Metal fusion bonding – With control means responsive to sensed condition
Reexamination Certificate
1999-10-19
2001-08-14
Dunn, Tom (Department: 1725)
Metal fusion bonding
With control means responsive to sensed condition
C228S033000, C228S037000
Reexamination Certificate
active
06273317
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application relates to and claims priority of Japanese Patent Applications No. 10-309115 filed on Oct. 29, 1998, No. 10-326606 filed on Nov. 17, 1998, and No. 10-326607 filed on Nov. 17, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow soldering apparatus, and more particularly to a flow soldering apparatus by which a substrate mounted with electronic circuit parts is contacted to a solder flow to solder the electronic circuit parts to the substrate.
2. Related Art
A flow soldering apparatus is used to solder electronic circuit parts to a circuit substrate such as a printed circuit board on which the electronic circuit parts are mounted. This flow soldering apparatus grips both side ends of the substrate firmly, transfers the same to a flow solder barrel and contacts the same to the solder flow for soldering by a robot arm as disclosed in JP-A-7-288380.
The substrate undergoes thermal expansion when it is contacted with the molten solder in the solder barrel. The substrate bows, because it is clamped at its both side ends. Thus, the quality of the soldering of the circuit parts on the substrate is lessened, and the resulting substrate will have a deformation.
Further, the molten solder in the solder barrel is oxidized when exposed in the air. Thus, an oxide film (oxides) is formed on the surface of the molten solder. When the substrate is transferred over the solder barrel in contact with the molten solder, the oxide film contacts the substrate and lessens the quality of the soldering. JP-U-58-119962 discloses a substrate holder unit having three peripheral walls. The walls hold the substrate and removes the oxide film. However, the walls tend to cause a space between the substrate and the molten solder right behind the front wall, because the substrate is held above the bottom end of the walls. As a result, unsoldered parts are likely to occur on the substrate, thus lessening the quality of the soldering.
The above JP-A-7-288380 proposes to rotate the substrate so that the soldering is effected from different directions. In this soldering operation, it is likely to occur that the molten solder jumps onto the upper surface of the substrate which should not be soldered.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to improve the quality of soldering. More specifically, the present invention is made to restrict a thermal deformation of a substrate. The present invention is made to remove an oxide film of molten solder without stopping a soldering operation. Further, the present invention is made to restrict jumping of molten solder onto a substrate.
According to a first aspect of the present invention, a substrate is clamped by a pair of nails of a chuck mechanism and transferred over a molten solder barrel while being held in contact with the molten solder. The nails are held resiliently to each other, so that the substrate is allowed to expand thermally between the nails without bowing.
According to a second aspect of the present invention, a chuck mechanism for clamping a substrate and transferring the substrate over a molten solder barrel. The chuck mechanism has a part which extends transversely over the entire lateral length of the substrate at the front side of the substrate in a substrate transfer direction to push away an oxide film formed on a molten solder. The chuck mechanism is constructed to allow the molten solder to enter underneath the substrate in the lateral direction with respect to the substrate transfer direction. Thus, the substrate is transferred in contact with the molten solder without contacting the oxide film. The part may be a scraper nail provided at the front side of the chuck mechanism in the substrate transferring direction.
According to a third aspect of the present invention, a chuck mechanism has a pair of nails for clamping a substrate at a set of opposing two sides of a substrate. The chuck mechanism transfers the substrate in a manner that the opposing two sides are maintained at a front side and a rear side with respect to a substrate transfer direction during a soldering operation. After completing the first soldering operation, the nails change the set of the opposing two sides to another set of two opposing sides of the substrate. The chuck mechanism subjects the substrate to the similar soldering operation while maintaining another set of two opposing sides of the substrate at the front side and the rear side with respect to the substrate transfer direction.
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Arai Kenji
Furumoto Atsushi
Ichikawa Ataru
Kubo Tatuya
Sugiura Mitsuhiro
Denso Corporation
Dunn Tom
Pillsbury & Winthrop LLP
Stoner Kiley
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