JPS6195797A - Flux for soldering - Google Patents

Abstract

PURPOSE:To obtain the flux suitable for the robotization by preparing the flux to be used for the robotization of the soldering of various sorts of components for wiring substrate from the prescribed percentage of a rosin, solid oil and fat, and alcohol having specified boiling point. CONSTITUTION:The flux for soldering is composed of, by weight, 50-95% rosin, 3-30% solid oil and fat and 10-30% alcohol having the boiling point <=100 deg.C. This flux has an adequate adhesion, viscosity and fluidity and can well perform the adhesion and further the build-up of adequate quantity of the flux 4 by a dispenser 5 onto the wiring pattern 2 above the substrate 1 of a printing board 3, for instance, in the robotization of a soldering stage. The tacking is also performed well by burying into the flux 4 the terminal load 7 of the soldering part of the component 6. Said compound flux has sufficient function as a soldering flux in soldering and various sorts of property deteriorations of a soldering property deterioration due to the residual flux after soldering, change in the lapse of time, etc. can be avoided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is particularly applicable to robotized soldering of various parts to a printed circuit board, that is, a wiring board on which a wiring pattern made of metal foil or the like is formed. The preferred soldering method used involves soldering flux.

[Conventional technology]

Conventionally, soldering fluxes include liquid flux and paste flux.

On the other hand, there is an increasing demand for robotization in order to efficiently mass-produce the soldering of components to the wiring patterns of printed circuit boards, for example. In this type of soldering robot, it is possible to first set and hold each component on a predetermined part of the wiring pattern to be connected, that is, temporarily fix it, and solder it in this state before soldering. Although this is desirable, using a jig to temporarily hold the parts together has drawbacks such as hindering robotization and complicating the work. In addition, it is possible to temporarily fix these components to the wiring pattern without using a jig, for example, by using an adhesive, but in this case, soldering may be inhibited, or soldering may affect the characteristics of the circuit later. leaving problems such as deterioration. Therefore, if parts can be temporarily fixed using fluffs in this type of robotized soldering, the trouble of obstructing soldering or eliminating soldering later can be omitted.

An example of a work procedure when a robot is used to solder components to a printed circuit board will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, a wiring pattern (2) is formed on a substrate (1) by selectively etching copper foil, for example.
As shown in FIG. 2, flux (4) is selectively applied to predetermined portions of the wiring pattern (2) on the printed circuit board (3) provided with the wiring pattern (2). In this case, although not shown, the parts i of the wiring pattern (2) other than the parts to be soldered are coated with, for example, a solder resist, but the application of the flux (4) is done by a robot. dispenser (5). Next, as shown in Fig. 3, the component (6) to be soldered to the wiring pattern (2) is soldered to the part (6), for example, the terminal lead (7) is buried in the flux (4). Temporarily fasten by placing it in place. The placement of these parts is also done automatically by the robot. Next, as shown in FIG. 4, solder (8) is fused using a robot soldering iron (9) to solder a predetermined portion of the wiring pattern (2) of the component (6). Soldering in this case is carried out well due to the presence of flux (4). In this way, as shown in FIG. 5, the component (6) is soldered to a predetermined portion of the wiring pattern (2) with the solder (8).

In this way, soldering can be performed rationally by using flux in robotized processes, but in this case, flux (4) is
As explained in FIG. 2, this requires adhesiveness and fluidity so that it can be deposited in a suitable amount onto the wiring pattern (2) by a dispenser. In other words, it is required to have fluidity that allows it to be pushed out by the dispenser (5), so that it does not drip accidentally from the dispenser, and it is also possible to heap up a predetermined amount of this flux onto the wiring pattern (2). Adhesiveness and fluidity are required to prevent careless casting. In addition, this flux (4) is used to hold the component (6) as explained in FIG.
6) Terminal leads, that is, are required to have good compatibility with metal and adhesion thereto.

However, with conventional liquid flux, as explained in Fig. 2, it is not possible to properly adhere it to the wiring pattern (2), and it is difficult to apply it dripping from a dispenser or from a predetermined part of the wiring pattern (2). Casting is a problem. Furthermore, paste flux cannot be applied by extrusion using a dispenser.

[Problem that the invention seeks to solve]

As described above, conventional soldering has a problem in that, depending on the flux used, it is difficult to realize robotic soldering of components to printed circuit boards, for example.

The present invention provides a soldering flux that is compatible with the robotization or automation of soldering described above and can solve the above-mentioned problems.

[Means for solving problems]

In the present invention, the soldering flux comprises 50 to 95% by weight of rosin, 3 to 30% by weight of solid oil, and 10 to 30% by weight of alcohol having a boiling point of 100 DEG C. or lower.

[Effect]

According to the flux used for φ soldering according to the present invention described above,
It has become possible to robotize soldering as explained in FIGS. 1 to 5-. In other words, the soldering flux according to the present invention described above can be extruded using a dispenser, and there is no inconvenience of a dripping ring, and it is also possible to apply the soldering flux to metals such as the wiring pattern (2) and the terminal lead (7). It has a viscosity that allows a suitable amount of adhesion to be obtained, and it is possible to adhere an appropriate amount to the wiring pattern (2), as well as to retain the function of temporarily fixing the component (6), and on top of that, when soldering. It has sufficient functionality as solder flux,
In addition, it was possible to avoid deterioration of soldering characteristics, aging change, and other deterioration of various characteristics due to residual soldering flux after soldering.

The composition of soldering flux was created and used. The flux for soldering with this composition had appropriate adhesiveness and fluidity. In other words, when going through the steps explained in FIGS. 1 to 5, the terminal lead (6) to be soldered is
7) It is desired that the amount of silanox deposited is 0.5 g or more per wire, and the coating thickness of the flux (gradient) to the wiring pattern (2) is desired to be 200 μm, and the extrusion pressure of the dispenser (5) is 2kg
/- or less is desired, but this soldering was able to satisfy these requirements in terms of the composition of the flux used.

In addition, in the flux according to the present invention, the rosin is
The amount of rosin selected from 0 to 95% by weight is 50% by weight.
This is because we recognized that if the amount is less than 200 μm, it will be difficult to maintain the coating thickness of 200 μm or more, and if it exceeds 95% by weight, high pressure will be required for dispensing, making it difficult to achieve good dispensing. . Furthermore, the reason for selecting 3 to 30% by weight of hydrogenated castor oil is that if it is less than 3% by weight, it will be difficult to obtain a thick coating film of 200 μm or more, and if it exceeds 30% by weight, the tackiness will be too high. In addition, the pressure required for dispensing increases, which may make it difficult to perform the dispensing properly.

The reason for selecting 10 to 30% by weight of Yota alcohol is as follows.
This is because, as mentioned above, appropriate viscosity, adhesion, and fluidity were observed within this range. Note that this alcohol is not limited to the above-mentioned isopropyl alcohol, but may be a low-boiling alcohol that has a boiling point of 100°C or lower, and can completely scatter and burn off at a temperature of, for example, 350°C without leaving any residue. Use. This is because it has been recognized that when a high boiling point alcohol is used, it causes poor insulation resistance, and it has been found that the boiling point is preferably 100° C. or lower. Incidentally, high molecular alcohol and glycerin are used in ordinary fluxes.

Further, hydrogenated castor oil is a so-called solid fat, and as this solid fat, wax, hydrogenated oil, saturated fatty acid, carnauba wax, hydrogenated beef tallow fatty acid, lauric acid, stearic acid, etc. can be used.

As mentioned above, the flux according to the present invention contains 50 to 95% by weight of rosin, 3 to 30% by weight of solid oil, and 10 to 30% by weight of alcohol with a boiling point of 100°C or less.
The basic composition is as follows, but in order to improve the soldering properties, organic amine halide salts, such as cyclohexylamine hydrochloride, are added, and in order to further improve the properties of the dispenser. It is also possible to add surfactants, such as calcium stearate, and small amounts of organic solvents other than alcohol, such as petroleum ether, to promote the dissolution of solid fats and oils.

〔Effect of the invention〕

As mentioned above, the soldering according to the present invention can obtain appropriate adhesion, viscosity, and fluidity by using the flux, and the soldering described in Figs. 1 to 5 can be performed by robots. Therefore, it can be applied to, for example, the assembly of electrical and electronic circuits using printed circuit boards, and has great industrial advantages.

[Brief explanation of drawings]

1 to 5 are process diagrams of an example of soldering work for explaining the present invention. (1)... Board, (2)... Wiring pattern, (
3)...Printed circuit board, (4)...Flux according to the present invention, (5)...Dispenser, (6)
... Parts, (7) Its terminal leads, (8) ...
Solder, (9)...Soldering iron.

Claims (1)

[Claims] Rosin: 50-95% by weight, solid fat: 3-30% by weight
, a soldering flux consisting of 10 to 30% by weight of alcohol with a boiling point of 100°C or less.