JP3525752B2 - Component soldering method and circuit board manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering method and a circuit board manufacturing method capable of soldering lead parts, surface mount parts and the like to an electronic circuit board without using flux.

[0002]

2. Description of the Related Art When an electronic component is soldered to an electronic circuit board, in order to prevent displacement, movement, drop, etc. due to a shock such as transportation of the electronic component in the pre-soldering process,
It is temporarily necessary to fix the electronic circuit board. Conventionally, as a fixing method used for such a purpose,
Known are (1) a method of utilizing the viscosity of flux, (2) a method of using a thermosetting resin such as an epoxy resin, and (3) a method of using an ultraviolet curable acrylic resin. As related to this type of conventional technology,
JP-A-1-150493 and the like can be mentioned.

[0003]

The above-mentioned conventional techniques have the following problems, respectively. That is, the method of utilizing the viscosity of the flux described in (1) above has the advantage of preventing oxidation during reflow because the solder material and the surface to be joined are covered with the flux, but the adhesion of flux However, there is a problem that the transfer system has a problem due to the above, and that cleaning with an organic solvent is necessary to prevent corrosion due to flux residue after soldering. Regarding the cleaning with organic solvent, it is more important because it will be difficult to use the organic solvent from the viewpoint of environmental protection in the future, and the cleaning will be difficult to ensure reliability due to the miniaturization and high density of the soldered part. May be a problem.

The methods using various resins described in the above (2) and (3) have a problem that stress is generated in the soldered portion because the adhesive remains between the electronic component and the electronic circuit board. It was In addition, when soldering a component such as a flip chip, it is necessary to apply these adhesives to the surfaces to be joined, which causes a problem such as soldering failure.

An object of the present invention is a method of soldering without using a flux, which has a sufficient fixing force (adhesive force) for parts and does not require a cleaning step after soldering. It is to provide a method for manufacturing a substrate.

[0006]

In order to achieve the above object, the soldering method of the present invention comprises an electronic component and a substrate,
A material having a boiling point lower than the melting point of the solder material is applied through the solder material, and the board and the electronic component are heated to a temperature higher than the melting point of the solder material for soldering.

The above substance is preferably a liquid at room temperature. Before reflow, it is preferable to have a viscosity that can withstand the vibration of the mounted electronic component. For example, the viscosity is preferably 10 poise or more at 20 ° C. The boiling point thereof is preferably equal to or higher than the preheating temperature, more preferably equal to or higher than 150 ° C. and equal to or lower than the melting point of the solder material. Further, it is preferable to use an amount of this substance that can cover the solder material. Thereby, the oxidation of the solder material can be prevented. Furthermore, it is preferred that the liquid is non-toxic or extremely low and non-toxic or extremely low when decomposed. Examples of such liquid include ethylene glycol and trimethylene glycol.

When an electronic component is mounted, the surface tension and viscosity of the liquid serve to keep the component from shifting, and the solder material and the surface to be joined are completely covered to protect the soldered portion, It maintains its effectiveness until the solder material melts. Furthermore, since the liquid evaporates just before melting, there is no residue after reflow.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a partial sectional view of a ceramic substrate on which an electronic component is mounted for explaining an embodiment of a method for fixing an electronic component of the present invention, and FIG. 2 is a process diagram for explaining the present invention.

In the fixing method of the present embodiment, as shown in FIG. 1, a plurality of electronic components 5 such as an LSI or the like to which a solder material 3 has been supplied in advance is placed on a ceramic substrate 1 on which a connection pattern 2 is provided. It is carried out by holding it by No. 4. As a fixing method at the time of soldering by such a method, conventionally, a method of using a flux or the like instead of the liquid 4 has been widely and generally used. This example is a method of using ethylene glycol, trimethylene glycol or the like shown in Table 1 as the liquid 4, and the method will be described below with reference to FIG.

[0011]

[Table 1]

As shown in FIG. 2 (a), a pre-controlled amount of the liquid 4 is supplied onto the ceramic substrate 1 by a dispenser. This supply amount is controlled so that the solder material 3 and the connection pattern 2 are completely covered and the electronic component 5 is not lifted by the surface tension of the liquid 4 in the subsequent process.

Next, as shown in FIG. 2 (b), a plurality of electronic components 5 such as LSI to which the solder material 3 has been previously supplied are connected to the connection pattern 2 on the ceramic substrate 1 to which the liquid 4 is applied.
Align and install. At this time, the liquid 4 completely covers the connection pattern 2 and the solder material 3 and blocks the atmosphere. After that, reflow soldering (for example, gas reflow using an N2 atmosphere) is performed as in the case of using flux. The ceramic substrate 1 on which the electronic component 5 is mounted is preheated to about 120 ° C. in the reflow furnace and then transported.
During this time, the solder material 3 is covered with the liquid 4 to prevent the solder material 3 from being oxidized. The liquid 4 starts to evaporate immediately before the melting of the solder material 3, and the solder material 3 and the connection pattern 2
Starts joining. At this time, even if the solder material 3 and the connection pattern 2 are slightly misaligned during alignment, the liquid 4 is used as the electronic component 5 in a manner that promotes the self-alignment effect that originally works when the solder material 3 and the connection pattern 2 are joined. Works well as buoyancy against.

After the reflow, as shown in FIG. 2 (c), there is no residue of the liquid 4, and a cleaning process for removing the liquid 4 is not necessary. Further, the bondability of the soldering portion is not hindered by the liquid 4, and it is possible to reliably solder to the predetermined connection pattern 2. As the liquid 4, any of ethylene glycol and trimethylene glycol shown in Table 1 was used, and the soldering could be surely performed.

In this embodiment, the soldering is performed without using the flux, and the liquid 4 does not have the action of removing the solder material 3 and the oxide film of the connection pattern 2 unlike the flux.
These surfaces have been cleaned beforehand by some method. Further, the liquid 4 described in the present embodiment uses a liquid selected in advance regarding toxicity, solderability, and the like. Further, as long as it is a liquid having the above-mentioned action, it does not need to be the liquid described in the embodiment, and may be a solid or the like at room temperature.
Although the example in which the solder material 3 is applied to the electronic component 5 has been described, the solder material 3 can be similarly processed when applied to the connection pattern 2 of the ceramic substrate 1 and when applied to both.

[0016]

As described above, according to the present invention,
By using a substance that has a boiling point below the melting point of the solder material used and a viscosity for fixing when soldering electronic components such as LSI without using flux, it may be caused by shock during transportation in the previous process of soldering. It was possible to prevent displacement, movement, drop, etc., and securely hold and fix electronic components and the like on the connection pattern. In addition, in the reflow process after mounting electronic components on an electronic circuit board, the material applied for fixing just before the solder material melts evaporates, and the cleaning process after reflow can be omitted. Therefore, there is no problem in soldering, connection reliability due to stress on the joint surface, or the like. Further, the soldering process is simplified, which leads to cost reduction.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a ceramic substrate on which an electronic component is mounted for explaining an embodiment of a method for fixing an electronic component of the present invention.

FIG. 2 is a process drawing for explaining an embodiment of a method for fixing an electronic component of the present invention.

[Explanation of symbols]

1 ... Ceramic substrate 2 ... Connection pattern 3 ... Solder material 4 ... Liquid 5 ... Electronic components

Continuation of front page (56) Reference JP-A-1-236636 (JP, A) JP-A-3-216277 (JP, A) JP-A-5-177385 (JP, A) JP-A-5-185277 (JP , A) JP-A-6-155068 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 3/00-3/34 B23K 1/00-3/00

Claims (4)

(57) [Claims] 1. A method for manufacturing a circuit board by connecting a substrate on which a connection pattern is formed and a component using a connecting material, the method comprising: supplying a solution for temporarily fixing the component to the substrate; Is placed on the connection pattern supplied with the solution via the connecting material, and the step of heating the substrate and the component, the solution is evaporated in the heating step. And a method for manufacturing a circuit board. 2. A method of soldering a substrate on which a connection pattern is formed and a component without using a flux, the step of supplying a solution for temporarily fixing the component to the substrate,
There is a step of placing the component on the connection pattern supplied with the solution via a solder material, and a step of heating the substrate and the component, and the solution evaporates in the heating step. Characteristic soldering method. 3. A method of manufacturing a circuit board by connecting a substrate on which a connection pattern is formed and a component by using a connecting material, wherein a solution is supplied to the substrate, and the connection pattern supplied with the solution. Mounting the component on the connector via the connecting material,
A first fixing step of fixing the component to the substrate by the solution, and a second fixing step of heating the component and the substrate, and fixing the component to the substrate by the connecting material, The method for manufacturing a circuit board, wherein the solution can be evaporated by the heating in the second fixing step. 4. A method for manufacturing a circuit board by connecting a substrate on which a connection pattern is formed and a component using a connecting material, wherein a solution is supplied to the substrate and the connection pattern supplied with the solution. Mounting the component on the connector via the connecting material,
A first fixing step of fixing the component to the substrate by the solution, and a second fixing step of heating the component and the substrate, and fixing the component to the substrate by the connecting material, The method for producing a circuit board, wherein the solution used in the first fixing step has a property of evaporating by heating.