JPH0216856Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus used for soldering printed circuit boards, and particularly to a reflow oven for heating and melting printed circuit boards coated with cream solder.

[Conventional technology]

Soldering of printed circuit boards coated with cream solder is carried out in a reflow oven in which a transport device runs through a tunnel with heaters installed above and below.

Conventional reflow ovens have often used an endless mesh belt as a conveyance device, but in recent years, double-sided printed circuit boards with electronic components mounted on both sides of the printed circuit board have a mesh belt that comes into contact with the electronic components. may be misaligned,
Alternatively, because the mesh belt prevents uniform heating, recently printed circuit boards have been conveyed using conveyor claws. As shown in Fig. 5, the conventional conveying claw is a cylindrical pin 4 made of a pair of endless chains 3, 3, which are arranged in two stages with a large diameter part 5 and a small diameter part 6 made of metal in opposing directions. The printed circuit board P is placed on the narrow diameter portion and transported.

[Problem that the invention attempts to solve]

The longer the narrow diameter part of the transport claw on which the printed circuit board is placed, the more stable the printed circuit board can be placed on it. Electronic parts are mounted up to the ends of the belt, and in this case, the narrow diameter part may come into contact with the electronic parts, causing the problem like a mesh belt.
Electronic components will be moved during transportation.
In addition, if the transport claws are too close to the soldering part of the electronic component, even if they do not come into contact with the electronic component, the heat of this part will be absorbed by the transport claw, causing the temperature to drop and causing soldering defects. It will also happen.
This phenomenon is particularly noticeable when the conveying claws are made of metal.

Therefore, it is preferable for the transport claws in a reflow oven to be as short as possible in terms of contact with electronic components and thermal effects, but if they are too short, vibrations during transport and misalignment during placement may occur. This will cause the printed circuit board to fall. Therefore, it is preferable that the transport claws can be appropriately selected according to the printed circuit board, but since the transport claws in conventional reflow ovens are fixed to an endless chain, it takes a lot of effort to replace them.

Furthermore, conventional conveying claws have had problems with the stability of printed circuit boards. Conventional conveyance claws are made by cutting out a metal rod to form a small diameter portion, so in terms of strength, there is not much difference in level between the large diameter portion and the small diameter portion. During transportation, the step part that is a step prevents the printed circuit board from moving. However, if the difference in the step of the transport claw is small, the printed circuit board placed on the narrow diameter part will easily move to one of the endless chains due to vibrations during transport. It moves to the large diameter part of the installed conveyance claw, and falls off the conveyance claw installed on the other endless chain. Further, if the height difference in the conveyance claw is small, when the printed circuit board is placed on the conveyance claw, it is easy to ride on the large diameter part, which results in the printed circuit board falling.

[Means for solving problems]

In the present invention, it is possible to easily select a conveying claw that matches the electronic component mounting state of the printed circuit board, and the step height is increased to further improve the stability during conveyance and placement of the printed circuit board.

The feature of this invention is that a pair of chainless chains rotate inside a tunnel with heaters installed above and below, and the printed circuit board is placed on the conveyor claws installed on the endless chain and transported into the tunnel. transport,
In a reflow oven for soldering printed circuit boards, the transport claw has a flange installed at one end of a cylinder, and a hole is bored at the center of the cylinder at the flange side end.
The hole is attached to a cylindrical body installed in an endless chain in a reflow oven.

[Effect]

The removable transport claw can be selected as appropriate depending on the mounting state of electronic components on the printed circuit board, and the collar of the transport claw ensures stable transport of the printed circuit board.

Furthermore, if the removable conveying claws are made of heat-resistant resin such as Teflon or ceramic such as zirconia, uneven temperature distribution will be eliminated.

〔Example〕

The reflow furnace 1 is a tunnel type heating furnace,
Heaters are installed above and below the tunnel 2, and a pair of endless chains 3, 3 are rotating inside the tunnel. A large number of metal pins 4 are installed in the endless chain in opposing directions. The pin shown in FIGS. 2 and 4 has a small diameter portion 6 at the tip of a large diameter portion 5.
was formed. In the reflow oven of the present invention, a transfer claw is inserted into the pin, and the transfer claw 7 used in the present invention has a flange 9 formed at one end of the cylinder 8, and the flange 9 of the cylinder 8 is formed on the flange side. A hole 10 substantially the same as the cylinder 8 is bored at the center position. Second,
The conveyance claw of the embodiment shown in FIG. 4 is attached by fitting the hole 10 with the narrow diameter portion 6 of the pin 4. At this time, if the fitting is already strong, it may be left as is, but in order to make this attachment even stronger, apply a small amount of thermosetting adhesive to the hole beforehand before fitting. In the embodiments shown in FIGS. 2 and 4, a conventional pin-shaped conveying pawl as shown in FIG. 5 may be used and the conveying pawl 7 may be fitted therein.

FIG. 3 shows another embodiment in which the pin 4 has a narrow diameter portion 6 at the tip of the large diameter portion 4 having a male thread 11, and a hole 10 in the conveying claw 7 having a female thread 12. These can be attached simply by screwing together the male screw 11 and the female screw 12, making it even easier to replace the conveyor claws.

In the present invention, as shown in FIG. 4, a printed circuit board P is placed on a cylindrical column 8 and transported.

[Effect of idea]

The reflow oven of the present invention has removable transport claws, and the transport claws can be selected appropriately according to the printed circuit board.This not only prevents contact problems with mounted electronic components and thermal effects on soldered parts, but also allows the printed circuit board to be easily removed. Since the stepped portion that suppresses the movement of the board is a large flange, the printed board does not fall due to vibration during transport or misalignment when placed, which is an excellent effect never seen before.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the reflow oven of the present invention, Figure 2 is an enlarged perspective view of the main parts explaining the installation of the conveyor claw, and Figure 3
The figure is an enlarged perspective view of the main part to explain the installation of the conveyance claw in another embodiment, FIG. 4 is an enlarged front view of the main part of the reflow oven of the present invention, and FIG. 5 is an enlarged front view of the main part of the conventional reflow oven. be. 1... Reflow oven, 2... Tunnel, 3... Endless chain, 4... Pin, 5... Large diameter part, 6...
Narrow diameter part, 7... Conveyance claw, 8... Cylinder, 9... Tsuba,
10...hole, 11...male screw, 12...female screw.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A pair of endless chains rotates inside a tunnel in which heaters are installed above and below, and a printed circuit board is placed on the conveyor claws installed on the endless chains and moved through the tunnel. In a reflow oven for soldering printed circuit boards, the conveying claw has a flange formed at one end of the cylinder, and a hole is bored at the center of the cylinder at the flange side end. A reflow oven characterized by being attached to a pin installed in an endless chain. (2) Reflow reflow according to claim 1 of the utility model registration claim, characterized in that attachment to the hole drilled in the collar side of the conveying claw and the pin installed in the endless chain is performed using an adhesive. Furnace. (3) The hole drilled in the flange side of the conveying claw is a female thread, and the cylindrical part installed in the endless chain is a male thread, and these are attached by screwing. A reflow oven according to claim (1) of patent registration. (4) The reflow oven according to claims (1) to (3) of the utility model registration, wherein the conveying claws are made of a non-metallic material such as heat-resistant resin or ceramic.