JPH0825031A - Soldering device and its soldering method - Google Patents

Abstract

PURPOSE:To enable stable solder joining even if electronic parts and electrodes on respective circuit boards are narrow spaced. CONSTITUTION:Solder 9 is supplied to the electrodes 10 on the circuit board 11 and the electronic parts are superposed thereon after the leads 8 of these parts are aligned. This soldering device is constituted to execute solder joining by moving an iron tip 1a provided with a wetting surface of a stable shape by a polishing device at a predetermined contact angle while a flux 7 is supplied thereon by a flux supplying device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for mounting electronic components on a circuit board and a joining method for the same.

[0002]

2. Description of the Related Art In recent years, a TAB (Tape Automat) for driving a liquid crystal
ed bonding) is mounted on the circuit board by the FOB (Fi
lm On Board) implementation. FIG. 2 shows a mounting cross-sectional view of the FOB.

The driving TAB is composed of leads 8, an IC 14, a polyimide material 15, and a sealing material 16, and converts an electric signal input from the circuit board 11 and outputs it to an electrode on the surface of the glass panel 17. The liquid crystal element on the glass panel 17 is driven.

The above-mentioned FOB mounting means a joint portion of the solder 9 for joining the electrode 10 on the circuit board 11 and the lead 8 of the liquid crystal driving TAB. In the conventional FOB mounting technology, a method in which a worker holds a soldering iron to join the mainstream is the mainstream, and a conical cone-shaped soldering iron is used.

An example of the conventional FOB mounting technique described above will be described with reference to FIG. In FIG. 10, the electrodes 10 on the circuit board 11 and the leads 8 of the liquid crystal driving TAB are connected to the electrodes 10
It is the figure which is joined using the solder 9 printed on. Iron plating is formed on the tip of the heated soldering iron 1 as a wetting surface with the solder 9.

The iron plating 3 has a wetted surface shape that does not cause a problem even when the operator rotates the soldering iron 1 by spreading it around the tip and the periphery of the cone-shaped soldering iron. The bonding method is the solder 9 printed on the electrode 10 on the circuit board 11.
Then, the aligned leads 8 are brought into close contact with each other, and the tip of the soldering iron 1 supplied with the preliminary solder on the iron plating layer 3 is brought into contact with the lead 8 to join them.

FIG. 11 shows a tip shape manufactured by a conventional soldering iron tip manufacturing process. 1 in the figure
a is a tip, 2 is a copper body forming the tip 1a, 3 is a plating layer, 9 is solder, and 29 is masking. In the conventional iron tip manufacturing process shown in FIG. 12, since the solder wetting surface as shown in FIG. 10 is not limitedly defined, the work of forming the wetting surface is a manual operation. As shown in FIG. 12, soldering treatment IV is applied to the tip that determines the wet surface area of the tip.
The step of the masking process V is performed manually, and even if the wetted surface is defined up to the part 13 that can be separated from the lead as shown in FIG. When a solder wetting surface exceeding the portion 13 separated from the lead is formed in this way, a solder pool 12 is formed in the opposite example to the scanning direction 5 of the tip 1a as shown in FIG. Frequent poor solder wetting of leads.

[0008]

However, in the conventional structure as described above, at the time of solder joining, the solder pool 12 that accumulates around the iron-plated layer 3 that is the solder wetting surface and the solder that wets the leads 8 are used. The separated state is unstable due to the amount of the solder pool 12 and wear deformation of the tip, and short circuits due to solder between adjacent electrodes frequently occur in the actual manual soldering process.

The present invention has been made in consideration of the above conventional problems, and an object of the present invention is to provide a soldering device in which the amount of solder accumulated on the tip is stable and the joining can be performed without causing unjoining or short circuit due to soldering of adjacent leads. To do.

[0010]

In order to solve the above-mentioned problems, the present invention forms a flat-shaped portion on the tip of a soldering iron to which the solder is wet, and does not wet all the surfaces other than the flat-shaped portion with the solder. The soldering device is covered with a material member.

[0011]

According to the above construction, the amount of solder accumulated on the tip is stable, and it is possible to obtain a joint that is not joined or short-circuited due to the solder of the adjacent lead, and a fully automatic soldering apparatus by a robot can be realized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solder bonding apparatus for a liquid crystal driving TAB and a circuit board according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a process of joining a liquid crystal driving TAB and a circuit board in an embodiment of the present invention. As shown in the figure, the tip 1a of the soldering iron 1 uses a copper body 2 made of oxygen-free copper, which is excellent in heat conduction, as a material, and has excellent solder wettability on the copper body 2. The iron plating layer 3 having excellent wear resistance as compared with copper is attached. Although the iron-plated layer 3 forms a solder wetting surface, a black chrome-plated layer 4 is attached to the surface of the portion that should not be wet with solder. That is, the solder wetting surface of the iron tip 1 a is the iron plating layer 3 portion not covered with the black chrome plating layer 4, and the wetting surface range is determined by the black chrome plating layer 4. The object to be soldered is a liquid crystal on a solder 9 formed by cream solder printing → heating → cooling on the electrode 10 on the circuit board 11.
The lead B of B is aligned and then superposed.

A soldering device using the soldering iron and the object to be soldered, which are configured as described above, and a joining method thereof will be described. First, the tip 1a is heated to 280 ° C. to 340 ° C., and air is blown to the tip 1a in order to suck out impurities at the tip of the tip 1a. Next, as shown in FIG. 1, the soldering iron 1 is lowered onto a portion of the circuit board 11 where no electronic component is mounted with a load of 40 g to 60 g, and the tip 1a is brought into contact therewith. Next, the flux 7 is supplied from the flux pipe 6 to 0.
While ejecting at a flow rate of 1 to 0.2 g / min, the tip 1a and the flux pipe 6 are synchronized with each other and 5 m in the scanning direction 5.
It is moved at a speed of m / sec to 10 mm / sec.

By the movement, the iron plating layer 3 of the tip 1a comes into contact with the lead 8 and the solder 9, and the tip 1
The heat supplied from a melts the solder 9 and wets the iron plating layer 3 and the lead 8. This state is as shown in FIG.
The solder pool 12 is formed at the tip of the tip 1a. In the solder pool 12, the leads 8 and the electrodes 10 are wet with the molten solder, but the adjacent leads are short-circuited by the molten solder. However, the tip 1a moves, and is separated from the electrode 10. The effect of separating the short-circuited molten solder by the black chrome plating layer 4 of the tip portion 13 of the tip and the surface tension of the solder itself is applied to the lead 8. Due to the gathering effect, a solder short defect does not occur at the end of soldering.

As described above, in the soldering using the soldering iron 1, the black chrome plating layer 4 for separating the solder pool 12 of the iron tip 1a and the solder 9 is very important, and the molten solder It is also important to stably supply the flux 7 that has an antioxidant and a reducing action and greatly affects the surface tension of the solder.

The configuration shown in FIG. 1 is shown in FIG. 3 as a perspective view. FIG. 3 shows a process of soldering with the soldering iron 1. The flux 7 supplied from the flux pipe 6 is necessary to remove the oxide film and perform good soldering, but the surface electrode 2 formed on the glass panel 17
If attached to 0, an electrical short circuit may occur.
Therefore, the flux scattering prevention plate 18 is provided so as not to adhere to the surface electrode 20 due to the scattering of the flux 7. In addition, in the state before soldering, the TAB is pushed vertically downward so that the leads 8 of the TAB are closely attached to the solder 9, and the warpage of the TAB when the leads 8 are present in the melted solder 9 immediately after the solder joining. Therefore, a device for holding the TAB, which has an effect of preventing the floating, is provided. In this embodiment, as shown in FIG. 3, the configuration of the TAB retainer / flux scattering prevention plate 18 was able to obtain two effects at the same time. In the figure, 14 is an IC, 15 is a polyimide material,
Reference numeral 19 is a flux pipe introduction pipe. With such a configuration, a soldering device that performs good soldering has been realized.

Next, a detailed examination of the shape of the soldering iron tip 1a and another embodiment of the iron tip manufacturing process will be described. FIG. 4 shows the shape of the tip 1a of this embodiment. FIG.
The point different from the iron tip in use is that the black chrome plating layer 4 covers the entire surface of the iron tip 1a, the iron plating layer 3 is not exposed, and the solder wetting surface is not formed. .
As shown in FIG. 5, the black chrome plating layer 4 on the polishing surface 21 is polished with the sandpaper 2 immediately before the tip 1a is used for soldering.
The iron plated layer 3 is exposed by scraping off with 2. By this step, only the iron-plated layer 3 of the polishing surface 21 is exposed, and the iron-plated layer 3 becomes a stable solder-wetting surface without oxidation. The solder wire is supplied while the flux is being supplied so that the solder is stably wetted by the solder wet surface. Thus, it becomes possible to process the wetted surface only in the area determined by the polishing process immediately before use, and the tip portion 13 of the tip, which is separated from the lead, is covered with the black chrome plating layer 4. Can be realized. Note that the trowel manufacturing process is shown in FIG.

Next, an example in which the optimum contact angle with the object to be soldered is examined using the soldering iron 1 will be shown. FIG. 7 shows the state of the copper electrodes 10, leads 8 and solder 9 before joining. In this example, each volume is 0.00 lead volume.
75 mm ^3, the electrode volume 0.016 mm ^3, the solder volume 0.
It was 037 mm ³ . The wetted surface of the soldering iron tip 1a was set to be about 3 times as long as the bonding pitch so as not to fall on the circuit board 11 between the electrodes 10 and get caught by the TAB lead 8. In order to wet the lead 8 at the time of joining shown in FIG. 7, the solder pool 12 at the tip of the tip 1a is sufficient when the tip 1a reaches the third lead from the lead lead as shown in FIG. It must be
In this embodiment, three times the volume of the lead 8, the solder 9 and the electrode 10 is 0.18 mm ³ . Further, as shown in FIG. 8, the tip angle 24 was 5 ° by forming the solder pool 12 of 0.18 mm ³ shown by the hatched portion.

As described above, the solder pool volume formed on the tip 1a is equal to or 0.8 times to 1.2 times the total volume of the solder volume, the lead volume, and the electrode volume, and the tip wetting area is And by setting the contact angle to 24, a good soldering device can be realized.

Next, the flux supply device used in the above embodiment will be described. As shown in FIG. 9, the flux supply device is a method of supplying the flux 7 flowing in the flux tube 6 to the root in the scanning direction 5 of the tip 1a. By supplying the iron tip 1a to the root in this manner, the highly active flux 7 can be stably supplied to the iron tip 1a.

As shown in FIG. 9, the feeding method is as shown in FIG. 9, in which the introducing pipe 19 is supported by a fixing rod 28 which is connected to the rotation holding portion 26 of the heater 25 for heating the iron tip 1a, and the flux pipe 6 is fixed to the introducing pipe 19. To do. At this time, the heat conducted by the heater 25 heats the flux pipe 6 to 50 ° C. to 100 ° C., which has the effect of improving the activity of the flux 7. In this embodiment, a Teflon tube is used as the flux pipe 6, and the tip discharge port of the Teflon tube 6 is defined to be a distance of 0 mm to 2 mm from the tip 1a. As shown in FIG. 1, the tip of the flux tube is inclinedly cut, the flux discharge port is directed downward, and the flux 7 is supplied to the linear tip 1a by contacting the lead 8.
It has been possible to stably supply the flux 7 onto the leads 8 without vaporization. 27 in the figure
Is a heater cable.

Next, uneven wear of the tip 1a is prevented, and the tip 1
An example of a cleaning device for stabilizing the wet surface of a will be described. The tip 1a of the soldering iron 1 comes into contact with the lead 8 while being heated to a high temperature, which causes uneven wear, and the solid content of the flux 7 adheres to the tip 1a, so that the tip 1a is projected. Were formed or the area of the wet surface was unstable. For this reason, the cleaning device of this embodiment stabilizes the wetting surface by sanding the tip wetting surface as shown in FIG. 5 after joining 2500 to 5000 TAB.

This cleaning device has the same mechanism as a polishing device for forming a wet surface on a new iron tip 1a covered with a black chrome plating layer 4 on the whole surface. It is very effective in stabilizing the wet surface during use.

[0025]

As is apparent from the description of the above-mentioned embodiment, the soldering apparatus of the present invention comprises a soldering iron having a stable wetting surface at its tip, a flux supplying device, and a tip cleaning device. Achieve stable production quality when mounting electronic components on circuit boards.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a soldering device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a soldering object by the soldering device.

FIG. 3 is a perspective view of a main part of the soldering device.

FIG. 4 is a sectional view showing a tip shape of a soldering iron in the soldering device.

FIG. 5 is an explanatory view showing a method of manufacturing a soldering iron of the soldering device.

FIG. 6 is a flowchart of the method for manufacturing the soldering iron.

FIG. 7 is a cross-sectional view of a portion to be soldered before joining by the soldering device.

FIG. 8 is a sectional view of the same soldering device during soldering.

FIG. 9 is a side view of the soldering device.

FIG. 10 is a sectional view of a main part of a conventional soldering device.

FIG. 11 is a sectional view of the tip of a soldering iron in a conventional soldering device.

FIG. 12 is a flowchart of a method for manufacturing a soldering iron tip in a conventional soldering device.

FIG. 13 is a cross-sectional view during mounting using a conventional soldering iron

[Explanation of symbols]

 1 Soldering Iron 1a Iron Tip 2 Oxygen Free Copper Body 3 Iron Plating Layer 4 Black Chromium Plating Layer 5 Scanning Direction 6 Flux Pipe 7 Flux 8 Lead 9 Solder 10 Electrode 11 Circuit Board 12 Solder Pool 13 Lead Tip Separated from Lead 14 IC 15 Polyimide material 16 Encapsulation material 17 Glass panel 18 TAB retainer / flux scattering prevention plate 19 Flux pipe introduction pipe 20 Glass upper electrode 21 Tip polishing part 22 Polishing file 23 Polishing stage 24 Tip angle 25 Heater 26 Rotation holding part 27 Heater cable 28 Fixing rod 29 Masking 30 Solder short part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H05K 3/34 507 N 8718-4E

Claims (12)

[Claims] 1. A soldering iron having a solder wetting surface at its tip, a flux supplying device for supplying flux to the tip of the soldering iron, and the soldering iron are moved at a contact angle at which the solder wetting surface is determined. A soldering device comprising moving means for moving. 2. A soldering device comprising a soldering iron having a flat-shaped solder wetting surface at its tip end, and all other surfaces being covered with a material which does not wet the solder. 3. The soldering apparatus according to claim 2, wherein the solder wetting surface has a flat and rectangular shape. 4. The soldering device according to claim 1, wherein the moving means moves the soldering iron at an angle of 0 <θ ≦ 15 ° formed by the solder wetting surface and the object to be soldered. 5. The soldering device according to claim 1, further comprising means for polishing the tip of the soldering iron. 6. The soldering device according to claim 5, wherein the polishing means comprises a file for polishing the tip of the soldering iron. 7. The polishing means forms a solder wetting surface by scraping off a soldering iron whose entire portion is covered with a material that does not wet the solder just before soldering.
The described soldering device. 8. The soldering device according to claim 1, wherein the flux supply device has an elastic pipe through which the flux is passed and whose tip is brought into contact with the object to be soldered. 9. The soldering device according to claim 1, wherein the flux supplying device is arranged such that a portion fixing the pipe supplying the flux is synchronized with the movement of the tip. 10. The flux supply device directly connects the heater part for heating the tip and the flux pipe fixing part,
The soldering device according to claim 1, wherein the flux pipe is heated by the heat of the heater. 11. The soldering apparatus according to claim 1, further comprising: a TAB retainer and a flux scattering prevention plate that suppresses the flux scattering, while suppressing the soldered object. 12. A soldering iron having a solder wetting surface at its tip while supplying solder to electrodes on a circuit board, aligning leads of electronic components to be joined, superposing them, and supplying flux with a flux supply device. A soldering method in which the solder is moved at a predetermined contact angle and soldered.