JP2006186086A - Method for soldering printed circuit board and guide plate for preventing bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soldering method for effectively preventing the so-called bridge phenomenon in which melted solder strings out between adjacent leads, and to provide a guide plate for preventing bridges used for the soldering method in an automatic soldering method of a printed circuit board by a dipping method. <P>SOLUTION: In the method for soldering each kind of electronic component to a through-hole on the printed circuit board via a lead in a process for passing a melted solder bath, the sheet-like guide plate for preventing bridges in which the surface is machined in a mesh is interposed on the substrate surface of a soldering tool, an intermediate layer, and a soldering surface before soldering in the melted solder bath. The guide plate for bridges is used in the soldering method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention prevents a so-called bridge phenomenon in which molten solder continues between leads during soldering by bringing a printed circuit board into contact with molten solder in a molten solder bath and soldering various electronic components on the substrate. The present invention relates to a bridge prevention guide plate.

  Soldering methods for various electronic components and the like to a printed circuit board are roughly classified into a brazing method, a reflow method, and an immersion method. Among these methods, the soldering method is a method in which a solder wire filled with pine resin is brought into contact with a soldering portion of a printed circuit board, and soldering is performed while the solder wire is heated and melted with a soldering iron. Although it is extremely poor, it is still invaluable as a method of soldering electronic components that are inferior in heat resistance or correcting unsoldering defects such as unsoldering and bridges that occur in other soldering methods. . In the reflow method, a viscous solder paste prepared by solder powder and paste-like flux is applied to a necessary place on a printed board by means of screen printing or dispenser discharge, and then the board is applied to a reflow furnace. This is a method of performing soldering by heating in a heating device (see, for example, Patent Document 1). This reflow method is excellent in reliability and productivity because it can be soldered to a plurality of required locations at the same time, but it requires many steps to produce a predetermined solder powder. In order to obtain solder powder of a specific particle size, there is a problem that the yield is low and the cost is high, and as a result, the solder is used only for electronic devices with relatively high added value such as computers and mobile phones. It is a method of attaching.

  On the other hand, the dipping method is a method of simultaneously soldering a plurality of electronic components to a printed circuit board using an automatic soldering apparatus, and the printed circuit board is applied to the molten solder jetted from the jet nozzle of the jet solder bath of the automatic soldering apparatus. Since soldering is performed sequentially while in contact, it does not require labor-intensive processing to obtain the solder itself, and it is an economical and productive method in which a large number of soldering points are soldered in a series of operations. . Therefore, at present, it is widely used as a soldering method for printed circuit boards for constituting electronic circuits such as televisions, videos, DVDs, various audio devices, and home appliances.

A conventional automatic soldering apparatus in the above immersion method is provided with processing devices such as a fluxer 20, a pre-heater 30, a jet solder bath 40, a cooler 50 and the like sequentially as shown in FIG. 8, for example. A transport device for transporting the printed circuit board is installed on the top. The method of soldering the printed circuit board in the automatic soldering apparatus is to apply the flux by the fluxer 20 while transporting the printed circuit board (not shown) in the direction of the arrow by the transport device, and then preheat the preheater 30. Then, the jet solder bath 40 urges the penetration of the molten solder into the soldering portion, and the cooling solder 50 then cools and solidifies the molten solder that has entered to complete the brazing. At this time, the jet solder bath 40 constitutes a double wave solder bath of the rough wave solder bath 60 and the finish solder bath 70, and the soldering defects such as tsura and bridge formed in the rough wave solder bath 60 are moderated in the finish solder bath 70. It is comprised so that it may correct by a simple jet wave (for example, refer patent document 2).
JP-A-5-198932 (pages 1 to 4, FIGS. 1 to 6) Japanese Patent No. 2687218 (pages 1 to 3, FIG. 2)

  By the way, the soldering of the printed circuit board is performed by inserting a lead of an electronic component such as a connector from the surface of the through hole formed on the printed circuit board and connecting the lead and the through hole by soldering. This is done by connecting the electrode of the electronic component mounted on the back side of the board and the land of the printed circuit board, so the molten solder must penetrate sufficiently into the inside of the narrow through-hole and the corner of the angular electronic component. Unsoldered solder does not adhere. Further, as is apparent from the above prior art, the jet solder tank for adhering the molten solder to the printed circuit board has a primary jet nozzle for jetting the molten solder in a rough state and jets the molten solder in a gentle state. A secondary jet nozzle is provided to constitute a so-called double wave solder bath. This primary jet nozzle functions to prevent unsoldering by injecting molten solder into the corners of the printed circuit board through holes and electronic parts with a strong discharge force, but the molten solder formed by the primary jet nozzle Since the rough wave is literally in contact with the soldered portion in a rough state, a tsura or bridge is formed in the soldered portion. If a wiggle is formed on a printed circuit board, there is a concern that the electronic device may be destroyed by discharging from its sharp tip, and if a bridge is formed and leads are connected, a short circuit occurs in the electronic circuit, and the electronic circuit is damaged. Equipment functions may be impaired. In view of this, the slurry and nozzles generated by the primary jet nozzle are remelted and removed by the gentle molten solder wave generated by the secondary jet nozzle.

  In this way, the development of the double wave type jet solder bath and the improvement of the process have combined, and the soldering method on the printed circuit board has been remarkably improved. In addition to the improvement in productivity, the reliability of the product has been greatly improved. However, in recent years, the development of multifunctional electronic components such as IC chips for high-density integrated circuits has remarkably evolved, and in the method of soldering printed circuit boards for mounting these electronic components, the lead pitch interval is increased. Despite adopting a soldering method that leaves room for improvement, such as narrowing, and repeated complicated processes, sufficient prevention measures are still established for soldering defects, especially bridges. However, there are still problems that need to be solved in terms of improving productivity and ensuring quality reliability, such as the need for time-consuming correction work after soldering. The present invention is intended to solve such a problem, and provides a soldering method for a printed circuit board that prevents the occurrence of a bridge by a simple means and a bridge prevention guide plate.

  In order to solve the above problems, a printed circuit board soldering method according to the present invention is a method for soldering various electronic components to through-holes of a printed circuit board through leads while passing through a molten solder bath. A characteristic structural requirement is that a sheet-shaped bridge prevention guide plate whose surface is processed into a mesh is interposed on the substrate surface, intermediate layer and solder surface of the jig, and then soldered in a molten solder bath. is there.

  In the printed circuit board soldering method according to the present invention, the bridge prevention guide plate is formed of a sheet-like thin plate made of a metal or heat-resistant resin whose surface is processed into a mesh shape. Is.

  Furthermore, the bridge prevention guide plate according to the present invention is a method of soldering various electronic components to a through hole of a printed circuit board through a lead while passing through a molten solder bath. Further, a characteristic constituent requirement is to prevent the formation of a bridge by molten solder, interposing on the solder surface.

  The bridge prevention guide plate according to the present invention is formed of a sheet-like thin plate made of metal or heat-resistant resin whose surface is processed into a mesh shape.

  According to the method for soldering a printed circuit board according to the present invention, the soldering of the lead to the through hole of the printed circuit board is completed by contact with the solder bath in a static wave state, so that the molten solder particles are scattered mainly in the rough wave jet bath. The bridge due to the occurrence of the occurrence of a bridge is prevented, and the bridging prevention guide plate interposed between the printed circuit board and the solder bath surface prevents the molten solder connected between the leads from being cut off, or prevents the formation of a bridge. By removing the guide plate for preventing bridges, the bridge formed continuously between the lead pitches is removed at the same time, so that the correction work after soldering is completely omitted. In addition, after soldering using the conventional rough wave jet solder bath, the bridge on the soldering surface is easily removed without the need for a solder defect correction process in the finished solder bath. Soldering for forming can be easily performed by a simple operation. Therefore, it is possible to provide a printed circuit board on which various electronic components having a high-density integrated circuit are mounted at a low price while maintaining high reliability.

  In addition, since the bridge prevention guide plate used in the printed circuit board soldering method of the present invention can be easily manufactured using a versatile material, it is inexpensive as a bridge prevention guide plate in the printed circuit board soldering method. Can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an enlarged cross-sectional view showing an embodiment of the printed circuit board soldering method of the present invention, FIG. 2 is an enlarged cross-sectional view showing another embodiment of the printed circuit board soldering method of the present invention, and FIG. FIG. 4 is an enlarged plan view schematically showing an embodiment of a bridge prevention guide plate used in the printed circuit board soldering method of the present invention. FIG. 4 is a further embodiment of the printed circuit board soldering method of the present invention. FIG. 5 is an enlarged sectional view showing still another embodiment of the printed circuit board soldering method of the present invention, and FIG. 6 is a bridge prevention guide plate used in the printed circuit board soldering method of the present invention. 7 is an enlarged plan view schematically showing another embodiment, and FIG. 7 is an enlarged plan view schematically showing a bridge prevention guide plate of still another embodiment.
[Example]

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto, and can be freely modified within the scope of the gist of the present invention.

  The bridge prevention guide plate used in the present invention is basically formed of a sheet of a corrosion-resistant metal thin plate such as stainless steel, and the surface thereof is meshed corresponding to the through hole of the printed circuit board. And fixed by a soldering jig so as to be interposed between the printed circuit board and the solder bath surface. At this time, the lead of the electronic component mounted on the printed circuit board is inserted into a through hole formed in the printed circuit board and comes into contact with the solder bath surface through the mesh-shaped through hole of the bridge prevention guide plate. Next, as the solder bath surface rises, the molten solder enters the through hole, and the connection between the lead and the through hole of the substrate by the solder is completed. When the printed circuit board is removed from the solder jig after cooling and solidification has been confirmed, the sheet-shaped bridge prevention guide plate is easily peeled off from the back surface of the printed circuit board, and the bridge formed by the molten solder connected between the lead pitches At the same time, the lead and the through hole of the printed circuit board are configured to be welded in a sound manner.

  On the other hand, another bridge prevention guide plate related to the present invention is formed using a sheet-like heat-resistant resin as a raw material, is in contact with the intermediate layer of the soldering jig or the solder bath surface, and when the molten solder leaves It functions to cut off the solder connected between the leads and prevent the bridge from being formed, and polyamides are preferably employed as the heat-resistant resin used. In this case, in place of the bridge-preventing guide plate formed from a sheet-like heat-resistant resin, a sheet-like bridge-preventing guide plate obtained by processing the metal thin plate into a mesh shape is used without any problem. Needless to say.

  As the printed board 1, a rigid board made of glass fiber is used as a base material having a plate thickness of 1.6 mm. When the electronic component 2 with leads 3 is soldered to the board 1 as shown in FIG. A sheet-shaped bridge prevention guide plate 5 made of austenitic stainless steel having a thickness of 0.15 mm was placed so as to be interposed between the substrate 1 and fixed by a soldering jig. A mesh 5-1 as schematically shown in FIG. 3 is formed on the surface of the bridge prevention guide plate 5 so as to correspond to the through hole 4 of the printed circuit board 1, and the lead 3 of the electronic component 2. Is inserted into the through hole 4 and penetrates through the mesh 5-1 of the bridge prevention guide plate 5 and protrudes toward the bath surface (not shown) of the molten solder. The printed circuit board 1 set in this manner is moved onto the jet solder bath by a conveying means in an automatic soldering apparatus (not shown) and immersed in the raised solder bath surface so that molten solder enters the through hole 4. And the joining of the lead 3 to the through hole 4 is completed. Thereafter, when the printed circuit board 1 forcibly cooled and solidified is removed from the soldering jig in the process flow in the automatic soldering apparatus and the bridge prevention guide plate 5 is further peeled off, the pitch between adjacent leads 3 is increased. The bridges formed in series were also removed at the same time, and there was no bridge between the pitches of the leads 3. In addition, it was confirmed that the lead 3 was soldered in a sound state in the through hole 4.

  As shown in FIG. 2, the electronic component 2a to be soldered to the printed circuit board 1a is a connector component having multiple rows of leads 3a in two rows. The electronic component was soldered to the printed circuit board 1a. Note that the bridge prevention guide plate used at this time is the same material as in Example 1, and adopts a bridge prevention guide plate 5a processed as schematically shown in FIG. Results similar to those in Example 1 were confirmed with respect to the removal of the bridge after completion of the attachment and the soldering state of the lead 3a in the through hole 4a.

  As the electronic component 2b to be soldered to the printed circuit board 1b, a connector provided with five rows of leads 3b is adopted, and as shown in FIG. 4, the intermediate layer of the soldering jig 6b (the back surface of the printed circuit board 1b and the solder) The embodiment is substantially the same except that a bridge prevention guide plate 5c made of austenitic stainless steel with a thickness of 0.15 mm processed into a mesh structure as shown in FIG. 7 is interposed in the intermediate layer of the bath surface). In the same manner as in Example 1, the electronic component 2b was soldered to the printed circuit board 1b. The bridge prevention guide plate 5b in the present embodiment, which is located in the intermediate layer of the soldering jig 6b and is interposed between the molten solder bath and the printed circuit board 1b, is a molten solder that continues between the leads 3b when leaving the solder bath surface. And the formation of a bridge connected between the pitches of the adjacent leads 3b is prevented, and the through holes 4b in the printed circuit board 1b and the respective leads 3b are soldered in a perfect state, and the obtained prints are obtained. It was confirmed that the electronic circuit of the substrate functions in a healthy state.

  The electronic component 2c to the printed circuit board 1c is the same as in the third embodiment except that the bridge prevention guide plate 5c is installed close to the lower end of the solder jig 6c and the solder bath surface as shown in FIG. Soldering was performed. As a result, almost the same results as in Example 3 were confirmed.

  As is clear from the above embodiments, according to the method for soldering a printed circuit board according to the present invention, the soldering of the lead to the through hole of the printed circuit board is completed by contact with the solder bath in a static wave state. In the rough wave jet tank, no flickering due to the scattering of molten solder particles occurs, and the bridge prevention guide plate interposed between the printed circuit board and the solder bath surface is removed, thereby removing the gap between the leads. Since the bridges formed in series are removed at the same time, the correction work after soldering is completely omitted. In addition, after soldering using the conventional rough wave jet solder bath, the bridge on the soldering surface is easily removed without the need for a solder defect correction process in the finished solder bath. Soldering for forming can be easily performed by a simple operation. Therefore, it is possible to provide a printed circuit board on which various electronic components having a high-density integrated circuit are mounted at a low price while maintaining high reliability.

  In addition, since the bridge prevention guide plate used in the printed circuit board soldering method of the present invention can be easily manufactured using a versatile material, the bridge prevention guide plate in the printed circuit board soldering method is used. Therefore, it is expected to be widely adopted as a bridge prevention guide plate or a printed circuit board soldering method in the technical field.

It is an expanded sectional view which shows one Example which concerns on the soldering method of the printed circuit board of this invention. It is an expanded sectional view which shows the other Example which concerns on the soldering method of the printed circuit board of this invention. It is an enlarged plan view which shows typically one Example of the bridge | bridging prevention guide plate used for the soldering method of the printed circuit board of this invention. It is an expanded sectional view which shows the further another Example which concerns on the soldering method of the printed circuit board of this invention. It is an expanded sectional view which shows the further another Example which concerns on the soldering method of the printed circuit board of this invention. It is an enlarged plan view which shows typically the other Example of the bridge | bridging prevention guide plate used for the soldering method of the printed circuit board of this invention. It is the enlarged plan view which shows typically the bridge | bridging prevention guide plate of the further another Example similarly used for the soldering method of the printed circuit board of this invention. It is a flowchart which shows typically the automatic soldering apparatus used for the soldering method of the conventional printed circuit board.

Explanation of symbols

1, 1a, 1b, 1c Printed circuit board 2, 2a, 2b, 2c Electronic component 3, 3a, 3b, 3c Lead 4, 4a, 4b, 4c Through hole 5, 5a, 5b, 5c Bridge prevention guide plate 5-1 5a-1, 5b-1 Mesh 5-2, 5a-2, 5b-2 Hole 5-3, 5a-3, 5b-3 Mounting hole 6, 6a, 6b, 6c Soldering jig

Claims (4)

In the method of soldering various electronic components through the leads to the through hole of the printed circuit board in the process of passing through the molten solder bath, the surface is processed into a mesh shape on the board surface, intermediate layer and solder surface of the soldering jig A printed circuit board soldering method, comprising interposing a sheet-shaped bridge prevention guide plate and then soldering in a molten solder bath. 2. The printed circuit board soldering method according to claim 1, wherein the bridge prevention guide plate is formed of a sheet-like thin plate made of metal or heat-resistant resin whose surface is processed into a mesh shape. In the method of soldering various electronic components to the through hole of the printed circuit board through the lead in the process of passing through the molten solder bath, it intervenes on the substrate surface, intermediate layer and solder surface of the soldering jig, A bridge prevention guide plate characterized by preventing formation of a bridge. 4. The bridge prevention guide plate according to claim 3, wherein the bridge prevention guide plate is formed of a sheet-like thin plate made of a metal or a heat-resistant resin whose surface is processed into a mesh shape.

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