JPH07122595A - Method and equipment for removing flux residue - Google Patents

Abstract

PURPOSE:To provide a method and an equipment for removing flux residue capable of continuously removing flux residue easily in a short time without using an organic solvent, etc., resulting in environmental destruction. CONSTITUTION:In the soldering of a chip 3, in which solder bumps 4 mounted on the chip 3 are coated with flux 5, the chip 3 is positioned onto a ceramic board 1 by the adhesion of the flux 5 and the flux 5 is reflowed, plasma is sprayed against soldered sections, an organic component in redisual flux 5A is oxidative-destructed and gasified, the organic component is removed, an inert gas is sprayed against an inorganic matter 5a remaining as residue, and the inorganic matter 5a is blown off and taken off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux residue in soldering in which flux is applied to preliminary solder provided on a chip or a board conductor, and the adhesive force of this flux positions the chip on the board conductor for reflow. The present invention relates to a method and an apparatus for removing the slag.

[0002]

2. Description of the Related Art For example, flip-chip soldering is known as soldering for semiconductor elements. This soldering method consists of 1) plating the board conductor with preliminary solder,
The chip is positioned and reflowed by the adhesive force of the flux applied to the bump side of the flip chip, or 2) solder bumps are provided on the flip chip, flux is applied to this, and the chip is bonded to the board conductor by the adhesive force of this flux. It is designed to be positioned on the surface of the electrode on the side for reflow. In such soldering, flux remains after the soldering, and corrosion becomes a problem. In other words, the work of removing the residue from the flux is important as the final step of soldering, and the corrosive residual flux not only corrodes the parts, but also causes electrical leaks, short circuits, migration, etc. It must be removed.

Therefore, the flux residue after soldering is removed by using various techniques, and as a general method, a method of cleaning using an organic solvent such as CFC is used.

[0004]

However, the above-mentioned method of cleaning using an organic solvent such as CFC requires a complicated cleaning step, particularly cleaning with a liquid which is inconvenient to handle. For this reason, there arises a problem that the cleaning facility becomes large in size and the cost becomes high, and when an environmentally destructive substance such as CFC is used, an environmental problem such as destruction of the ozone layer occurs.

The present invention has been made in view of the above problems, and an object thereof is to easily remove a flux residue continuously in a short time without using an organic solvent or the like which causes environmental damage. It is intended to provide a flux residue removing method and an apparatus therefor.

[0006]

According to the present invention, a flux is applied to a preliminary solder provided on a chip or a board conductor, and the chip is placed on the board conductor by the adhesive force of the flux. In the soldering of the chip to be positioned and reflowed, the plasma is sprayed on the soldered part to oxidize and decompose the organic component of the residual flux to gasify it, and after removing the organic component, the residual inorganic substance is left with a gas. This is achieved by spraying and flying to remove the residual flux. In addition,
A flip chip may be used as the chip,
It is preferable to use an inert gas as the gas.

Further, in this invention, a flux is applied to a preliminary solder provided on a chip or a board conductor, and the chip is positioned on the board conductor by the adhesive force of the flux. In a reflow soldering flux residue removal apparatus, plasma generation means for generating plasma and blowing the plasma to the soldered portion to oxidize and decompose the organic components of the residue flux to gasify, and the organic It is achieved by providing a gas generating means for blowing a gas to the inorganic material remaining as a residue after removing the components. A flip chip may be used as the chip.

[0008]

According to this, plasma is sprayed on the soldered portion to oxidize and decompose the organic component of the residual flux to gasify it, and after removing this organic component, the residual inorganic substance is sprayed with gas. The residual flux can be easily removed simply by skipping. Moreover, the plasma and gas can enter the narrow gap between the substrate conductor and the chip, so that they can be cleaned and removed in a short time. In addition, since cleaning is not performed using organic solvents or liquids such as CFCs, the cleaning process equipment is simple and easy to handle,
It is possible to solve the cost problem, the work environment and the global-scale environmental problem, which have been problems in the conventional method.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a soldering process diagram for explaining an embodiment of the present invention.

In FIG. 1, this soldering process is flip-chip soldering, and processes from soldering to flux residue removal are performed in the order of processes A to F. Hereinafter, this process will be described in the order of steps A to F.

In step A (flux application), the ceramic substrate 1 provided with lands (conductors) 2 formed in advance on the mounting surface, and the land 2 of the ceramic substrate 1 which itself serves as a terminal and a solder. A bare chip 3 is prepared in which the flux 5 is applied to the solder bumps 4 to be soldered to the substrate with a thickness of about 0.1 to 0.5 mm.

In step B (flip chip mount),
The bare chip 3 is placed on the ceramic substrate 1 prepared in the step A, and the solder bumps 4 are placed on the lands 2 in a corresponding manner.
Then, the land 2 and the solder bump 4 are positioned and temporarily fixed by the adhesive force of the flux 5.

In step C (soldering), reflow is performed. As a result, a part of the solder bump 4 is melted, the bare chip 3 is soldered on the ceramic substrate 1 by the solder bump 4, and the work 7 in which the ceramic substrate 1 and the bare chip 3 are fixed is formed.

In step D (plasma cleaning), plasma 8 is sprayed onto the portion of the work 7 soldered in step C to oxidize and decompose the organic components of the residual flux 5A,
For example, CO ₂ , H ₂ O, etc. are gasified and removed.

In step E (spraying with an inert gas), the inorganic substance 5 left as a residue after removing the organic components in step D
An inert gas 9 is blown to a, and the inorganic substance 5a is blown off and removed. The gas blown here may not necessarily be an inert gas, but may be air or the like.

In step F (completion), the work 7 is cleaned and finished to have no residual flux 5A, 5a, etc., which is inspected and if there is no problem, it is conveyed to the next step.

Therefore, when the soldering process is performed in this manner, plasma 8 is sprayed on the soldered portion to oxidize and decompose the organic component of the residual flux 5A to gasify it, and then the organic component is removed. The residual flux 5A, 5a can be easily formed by spraying a gas such as an inert gas 9 on the inorganic material 5a remaining as a residue after it is blown.
Can be removed. Moreover, since the plasma 9 and the gas (inert gas 9 or the like) can enter the narrow gap between the ceramic substrate (substrate conductor) 1 and the bare chip 3, it can be cleaned and removed in a short time. In addition, since cleaning is not performed using an organic solvent such as CFCs or a liquid, the equipment for the cleaning process can be simplified.

FIG. 2 is a schematic diagram schematically showing a process apparatus for realizing the flux residue removal processing step shown in FIG. In FIG. 2, the same reference numerals as those in FIG. 1 denote the same parts as those in FIG.

The process apparatus 10 is mainly composed of a soldering section 11 and a cleaning section 12.

Of these, the soldering section 11 is provided with an apparatus for performing the steps A to C shown in FIG.

On the other hand, the cleaning unit 12 has a plasma generator 13 for performing the process D (plasma cleaning) shown in FIG. 1 and a non-operating device for performing the process E (inert gas spraying). An active gas generator 14 is provided.

Then, in this process device 10, the soldering process is completed at the soldering portion 11, and the residual flux 5
When the work 7 that has not been subjected to the cleaning treatment of A is sent in, ozone O ₃ ²⁺ is generated from the plasma generator 13 to form plasma 8, and this plasma 8 is sprayed onto the soldered portion of the work 7. Then, the process of step D (plasma cleaning) shown in FIG. 1 is performed, in which the organic component of the residual flux 5A is oxidatively decomposed to be gasified and removed.

When the plasma cleaning is completed, the inert gas 9 is then generated from the inert gas generator 14.
The inert gas 9 is sprayed onto the inorganic material 5a remaining in the soldered portion of the work 7, and the inorganic material 5a is blown away and removed. As a result, the cleaning process of the soldered work 7 is completed, and the work 7 is conveyed to the next step from the process device 10 by means not shown.

In the above-mentioned embodiment, the case of application to flip-chip soldering has been described, but the present invention is not limited to this and can be similarly applied to removal of residual flux in other soldering. . Although the case where the solder bumps 4 are used has been described, the preliminary solder may be provided on the ceramic substrate 1 by plating or the like.

[0025]

As described above, according to the present invention,
After spraying plasma to the soldered part to oxidize and decompose the organic component of the residual flux to gasify it, simply remove the organic component and then blow the gas to the residual inorganic substance to blow away the residual flux. Can be removed. Moreover, the plasma and gas can enter the narrow gap between the substrate conductor and the chip, so that they can be cleaned and removed in a short time. In addition, since cleaning is not performed using organic solvents or liquids such as CFCs, the equipment for the cleaning process is simple, and the handling is also easy, resulting in cost problems and work that have been problems with conventional methods. Effects such as the ability to solve environmental and global environmental problems can be expected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of processing steps shown as an example of the present invention.

FIG. 2 is a schematic view of a process device shown as an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Land 3 Bare chip 4 Solder bump (preliminary solder) 5 Flux 5A Residual flux 5a Inorganic substance 10 Process equipment 11 Soldering part 12 Cleaning part 13 Plasma generator 14 Inert gas generator

Claims (5)

[Claims] 1. Soldering in soldering a chip in which flux is applied to preliminary solder provided on a chip or a board conductor, and the chip is positioned on the board conductor by the adhesive force of the flux and reflowed. The organic component of the residual flux is oxidatively decomposed and gasified by spraying a plasma to the exposed portion, and after removing the organic component, the residual inorganic flux is blown by blowing gas to remove the residual flux. Characteristic flux residue removal method. 2. The flux residue removing method according to claim 1, wherein a flip chip is used as the chip. 3. The method for removing flux residue according to claim 1, wherein an inert gas is used as the gas. 4. A flux residue removing apparatus for soldering, wherein flux is applied to preliminary solder provided on a chip or a board conductor, and the chip is positioned on the board conductor by the adhesive force of the flux and reflowed. Plasma generating means for spraying the plasma to the soldered portion to oxidize and decompose the organic component of the residual flux to gasify it, and to remove the organic component and to leave the residual inorganic substance as a residue. A flux residue removing device comprising: a gas generating unit that blows and blows gas. 5. The flux residue removing apparatus according to claim 4, wherein a flip chip is used as the chip.