Metal fusion bonding – Process – With pretreating other than heating or cooling of work part...
Reexamination Certificate
2002-03-04
2004-07-06
Stoner, Kiley (Department: 1725)
Metal fusion bonding
Process
With pretreating other than heating or cooling of work part...
C228S223000
Reexamination Certificate
active
06758389
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a composition to be used for pretreatment for soldering an electronic part having electric contact points or a printed board having electric contact points, which prevents creeping of a flux for soldering. Further, the present invention relates to a method for soldering by means of such a composition, an electronic part or printed board obtained by such a method, and further an electric appliance.
BACKGROUND ART
When various parts are soldered to a printed board, or IC is soldered to an IC socket, it is common to preliminarily treat the printed board with a flux in order to improve the adhesion of the solder. Usually, a flux contains an acidic component and thus is corrosive. Accordingly, it is necessary to prevent adhesion or penetration of a flux at an electric contact portion of an electronic part such as a connector, a switch, a volume or a pre-set resistor or at a portion where no soldering is required in a printed board. Especially in a case of an electronic part, soldering is frequently carried out at a through-hole portion. A phenomenon such that a flux creeps such a through-hole portion by e.g. a capillary phenomenon and penetrates or deposits at an unnecessary portion of the electronic part, is called “creeping of a flux”, and it is necessary to prevent such a phenomenon.
For the purpose of preventing penetration or deposition of the flux mentioned above, an agent for preventing creeping of a flux is used. As agents for preventing creeping of a flux for soldering, the following examples are known.
(1) A composition containing a compound having a polyfluoroalkyl group or a polymer thereof, and an organic solvent (JP-A-60-49859). Such a organic solvent may be a hydrocarbon type solvent such as heptane, an ester type solvent such as ethyl acetate, a chlorofluorocarbon (CFC) such as 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113), or a perfluorocarbon (PFC) having a boiling point of from 60 to 120° C., or a fluorine-containing aromatic hydrocarbon type solvent such as 1,3-bis(trifluoromethyl)benzene.
(2) A composition having a low molecular compound containing polyfluoroalkyl groups or a polymer containing polyfluoroalkyl groups, dissolved in an alcohol solvent such as ethanol.
(3) A composition having a fluorine polymer obtained by polymerizing tetrafluoroethylene, a perfluoro(alkylvinyl ether) or vinylidene fluoride, a surfactant and an extender, dispersed in water (JP-A-5-175642).
(4) A composition containing a polymer of an unsaturated ester having a polyfluoro group, a fluorine-containing type surfactant and aqueous medium (JP-A-11-154783).
However, conventional agents for preventing creeping of a flux for soldering, have the following problems.
The composition (1) requires a due care, since the organic solvent is inflammable, and further, it has a problem from the viewpoint of the working environment, since it contains a volatile solvent. Further, when the solvent is a hydrocarbon type solvent, there will be problem that the solubility of the fluorine-containing component in the composition is poor. Further, with respect to CFC among the solvents, its influence over the ozone layer is feared, and its use is restricted by regulations relating to fluorocarbons. HCFC-225 or HCFC-141b, as a substitute for CFC, has similar problems. Further, PFC, a fluorine-containing type solvent, has a high coefficient for warming up the earth, and its influence over the environment is feared. The fluorine-containing aromatic hydrocarbon type solvent is inflammable and has a problem of odor.
The composition (2) is required to have the fluorine content of the low molecular weight compound or the polymer containing polyfluoro alkyl groups lowered in order to increase the solubility of such a compound or a polymer in the alcohol solvent. Further, the effect for preventing creeping of a flux is inadequate.
The fluorine polymer in the composition (3) is non-adhesive and poor in wettability and adhesion to the surface of an electronic part as a substrate. Accordingly, it is practically required to add a spreader. Further, this fluorine polymer has a softening point higher than 150° C., and heat treatment at a high temperature of at least the above softening point is required in order to form a film by drying the fluorine polymer particles deposited on a substrate by means of a spreader. The temperature for this heat treatment will be often higher than the heat resistant temperatures of the plastic portions incorporated into electronic parts, and practically, there is a problem that such heat treatment can not be done. On the other hand, if no heat treatment is applied, white fluorine polymer particles are likely to deposit as white solid on electronic parts, and there will be a drawback that the gloss of the treated surface for creeping of a flux is impaired.
In the composition (4), the polymer containing polyfluoro groups is still insufficient in its adhesion, although it is improved as compared with the fluorine polymer particles in the composition (3). Thus the satisfactory adhesion to the surface of an electronic part is not obtained. Further, the hardness of surface of the film obtained from the composition is also insufficient so that the surface tends to be scratched during the working operation, and there will be problem that a flux will be deposited on the scratched parts of the surface.
DISCLOSURE OF THE INVENTION
The present invention has been made to solve the above problems and provides a composition for preventing creeping of a flux for soldering, which comprises a polymer (A) containing the following polymer units (a
1
), and the following polymer units (b
1
), and an aqueous medium (B).
Polymer units (a
1
): Polymer units derived from an unsaturated ester containing a polyfluoroalkyl group, or polymer units derived from an unsaturated ester containing a polyfluoroalkyl group having an etheric oxygen atom inserted in the carbon-carbon bond.
Polymer units (b
1
): Polymer units derived from a compound containing a silicon atom and an unsaturated group.
The preferred embodiment in the present invention, the polymer unit (a
1
) is a polymer unit of the compound having the following formula (1).
In the formula (1), Q
1
, R
1
and R
f
are defined as follows:
Q
1
: a single bond or a bivalent connecting group.
R
1
: a hydrogen atom or a methyl group.
R
f
: a polyfluoroalkyl group or a polyfluoroalkyl group having an etheric oxygen atom inserted in the carbon-carbon bond.
The preferred embodiment in the present invention, the polymer unit (b
1
) is a polymer unit of the compound having the following formula (2).
In the formula (2), R
2
, R
3
, R
4
, and R
5
are defined as follows:
R
2
: a hydrogen atom or a methyl group.
R
3
, R
4
and R
5
: independently from one another an alkyl group having a carbon number of from 1 to 5, or an alkoxy group having a carbon number of from 1 to 5.
The preferred embodiment in the present invention, the composition is one containing a fluorine type surfactant (C).
The preferred embodiment in the present invention, the softening point of the polymer (A) is at least 40° C. and less than 150° C.
The preferred embodiment in the present invention, the aqueous medium (B) is a water soluble organic solvent having a boiling point of from 40 to 200° C.
The preferred embodiment in the present invention, the surface tension is from 10 to 25 mN/m.
The present invention also provides a method for soldering an electronic part or printed board, which comprises forming a coating film of any one of compositions mentioned above on a part of or the while surface of an electronic part or a printed board, then treating the surface having the coating film thus formed, with a flux for soldering, and then carrying out soldering.
Further, the present invention provides an electronic part or printed board having a property of preventing creeping of a flux for soldering, obtained by forming a coating film of any one of compositions mentioned above on the surface thereof.
Further, the present invention provides an electric ap
Fukatsu Yutaka
Odaka Syunji
Seimi Chemical Co. Ltd.
Stoner Kiley
LandOfFree
Composition for preventing creeping of a flux for soldering... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition for preventing creeping of a flux for soldering..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition for preventing creeping of a flux for soldering... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3193343