JPH03225895A - Soldering and device therefor - Google Patents

Abstract

PURPOSE:To mount and demount parts to be mounted, and hence improve soldering quality for assurance of no correction and no cleaning by connecting a molten solder to a solder in a through-hole and re-melting the solder in the through-hole for soldering. CONSTITUTION:A parts lead 5 is inserted from the upper portion upon a solder 6 in each through-hole 3 part being reflown, and thereupon the lead protruding from the through-hole 3 to the side of a soldered surface is received by each crucible 21 and the lead 5 part is also sufficiently heated in the crucible 21, for assurance of ideal soldering. Further, the solder 6 in the crucible 21 tends to slightly overflow owing to the volume of the inserted lead 5, but since a small hole 22 provided in the middle of the crucible 21 serves to discharge excess solder, the solder is allowed to flow out from an opening in the crucible 21, preventing solder balls and solder crumbs to stick to the surroundings of the soldered part. Hereby, high quality, clean soldering is assured without requiring correction and cleaning.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a soldering method suitable for work such as attaching retrofitted parts and removing parts for modification after electronic circuit parts are mounted on a board and soldered. The present invention relates to an attachment method and an apparatus using the method.

[Prior Art] A conventional soldering device is, for example, disclosed in Japanese Patent Application Laid-Open No. 641856.
As described in Publication No. 7, a solder supply section made of metal such as stainless steel or titanium to which solder does not adhere is provided with a groove in which solder accumulates corresponding to the soldered parts of electronic components, and the solder supply section is is placed in the solder bath of the solder tank, and is raised only when soldering to solder the printed circuit board pattern to the electronic component lead wire, thereby supplying solder only to the peripheral area of the solder supply section and heat. It has been proposed that even electronic components that are sensitive to heat can be soldered without thermal damage.

Furthermore, as described in JP-A-1-44266, for example, the shape of the solder ejection nozzle connected to the guide is formed in the same shape as the necessary part of the solder on the printed circuit board, and the nozzle is A cutout is provided to allow excess molten solder to flow out during soldering work.
The solder injected from the nozzle is used to solder the leads and through-holes of electronic components, and excess solder flows out from the notch, increasing the solder pressure to improve soldering accuracy and taping unnecessary parts. Some proposals have been made to simplify the work by making it unnecessary.

[Problems to be Solved by the Invention] In the former prior art, no special devises have been made to the structure of the groove in which the solder accumulates, so when soldering is carried out, many solder balls etc. are likely to be generated in the peripheral area. There are problems in that the temperature of the solder decreases as the supply part rises and the time elapses, and that it is difficult to control the temperature of the solder pool to an optimum temperature due to the heat capacity of the soldered part.

Further, in the latter conventional technique, a notch for solder outflow is provided in the nozzle portion, and excess molten solder is discharged from the notch. However, if sufficient flux is not uniformly applied to the area around the nozzle where the solder melts, there is a problem that the solder layer will inevitably adhere to the board surface, contaminating the board surface, or creating a risk of solder bridging. .

Therefore, post-soldering correction work was required, and a cleaning process to remove a large amount of applied flux was also essential. Note that, in all of these conventional techniques, it is necessary to supply solder to the soldering portion at the time of soldering.

The purpose of the present invention is mainly to reuse the solder filled in the through-holes of the circuit board, or to easily attach and detach retrofitted parts in the flow soldering method, and to improve soldering quality without modification. An object of the present invention is to provide a soldering method that allows no cleaning and an apparatus using the method.

1. Means for Solving the Problem] In order to achieve the above object, in the soldering method of the present invention, a soldering iron is applied only to the vicinity of soldering of the through hole on the bottom surface of an electronic circuit board held horizontally at a fixed position. Soldering is performed by bringing the tips of the iron into contact with each other, connecting the molten solder in the crucible formed on the tip to the solder in the through-hole, and remelting the solder in the through-hole with the molten solder. It is.

Further, in order to achieve the above object, the soldering apparatus of the present invention includes a means for positioning the electronic circuit board at a predetermined position, and a means for moving the electronic circuit board in the vertical direction together with a heater to connect the upper end surface to the through hole on the lower surface of the electronic circuit board. A soldering tip that is in contact only near the soldering area, and a soldering tip that is formed on the upper end surface of the soldering tip so as to be connected to the component lead inserted in the through hole, and is filled with molten solder, and the solder in the through hole is It is equipped with a crucible for remelting the melt.

Further, the soldering iron tip is provided with a temperature sensor probe that detects the temperature inside the crucible, and automatic temperature adjustment means that adjusts the temperature of the heel based on the detection result from the temperature sensor probe.

Further, the soldering iron tip is provided with a discharge hole for discharging excess solder in the crucible.

[Function] Positioning of the soldering part using the index lever can be performed with one-touch operation by providing index levers capable of step-by-step scanning of the soldering part in each of two horizontal axes directions.

The use of an air cylinder to move and press the tip of the soldering iron to the soldering area achieves the soft-touch access operation that is essential for iron operation.

A crucible that opens onto the surface to be soldered is provided on the top of the tip of the soldering head, and this crucible is always filled with molten solder by the heater of the electric soldering iron. maintained at a constant temperature. During soldering, the solder on the part to be soldered comes into contact with this luppolo and is refried. At this time, the solder temperature momentarily drops as the crucible's soldering heat is taken away, but the automatic temperature controller quickly recovers, so the soldering temperature does not deviate from the specified temperature. Since a crucible is provided for each through hole or each soldering point, heating to areas other than the soldering area can be kept to a minimum, and there is no risk of thermal damage to the surrounding base material.

Now, to explain the function of the crucible when inserting and soldering retrofitted parts, once the solder in each through-hole has been re-opened, the component leads are inserted from above, but at this time the solder is removed from the through-hole. Each crucible receives the leads protruding toward the attachment surface, and the lead portions are also sufficiently heated within the crucible, resulting in ideal soldering. Note that due to the volume of the inserted lead, the solder in the crucible tends to overflow to some extent, but the small hole in the middle of the crucible plays the role of discharging excess solder, so it flows out from the opening of the crucible. No solder balls or solder debris will adhere to the periphery of the soldered area.

In view of the above, according to the soldering apparatus and the soldering method of the present invention, high quality and clean soldering can be performed, and there is no need for correction, cleaning, etc.

[Example] Hereinafter, FIGS. 1 to 3 showing an example of the present invention will be described.

In FIGS. 1 to 3, reference numeral 1 denotes a substrate on which a plurality of electronic components 2 are mounted and a plurality of through holes 3 are formed at predetermined intervals. In the present invention, lead wires 5 provided at both ends of the resistor 4 are soldered into the through-hole 3 using solder 6.

Reference numeral 7 designates a pedestal, and a reciprocating table 9 is provided at the upper part of the frame, which is supported reciprocally by two guides 8, and which mounts the substrate I in the horizontal direction. A positioning means 12 consisting of an index par 10 and an operating lever 11 for positioning is installed.

Further, a soldering means 13 is supported at the lower part of the pedestal 7. The soldering means 13 includes an air cylinder 15 fixed to the center of a frame 14, a soldering iron 16 that is vertically movable and supported by the air cylinder 15, and an upper end of the soldering iron 16. The soldering iron tip 19 is provided with a heater 17 supported by a heater 17 and an iron tip 19 fastened to the upper end of the heater 17 with a screw 18. The iron tip depth 19 has an L-shape (1), and a protrusion 19b is formed on the upper end surface of the upright wall 19a, and the protrusion 19b contacts only the vicinity of the through hole 3 of the board 1, that is, the vicinity of the soldering part. A crucible 21 is connected to the through hole 3 and filled with molten solder 20, and a discharge hole 22 is provided in the depth direction of the crucible 11 to discharge excess solder. When the crucible 21 and the through hole 3 are filled with solder 6.20, the discharge hole 22 will not be discharged from the discharge hole 22 due to surface tension, but by inserting the lead wire 5 into the through hole 3. The position and inner diameter are set in advance based on experimental results so that when excess solder is generated, the excess solder is discharged. Further, the tip of the temperature sensor probe 23 is fastened to the upper surface of the horizontal wall 19c of the soldering tip 19 by a screw 18 for fastening to the heater 17.

The temperature sensor probe 23 has its rear end supported by an automatic temperature adjustment means 2 with a built-in microcomputer supported at the lower part of the pedestal 7.
Connected to 4. The automatic temperature adjustment means 24 is code 2.
It is connected to a power source (not shown) through an outlet 26 at the tip of 5. 27 is an air switching valve and an air supply source (
When the foot petal 28 is stepped on, air is supplied into the air cylinder 15 and the soldering iron 16. The heater 17 and the iron tip 19 rise.

Next, the operation will be explained.

First, the through hole 3 is filled with solder 6, and the board 1 is mounted horizontally on the carriage 9 without inserting the lead wire 5, and is positioned at a predetermined position by the positioning means 12.

Also, step on the hood betal 28 and soldering iron 16. When the heater I7 and the soldering iron tip I9 are raised to bring the upper end surface protrusion 19b of the upright wall 19a into contact with the soldering part on the lower surface of the substrate l, the molten solder 20 in the crucible 21 heated by the heater 17 is heated. The solder 6 in the through hole 3 is re-opened. At this time, the temperature of the molten solder 20 in the crucible 21 decreases, which is detected by the temperature sensor probe 23, and the temperature of the molten solder 20 in the crucible 21 is adjusted to a predetermined temperature by the heater 17 via the automatic temperature adjustment means 24. rise to.

After that, the solder 6 in the through hole 3 is placed in the crucible 21.
When the temperature reaches the same as that of the molten solder 2o in the resistor 4,
When the lead wires 5 at both ends of the solder 6 are inserted into the solder 6, an amount corresponding to the volume of the lead wires 5 becomes surplus, and the surplus solder is discharged from the discharge hole 22. Therefore, it is possible to prevent excess solder from becoming solder balls and solder debris and adhering to the periphery of the soldering portion.

Furthermore, by inserting the lead wire 5 into the solder 6, the temperature of the solder 6 and the molten solder 20 in the crucible 21 is lowered, but as described above, the temperature of the molten solder 20 in the crucible 21 is lowered by the temperature sensor probe 23. Automatic temperature adjustment means 2
4 and heater 17 to raise the temperature to a predetermined temperature.

Furthermore, since the temperature sensor probe 23 is installed near the crucible 21, the temperature of the molten solder 20 inside the crucible 21 can be measured instantly and accurately.

Therefore, according to this embodiment, the substrate 1 can be positioned at a predetermined position by the positioning means 12, and the temperature sensor probe 23. The automatic temperature adjustment means 24 and heater 17 can always maintain a constant soldering temperature and prevent the generation of solder balls and solder debris, making it possible to perform clean and reliable soldering. This eliminates the need for post-process corrections and cleaning operations, thereby significantly reducing the number of soldering operations.

[Effects of the Invention] According to the present invention, the solder filled in the through-hole can be used by the refill port when attaching retrofitted parts, so there is no need to suck up the solder, and there is no need to supply solder at the time of attachment. can do.

Since there are no solder balls or solder debris attached around the soldered portion, solder correction, cleaning, etc. can be made unnecessary.

Since the soldering temperature is stably controlled to a specified temperature, a high quality and uniform solder finish can be obtained, and no modification can be made.

Since soldering point-by-soldering heating is performed on a soldering point basis, there is no thermal damage to surrounding component materials, and repair work can be carried out with peace of mind even on boards equipped with heat-sensitive components.

Taking all the above effects into account, the work can be done in about one-fifth of the man-hours compared to the conventional post-installation work using manual soldering.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2 is a re-opening state diagram when a resistor, which is a two-terminal lead component, for example, is soldered using the inventive device, and Fig. 3 is a diagram of the inventive device. 1 is a perspective view of an iron tip having a crucible with a special solder discharge hole used in the soldering iron tip. 1... Board 2... Electronic component 3... Through hole 4... Resistor 5... Lead wire 6.
...Solder 781. Frame 12... Positioning means 13... Soldering means 15... Air cylinder 16... Soldering iron 17... Heater 19...
Iron tip 20... Molten solder 21... Crucible 22... Discharge hole 23... Temperature sensor probe 24... Automatic temperature adjustment means 27... Air switching means 28... Foot pedal connection diagram 5 12? ---Eichiboku aa 15 Ikyoki Shigumezuto 1/I4r Niiger Ayo 2 21---Lunobo. 22-4/Toniku 6--Hanf; 7-Song-Uj3--Where is this →-Tsuf? 0---Soluble M1 YuLE 23-7-)■ Tar porridge 2 figure porridge 5 figure 2 Z

Claims (6)

[Claims] 1. In a partial soldering method for an electronic circuit board, a soldering iron tip is brought into contact with only the soldering area of a through hole on the bottom surface of an electronic circuit board held in a fixed position horizontally, and a soldering iron tip formed on the soldering iron tip is used. A soldering method in which molten solder in a crucible is connected to solder in the through hole, and the solder in the through hole is remelted by the molten solder to perform soldering. 2. 2. The soldering method according to claim 1, wherein said iron tip is provided with means for detecting the temperature inside the crucible and always maintaining the temperature at a constant temperature. 3. 3. The soldering method according to claim 2, wherein the iron tip is provided with a means for discharging excess solder in the crucible. 4. In a partial soldering device for electronic circuit boards, there is provided a means for positioning the electronic circuit board in a predetermined position, and a means for moving the electronic circuit board in the vertical direction together with a heater so that the upper end surface is only connected to the vicinity of the through hole on the lower surface of the electronic circuit board, that is, the vicinity of the soldering area. Soldering comprising a soldering iron tip in contact with the soldering tip, and a crucible connected to the component lead inserted into the through hole on the upper end surface of the soldering iron tip and filled with molten solder to remelt the solder in the through hole. Device. 5. 5. The soldering apparatus according to claim 4, wherein said iron tip is provided with means for detecting the temperature inside the crucible and always maintaining the temperature at a constant temperature. 6. 6. The soldering apparatus according to claim 5, wherein said soldering iron tip is provided with means for discharging excess solder in the crucible.