JP3205867B2 - Reflow furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow furnace for attaching solder to a multifunctional electronic component connected in a tape shape.

[0002]

2. Description of the Related Art In recent years, electronic components have become smaller and smaller.
It has become multifunctional with the reduction in weight. In order to make electronic components multifunctional, it is necessary to install a large number of leads. For multifunctional electronic components such as QFP and SOIC, the leads protrude from both sides and four sides of the main body to increase the number of leads. I have. However, the number of leads protruding from the side surface of the main body is limited, and the function is also restricted. Therefore, recently, electronic components such as BGA and CSP, in which leads are provided on the back surface of the electronic component to increase the number of leads, have appeared.

[0003] When a high-performance electronic component such as a BGA or a CSP is mounted on a printed circuit board, the lead of the multi-functional component and the land of the printed circuit board are joined by soldering. At this time, if the solder is separately supplied to the soldering portion, it is not only time-consuming but also impossible to accurately place the solder on the minute soldering portion. Therefore, in high-performance electronic components, solder bumps are formed in which solder is previously attached to lead portions. In other words, if solder bumps are formed on the leads of high-performance electronic components, simply mounting the high-performance electronic components on a printed circuit board and heating the printed circuit board with a heating device will allow the high-performance electronic components to be easily connected to the printed circuit board. This means that you can solder.

[0004] As a method of forming solder bumps of a high-performance electronic component, an adhesive flux is applied to the leads of the high-performance electronic component, and fine solder balls are placed thereon, followed by heating in a reflow furnace. A solder bump is formed by melting a solder ball.

[0005] Conventionally, high-performance electronic components have a semiconductor element mounted on a hard substrate. However, since a hard substrate has a large thickness and is expensive, it has recently been developed. 2. Description of the Related Art High-performance electronic components using thin-film substrates that are thin and can be manufactured at low cost have emerged. The high-performance electronic components on this thin-film substrate are in the form of a continuous tape. Solder bumps are formed in the same way as solder bumps on hard substrates by placing small solder balls on the leads and then using a reflow oven. This is done by heating.

A conventional reflow furnace used for forming solder bumps on a tape-shaped electronic component is a reflow furnace used for a high-performance electronic component having a hard substrate, that is, a chain conveyor or a mesh conveyor having a large number of pins on a transport portion. Was installed in the reflow furnace.

[0007]

When a tape-shaped electronic component is conveyed on a chain conveyor or a mesh conveyor, the tape-shaped electronic component may meander in a tunnel of a reflow furnace, or may rise upward due to thermal strain, resulting in improper operation. not only a uniform heating, there may result in cutting the tape-like electronic component I middle or Hikka. An object of the present invention is to provide a reflow furnace in which a tape-shaped electronic component does not meander or float.

[0008]

Means for Solving the Problems The present inventors have completed the present invention by noting that a long tape-shaped object needs to be pulled with a strong force on both sides in order to travel in a flat state. I let it.

According to the present invention, in a reflow furnace in which a heating zone and a cooling zone are sequentially formed from an entrance side to an exit side in a tunnel, the entrance side is always braked in conjunction with a torque control device. with sprocket are is installed, the exit side are installed a sprocket in conjunction with the drive device, yet the entry side spray
Tape-shaped electronic part between the rocket and the exit sprocket
A slit guide that can support both sides of the product from above and below
It is a reflow furnace characterized by being installed .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A reflow furnace according to the present invention applies a constant torque to a sprocket on the ingress side to keep the brake state at all times, and pulls the sprocket on the exit side to flatten the tape-shaped electronic component. is there. Any device that can adjust the torque applied to the entry side sprocket can be used.However, a torque control device in which a pair of magnets are opposed to each other and the torque is variable by adjusting the distance between the magnets is known. Are suitable.

[0011] Even if a torque is applied to the entry sprocket and the tape-like electronic component is pulled by the exit sprocket, the tape-like electronic component may become slack in the middle of a long tunnel in a reflow furnace. Therefore Between the entry sprocket of the reflow furnace exit sprocket are installed a guide to prevent the loosened tape-shaped electronic component. The guide supports both sides of the tape-shaped electronic component from above and below.
It is a slit that can be cut.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reflow furnace according to the present invention will be described below with reference to the drawings. FIG. 1 is a central sectional view of the reflow furnace of the present invention, and FIG.
FIG. 3 is a front view of a torque sprocket installed on the entrance side of the reflow furnace, FIG. 3 is a front view of a driving sprocket installed on the exit side of the reflow furnace, FIG. It is sectional drawing of a guide.

The reflow furnace of the present invention has a tunnel 1 inside.
The tape-shaped electronic component 2 enters the tunnel 1 in the direction of arrow A. Inside the tunnel 1 is a heating zone 3 and a cooling zone 4 from the entrance side to the exit side.
Are formed.

A plurality of heaters 5 are provided in the upper and lower portions of the heating zone 3. As a heater used in the present invention, an infrared heater, a hot air blowout type heater, or the like is used. Blow-out heaters are suitable. Coolers 6, 6 capable of blowing cold air are installed in the upper and lower portions of the cooling zone 4.

In the tunnel 1, guides 7 for preventing the tape-shaped electronic component 2 from being slackened in the tunnel are installed in parallel with the longitudinal direction of the tunnel. Guide 7
As shown in FIG. 5, slits 8 are formed so that both sides of the tape-shaped electronic component 2 can be supported from above and below.

A pair of torque sprockets 9 and 9 are installed on the entrance side of the reflow furnace, and a torque control device 11 linked with a shaft 10 is installed on the torque sprocket. The torque control device is in a state where a load is constantly applied to the torque sprocket 9, that is, the torque sprocket is hardly rotated.

A slip-off prevention wheel 12 is provided on the torque sprocket 9. A groove 13 having a width slightly larger than the thickness of the torque sprocket 9 is engraved on the outer periphery of the slip-off prevention wheel, and the wall of the groove is set so as to sandwich the outer periphery of the torque sprocket 9.

A pair of driving sprockets 1 are provided on the exit side.
4 and 14 are installed. The pitch of the projecting teeth of the drive sprocket 14 is the same as the pitch of the projecting teeth of the torque sprocket 9 described above. A pulley 16 is mounted on a shaft 15 of the driving sprocket 14, and the pulley is linked with a pulley 18 of a motor 17 by a belt 19.
The motor 17 is interlocked with the pair of driving sprockets 14 and 14 so that the pair of driving sprockets rotate in the same direction at the same speed. Also, the slip-off prevention wheel 12 is disposed on the driving sprockets 14,14.

Next, the formation of solder bumps on a tape-shaped electronic component in the reflow furnace of the present invention having the above structure will be described.

First, the heaters 5 in the tunnel 1 are energized to heat the inside of the tunnel 1 to a predetermined temperature. At this time, if the interior of the tunnel 1 is to be made an inert atmosphere, an inert gas such as a nitrogen gas is supplied into the tunnel to make the tunnel an inert atmosphere having a predetermined oxygen concentration.

A tape-shaped electronic component 2 is mounted on a reel (not shown).
Is wound. Feed holes 20 are formed on both sides of the tape-shaped electronic component at the same pitch as the projecting teeth of the torque sprocket 9 and the drive sprocket 14. A small solder ball is adhered to the tape-shaped electronic component 2 at the lead portion with an adhesive flux.

From a reel (not shown), a tape-shaped electronic component 2
And the feed holes 20 of the tape-shaped electronic component are engaged with the projecting teeth of the torque sprocket 9. Then, the tape-shaped electronic component 2 is sent to the drive sprocket 14 along the slit 8 of the guide 7. When the tape-like electronic component reaches the drive sprocket 14, the tape-like electronic component feed hole 2
0 is engaged with the protruding teeth of the drive sprocket 14,
The motor 17 is operated. Then drive sprocket 1
Numeral 4 pulls the tape-shaped electronic component 2 to run in the tunnel 1.

When the tape-like electronic component is pulled by the driving sprocket in this way, the tape-like electronic component travels in a tight state without slackening in the tunnel because the torque sprocket has resistance to rotation. Inside the tunnel,
The tape-shaped electronic component 2 is pre-heated and main-heated by heaters 5... Installed in the heating zone 3 to melt the minute solder balls, and cooled by cooling machines 6.
The solder is solidified by cooling in step (2) to form solder bumps.

[0024]

As described above, in the reflow furnace of the present invention, when the tape-shaped electronic component is run in the reflow furnace, the tape-shaped electronic component can be run while always being pulled with a constant force. This not only prevents the tape-shaped electronic component from being loosened in the tunnel and being caught or cut off in the middle, but also has an excellent effect that the entire tape-shaped electronic component can be uniformly heated, which is not available in the conventional reflow furnace.

[Brief description of the drawings]

FIG. 1 is a central sectional view of a reflow furnace of the present invention.

FIG. 2 is a front view of a torque sprocket installed on an entrance side of a reflow furnace.

FIG. 3 is a front view of a driving sprocket installed on an exit side of a reflow furnace.

FIG. 4 is a view for explaining the relationship between a sprocket and a slip-off prevention wheel.

FIG. 5 is a sectional view of a guide.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tunnel 2 Tape-shaped electronic component 3 Heating zone 4 Cooling zone 5 Heater 6 Cooler 9 Torque sprocket 11 Torque control device 12 Prevention wheel 14 Drive sprocket 17 Motor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/34 B23K 1/008

Claims (2)

(57) [Claims] In a reflow furnace in which a heating zone and a cooling zone are sequentially formed from an entrance side to an exit side in a tunnel, the entrance side is always linked with a torque control device and is connected to a torque control device.
When the sprocket is in a braking state, a sprocket that is linked to a drive device is installed on the exit side , and the entry-side sprocket is
Between the sprocket and the exit sprocket.
A slit guide that can support the
Reflow furnace, characterized in that is. 2. The width of the sprocket on the entry side sprocket and the exit side sprocket is smaller than the thickness of these sprockets.
The slip-prevention wheel with a wide groove makes it easy to
2. The reflow furnace according to claim 1, wherein the reflow furnace is installed so as to sandwich the outer periphery of the ket .