Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1998-04-02
2001-01-30
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of metal
C148S283000, C204S192150, C228S206000, C228S220000, C427S255390, C427S372200, C428S614000, C428S628000, C428S696000
Reexamination Certificate
active
06180253
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brazing or soldering material and a production method thereof More particularly the present invention relates to a brazing or soldering material suitable for use in bonding a lead frame or the like, and a production method thereof
2. Description of the Related Art
A brazing material is used for bonding base materials by heat-melting a metal or an alloy having a melting point lower than that of the base materials to fill the gap between the base materials with the brazing material. Particularly, the brazing material permits bonding of complicated fine parts and bonding of different metals, has little influence on base materials, and is thus widely used for electronic apparatus. Of such brazing or soldering materials, solder frequently contains tin and lead as main components, and is frequently used for bonding a lead frame of an electronic apparatus which is required to have electrical conductivity. For solder, generally, consideration is mainly given to electrical conductivity rather than strength, and particularly solder is required to have high solderability for base materials.
In soldering, solderability is significantly affected by an oxide film on the surface of a base material. Japanese Patent Unexamined Publication No. 5-304235 discloses that solderability deteriorates due to an NiO
2
film on the surface of a nickel-plated lead frame, Japanese Patent Unexamined Publication No. 7-164136 discloses deterioration in solderability due to an oxide film during brazing of aluminum, and Japanese Patent Application No. 2527278 discloses that solderability deteriorates due to tin oxide on the surface of a material to be soldered. In these publications, as improving means, the bonded surfaces of base materials, i.e., materials to be bonded, are modified.
However, surface treatment of the base materials is performed for a lead frame or the like which has already been incorporated into a circuit board, and thus circuits and a package thereof must be subjected to modification treatment. There is thus the drawback that in treatment under the condition of high temperature, for example, in plasma processing or the like, various equipment loads such as a measure for preventing damage to a circuit element, etc. are significantly increased.
In addition, although a flux is used for removing an oxide film from a base material, even when a non-corrosion type flux is used for bonding a lead of an electronic apparatus, a problem occurs in which peripheral device materials area are contaminated by coating the flux.
Further, since a flux must be coated before the soldering step, the process is limited.
Although, in some examples, a hydrogen-containing flux is used for soldering, it is necessary to wash out the residual flux after soldering. In some cases, the residual flux is not washed out after soldering. However, in such cases, a flux containing a small amount of halogen is used to sacrifice the solderability, or a flux containing a large amount of halogen is used for maintaining solderability, thereby causing the probability of generating migration due to the halogen component in the residual flux.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome the aforementioned problems.
Another object of the present invention is to provide a brazing or soldering material in which the solderability thereof can effectively be improved without using a flux, and a production method thereof.
SUMMARY OF THE INVENTION
In order to achieve the objects of the present invention, rather than modifying of the surfaces of base materials, the function to improve solderability for base materials may be imparted to a brazing or solder material as a bonding main material.
Namely, a brazing or soldering material of the present invention is formed by dispersing 10 ppm to 10% of halogen compound, by weight, in a raw material comprising a brazing or soldering material for bonding base materials. The surface of a brazing or soldering material for bonding base materials may be coated with a halogen compound or halogenated to form a halogen compound-substituted layer as a surface layer. In such cases, the halogen compound is preferably a fluorine or chlorine compound.
Another method of producing a brazing or soldering material of the present invention comprises dissolving a halogen compound and coating the resultant solution on the surface of a brazing or soldering material body as a semi-processed product for bonding base materials, and then naturally drying to form a film of the halogen compound, or placing a brazing or soldering material body as a semi-processed product for bonding base materials in a sputtering or vaporization apparatus, and then forming a sputtered or deposited film of a halogen compound on the surface of the brazing or soldering material body while introducing a halogen-containing gas into the apparatus.
Further, a brazing or soldering material of the present invention may be produced by immersing a brazing or soldering material body as a semi-processed product for bonding base materials in a halogen-containing solution, and naturally drying to halogenate the surface layer of the brazing or soldering material body, or placing a brazing or soldering material body as a semi-processed product for bonding base materials in a closed vessel containing heating means, and halogenating the surface layer of the brazing or soldering material body by the heating means under a temperature condition ranging from the gas decomposition temperature to the melting temperature of the brazing or soldering material while introducing a halogen-containing gas into the vessel.
In the above production methods, the halogen is preferably fluorine or chlorine.
The brazing or soldering material to which a halogen compound is added and dispersed is produced, the surface of the thread- or rod-shaped brazing or soldering material is coated with a halogen compound, or the surface layer of the brazing or soldering material is directly halogenated. In brazing or soldering using the brazing or soldering material under heating, oxygen of the oxide films formed on the surfaces of members to be bonded is replaced by halogen. For example, tin oxide (SnO) formed on the surface layer of a lead frame plated with solder is replaced by a halogen compound (SnFx). This improves solderability of the brazing or soldering material. Such a halogen compound prevents re-oxidation of the brazing or soldering material itself, and thus permits long-term storage of the brazing or soldering material.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4139660 (1979-02-01), Tur
patent: 4921157 (1990-05-01), Dishon et al.
patent: 5615825 (1997-04-01), Bobbio et al.
patent: 5-304235 (1993-11-01), None
patent: 7-164136 (1995-06-01), None
patent: 2527278 (1996-06-01), None
Miyakawa Takuya
Mori Yoshiaki
Takahashi Katsuhiro
Jones Deborah
Koehler Robert R.
Seiko Epson Corporation
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