JPH08155633A - Soldering iron tip - Google Patents

Abstract

PURPOSE: To provide a soldering iron tip free from deterioration caused by use long-term by suppressing the occurrence of defective soldering associated with making the soldering iron tip fine. CONSTITUTION: A surface perpendicular to the high heat conducting direction of a carbon-based fiber substrate 1 is formed on a solder wetting surface 2, and a surface perpendicular to a low heat conducting direction is formed on a nonwetting surface 3 of solder. A soldering iron tip is constituted by forming on iron plated layer 4 on the surface, by forming a solder plated layer 5 on the solder wetting surface on it, and by forming a chromium plated layer 6 on the solder nonwetting surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering tip used for soldering electronic parts and the like.

[0002]

2. Description of the Related Art In recent years, a soldering apparatus has been developed which is suitable for high-density mounting of electronic circuits, and which is capable of collectively soldering a plurality of solders with high quality including flow and reflow. . However, a soldering iron is often used for subsequent soldering that cannot be processed by flow, reflow, or the like.

Usually, at the time of soldering, in order to obtain an alloy layer between the object to be soldered and the solder, it is necessary to heat the temperature of the object to be soldered to a predetermined temperature. Therefore, in the soldering iron, copper with good thermal conductivity is used for the base of the soldering tip, the solder wetted surface is made of iron or nickel and solder plated, and the non-soldered surface is plated with chrome. The solder wetted surface is pressed against the soldered surface and the object to be soldered, and the soldered surface and the object to be soldered are heated by heat transfer by the hot solder and the molten solder on the wet surface.

Therefore, with the soldering iron, the soldering surface is pressed against the soldering surface and the object to be soldered, and the soldering surface and the soldering object are heated by the heat transfer by the high temperature iron.

When the temperature of the surface to be soldered rises, a predetermined amount of solder is supplied and heated, the supplied solder is melted on the iron wetting surface, and then the molten solder metal flows toward the object to be soldered. In addition to the direct heat transfer from the iron, indirect heat transfer from the iron wetting surface through the molten solder is also added to promote heat transfer to the soldered surface, and the alloy layer between the soldered surface and Is formed.

[0006]

However, in the above-mentioned conventional structure, the tip having a thin tip corresponding to the miniaturization of the soldering interval due to the recent high-density mounting of electronic circuits,
It is difficult to supply a sufficient amount of heat to heat the object to be soldered to the temperature required for soldering, and insufficient heating of the object to be soldered results in insufficient soldering, so-called solder shortage have.

Further, the plating layer on the tip is eroded by the molten solder due to use, and the shape of the solder wetting surface changes when used for a long period of time. There is also a problem that a so-called bridging defect in which parts are connected is likely to occur.

The present invention solves the above-mentioned problems of the prior art by providing a soldering iron tip which suppresses the occurrence of defective soldering due to the fineness of the tip of the iron tip and does not deteriorate due to long-term use. The purpose is to do.

[0009]

In order to achieve this object, in the soldering iron tip of the present invention, the soldering iron tip base body is formed of carbonaceous fibers having thermal conductivity anisotropy.

It is preferable that the carbon fiber having heat conduction anisotropy has a surface perpendicular to the high heat conduction direction formed on the solder wetting surface and a surface perpendicular to the low heat conduction direction formed on the solder non-wetting surface.

Further, a plating layer is formed on the surface of the carbon fiber having the thermal conductivity anisotropy of the soldering iron base, and the plating layer is made of iron-based material, nickel, or metal or alloy having good solder wettability. are doing.

Preferably, the solder wetting surface is formed of iron, nickel, or a metal or alloy having a good solder wettability, and the solder non-wetting surface is formed of chrome or a metal or alloy having a poor solder wettability. There is.

Further, the surface plating layer may be formed of iron or nickel, or a metal or alloy having a good solder wettability, and the solder non-wetting surface may be formed of chromium or a metal or alloy having a poor solder wettability. Good.

[0014]

According to the present invention, as a representative of the high-quality carbonaceous fiber constructed as described above, Japanese Patent Application No. 6-154627.
The product name is Panasonic Super Graphite.

The thermal conductivity of copper is 336 Kcal / m · h ·
The typical thermal conductivity of the high-quality carbonaceous fibers used for the soldering iron tip substrate of the present invention at 8 ° C. is 8 in the high thermal conductivity direction.
60Kcal / m ・ h ・ ℃, 5 for low heat conduction direction
It is 0 Kcal / m · h · ° C. Also, it has a heat resistance of 850 ° C. in air and an elastic modulus of 84300 Kg.
It is as hard as f / mm ² as diamond and hard to be deformed even as a soldering iron tip. Further, the tensile strength is 72 Kgf / mm ^{2 in the} high heat conduction direction, which is equivalent to that of iron, but 0.1 Kgf in the low heat conduction direction.
/ Mm ² or less, which is brittle. In addition, the electrical conductivity is 23000 S / cm, which is 1/4 that of iron in the high heat conduction direction.
The metal film can be easily formed by plating on the surface of the high-quality carbonaceous fiber having a degree of 100 S / cm in the low heat conduction direction.

According to the present invention, the high-quality carbonaceous fiber used for the base of the soldering iron tip has excellent thermal conductivity, and the soldering iron tip base material has a heat resistance 2.5 times higher than that of copper. Because it is made of high-quality carbon fiber with heat conduction anisotropy of conduction, even if the tip of the tip becomes finer, the high heat conductivity will heat the object to be soldered to the temperature required for soldering. The necessary amount of heat can be supplied, and there is no occurrence of so-called solder shortage in which solder is not placed due to insufficient heating of the soldering object.

In addition, a high-quality carbonaceous fiber having a heat-conducting anisotropy is used as a solder wetting surface having a high heat-conducting surface which is 2.5 times as high as that of copper, and a low heat-conducting surface having a high heat-conducting direction of 1/17 By forming on the solder non-wetting surface, the amount of heat required to heat the object to be soldered to the temperature required for soldering due to high thermal conductivity even if the wetting surface is made smaller by making the tip of the iron tip smaller Can be supplied, and the solder is not placed due to insufficient heating of the soldering object, so-called solder shortage does not occur, and at the same time, even if solder is supplied to the non-wetting surface due to the low thermal conductivity of the non-wetting surface The amount of heat required for melting cannot be supplied sufficiently, it is difficult to flow the molten solder into the non-wetting surface, and so-called bridging defects in which the solder portions are connected between the objects to be soldered do not occur.

Further, by plating the surface of the high-quality carbonaceous fiber having the thermal conductivity anisotropy of the soldering iron tip substrate with a metal having good solder wettability, the solder wettable surface having high thermal conductivity has further solder wettability. In addition, the high-quality carbonaceous fiber having a heat conduction anisotropy that is as strong as iron in the high heat conduction direction but is brittle in the low heat conduction direction does not hit the surface to be soldered or the object to be soldered and is not broken.

Further, by plating the solder non-wetting surface with chromium or a metal having poor solder wettability, the solder non-wetting surface having low thermal conductivity is further deteriorated in solder wettability.

Further, by forming the plating layer on the surface with a metal having a good solder wettability and then plating only the solder non-wetting surface with a metal having a poor solder wettability, the solder wettable surface can be easily formed. .

[0021]

An embodiment of the present invention will be described below with reference to the drawings.

1 (a), 1 (b), 2 (a),
3 (b), 3 (a), and 3 (b) are a horizontal sectional view and a vertical sectional view, respectively, of a soldering iron tip according to an embodiment of the present invention.

The embodiment shown in FIGS. 1 (a) and 1 (b) has a surface perpendicular to the high heat conduction direction (direction parallel to the paper surface) of the prismatic high-quality carbonaceous fiber base body 1 with one end having a sharp tip. On the solder wetting surface 2, a surface perpendicular to the low heat conduction direction (direction perpendicular to the paper surface) on the solder non-wetting surface 3, and an iron plating layer 4 is formed on the surface.
Further, a solder plating layer 5 is formed on the solder wetted surface in order to improve the solder wettability, and a soldering tip is formed.

The embodiment shown in FIGS. 2 (a) and 2 (b) is a surface perpendicular to the high heat conduction direction (direction parallel to the paper surface) of the prismatic high quality carbonaceous fibrous substrate 1 having one end as a tip. Is formed on the solder wetting surface 2, a surface perpendicular to the low heat conduction direction (direction perpendicular to the paper surface) is formed on the solder non-wetting surface 3, an iron plating layer 4 is formed on the solder wetting surface, and the solder wettability is formed thereon. In order to improve the solderability, a solder plating layer 5 is formed, and a chromium plating layer 6 is formed on the surface of the solder non-wetting surface to form a soldering iron tip.

The embodiment shown in FIGS. 3 (a) and 3 (b) is a surface perpendicular to the high heat conduction direction (direction parallel to the paper surface) of the prismatic high-quality carbonaceous fiber base 1 having one end having a sharp tip. On the solder wetting surface 2, a surface perpendicular to the low heat conduction direction (direction perpendicular to the paper surface) on the solder non-wetting surface 3, and an iron plating layer 4 is formed on the surface.
A solder plating layer 5 is formed on the solder wetted surface to improve the solder wettability, and a chrome plated layer 6 is formed on the solder non-wetted surface to form a soldering tip. .

[0026]

As described above, according to the present invention, a carbon fiber having heat conduction anisotropy is used for a base of a soldering iron tip, and a solder wetting surface is formed on a surface perpendicular to a high heat conduction direction. With this, even if the tip of the tip becomes thin, it is possible to supply the necessary amount of heat to heat the soldering target to the temperature required for soldering due to its high thermal conductivity, and insufficient heating of the soldering target. Therefore, a so-called solder shortage in which solder is not placed does not occur. Further, by covering the surface of the high-quality carbonaceous fiber, which is brittle in the direction of low heat conduction, with the iron-plated layer, the surface to be soldered or the object to be soldered is not destroyed. At the same time, by forming the solder non-wetting surface on the surface perpendicular to the low heat conduction direction, even if the solder is supplied on the non-wetting surface, it is not possible to sufficiently supply the amount of heat necessary for melting the solder,
It is difficult for the molten solder to flow into the non-wetting surface, and a so-called bridging defect in which the solder portions are connected between the objects to be soldered does not occur. Further, it is difficult for the molten solder to flow into the non-wetting surface, and the solder non-wetting surface is not eroded by the molten solder and the shape of the solder wetting surface does not change.

Further, according to the present invention, the solder wetted surface is covered with the iron plating layer and the solder plated layer thereon, and the non-soldered surface is covered with the chrome plated layer. The solder non-wetting surface of low thermal conductivity further deteriorates in solder wettability, and the high quality carbonaceous fibers brittle in the direction of low thermal conductivity do not hit the surface to be soldered or the object to be soldered and are destroyed.

According to the present invention, the surface plating layer is formed of an iron plating layer having good solder wettability, the solder non-wetting surface is formed of a chrome plating layer, and then the solder wetting surface is formed of a solder plating layer. As a result, the solder wetting surface can be easily formed.

In this embodiment, the iron plating layer and the chrome plating layer are used. However, instead of the iron plating layer, a nickel plating layer or a metal layer having a good solder wettability, and instead of the chrome plating layer, a solder wettability layer is used. It may be formed of a bad metal layer.

According to the present invention as described above, it is possible to suppress the occurrence of soldering defects due to the fineness of the tip of the tip when using a copper trowel that is difficult to supply a sufficient amount of heat, and to plate with a copper trowel. Solder wet surface and non-wet surface that were formed only by layers,
By forming by taking into consideration the anisotropy of heat conduction, it is possible to eliminate the change in the shape of the solder wetted surface and to provide an excellent soldering iron tip that is less deteriorated by long-term use.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of a soldering iron tip having a carbon fiber surface plated with iron and a solder plating layer formed thereon (b) is a vertical cross-sectional view of the same soldering iron tip.

FIG. 2 (a) is a cross-sectional view of a soldering iron tip in which iron is plated on the wet surface of carbon-like fibers, a solder plating layer is formed on the wet surface, and a chrome plating layer is formed on the non-wetting surface. Vertical cross section

[FIG. 3] (a) A soldering tip having iron-plated carbon-like fibers on the surface, a solder-plated layer on the iron-plated wet surface and a chrome-plated layer on the iron-plated non-wet surface Cross-sectional view (b) is a vertical cross-sectional view of the same soldering iron tip

[Explanation of symbols]

 1 High-quality carbon fiber substrate 2 Solder wetted surface 3 Solder non-wetted surface 4 Iron plating layer 5 Solder plating layer 6 Chrome plating layer

Claims (6)

[Claims] 1. A prismatic soldering iron tip having at least one end having a sharp tip, wherein the soldering iron tip substrate is formed of carbon fibers having thermal conductivity anisotropy. Tip. 2. A surface perpendicular to a high heat conduction direction of a carbon fiber having thermal conductivity anisotropy is formed on a solder wetting surface, and a surface perpendicular to a low heat conduction direction is formed on a solder non-wetting surface. The soldering iron tip according to item 1. 3. The soldering iron tip according to claim 1 or 2, wherein a plating layer is formed on the surface of the carbonaceous fiber having the thermal conductivity anisotropy of the soldering iron tip substrate. 4. A plating layer on the surface of a carbon fiber having a thermal conductivity anisotropy of a soldering iron base is made of iron or nickel,
4. The soldering iron tip according to claim 3, which is formed of a metal or an alloy having good solder wettability. 5. The plating layer on the surface of the carbon fiber having the thermal conductivity anisotropy of the soldering iron tip substrate is formed by iron-based, nickel, or a metal or alloy having good solder wettability on the solder-wetting surface, The solder non-wetting surface is formed of chromium or a metal or alloy having poor solder wettability.
Solder tip as described. 6. A plating layer on the surface of a carbon fiber having thermal conductivity anisotropy of a soldering iron base is made of iron or nickel,
4. The soldering tip according to claim 3, wherein the soldering tip is formed of a metal or alloy having a good solder wettability, and the solder non-wetting surface is formed of chromium or a metal or an alloy having a poor solder wettability.