JP2001251048A - Method of detecting height of secondary jet solder in jet soldering and printed wiring board having detection means - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect the height of secondary jet solder without reducing the availability of production line. SOLUTION: The height of secondary jet solder 4b is detected as follows: a slit-shaped elongated hole 2 is made in a printed wiring board 1 or in the boundary portion between the printed wiring board 1 and a board to be scrapped and the contact width of the jet solder contacting the bottom surface of the printed wiring board 1 is detected as a contact length through the slit-shaped elongated hole 2 and the height of the jet solder is judged from the detected contact length. Therefore, the height of the secondary jet solder 4b is judged through the slit-shaped elongated hole 2 made in the printed wiring board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called jet-type soldering method in which a molten solder is jetted, and the lower surface of a printed wiring board is brought into contact with the jet solder to perform soldering. The present invention relates to a method for detecting a height, and a printed wiring board having a detection function for use in jet-type soldering.

[0002]

2. Description of the Related Art With respect to this type of jet-type soldering, as a device for detecting and adjusting the height of a jet-type solder, for example, Japanese Patent Application Laid-Open Nos.
Japanese Unexamined Patent Application Publication No. 7-21593 discloses a configuration disclosed in JP-A-205593, which is known as a conventional example.
It is disclosed in Japanese Patent No. 4297 and known.

The above-mentioned known technique is a jet solder bath having a jet nozzle and a jet pump for jetting molten solder, wherein a light source is provided so that light passes through the top of the jet of molten solder from an oblique direction. And a light receiving unit for receiving light from the light receiving unit, the amount of light received by the light receiving unit is used as a jet height detection signal of the molten solder, and the detection signal is applied to a control device to control the motor of the jet pump. Further, since the light source and the light receiving portion are provided so as to cross the top of the jet of the molten solder in an oblique direction, light from the light source is blocked by the printed wiring board, so that the height immediately before the printed wiring board reaches the top of the jet is jetted. The control device is stopped while the printed circuit board is in contact with the top of the jet solder.

The above-mentioned known technique discloses a method and an apparatus for automatically adjusting the height of a jet solder by detecting the height thereof. A transparent heat-resistant plate is used as a detecting means, and the transparent heat-resistant plate is used as a carrier. Is attached to the fixed part of the solder and is supported by the jet solder. The contact width of the jet solder is optically (camera) detected and measured, and the measured shape is fed back to the control unit to determine the height of the jet solder. And to adjust the inclination of the printed wiring board to be conveyed.

Further, the above-mentioned prior art discloses a jet-type soldering method and apparatus equipped with the above-mentioned and more advanced primary nozzles and secondary nozzles, which are equipped with the primary nozzles and the secondary nozzles. The general soldering method, that is, the printed wiring board, which is the work, is inclined and transported, and the solder is carried out by contacting the jet solder with the inclined transport state. Even if the wiring board is transported horizontally, the bridge,
It is capable of preventing icicles or fogging, and has a configuration in which the primary nozzle and the secondary nozzle are arranged not in a direction perpendicular to the moving direction of the work but in a horizontal plane. .

[0006] The fact that a jet nozzle is equipped with a primary nozzle and a secondary nozzle in the generally performed jet-type soldering means that two different jet states for different purposes are formed. The primary jet is intended to accurately solder electronic components mounted on a printed wiring board, and is relatively strong and the top of the jet vibrates violently so that the solder spreads to a highly dense portion ( The top portion is narrowed so as to flow rapidly, so that excessive solder adheres. The secondary jet is intended to bring back the excessively attached solder from the primary jet and to reshape the soldering area. The top of the jet is wide and gentle (gently). It is flowing.

[0007]

However, in the above-mentioned and prior art jet-flow soldering, the primary nozzle and the secondary nozzle are not provided, so that they are excessively adhered to each other and become covered or bridged. Not only does not have the idea of retrieving or secondary shaping the solder that has become, but the conventional example described above cannot detect the state when the printed wiring board is actually in contact with the jet solder. And when the control is performed intermittently,
Due to the transfer speed of the printed wiring board which is continuous at intervals considering the work efficiency, and the relationship between the motor start speed and the flow reaction speed of the molten solder, the control follow-up is delayed and the height fluctuation of the jet solder becomes remarkable, There is a problem that proper control cannot be performed.

Further, in the above-mentioned conventional example, the transparent heat-resistant plate is always in contact with the jet solder, and the printed wiring board is transported at a predetermined interval. Sometimes there is no contact,
Each time the top of the jet solder is pushed or not pushed, the shape of the contact width of the jet solder on the transparent heat-resistant plate changes, and it must be adjusted according to the change. There is a problem that there is a difficulty in a proper control.

Further, in the above-mentioned conventional example, a primary nozzle and a secondary nozzle are provided, but the main object of the invention is to convey a printed circuit board, which is a work, in the horizontal direction, and By making the jet direction of the molten solder flow opposite to the transport direction, the relative speed between the substrate and the jet solder is increased, the solder cutability is improved, and bridges, icicles or fogging are prevented. However, the idea of detecting the height of the top of the jet solder and adjusting the height during the soldering process is not disclosed.

Therefore, in the conventional jet-type soldering, there is a possibility that adjacent components may be short-circuited due to excessive soldering due to being put on or being in a bridge state. It is important that the height of the secondary jet is in an appropriate height and state, and there is a problem that must be solved to accurately detect the height of the secondary jet to bring it into an appropriate jet state.

[0011]

According to the present invention, as a specific means for solving the problems of the prior art, the lower surface of a printed wiring board on which electronic components are temporarily mounted is brought into contact with a primary jet solder and a secondary jet solder. Soldering,
A slit-shaped long hole is provided in the printed wiring board or at a boundary portion with the discarded board, and a contact width of the jet solder contacting the lower surface of the printed wiring board through the slit-shaped long hole is detected as a contact length. A method for detecting the height of a secondary jet solder in jet soldering, characterized by determining the height of the jet solder by the detected contact length, and a printed wiring board to be subjected to jet soldering, A printed circuit board provided with detecting means for detecting the height of the jet solder in contact with the lower surface in the printed circuit board or at a boundary portion with the discarded board.

Also, in the present invention, the height of the secondary jet solder is visually or optically determined; the detecting means is a slit-shaped elongated hole; And a scale is provided as an additional requirement.

[0013] The method for detecting the height of a secondary jet solder according to the present invention is characterized in that the jet solder contacting the lower surface of the printed wiring board during the soldering process through a slit-shaped elongated hole provided in the printed wiring board. The contact width of the solder can be directly detected, which determines the height of the secondary jet solder and adjusts it to the appropriate contact state (height) at all times, greatly reducing the occurrence of defective products in the soldering process. It can be suppressed.

Further, the printed wiring board provided for the jet type soldering according to the present invention is provided with a detecting means for detecting the height of the jet solder which comes into contact with the lower surface during the soldering process. This eliminates the need for an extra detection means of a different configuration from the jet type soldering apparatus, and simplifies the entire apparatus.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In the first embodiment shown in FIGS. 1 to 3, for example, a printed wiring board 1 on which a plurality of electronic components such as an IC, an LSI, and a capacitor is mounted, and which is located at an appropriate position in the printed wiring board 1. A slit-shaped long hole 2 is provided. The direction in which the elongated hole 2 is provided is a direction parallel to the direction in which the printed wiring board 1 is conveyed and a position avoiding the printed wiring position in the jet-flow soldering process, and is as close to the edge of the board as possible. Formed at a close position, and further along the slot 2 with a scale 3
Has been given. In the design stage of the printed wiring board 1, in order to form the slit-shaped elongated hole 2 and the scale 3 at the most convenient position for detection, the printed wiring portion and the mounting position of the electronic component are taken into consideration. What is necessary is just to design in advance, and a printed wiring board can be manufactured without changing a production process.

In this case, as shown in FIG. 2, the slit-like long hole 2 has, for example, a length of about 50 ± 5 mm and a width of about 1.0 to 3.0 mm. If the length of the long hole 2 is too long, it cannot be formed in the printed wiring board 1 due to the restriction of the printed wiring portion, and if it is too short, the action of the surface tension acts and the whole of the long hole 2 becomes large. As a result, the actual contact length of the jet solder cannot be determined. Therefore, the preferred length is about 50 mm.

The width of the elongated hole 2 is 1.0 mm
In the following case, the contact state of the jet solder is not only difficult to see, but also due to the action of the surface tension, the contact length may be longer than the actual contact length, and the judgment may be erroneous. Therefore, there is a possibility that the solder cannot be formed in the printed circuit board 1 or the jet solder overflows to the surface side. Therefore, the preferred width is approximately 1.0
範 囲 3.0 mm.

Further, the scale 3 is to be printed at the same time along the elongated holes 2 when printing the printed wiring portion, and is formed of copper foil of the same material as the printed wiring. The width of each line of the scale 3 is approximately 0.3 mm, and the length is approximately 3.0 mm for a long line and approximately 2.0 mm for a short line. In short, it is only necessary that the operator can read the scale 3 visually.

The printed wiring board 1 thus formed
In FIG. 3, a predetermined electronic component is provisionally mounted and supplied to a general jet-type soldering apparatus to perform soldering.
As shown in the figure, the solder bath 5 containing the molten solder 4 is provided with a primary nozzle 6 and a secondary nozzle 7 in close proximity to each other. A jet motor to be controlled is connected. By driving the jet motor, the primary nozzle 6 ejects the steep primary jet solder 4a having a relatively strong wave motion, and the secondary nozzle 7 ejects the secondary jet solder 4b which has a relatively gentle and wide flow. is there. However, the illustrated jet-type soldering device is merely an example, and the height and shape of the primary and secondary jet solders 4a and 4b may differ depending on the device manufacturer.

When the printed wiring board 1 to be soldered is inclined with respect to the jet type soldering apparatus as shown by an arrow a, the primary nozzle 6 has a primary jet solder 4a and a secondary nozzle 7, It is conveyed while sequentially contacting the next jet solder 4b. The transport inclination angle in this case is approximately 3 to 5
Degree, and the inclination improves the solder cut in the printed wiring board 1.

First, the printed circuit board 1 is brought into contact with the primary jet solder 4a of the primary nozzle 6 in which the top of the jet flows violently oscillates to flow, so that the solder spreads to a portion with high density and is reliably soldered. Is performed, and as a result, excessive solder adheres. Subsequently, by contacting the gently flowing secondary jet solder 4b of the secondary nozzle 7 with the secondary jet solder 4a, excess solder that has excessively adhered in the contact with the previous primary jet solder 4a and is in a bridge state or overlaid is removed. At the same time, the soldering part is shaped into an appropriate state.

Therefore, whether or not the secondary jet solder 4b of the secondary nozzle 7 is properly in contact with the printed wiring board 1 is detected by the slit-shaped slot 2. That is, the standard of whether or not the contact is proper is based on the secondary jet solder 4b.
Whether it is jetting at the set height,
This is because, when the jet is jetted at the set height, the contact with the printed wiring board 1 becomes a substantially constant band-shaped contact width as expected.

Accordingly, the state in which the secondary jet solder 4b of the secondary nozzle 7 is in contact with the conveyed printed wiring board 1 in a strip shape, that is, the strip-shaped contact width is changed to the slit-shaped slot 2
For example, if the band-shaped contact width is approximately 30 mm, it can be determined that the secondary jet solder 4b is properly jetting at the set height, and the band-shaped contact width is determined. Can be detected (measured) as the contact length in the slit-shaped long hole 2.

This detection can be confirmed by an optical means in addition to being visually confirmed by the operator in association with the scale 3. For example, CC at a position where the slit-shaped elongated hole 2 of the printed wiring board 1 to be conveyed passes and at a position facing the top of the secondary jet solder 4b
A D-camera 8 is provided, an image captured by the camera is enlarged and displayed on a display unit, and the display is checked by an operator, or the slit-shaped long hole 2 in an appropriate contact state is previously determined. Is stored as a reference pattern,
The reference pattern and the image pattern to be sequentially imaged are sequentially compared (for example, pattern matching or the like), and the contact length of the secondary jet solder 4b in the slit-shaped long hole 2 is detected. When the length is longer than the reference length, the degree of the jet can be suppressed, and when the contact length is shorter than the reference length, the degree of the jet can be automatically controlled to be increased.

These controls are performed by controlling the driving of the jet motor, and the driving control of the jet motor is performed via an appropriate control unit based on the detected information. When visually confirmed, the degree of the jet can be adjusted by manually operating the control unit.

The position where the CCD camera 8 is attached is
It can be mounted at an upper part of the solder bath 5 with a space that is not so much affected by heat, or can be provided at a position that is not directly above the solder bath 5 but is slightly outside the solder bath 5 and can be photographed from an oblique direction, Even if the printed wiring board 1 being conveyed is photographed from a slightly oblique direction, the contact length of the secondary jet solder 4b facing the slit-shaped long hole 2 can be detected (measured).

Next, a second embodiment shown in FIG. 4 will be described. The printed wiring board 11 according to this embodiment is a so-called collective printed board, and a plurality of main boards 11a and a discarded board 11b are still connected in series through a slit-shaped cut 12. The main substrate 11a is cut off along the slit-shaped cut 12 when each main body substrate 11a is used.

Also in this printed wiring board 11, a plurality of electronic components are naturally mounted and soldered on each main body board 11a before being separated, and the soldering is performed in the first embodiment. In the same manner as in the above embodiment, this is performed by a jet-type soldering apparatus.

In the soldering step, the main board 11a and the discarded board 11b are connected to each other in order to detect the contact width at which the printed wiring board 11 comes into contact with the secondary jet solder 4b, that is, the height of the secondary jet solder 4b. Detection is performed using the slit-shaped cut 12 formed at the boundary portion.

In this case, the slit-shaped cut 12 is a straight cut parallel to the conveying direction of the printed wiring board 11 and has a length of 50 mm or more and a width of 1.
If the length is more than 0 mm, the cut can be used as it is, but if the length is 40 mm or less and the width is 1.0 mm or less, the printed wiring can be visually or optically controlled. Accurate detection (measurement) of the contact width, ie, height, of the secondary jet solder 4b with the substrate 11 becomes relatively difficult.

Therefore, for example, one of the cuts parallel to the transport direction of the printed wiring board 11 is inserted into the elongated hole 12 for detection.
a. In this case, the length of the long hole 12a is set to 50 mm or more, and the width thereof is set to 1.0 to 3.0 mm (preferably 2.1.0 mm).
0mm) and scale 1 along the long hole 12a.
Form 3

The detection slot 12a is formed together with the notch 12 at the stage of forming the printed wiring board 11, and the scale 13 is printed simultaneously with the printing of the printed wiring portion. To form. The scale 13 has the same width and length as those of the first embodiment. The long hole 12a for detection is not limited to one location, but may be provided at a plurality of locations.

The same soldering process as that described in the first embodiment is performed on the printed wiring board 11 according to the second embodiment. , And will be omitted.

In any case, according to the present invention, the printed wiring boards 1 and 11 to be subjected to the jet-type soldering are:
In the soldering process, the state of contact with the secondary jet solder, that is, the contact width can be directly detected, so that the jet height of the secondary jet solder can be accurately detected and adjusted or controlled.

[0035]

As described above, in the method for detecting the height of the secondary jet solder according to the present invention, the lower surface of the printed wiring board on which the electronic components are temporarily mounted is brought into contact with the primary jet solder and the secondary jet solder. A slot-shaped elongated hole is provided in the printed wiring board or at a boundary portion with the discarded board, and the contact of the jet solder that contacts the lower surface of the printed wiring board through the slit-shaped elongated hole is performed. By detecting the width as the contact length and determining the height of the jet solder based on the detected contact length, the soldering process can be performed through the slit-shaped long hole provided on the printed wiring board. It is possible to directly detect the contact width of the jet solder that is in contact with the lower surface of the printed wiring board, thereby determining the height of the secondary jet solder and always maintaining an appropriate contact state (height). The adjustment can be performed without interrupting the soldering process, without reducing the operation rate (productivity), and maintaining the height of the secondary jet solder at an appropriate height. As a result, an excellent effect that generation of defective products can be significantly suppressed can be achieved.

Further, the printed wiring board used for the jet type soldering according to the present invention is a detecting means for detecting the height of the jet solder in contact with the lower surface in the printed wiring board or at a boundary with the discarded board. With this configuration, the detecting means can be formed without changing the production process of the printed wiring board, so that it can be provided at a low cost, and can contact the printed wiring board itself with the lower surface during the soldering process. Since the detecting means for detecting the height of the jet solder is provided, there is no need for an extra detecting means of a separate configuration for the jet soldering apparatus, and an excellent effect that the entire apparatus can be simplified can be obtained. .

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an enlarged example of a detection unit in the printed wiring board.

FIG. 3 is an explanatory diagram for explaining a situation in which the height of a secondary jet solder is detected using the printed wiring board.

FIG. 4 is a plan view schematically showing a printed wiring board according to a second embodiment of the present invention.

[Explanation of symbols]

1, 11 printed wiring board; 2 slit-shaped long hole; 3, 13 scale; 4 molten solder; 4a
Primary jet solder; 4b Secondary jet solder; 5 Solder bath; 6 Primary nozzle; 7 Secondary nozzle;
Camera; 11a Body board; 11b Discard board; 1
2 slit-shaped notch; 12a long hole for detection;
a Arrow indicating the transport direction of the printed wiring board.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 1/08 320 B23K 1/08 320Z H05K 1/02 H05K 1/02 R G C

Claims (5)

[Claims] 1. A method according to claim 1, wherein a lower surface of the printed wiring board on which the electronic component is temporarily mounted is brought into contact with a primary jet solder and a secondary jet solder to perform soldering. A slit-shaped long hole is provided at the boundary portion, and the contact width of the jet solder contacting the lower surface of the printed wiring board through the slit-shaped long hole is detected as a contact length, and the height of the jet solder is determined based on the detected contact length. A method for detecting the height of a secondary jet solder in jet soldering, wherein the height is determined. 2. The method for detecting a height of a secondary jet solder according to claim 1, wherein the determination of the height of the secondary jet solder is performed visually or optically. 3. A printed wiring board to be subjected to jet-type soldering, wherein:
A printed wiring board provided with a detecting means for detecting a height of a jet solder contacting a lower surface. 4. The printed circuit board according to claim 3, wherein the detecting means is a slit-shaped elongated hole. 5. The printed wiring board according to claim 4, wherein a scale is provided along the slit-like elongated hole.