JP2010272605A - Method of manufacturing electronic equipment by fine soldering of lead wire or the like, and soldering iron therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high-quality manufacture of electronic equipment that is compact and requires fine soldering by determining a position and accurately soldering a terminal and a lead wire in a narrow and fine land part, and further adjusting the amount of solder to be used by the length of thread solder fed into a through hole. <P>SOLUTION: An iron tip having a cylindrical through hole is used so as to prevent flux from scattering, and a convex projection portion is formed at an opening of the iron tip. The convex projection portion is bonded to a soldering part of the lead wire or land and heated to achieve soldering to the suitable part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an electronic device that melts thread solder and solders a lead wire or the like installed in a fine portion accurately and a soldering iron used for the method.

  As a soldering iron for soldering a land of a wiring board and terminals such as metal pins and wires, a soldering iron having a hook shape or a cap shape is known (Patent Document 1). In this method, the pin protruding from the land is surrounded by the opening of the tip of the hook, the thread solder is supplied into the cap of the hook, the solder is heated, the solder is melted, and the pin is soldered. Is the method. As a further improvement, a soldering method using a cylindrical solder rod having a through hole is known (Patent Document 2). This method is a method in which solder is melted and soldered to a metal pin in the through hole at the tip of the solder iron. This is characterized by preventing soldering to unnecessary portions and scattering of flux.

On the other hand, in the fine soldering of minute precision equipment such as a vibration motor built in a mobile phone, it is very difficult to perform an appropriate amount of soldering at an accurate position with the conventional soldering methods. there were. That is, for example, in order to solder a lead wire to a small land, accurate preheating of the soldering position and melting of the solder have a great influence, but in the conventional methods, the position of soldering and the amount of solder are accurate. It was not something. For this reason, regarding the soldering of the lead wire to a fine part, it is difficult to control the soldering position and the amount of solder, and it is difficult to perform soldering with high accuracy.
As described above, there has been a demand for a method for manufacturing an electronic device by a new soldering method for a precision electronic device that requires fine soldering.

JP-A-11-245029 WO2008 / 023461

  An object of the present invention is to provide a soldering iron capable of preventing the flux from being scattered and performing the soldering of lead wires in a minute portion with high accuracy. Many attempts have been made so far, but it has been difficult to perform accurate soldering on a fine soldered portion of a fine precision device. For example, when a cylindrical solder rod having a through hole described in Patent Document 2 is used for soldering a lead wire, the solder melted in the through hole flows into a land portion heated by contact with the tip. , It tends to stay and solidify in the heated land portion instead of the intended portion. Therefore, if the hole diameter of the tip opening is too large, soldering will not be performed in the opening of the tip, but the molten solder will flow to the heated part by contact with the tip, and the target soldering location There is a tendency that the molten solder does not solidify. Therefore, there has been a demand for accurate soldering to a minute portion, particularly minute soldering to a lead wire.

  The present inventors have studied various improvements of the cylindrical solder iron having a through hole described in Patent Document 2. As a result, a convex protrusion is formed at the tip of the soldering iron, and the convex protrusion is brought into contact with a terminal, a lead wire or a land to be soldered and preheated, thereby achieving good soldering. I understood that I can do. That is, when the terminal, lead wire, or land part of the soldered part is preheated by the protruding protrusion on the tip, solder melted in the through hole of the tip flows to the preheated part and stays there. To solidify. It has been found that terminals and lead wires can be soldered at desired sites. Furthermore, the present inventors, as shown in FIG. 1, various aspects of the protruding protrusion (contact area of the protrusion to the soldered part, distance between the tip of the protrusion and the tip of the protrusion, etc.) As a result of examining the diameter of the opening of the through hole at the tip of the hook, the following was found.

a) Distance A between the flat surface of the heel and the tip of the convex protrusion (height of the protrusion):
The distance A is a distance at which the solder piece can be held and heated in the through hole at the tip. When the amount of solder used is small, it is preferable that the diameter of the solder piece is reduced and the length of the solder piece is about 1 mm or more. Therefore, good results can be obtained when the distance A is in the range of 0.1 to 1.5 mm.
b) The shape of the protruding protrusion can be appropriately selected according to the shape of the preheating portion (soldered portion) (the shape of the land portion and the lead wire). However, in order to preheat the soldered portion to an appropriate temperature, the area of the convex protrusion necessary for heat conduction is preferably about 0.1 to 9 square mm.
c) The hole diameter of the through hole opening at the solder iron tip is not particularly limited as long as it is a distance through which the solder piece passes. However, when the hole diameter of the opening at the tip of the soldering iron is 3.5 mm or more, the distance between the land portion heated by the convex protrusion and the molten solder is greatly separated, and the molten solder is placed on the heated land portion. It happens not to flow. Therefore, the range of 0.5 to 3.5 mm is preferable.

Furthermore, the present inventors examined the influence of the shape of the solder iron tip (the diameter of the solder iron tip and the diameter of the through hole / the cylindrical wall thickness) on the temperature in the through hole. First, the temperature in the through hole was measured with a thermocouple using a soldering iron having the shape shown in FIG. Type B had a thinner solder iron tip, so it was more susceptible to external temperature and was thought to be lower in temperature than type A, but there was no significant difference in the temperature in the through hole as shown in FIG. .
The present inventors combined these findings and completed the present invention.

That is, the gist of the present invention is as follows.
(1) Using a soldering iron with the following shape:
a) a cylindrical soldering iron having a through hole,
b) The tip of the solder iron and the inner surface of the through hole are formed of a material of ceramic, tungsten, stainless steel or titanium,
c) A convex protrusion is installed at the tip of the soldering iron,
d) The distance between the protruding protrusion and the solder iron tip is 0.1 to 1.5 mm,
e) The area of the contact surface of the convex protrusion that contacts the soldered member and the soldered portion of the electronic device substrate (land) is 0.1 to 9 square mm.
Pre-heat the contact surface of the convex protrusion in contact with the member to be soldered and the part to be soldered,
Insert the thread solder piece into the through hole and melt it in the through hole at the tip,
Let the molten solder flow into the part preheated and heated at the convex protrusion,
A method for manufacturing an electronic device, comprising: solidifying at an inflow portion and soldering a member to be soldered to a substrate (land).
(2) The method for manufacturing an electronic device according to (1) above, wherein the inner diameter of the through hole at the tip of the cylindrical soldering iron is 0.5 to 3.5 mm.
(3) The method for manufacturing an electronic device according to (1) or (2), wherein the thread solder piece is 1 to 5 mg.
(4) The inner diameter of the through hole at the tip of the solder iron is 0.6 to 1.5 mm,
The area of the contact surface of the convex protrusion is 0.3-5 square mm,
The method for manufacturing an electronic device according to (3) above, wherein the distance between the convex protrusion and the solder iron tip is 0.3 to 1.0 mm.

(5) A soldering iron having a protruding portion and a through hole at the tip,
The tip of the solder iron and the inner surface of the through hole are made of ceramic, tungsten, stainless steel or titanium material,
The inner diameter of the through hole at the solder iron tip is 0.6 to 1.5 mm,
The area of the contact surface of the convex protrusion is 0.3-5 square mm,
A soldering iron for a thread solder piece, wherein a distance between the convex protrusion and the tip of the soldering iron is 0.3 to 1.0 mm.
(6) The soldering iron according to (5) above, wherein the distance between the tip of the soldering tip and the protruding protrusion is 0.3 to 0.5 mm.
(7) The soldering iron according to (5) or (6) above, wherein the inner diameter of the through hole at the tip of the soldering iron is 1 to 1.5 mm.
(8) The soldering iron according to any one of (5) to (7) above, wherein a lead wire escape groove and a pin relief hole are provided on the contact surface of the convex protrusion.

By using the manufacturing method of the present invention, it has become possible to accurately determine the position of soldering of terminals and lead wires in narrow and minute land portions. Moreover, since the amount of solder to be used can be adjusted depending on the length of the thread solder to be inserted into the through hole, for example, soldering of an extremely small electronic device such as a vibration motor of a mobile phone as shown in FIG. It became possible to carry out with accuracy. Moreover, the flux can be prevented from scattering. As described above, according to the present invention, it is possible to manufacture a high-quality electronic device that requires small soldering.

It is the schematic (sectional drawing) explaining the feature of the shape of the tip of this invention, and the condition of soldering. It is a perspective view showing an example of the shape of the convex protrusion part installed in the tip of the present invention. It is a perspective view showing an example of the shape of the convex protrusion part installed in the tip of the present invention. It is a perspective view showing an example of the shape of the convex protrusion part installed in the tip of the present invention. It is the schematic diagram (sectional drawing) showing the implementation condition of the soldering which uses the tip of this invention. It is the schematic (sectional drawing) showing the shape with which the convex protrusion part became large and integrated with the heating block in this invention. It is the schematic (sectional drawing) showing the shape with which the convex protrusion part became large and integrated with the heating block in this invention. In the soldering iron of this invention, it is the schematic (sectional drawing, unit mm) showing the difference in shape (difference in the thickness around a through-hole). It is the figure which compared the difference in the temperature in the through-hole in two types of soldering irons of FIG. It is a perspective view (unit mm) of the soldering location of the vibration motor for portable telephones manufactured by this invention. It is a perspective view (unit mm) showing the shape of the front-end | tip part of the soldering iron for carrying out minute soldering to the vibration motor of FIG. It is sectional drawing showing soldering a feeding terminal and a current-carrying terminal by preheating a to-be-soldered part using the soldering iron of FIG. 12, throwing in a solder piece, and melt | dissolving.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.
The tip of the present invention has the shape shown in FIGS. 2 to 4, and an electronic device is manufactured as shown in FIG. 5. That is, the process shown in FIG. 5 is divided into the following four processes.
(1) Preheat the part to be soldered with a soldering iron.
As shown in the left figure (a) of FIG. 5, the front end surface of the convex portion of the soldering iron is brought into contact with a part to be soldered (lead wire and land) and the part to be soldered is preheated. This step can be omitted when the heat capacity of the part to be soldered is small.
(2) After preheating, a solder piece is supplied.
As shown in the central view (b) of FIG. 5, a solder piece (thread solder piece) is supplied from the opening above the through hole of the solder iron.
(3) The solder piece is melted in the through hole.
As shown in FIG. 1, when the solder piece is heated in the through hole at the tip of the solder iron, the flux is melted from the solder piece and the soldered portion is purified. Since the part to be soldered is heated by the convex tip surface of the soldering iron, the flux permeates between the convex tip surface and the part to be soldered.
(4) The molten solder moves to the preheating site.
The melted solder moves to the preheated portion (high temperature portion) and has a property of staying there. Therefore, as shown in the right figure (c) of FIG. 5, the molten solder permeates between the soldered portion purified by the flux and the convex tip end surface. Next, when the soldering iron is raised, the penetrated molten solder is solidified, and the soldering of the land and the lead wire can be completed.

  The soldering iron of the present invention may be any material as long as it can withstand a temperature of about 600 ° C. and at least the tip of the tip and the inner surface of the through hole are difficult to get wet with the solder. Or a combination of a plurality of members. In the case of a single member, ceramic or a non-solder wettable metal such as tungsten, stainless steel or titanium is desirable. In the case of a ceramic, a high thermal conductive ceramic such as aluminum nitride or silicon carbide is particularly desirable. As a combination of multiple members, high thermal conductivity metal such as copper is coated with ceramic or non-solder wettability metal such as tungsten, stainless steel, titanium, etc. It is possible to fit a chip or a tube of a conductive metal member.

  The inner diameter of the through hole of the present invention is not particularly limited as long as it is a distance through which the solder piece passes. In particular, the hole diameter of the opening portion of the solder iron tip where the solder melts is important, and the inner diameter of the opening portion may be not less than the diameter of the solder piece to be used, and preferably not more than the length of the solder piece to be used. . In addition, when the hole diameter of the opening part of the soldering iron tip becomes 3.5 mm or more, the distance between the substrate (land) part heated by the convex protrusion and the molten solder is greatly separated, and the heated land part is separated. There are cases where molten solder does not flow. Therefore, the hole diameter of the opening can be in the range of 0.5 to 3.5 mm. Moreover, since a hole diameter that greatly exceeds the length of the thread solder is not preferable, a preferable hole diameter is 0.6 to 2.5 mm. More preferably, the diameter of 0.6-1.5 mm can be mentioned.

The present invention is a method capable of soldering a fine portion, and the amount of yarn solder used can be an amount of about 1 to 40 mg, which enables fine soldering. For finer soldering, a solder amount of about 1-10 mg can be used. Furthermore, soldering in the range of about 1 to 5 mg is also possible.
The diameter of the thread solder is generally in the range of 0.3 to 1.2 mm. Therefore, the diameter and length of the thread solder can be selected according to the amount of thread solder used. For example, when the amount of solder used is about 3 mg, a thread solder having a diameter of 0.8 mm and a length of about 1.1 mm can be used. A thread solder having a diameter of 0.6 mm and a length of about 2.0 mm can be used.
Therefore, the diameter and length of the thread solder can be adjusted as appropriate in accordance with the amount of solder used for the intended minute soldering. Corresponding to the diameter of the solder wire, an appropriate one is selected in which the inner diameter of the through hole of the solder iron (especially, the inner diameter of the opening of the iron tip) is selected. When the thread solder having a diameter of 0.8 mm is used, the inner diameter of the through hole (particularly, the inner diameter of the opening of the tip) can be 1.2 mm.

In the present invention, the distance A (the height of the protruding portion) between the tip of the solder iron and the protruding protrusion tip is as shown in FIG. A possible distance is preferred. When A is large, the inserted solder piece cannot be retained in the through hole (near the convex portion). Therefore, when using a thread solder piece, the distance A is 0.1 mm or more, and preferably 1.5 mm or less. Further, although it depends on the length of the solder piece to be used, it is preferably less than or equal to one half of the length of the solder piece.
Since the present invention is a method capable of soldering a minute portion as described above, for example, when the amount of solder used is about 3 mg, the diameter is 0.6 to 0.8 mm as the thread solder and the length is About 1.1 to 2.0 mm can be used. Therefore, in the case of fine soldering, the distance A is preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.6 mm.

The shape of the convex protrusion in the present invention can be appropriately selected according to the shape of the preheating part (part to be soldered) (the shape of the land part and the lead wire). However, in order to heat the preheated part to a temperature suitable for soldering, a contact area for heat transfer is required. Therefore, it is preferable that the contact area of the convex protrusion part which contacts a preheating site | part is about 0.1-9 square mm. More preferably, about 0.3-5 square mm can be mentioned.
In order to effectively perform preheating, it is necessary to improve the contact between the land portion and the lead wire. Therefore, for example, it is preferable to take a planar shape as shown in FIGS. Further, the contact surface of the convex protrusion may be provided with a lead wire escape groove and a pin relief hole as shown in FIG.

Next, the influence of the shape of the solder iron tip of the present invention on the temperature in the through hole was examined. That is, the effect of the thickness of the solder iron tip (the thickness around the through hole) that affects the temperature in the through hole was evaluated. Using the two types (type A and type B) of the soldering iron shown in FIG. 8, the temperature inside the through hole is measured with a thermocouple, and the temperature inside the through hole due to the difference in the shape of the tip of the soldering iron is measured. The impact was evaluated. When the main body part (heating block) of the solder iron was set to about 520 ° C., the temperature in the through hole increased in proportion to the distance from the tip of the solder iron as shown in FIG. At the tip opening, the solder tip of type B (b) was thin, so the temperature was about 35 ° C. lower than that of type A (a). However, as expected, it was not affected by the shape of the solder iron tip.
From the above, the surface temperature of the convex protrusion of the soldering iron of the present invention is affected by the height (distance A) of the convex protrusion by extrapolating the data of FIG. It was estimated that it was about 20-50 degreeC lower than the part. Therefore, the necessary preheating time for the soldered portion can be appropriately increased or decreased based on the contact area of the convex protrusion and the temperature of the through hole opening.

  The part to be soldered according to the present invention refers to metal pins or lead wires inserted into a wiring board of an electronic device and a wiring board (land) of the electronic device. Depending on the material of the wiring board of the electronic device, there is a material that changes in quality by preheating at a high temperature. Therefore, the contact time of the solder iron and the temperature of the solder iron main body can be appropriately set in consideration of the heat resistance of the material. Also, if the metal pin or lead wire protrudes from the surface of the wiring board and the convex protrusion of the present invention is not sufficiently in contact with the land, the lead wire relief groove and pin relief hole are formed on the contact surface of the convex protrusion. The contact property to the land can be improved.

Another embodiment of the soldering manufacturing method of the present invention is the soldering manufacturing method shown in FIGS. As a solder rod to be used, as shown in FIG. 6, a straight tubular member made of ceramic or a non-solder wettable metal such as tungsten, stainless steel or titanium is used as a block of a high heat conductive ceramic or high heat conductive metal. It is made in a form attached to the side wall. This block has a role of transferring heat to the tubular member. Moreover, you may be united with a heating block like FIG. The distance between the tip of the tubular member and the tip of the block is the same as the distance A described above.
First, the tip of the block is brought into contact with the part to be soldered and preheated. Thereafter, a solder piece is introduced from the upper part of the tubular member, and the solder piece is melted at the lower part of the tubular member. The melted solder flows to the portion preheated by the block, solidifies and solidifies there, and soldering is completed. Therefore, in order to preheat the soldered portion, the tip of the block to be contacted has the same shape as the above-mentioned convex protrusion portion of the soldering iron. The material of the block is also high thermal conductivity such as high thermal conductivity ceramic such as aluminum nitride and silicon carbide, or copper whose tip is coated with non-solder wettable metal such as ceramic or tungsten, stainless steel, titanium, etc. Metal can be used.

Further, in FIG. 7, the straight tubular member portion made of non-solder wettable metal is not attached to the side wall of the heating block but is separated. Therefore, the tubular member is not heated, and the solder pieces are not melted in the tubular member. The tubular member plays a role of inducing a solder piece to contact the heating block. That is, the part to be soldered is heated as shown in FIG. 7 at the tip of the heating block, and the solder piece is introduced from the top of the tubular member. The solder pieces go down inside the tubular member and contact the heating block, where they are melted and penetrate into the portion preheated by the heating block. Next, when the heating block is pulled up, the molten solder that has flowed in is solidified and soldering is completed.
The tubular member used is made of the same ceramic as described above, or a non-solder wettable metal such as tungsten, stainless steel, titanium, etc., and for the heating block, for example, a high thermal conductive ceramic such as aluminum nitride, silicon carbide, For example, a ceramic or a highly thermally conductive metal such as copper whose tip is coated with a non-solder wettable metal such as tungsten, stainless steel, or titanium is used.

The heating block is a block in which a heating element is embedded as shown in FIG. A known general-purpose technique can be applied to the heating element, and for example, a ceramic heater or the like can be used. The heating temperature by the heating element is preferably about 550 ° C., and the temperature can be further lowered in consideration of the heat capacity of the part to be soldered and the thermal stability of the corresponding circuit board.
However, the temperature of the solder iron tip where the through hole exists must be equal to or higher than the melting temperature of the solder piece. Therefore, the temperature of the heat generating block is preferably about 500 to 550 ° C.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

(Example 1) Micro soldering of a vibration motor of a mobile phone A soldering iron formed with an aluminum nitride sintered body having a shape shown in FIG. 11 and having an inner diameter of 1.3 mm is used. The area of the convex protrusion contact surface is about 0.4 square mm (0.6 × 0.6 mm). Then, in order to solder the power feeding terminal and the current-carrying terminal of the vibration motor of FIG. 10, the current-carrying terminal and the convex protrusion of the soldering iron are brought into contact with each other as shown in FIG. Adjust. Next, a thread solder piece of eutectic solder having a diameter of 0.8 mm and a length of 1.1 mm is supplied into the through hole. When soldering is performed while maintaining the temperature of the opening of the solder iron tip at about 370 ° C., the solder can be soldered so as to include the preheated portion and the power supply terminal without spreading greatly.
For comparison, when soldering is performed in the same manner with a soldering iron having the shape shown in FIG. 11 and no protruding protrusion, the molten solder spreads, and a necessary amount of solder can be secured at the soldering portion. There wasn't. That is, the soldering strength tends to be insufficient.

By using the manufacturing method of the present invention, it is possible to accurately and satisfactorily perform soldering of precision fine equipment such as a mobile phone. Therefore, according to the present invention, it is possible to manufacture a lightweight, small-sized electronic device with high quality that is frequently used for soldering.

Claims (8)

Using a soldering iron of the following shape,
a) a cylindrical soldering iron having a through hole,
b) The tip of the solder iron and the inner surface of the through hole are formed of a material of ceramic, tungsten, stainless steel or titanium,
c) A convex protrusion is installed at the tip of the soldering iron,
d) The distance between the protruding protrusion and the solder iron tip is 0.1 to 1.5 mm,
e) The area of the contact surface of the convex protrusion that contacts the soldered member and the soldered portion of the electronic device substrate (land) is 0.1 to 9 square mm.
Pre-heat the contact surface of the convex protrusion in contact with the member to be soldered and the part to be soldered,
Insert the thread solder piece into the through hole and melt it in the through hole at the tip,
Let the molten solder flow into the part preheated and heated at the convex protrusion,
A method for manufacturing an electronic device, comprising: solidifying at an inflow portion and soldering a member to be soldered to a substrate (land).   2. The method of manufacturing an electronic device according to claim 1, wherein the inner diameter of the through hole at the tip of the cylindrical soldering iron is 0.5 to 3.5 mm.   The method of manufacturing an electronic device according to claim 1 or 2, wherein the thread solder piece is 1 to 5 mg. The inner diameter of the through hole at the solder iron tip is 0.6 to 1.5 mm,
The area of the contact surface of the convex protrusion is 0.3-5 square mm,
4. The method of manufacturing an electronic device according to claim 3, wherein a distance between the convex protrusion and a solder iron tip is 0.3 to 1.0 mm. A soldering iron having a protruding portion and a through hole at the tip,
The tip of the solder iron and the inner surface of the through hole are made of ceramic, tungsten, stainless steel or titanium material,
The inner diameter of the through hole at the solder iron tip is 0.6 to 1.5 mm,
The area of the contact surface of the convex protrusion is 0.3-5 square mm,
A soldering iron for a thread solder piece, wherein a distance between the convex protrusion and the tip of the soldering iron is 0.3 to 1.0 mm.   The soldering iron according to claim 5, wherein the distance between the tip of the iron tip and the convex protrusion is 0.3 to 1.0 mm.   The soldering iron according to claim 5 or 6, wherein an inner diameter of the through hole at the tip of the soldering iron is 1 to 1.5 mm. The soldering iron according to any one of claims 5 to 7, wherein a lead wire escape groove and a pin escape hole are provided on a contact surface of the convex protrusion.

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