 includes a substrate 12 made of an insulating material.
And a wiring pattern 13 made of copper foil formed on the surface thereof, and a resist 14 formed around the wiring pattern 13 on the surface of the substrate 12. A plurality of lands 15 are formed on the wiring pattern 13, and an electronic component (not shown) is mounted on each land 15 by cream solder 16 described later. The printed wiring board 11 is configured in this way. And
Plural types of printed wiring boards 11 having different shapes of the wiring patterns 13 and the number of lands 15 are prepared.

A cream solder 16 made of a metal powder such as lead (Pb) or tin (Sn) and a flux (resin component) is applied onto the land 15 by a solder applying device 17. The device 17 includes a base 20 on which the printed wiring board 11 is placed and a screen mask 18 arranged on the wiring board 11. The mask 18 is made of a material having corrosion resistance such as stainless steel, and a frame 19 is fixed around the mask 18. In a portion of the screen mask 18 corresponding to the land 15, a coating hole 21 having substantially the same shape as the land 15 is formed.
Has been opened. On this screen mask 18,
Cream solder 16 is manually put in.

The solder coating device 17 has a plate-shaped first squeegee 22 for moving the cream solder 16 on the screen mask 18 to the right in the drawing. The squeegee 22 is formed of a material having elasticity such as rubber, and is arranged so as to be inclined with respect to the screen mask 18 at a predetermined angle α. The angle α is set to a value suitable for the shape of the first squeegee 22, the type of cream solder 16, and the like.

A first squeegee driving device 23 is drivingly connected to the first squeegee 22. The drive device 23 operates the first squeegee 22 as follows. When the position where the lower end of the first squeegee 22 contacts the left end of the upper surface of the screen mask 18 (the position shown in FIG. 1) is the first reference position, the squeegee 22 slides on the upper surface of the screen mask 18 from the same reference position. While moving to the right. At this time, the cream solder 16 on the screen mask 18 is pushed by the first squeegee 22 and moved rightward together with the squeegee 22. When the first squeegee 22 reaches the right end of the screen mask 18, the first squeegee 22 temporarily stops and rises from that position. When the first squeegee 22 rises to a predetermined height, the first squeegee 22 temporarily stops and moves to the left while maintaining the height. When the first squeegee 22 moves above the first reference position, the first squeegee 22 temporarily stops, descends from that position, and returns to the first reference position. When applying the cream solder 16, the first
The squeegee 22 repeats such a series of operations.

Similarly, the solder coating device 17 is provided with a plate-shaped second squeegee 24 for moving the cream solder 16 on the screen mask 18 to the left. The squeegee 24 is formed of a material having elasticity such as rubber, and is arranged so as to be inclined with respect to the screen mask 18 at a predetermined angle β. This angle β
Is set to a value suitable for the shape of the second squeegee 24, the type of the cream solder 16, and the like.

A second squeegee driving device 25 is drivingly connected to the second squeegee 24. The drive device 25 moves the second squeegee 24 as follows. Assuming that the position where the lower end of the second squeegee 24 contacts the right end of the upper surface of the screen mask 18 is the second reference position, the squeegee 2
4 moves to the left from the same reference position while sliding on the upper surface of the screen mask 18. At this time, the screen mask 18
The upper cream solder 16 is pushed by the second squeegee 24 and is moved leftward together with the squeegee 24. The second squeegee 24 stops once reaching the left end of the screen mask 18 and rises from that position. The second squeegee 24 stops once it rises to a predetermined height,
Move to the right while maintaining its height. The second squeegee 24 is located above the second reference position (the position shown in FIG. 1).
When it moves to, it stops, then descends from that point and returns to the second reference position. When applying the cream solder 16, the second squeegee 24 repeats such a series of operations.

A first solder amount sensor 26, which constitutes a part of the solder amount detector, is attached to the front side in the sliding direction of the first squeegee 22, that is, in the vicinity of the right side of the squeegee 22. As shown in FIGS. 1 to 3, the sensor 26
Has a socket 27 containing an electronic circuit 28.
The socket 27 is drivingly connected to a first sensor driving device 29 having an electric motor or the like, and is reciprocated by the device 29 in a substantially vertical direction.

A sensor main body 31 formed of an insulating material such as synthetic resin in a substantially plate shape is detachably mounted on the socket 27. The sensor body 31 has a wedge shape whose thickness decreases toward the bottom. Sensor body 3
On the surface (hereinafter, referred to as a surface) 31a on the side facing the first squeegee 22 in FIG. 1, a large number of front electrodes 32 are formed in a state of being separated from each other by a constant interval. These front side electrodes 32 are made of a conductive material that is hard to be corroded by the flux in the cream solder 16 (has corrosion resistance) and hard to diffuse into the cream solder 16,
For example, it is formed of copper (Cu) plated with nickel (Ni), nickel, or the like.

Each front-side electrode 32 extends in a substantially vertical direction along the front surface 31a, and a lower end of the front-side electrode 32 penetrates the sensor main body 31 to form a surface (hereinafter referred to as a back surface) 31b on the side facing the second squeegee 24. Exposed. It is preferable that the distance d1 from the lower end edge 31c of the sensor body 31 to the exposed portion of each of the front electrodes 32 is as small as possible (close to zero). For example, the particle size of the metal particles in the cream solder 16 is 50
In the case of approximately μm, it is preferable to set the distance d1 so as to fall within the range of 0 to 0.1 mm.

On the back surface 31b of the sensor body 31,
A large number of back electrodes 33 are formed in a state of being separated from each other by a constant interval. These back electrodes 33 are made of the same material as the above-mentioned front electrodes 32.
Each back side electrode 33 extends in a substantially vertical direction along the back surface 31b, and the lower end portion thereof penetrates the sensor body 31 and is exposed on the front surface 31a. Of the exposed portion of each back electrode 33,
The distance d2 from the lower end edge 31c of the sensor main body 31 is set to be approximately the same as the distance d1. Each back electrode 33 is located at a position corresponding to an intermediate portion between a pair of adjacent front electrodes 32. The space P between the back electrode 33 and the closest front electrode 32 is adjacent in the width direction of the screen mask 18 (direction orthogonal to the sliding direction of both squeegees 22 and 24, that is, the direction orthogonal to the paper surface). The size is set to a size (for example, about 0.5 mm or 0.65 mm) corresponding to the interval between the matching application holes 21.

One circuit is composed of the front electrode 32 and the back electrode 33 adjacent to the front electrode 32. Therefore, when viewed from the entire first solder amount sensor 26, the sensor 26 has a large number of circuits in the width direction of the sensor body 31. Each circuit is closed only when both the front side electrode 32 and the back side electrode 33 are touched by the cream solder 16, and in other cases, that is, when neither of the electrodes 32 and 33 is touched by the cream solder 16, or When only one electrode 32 (or 33) is in contact with the cream solder 16, the circuit is opened.

Therefore, when the closed circuit is opened,
Alternatively, the position (height) of the first solder amount sensor 26 when the open circuit is closed is specified, and those electrodes 32,
It is possible to detect the amount (height) of the cream solder 16 at the location corresponding to 33. Since a large number of circuits are arranged in the width direction of the sensor body 31, if the position (height) of the first solder amount sensor 26 as described above is specified for each circuit, the cream solder 16 It is possible to detect the height of the object at multiple locations.

As shown in FIG. 1, a nozzle 34 is arranged around the sensor body 31, and the lower end of the nozzle 34 is open so as to face the front surface 31a and the back surface 31b of the sensor body 31. The nozzle 34 has a high-pressure nitrogen gas,
A cylinder (not shown) filled with an inert gas such as argon gas is connected through a valve. Then, as the first squeegee 22 rises, the first solder amount sensor 26
When the pressure rises, the valve is opened and the inert gas is ejected from the nozzle 34 toward the front surface 31a and the back surface 31b. With this inert gas, the cream solder 16 attached to the sensor body 31 is removed, and the front and back electrodes 32 and 33 are de-energized.

On the other hand, at the front side in the sliding direction of the second squeegee 24, that is, at the position near the left end of the squeegee 24, the second solder amount sensor 35 forming a part of the solder amount detector.
Is attached. Similar to the first solder amount sensor 26 described above, the sensor 35 includes a socket (not shown) and a sensor body 36, and a nozzle 37 is arranged around the socket. The second solder amount sensor 35 is drivingly connected to a second sensor driving device 39, and is reciprocated in the substantially vertical direction by the device 39.

The solder coating device 17 is provided with an input device 38 such as a keyboard, and an operator can use the input device 38.
By operating, the type of the printed wiring board 11, the type of the cream solder 16, the number of the printed wiring boards 11 to be applied (hereinafter referred to as the set number Ne), and the like can be input.

The solder coating device 17 has a first position sensor 41 for detecting the height of the first solder amount sensor 26 and a second position sensor 41 for detecting the height of the second solder amount sensor 35. Position sensor 42 of FIG. As these sensors 41 and 42, for example, eddy current type position sensors can be used. In this type of sensor, as shown in FIG. 2, when the metallic detection member 43 attached to the solder amount sensors 26 and 35 approaches the coil 44 in which an alternating current flows, the metal detection member 43 enters the detection target member 43. An eddy current flows to generate an AC magnetic field, which acts on the coil 44 to change the impedance of the coil 44.
By converting this change in impedance into a change in voltage or frequency, the distance between the detected member 43 and the coil 44 can be measured.

As shown in FIG. 1, the solder coating device 17
Is a third for detecting that the first squeegee 22 has slid on the screen mask 18 and has moved to the right end position.
Position sensor 45, and a fourth position sensor 46 for detecting that the second squeegee 24 has slid on the screen mask 18 and has moved to the left end position. Proximity switches can be used as the sensors 45 and 46, for example. This type of sensor outputs a detection signal when the squeegees 22 and 24 approach within a predetermined range. Therefore, by counting the number of detection signals output from the position sensors 45 and 46, the number of times the squeegees 22 and 24 slide, that is, the cream solder 16
It is possible to detect the number of printed wiring boards 11 (hereinafter referred to as the coating number Np) to which is applied.

Further, the solder coating device 17 is provided with a work completion switch 47. The switch 47 is a switch that is turned on after the worker performs work according to various instructions described later.

The solder coating device 17 is provided with a height alignment instruction lamp 48, a closing instruction lamp 49 and a closing instruction amount display 50. The height alignment instruction lamp 48 is turned on when the height variation in the width direction of the cream solder 16 is large. By this lighting, the operator is urged to make the heights of the cream solder 16 uniform so as to reduce the variation. The closing instruction lamp 49 is turned on when the variation is small and the height of the cream solder 16 is low. This lighting prompts the operator to put the cream solder 16 therein. The charging instruction amount display 50 is for displaying the amount of the cream solder 16 to be charged.

The operation of each part of the solder coating device 17 is controlled by a microcomputer (hereinafter, simply referred to as a microcomputer) 51 having a memory 52. More specifically,
The microcomputer 51 includes solder amount sensors 26, 35, position sensors 41, 42, 45, 46, an input device 38, a work completion switch 47, squeegee drive devices 23, 25, sensor drive devices 29, 39, instruction lamps 48, 49, and An input instruction amount display 50 is connected to each. The microcomputer 51 reads the signals from the sensors 26, 35, 41, 42, 45, 46, the input device 38 and the work completion switch 47, and performs predetermined arithmetic processing based on the signals. For example, the microcomputer 51 counts the number of times the squeegees 22 and 24 slide on the screen mask 18, that is, the number Np of applied cream solders 16 based on the signals output from the third and fourth position sensors 45 and 46. To do. Then, according to the calculation result, each operation of each of the drive devices 23, 25, 29, 39, each of the instruction lamps 48, 49 and the injection instruction amount display 50 is controlled.

Next, a method of applying the cream solder 16 on the lands 15 of the printed wiring board 11 using the solder applying device 17 configured as described above will be described with reference to the flowchart of FIG. Prior to the start of the coating operation, the printed wiring board 11 is arranged on the base 20 of the solder coating device 17, and the printed wiring board 11 is arranged so that the coating holes 21 are located on the corresponding lands 15. The screen mask 18 is arranged on the top. Further, a start switch (not shown) for starting the solder coating device 17
Is turned on.

First, the operator operates the input device 3 such as a keyboard.
8 is operated to input the type of the printed wiring board 11, the type of the cream solder 16, and the number Ne of the printed wiring board 11 to be applied (hereinafter referred to as the set number) (S in FIG. 4).
1).

When the input operation is completed, the microcomputer 51
Determines whether there is learning data (S2). If there is no such data, the operator is prompted to apply the cream solder 16 by turning on the injection instruction lamp 49 (S
3).

When the operator confirms that the closing instruction lamp 49 is lit, the cream solder 1 suitable for the coating conditions (type and number of printed wiring board 11, solder type, etc.) at that time.
The amount of the cream solder 16 is estimated, and the amount of the cream solder 16 is measured and put into the end portion (the left end portion in FIG. 1) of the upper surface of the screen mask 18 (S4). At this time, cream solder 16
Are charged in a straight line along the width direction and the height is almost uniform in any part. After this input,
The input amount 38 is input by operating the input device 38, and the work completion switch 47 is turned on.

When the work completion switch 47 is turned on, the microcomputer 51 turns off the closing instruction lamp 49. Further, it outputs a command signal for operating the squeegees 22 and 24 to the squeegee drive devices 23 and 25. Then, the application work of the cream solder 16 by the squeegees 22 and 24 is performed (S5).

For example, as shown in FIG. 1, the first squeegee 22 is lowered to the first reference position, and is moved to the right while sliding the upper surface of the screen mask 18 from the same position. At this time, the second squeegee 24 is made to stand by above the second reference position. The cream solder 16 on the screen mask 18 is pressed by the first squeegee 22. The cream solder 16 moves to the right as a whole with the flow in the clockwise direction as shown by the arrow in FIG. 1 (while rolling). Squeegee 2
If the conditions relating to the solder coating device 17 such as the types 2, 24, the postures (angles α and β), the sliding speed, etc. and the conditions relating to the atmosphere such as the ambient temperature and humidity are constant, the presence or absence of rolling is determined by the cream solder 16 It is determined by the amount and type (physical properties such as viscosity and tackiness).

When the cream solder 16 passes through the coating holes 21, it is pushed into the coating holes 21 by the pressing force from above due to the rolling. As described above, the cream solder 1 is sequentially applied to the large number of application holes 21 from left to right.
6 is filled. The cream solder 16 on the screen mask 18 decreases each time the application hole 21 is filled. Then, when the first squeegee 22 moves to the right end position on the screen mask 18, the cream solder 16 is filled in all the application holes 21 of the screen mask 18. Therefore, if the screen mask 18 and the printed wiring board 11 are separated after that, the cream solder 16 filled in the coating hole 21 is applied to the land 1 of the wiring board 11.
Remain on 5. That is, the cream solder 16 is applied onto the land 15 and so-called screen printing is performed.

When the first squeegee 22 moves to the right end position as described above, the detection signal is output from the third position sensor 45. As shown in FIG. 4, the microcomputer 51 counts the number of times of applying the cream solder 16 (the number of applying Np) based on this signal (S6). It is determined whether the applied sheet number Np is equal to or more than the set sheet number Ne input in S1 or is less than the set sheet number Ne (S7). The number of applied sheets Np is the set number of sheets N
If less than e, the microcomputer 51 determines that the first squeegee 22
The first solder amount sensor 26 is moved up and down by controlling the first sensor driving device 29 while keeping the state of being in contact with the screen mask 18 (the position after the movement of the right end).
Due to the downward movement, the cream solder 16 comes into contact with the front and back surfaces (front or back surface / front and back surface) of the sensor body 31. Same sensor 26
Based on the detection signal of 1 and the detection signal of the first position sensor 41, the height of the cream solder 16 at a number of positions in the width direction is detected (S8).

For example, a predetermined pair of front and back electrodes 32, 33
The first solder amount sensor 26 in a state where the cream solder 16 is not in contact with any of the above is lowered. When the electrodes 32, 33 touch the cream solder 16, the sensor 26 outputs a detection signal. On the other hand, the first position sensor 41 outputs a detection signal corresponding to the height of the first solder amount sensor 26. From the detection signal from the first position sensor 41 when the detection signal indicating that the first solder amount sensor 26 has contacted the cream solder 16 is output, the cream solder at the location corresponding to both electrodes 32 and 33 is detected. Find the height of 16. Similar processing is performed on a large number of positions in the width direction of the cream solder 16.

The heights in the width direction of the cream solder 16 thus obtained are h (1), h (2), h (3)
… Let h (n). If the size and number of the coating holes 21 in the screen mask 18 are different depending on the part of the mask 18, the reduction amount of the cream solder 16 when the first squeegee 22 is slid is different for each part in the width direction. different. Therefore, in this case, the heights h (1) to h (n) will vary even if the cream solder 16 is initially charged so as to be flat.

The minimum value hmin of the heights h (1) to h (n) of the cream solder 16 obtained as described above is specified,
It is determined whether or not the value is larger than the allowable value H obtained in advance (S9). The allowable value H here is set to a value slightly larger than the minimum value of the height at which the cream solder 16 can be rolled. If the minimum value hmin is larger than the allowable value H, it is determined that the cream solder 16 on the screen mask 18 can be applied to the next printed wiring board 11, and the above-described steps from S5 are performed.

By controlling the first squeegee driving device 23, the first squeegee 22 is raised to a predetermined height and then moved to the left while maintaining the height. When the first squeegee 22 reaches above the first reference position,
Hold at that location (standby). On the other hand, by controlling the second squeegee driving device 25,
Second squeegee 2 waiting above the reference position of
Lower 4 Then, the second squeegee 24 contacts the upper surface of the screen mask 18 on the right side of the cream solder 16. At this time, the second solder amount sensor 35 is located on the front side (the left side in FIG. 1) of the second squeegee 24 in the sliding direction.

Next, the cream solder 16 on the screen mask 18 is pushed by the second squeegee 24. The cream solder 16 moves to the left as a whole while flowing (rolling) in the counterclockwise direction, and is pushed into the application hole 21. The cream solder 16 is applied onto the land 15 corresponding to the application hole 21 (S5). The second squeegee 24 is the screen mask 18
When moving to the upper left end position, a detection signal is output from the fourth position sensor 46, and the number Np of coated sheets in S6 is "1".
Only increased. The applied sheet number Np is compared with the set sheet number Ne (S7). If the applied sheet number Np is still less than the set sheet number Ne, the second squeegee 24 is in contact with the screen mask 18 (the position after the left end movement). By controlling the second sensor driving device 39 while holding the second solder amount sensor 35, the second solder amount sensor 35 is moved up and down. Based on the detection signal of the sensor 35 and the detection signal of the second position sensor 42, the heights h (1) to h (n) of the cream solder 16 at a large number of positions in the width direction are calculated (S8). Minimum value h
min is specified, and it is determined whether or not the value is larger than the allowable value H obtained in advance (S9).

In this way, the steps S5 to S9 are repeated.
Every time the procedure of S6 is carried out, the number Np of coatings increases and the height of the cream solder 16 decreases. Then, before the number of applied sheets Np exceeds the set number of sheets Ne, S
When the minimum value hmin becomes less than or equal to the allowable value H in 9, if the squeegee 24 (or 22) is continuously slid,
Shearing force (horizontal force) is superior to the force acting on the cream solder 16 from above, and the cream solder 16 shown in FIG.
Slide sideways while maintaining the shape shown by the chain double-dashed line
It is judged that the squeegee 22 (or 24) related to the application of the cream solder 16 next time is judged to be not supplied to
Signal for stopping the sliding of the squeegee drive device 23
(Or 25) (S10).

The microcomputer 51, based on the heights h (1) to h (n) of the cream solder 16 obtained in S8, the height deviations Δh (1), Δh (2), and Δh at adjacent detection points. (3)…, Δ
Find h (n). Here, for example, Δh (1) is h (1) and h
(2) and Δh (2) is the deviation between h (2) and h (3). The maximum value Δhmax of the deviations Δh (1) to Δh (n) is specified, and the value is determined by a predetermined value Δh.
It is determined whether or not it is larger than H. That is, the degree of height variation is determined (S11).

When the maximum value Δhmax is larger than the predetermined value ΔH, the height h (1) to h (n) of the cream solder 16 has a large variation in the width direction. It is determined that the coating operation can be continued without re-supplying (supplementing), and the height alignment instruction lamp 48 is turned on (S12). When the operator confirms that the instruction lamp 48 is lit, the spatula or the like is used to manually move the cream solder 16 appropriately so as to reduce the variation in the height of the cream solder 16 in the width direction and smooth the cream solder 16. Yes (S13). Then, the work completion switch 47 is turned on. When the work completion switch 47 is turned on, the microcomputer 51 turns off the height alignment instruction lamp 48. After that, the procedure from S5 onward is repeated.

In the determination in S11, the maximum value Δh
When max is smaller than the predetermined value ΔH, there is little variation in the heights h (1) to h (n) of the cream solder 16 in the width direction, that is, the height of the cream solder 16 is generally low. The same solder 16
Is determined to be insufficient, and the charging instruction lamp 49 is turned on to prompt the operator to re-input the cream solder 16 (S14).

Next, the microcomputer 51 determines whether or not there is learning data (S15), and if there is no such data, waits for the operator to re-insert the cream solder 16 therein. When the operator confirms that the charging instruction lamp 49 is turned on, the operator estimates the amount of the cream solder 16 suitable for the application conditions at that time, and charges the amount of the cream solder 16 to the end portion of the upper surface of the screen mask 18 (S16). . After the input, the work completion switch 47 is operated. When the work completion switch 47 is turned on, the microcomputer 51 turns off the closing instruction lamp 49. After raising the second squeegee 24 to a predetermined height, the second squeegee 24 is moved to the right while maintaining the height. When the second squeegee 24 reaches above the second reference position, it is held (standby) at that position. On the other hand, by controlling the first squeegee drive device 23, the first squeegee 22, which has been waiting above the first reference position, is lowered. Then, the first squeegee 22 contacts the upper surface of the screen mask 18 on the left side of the cream solder 16. At this time, the first solder amount sensor 26 is located on the front side in the sliding direction of the first squeegee 22. afterwards,
The procedure after S5 is repeated.

As described above, the cream solder 16 is repeatedly applied by sliding the squeegees 22 and 24,
In the determination in S7, when the applied number Np matches the set number Ne, the operation of the squeegees 22 and 24 is stopped (S17).

By the way, the microcomputer 51 uses the number of application times Np,
The set number Ne, the input amount Q, etc. are stored in the memory 52 (S18, S19). FIG. 5 shows such a state, in which “X” indicates non-applicable data, “Δ” indicates height variation data, and “◯” indicates coatable data.

For example, the set number Ne of the printed wiring boards 11 can be formed only by the cream solder 16 which is initially charged.
If the same solder 16 can be applied to
The initial amount Q of the solder 16 and the set number Ne are stored as the coatable data. When the minimum value hmin of the height is smaller than the allowable value H, but the maximum value Δhmax is larger than the predetermined value ΔH, that is, when the variation of the height is large, the charging amount Q up to that time is increased. And the number of applied sheets Np are stored as height variation data. When the minimum value hmin of the height is smaller than the allowable value H and the maximum value Δhmax is smaller than the predetermined value ΔH, that is, when the cream solder 16 is entirely lacking, the dosage up to that time Q and the number of applied sheets Np are stored as the application impossible data. The height in the width direction of the cream solder 16 is made substantially constant, or the cream solder 16
When the coating is repeated and the coating is performed by the set number Ne, the amount Q and the number Np of coatings up to that time are stored as the coatable data.

After storing a predetermined number of data, the microcomputer 51 determines that the application-prohibited region Z1, the height variation region Z2, and the coatable region Z3 are in relation to the numbers Ne and Np and the input amount Q. Two boundary lines for dividing are obtained (S20). These boundary lines are indicated by L1 and L2 in FIG. Border line L1 is cream solder 1
If the heights of 6 in the width direction are made uniform, it means the minimum amount of injection when coating is possible. In addition, the boundary line L2 means the minimum input amount when the application work of the cream solder 16 is possible without performing the height alignment work described above. The same process as above is applied to all kinds of printed wiring boards 11 and cream solder 1.
Do all 6 types. In this way, the learning operation for obtaining the boundary lines L1 and L2 by accumulating data is completed.
After that, the coating work using these boundary lines L1 and L2 is performed. It is described below.

As shown in FIG. 4, in the above-described determination of the presence / absence of learning data in S15, the microcomputer 51 determines that there is data. Number of applied sheets Np and set number of sheets N
The deviation from e, that is, the remaining number of printed wiring boards 11 to be applied (hereinafter referred to as the remaining number Nr) is obtained (S21). From the remaining number Nr and the boundary line L2, the minimum value of the input amount Q required for coating on the remaining printed wiring board 11 is obtained, and the value is displayed on the input instruction amount display 50 (S22). Here, the amount of cream solder 16 that is close to the amount required for rolling cream solder 16 remains on screen mask 18. On the other hand, the boundary lines L1 and L2 in FIG. 5 include the minimum amount necessary for rolling. When the amount of cream solder 16 obtained from the boundary lines L1 and L2 is charged, an excessive amount is charged. Therefore, the microcomputer 51 displays the amount obtained by subtracting the amount required for rolling from the amount obtained from the boundary lines L1, L2 as the input amount Q. Therefore, in S16, if the operator measures and puts the displayed amount of cream solder 16 on the screen mask 18, it becomes possible to put the minimum required amount of cream solder 16.

Further, in the above-described determination of the presence / absence of learning data in S2, the microcomputer 51 determines that there is data. The type and number of printed wiring boards 11 (set number Ne) input in S1, the type of cream solder 16, and
The input amount Q of the cream solder 16 is obtained from the boundary line L2, and the value is displayed on the input instruction amount display 50 (S
23). Therefore, when the solder is charged in S4, the operator can accurately estimate the amount to be charged by looking at the amount-instructed-indication display 50.

As described above, according to the present embodiment, every time the pair of squeegees 22 and 24 are alternately slid to apply the cream solder 16 to the set number Ne of printed wiring boards 11, the screen mask 18 is moved. Cream solder 1
6 decreases. However, before operating the squeegees 22 and 24, the height of the cream solder 16 is set to the squeegee 2.
2 and 24 solder amount sensor 2 arranged on the front side in the sliding direction
6,35 detected. Therefore, compared to the case where the height of the solder is visually recognized by the operator, the number of human factors in the solder application work is reduced.

When the amount of the cream solder 16 decreases to the amount shown by the chain double-dashed line in FIG. 1, the solder 16 does not roll, slides along the upper surface of the screen mask 18 and is not supplied to the coating hole 21, but the solder amount sensor Since the operation of the squeegees 22 and 24 is stopped (prohibited) based on the detection results of 26 and 35, it is possible to prevent the cream solder 16 from being applied in an insufficient state and causing problems such as fading and poor soldering. it can.

The height of the cream solder 16 is detected by the contact of the electrodes 32, 33 of the solder amount sensors 26, 35 with the solder 16. These electrodes 32,
33 are arranged along the width direction while being spaced apart from each other. Therefore, even if the height of the cream solder 16 is different for each of a large number of locations along the width direction, the height can be accurately detected. For example, as shown in FIG. 2, when the amount of cream solder 16 used is greater on the right side and the height varies, the electrodes 32 and 33 located on the left side become conductive,
Since the electrodes 32 and 33 on the right side become non-conductive, it is possible to detect the occurrence of height variations. Therefore, the human factor is further reduced. Even in the printed wiring board 11 in which the number and size of the lands 15 differ depending on the parts, it is possible to apply the cream solder 16 to the lands 15 without causing a blur.

Further, when the detected values of the solder amount sensors 26 and 35 become smaller than a predetermined value, the height alignment instruction lamp 48 is turned on to prompt the introduction of the cream solder 16. For this reason, the worker is always required to use the solder amount sensors 26, 3
Even if the detection result of No. 5 is not monitored, the timing of charging the cream solder 16 can be accurately grasped.

The present embodiment has the following features in addition to the matters described above. (A) When the minimum value hmin of the height of the cream solder 16 becomes equal to or less than the allowable value H, not only the operation of the squeegees 22 and 24 is stopped, but also the height alignment instruction lamp 48 or the closing instruction lamp 49 is turned on. ing. For this reason, the worker can instantly grasp the contents of work to be performed next based on the lighting of these instruction lamps 48 and 49. And
After the indicator lamps 48 and 49 are turned on, the squeegees 22 and 2 can be adjusted by performing height adjustment work or cream solder 16 insertion work.
It is possible to shorten the stop time of No. 4 and improve the productivity.

(B) In the solder amount sensors 26 and 35, the sensor body 31 is configured to be attachable to and detachable from the socket 27. Therefore, a plurality of types of sensor bodies having different numbers of electrodes 32 and 33, intervals, etc. are prepared. Every time, every time the printed wiring board used for solder application is changed, it is possible to select a sensor main body suitable for the number, size, density, etc. of the lands of the printed wiring board and mount it in the socket 27. The height of the cream solder 16 can be detected by the sensor body suitable for the printed wiring board 11, and the detection accuracy can be improved.

(C) As a measure for preventing the product in a state where the cream solder 16 is not applied in an appropriate amount from being sent to the next step, for example, after applying the cream solder to the land, It is possible to directly detect and determine whether or not the product is non-defective based on the detection result.
However, this method cannot detect the occurrence of defective products because it is detected after solder application. In addition, not only is it susceptible to the fine unevenness of the cream solder on the land during detection, but the number of lands on the printed wiring board is usually several hundred, so the amount of cream solder on each land It takes a long time and a lot of capital investment to detect.

On the other hand, in the present embodiment, the squeegee 2
Since the height of the solder paste 16 is detected before the application of the cream solder 16 by the method 2 and 24, it is possible to prevent the occurrence of a product (defective product) in which the amount of the solder paste 16 applied is insufficient. .

Further, in the present embodiment, the amount of cream solder 16 on the land 15 is indirectly detected by utilizing the following phenomenon. The phenomenon is whether or not the application hole 21 is filled with the cream solder 16 (the land 15 is applied with a predetermined amount of the cream solder 16) and whether or not the cream solder 16 on the screen mask 18 rolls. That is, the presence or absence of rolling is determined by the amount and type of cream solder 16. By utilizing this phenomenon, if the height of the cream solder 16 on the screen mask 18 is larger than the allowable value H, the solder 16 can be rolled to fill the application hole 21, that is, the cream solder 16 having a predetermined height can be obtained. Cream solder 16 shall be applied on land 15.
The height is detected at once before the application of. In other words, the height detection of the cream solder 16 on the screen mask 18 substitutes the height detection of the cream solder 16 on the land 15.

Therefore, it is not necessary to individually detect the height of the cream solder 16 on the land 15. The solder height can be detected with a simple configuration and in a short time without being affected by the fine irregularities of the cream solder 16 on the land 15. Further, a control program by the microcomputer 51 for controlling the operation of the solder coating device 17 can be created relatively easily.

(D) In connection with (c) above, the land 1
As a method of detecting the amount of the cream solder 16 applied to No. 5, it is conceivable to irradiate the solder 16 with laser light and directly detect the height thereof. In this method, if the position of the land 15 of the printed wiring board 11 is different, a control program is required for each. Along with this, a process of creating a program, a setup change, and a fine adjustment for each printed wiring board are necessary. Therefore, although this method can accurately detect the height of each land, it is not suitable for mass production.

On the other hand, in the present embodiment, all kinds of printed wiring boards 11 are controlled by one control program.
The printed wiring board 1
It is not necessary to create a program for each type, which is useful for improving mass productivity.

(E) Every time one sliding movement of the squeegees 22 and 24 is completed, the solder amount sensors 26 and 35 are raised as the squeegees 22 and 24 are raised, and the inert gas is blown out from the nozzle 34. The cream solder 16 attached to the sensor body 31 is removed. For this reason,
It is possible to prevent the cream solder 16 from remaining attached to the solder amount sensors 26 and 35. It is possible to prevent erroneous detection due to the remaining cream solder 16.

(F) At the time of applying the cream solder 16, when the learning data does not reach the predetermined number, the microcomputer 51 determines the number of application times Np and the set number Ne for each type of the printed wiring board 11 and each type of the cream solder 16. The quantity of injection Q and the like is sequentially stored in the memory 52, and after storing a predetermined number of data, it is divided into a non-coatable area Z1, a height variation area Z2, and a coatable area Z3.
Two boundary lines L1 and L2 are obtained.

Therefore, after determining the boundary lines L1 and L2, if the type of the printed wiring board 11, the set number Ne and the type of the cream solder 16 are input in the first stage of the coating operation (S1), the boundary Based on the lines L1 and L2, it is possible to predict the amount of cream solder 16 to be added. The operator can accurately grasp the amount to be input (the minimum amount that can be applied for the set number Ne) only by looking at the input instruction amount display 50. Therefore, when the cream solder 16 is insufficient before the set number Ne is applied or when the set number Ne is applied, a large amount of the cream solder 1 is applied.
The problem that 6 remains can be prevented.

(G) In learning the boundary lines L1 and L2, in addition to the unapplicable data "x" and the applicable data "○",
The height variation data “Δ” is also stored in the memory 52. Therefore, two data "x",
The accuracy of learning can be improved as compared with the case where "○" is stored.

(H) In the solder amount sensors 26 and 35, a large number of electrodes 32 and 33 are alternately arranged on the front and back surfaces 31a and 31b of the sensor bodies 31 and 36, respectively. Therefore, as compared with the case where all the electrodes are arranged on only one surface, the interval between the adjacent electrodes becomes wider and the manufacturing becomes easier.

(I) The sensor bodies 31, 36 of the solder amount sensors 26, 35 are wedge-shaped with a sharp lower end.
Therefore, when the sensors 26, 35 move downward, the frictional force generated between the sensor bodies 31, 36 and the cream solder 16 becomes small. The sensor bodies 31 and 36 easily enter the cream solder 16. The original height of the solder 16 can be detected by reducing the amount of deformation of the cream solder 16 when the sensor bodies 31 and 36 enter.
The detection accuracy can be improved.

The present invention can be embodied in another embodiment shown below. (1) The configurations and types of the solder amount sensors 26 and 35 are not particularly limited as long as they can detect the amount of the cream solder 16 in addition to the types described above. It is preferable that the amount of cream solder 16 can be detected at a plurality of positions in the width direction. For example, it is possible to use a sensor of a type that detects the amount of the cream solder 16 in a non-contact state using laser light, infrared rays, or the like.

(2) An inert gas may be ejected from the nozzle 34 when the squeegees 22 and 24 slide. By doing so, the chances that a new portion of the cream solder 16 that comes out on the surface due to rolling of the cream solder 16 will come into contact with air (oxygen) or moisture, and deterioration (curing) of the cream solder 16 can be effectively suppressed. It is possible to prevent the problem that the cream solder 16 is hard to roll due to deterioration.

(3) In the above-described embodiment, the operation of inserting the cream solder 16 (S4, S16) and the height adjusting operation (S13) are performed by a dedicated device (automatic insertion device or the like) instead of manpower. May be.

(4) Even after the boundary lines L1 and L2 are obtained in S20, the coating number Np, the set number Ne, the input amount Q, etc. are successively stored in the memory 52, and the boundary lines L1 and L2 are stored.
2 may be updated.

(5) If the boundary lines L1 and L2 are obtained by learning, the values are used as the deterioration value of the cream solder 16 and
This can be used to detect an error in the type of the cream solder 16 that has been applied, an error in the application conditions (sliding speed of the squeegees 22 and 24, ambient temperature, etc.), an error in the type of the screen mask 18, and the like. If the solder coating work is performed under a condition different from the predetermined condition, the input amount Q or the like corresponding to the number Np of coatings at that time deviates from the regions Z1 to Z3 obtained by learning. When such a phenomenon occurs, the operator can confirm the occurrence of the abnormality by turning on the lamp or operating the buzzer.

(6) In the above embodiment, the actual input amount Q of the cream solder 16 that has been input is manually input in S4, but instead of this, the input amount (weight) is used.
May be measured by a measuring device such as an electronic balance, and the measurement result may be taken into the microcomputer 51. For example,
The weight of only the container is measured in advance by the measuring instrument, and the weight of the container containing the cream solder is measured by the measuring instrument for each coating operation. The deviation between the two weights may be obtained by the microcomputer 51 and used as the charged amount (weight) of the cream solder. By doing so, the operator does not have to input the input amount Q each time the cream solder 16 is input.

(7) In S20 of FIG. 4 in the above-described embodiment, only the dispensable data “x” and the disposable data “◯” may be stored in the memory 52 to obtain one boundary line. .

(8) The shape of the lower ends of the sensor bodies 31, 36 of the solder amount sensors 26, 35 is not limited to the wedge shape, but may be changed to various sectional shapes such as a circular sectional shape and a rectangular sectional shape. In this case, an acute angle is preferable from the viewpoint of easy penetration into the cream solder 16.

(9) In the above embodiment, the height is detected as the amount of the cream solder 16, but other elements such as weight, capacity, projected area, etc. are detected, May be detected in combination.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) The solder applicator according to claim 1, further comprising squeegee stopping means for stopping the squeegee when the solder amount by the solder amount detector is equal to or less than a predetermined value. In the above embodiment, the procedure of S10 by the microcomputer 51 corresponds to the squeegee stopping means. With such a configuration, it is possible to prevent the application work from being performed in the state where the cream solder is insufficient, and to reliably prevent the generation of defective products.

(B) In the solder coating apparatus according to the first aspect, the solder amount detector is made of a sensor body made of an insulating material and a conductive material, and is arranged on the surface of the sensor body in a separated state. And a pair of electrodes and a solder coating device. With such a configuration, when the cream solder comes into contact with both electrodes, both electrodes are electrically connected by the same solder. for that reason,
By utilizing the presence or absence of this conduction, it becomes possible to detect the positional relationship between the cream solder and the solder amount detector.

(C) In the solder coating apparatus described in (b) above, drive means for moving the solder amount detector up and down, a position detector for detecting the position of the solder amount detector, and the solder A solder application device provided with height calculation means for calculating the height of cream solder based on the detection results of the quantity detector and the position detector. In the embodiment, the first
The sensor driving device 29 and the second sensor driving device 39 correspond to driving means, the first position sensor 41 and the second position sensor 42 correspond to position detectors, and the microcomputer 51 corresponds to height calculating means. To do. With such a configuration, the height of the cream solder can be detected from the height of the solder amount detector by the position detector when both electrodes of the solder amount detector are conducted.

(D) In the solder applicator described in (a) above, further, after the operation of the squeegee is stopped by the injection indicator for instructing the injection of the cream solder and the squeegee stopping means, the injection instruction. A solder applicator equipped with an instructing means for instructing the injection of cream solder with a container. In the above embodiment, the closing instruction lamp 49 corresponds to a closing instruction device, and the microcomputer 51 corresponds to a closing instruction means. With such a configuration, if the worker puts in the cream solder according to the instruction content of the throwing-in indicator, the stop time of the coating work (the squeegee stop time by the squeegee stopping means) is shortened and the work efficiency is improved. Can be planned.

[0088]

According to the first and third aspects of the present invention, the amount of cream solder on the screen mask can be grasped more accurately than by visual inspection by reducing the human factors in the solder application work. it can. It is possible to reduce the variation in the application work for each operator and avoid performing the application work in the state where the cream solder is insufficient.

In particular, in the third invention, when the detected value of the solder amount detector becomes smaller than a predetermined value, the introduction of cream solder is prompted, so that the operator always monitors the detected value of the solder amount detector. Even without it, it is possible to accurately grasp the timing of charging the cream solder.

According to the second invention, even if the amount of cream solder varies among a large number of points along the direction intersecting the sliding direction of the squeegee, the amount of solder at each point can be detected. . Therefore, the effect of the first aspect of the present invention can be reliably achieved even with a printed wiring board in which the number and size of lands differ depending on the site.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a solder coating device.

FIG. 2 is an explanatory diagram showing a relationship between cream solder and a solder amount sensor.

FIG. 3 is a perspective view of a lower end portion of the solder amount sensor.

FIG. 4 is a flowchart illustrating a procedure for applying cream solder to a printed wiring board.

FIG. 5 is a characteristic diagram showing the relationship between the number of printed wiring boards used for coating and the amount of cream solder input.

[Explanation of symbols]

11 ... Printed wiring board, 15 ... Land, 16 ... Cream solder, 17 ... Solder application device, 18 ... Screen mask, 21 ... Application hole, 22 ... First squeegee, 24 ... Second
Squeegee, 26 ... First solder amount sensor forming part of solder amount detector, 32 ... Front side electrode, 33 ... Back side electrode, 35 ... Second solder amount sensor forming part of solder amount detector .

Claims (3)

[Claims] 1. A screen mask which is arranged on a printed wiring board and has a coating hole at a position corresponding to a land of the printed wiring board; and a screen mask which is slidably provided on the screen mask and which slides on the screen mask. A squeegee for moving the cream solder on the mask while rolling and applying the squeegee on the land through the application hole, and is arranged on the front side in the sliding direction of the squeegee, and decreases as the squeegee slides. A solder application device having a solder amount detector for detecting the amount of cream solder above. 2. The solder amount detector comprises a large number of electrodes arranged in a state of being separated from each other along a direction intersecting a sliding direction of the squeegee, and whether or not each electrode is in contact with the cream solder. The solder application device according to claim 1, wherein the amount of cream solder is detected at a plurality of positions in the intersecting direction according to the above. 3. The cream solder is put on a screen mask having an application hole, and the squeegee is slid on the screen mask to move the cream solder while rolling the squeegee, so that the cream solder is moved under the screen mask. In the method of applying cream solder from the application hole to the land of the printed wiring board arranged, the amount of cream solder on the screen mask is detected by a solder amount detector, and the detected value is higher than a predetermined value. When it gets smaller, a solder application method that encourages the introduction of cream solder onto the screen mask.