JP4263765B1 - Electronic component soldering method - Google Patents

Abstract

An electronic component soldering method is provided in which when a lead of an electronic component is inserted into a through hole, the filled solder does not fall out of the through hole or the land on the solder surface.
A component surface 3 of a printed circuit board 1 is placed on the lower side, a predetermined gap 5 is formed, and the metal mask 11 is aligned with the solder surface 9 on the upper side without a gap 5 on the solder holding plate 7. The cream solder 13 is applied from above the metal mask 11, and then the lead of the electronic component 17 is inserted into the through hole 109 filled with the cream solder 13 by application, with the component surface 3 of the printed circuit board 1 facing upward. Heat from the solder surface 9 side. At the time of lead insertion, a plurality of brush-like protrusions are arranged on the lower side of the through hole 109 to prevent the cream solder 13 from falling off.
[Selection] Figure 1

Description

  The present invention relates to a method for mounting an electronic component on a printed circuit board by soldering.

A method of mounting electronic components on a printed board by soldering is widely performed.
That is, as shown in FIG. 9, one surface of the printed circuit board 101, usually the upper surface, is a component surface 105 on which the electronic component 103 is mounted. The opposite surface is a solder surface 107 that is heated and soldered.
As shown in FIG. 10, in order to make electrical connection between the component surface 105 and the solder surface 107, a hole that is formed in a necessary portion and chemically plated on the inner surface side of the hole is referred to as a through hole 109. In many cases, the component hole 111 of the electronic component 103 is inserted into the through hole 109 and soldered. The hole diameter varies depending on the attachment component lead 111.

Further, as shown in FIGS. 10 and 11, a thin copper pattern 113 is formed on the component surface 105 in order to electrically connect a plurality of electronic components 103. A portion of the pattern 113 that does not require solder is covered with a resist film 115.
As shown in FIG. 11, a specific wide portion provided for attaching the electronic component 103 or the like in the pattern 113 is referred to as a land 117. The land 117 is often formed in a ring shape around the through hole.
Conventionally, solder has an alloy composition of 63% tin and 37% lead and a melting temperature of 183 ° C. This alloy composition has been generally used in the manufacture of electrical products because of its good solderability and good finish.
As shown in FIG. 12, in order to make a normal printed circuit board 101 in a large amount and quickly, after inserting the component lead 111 of the electronic component 103 into the through hole 109 of the substrate, the molten solder 119 is blown directly onto the solder surface, This is soldering to fill the through hole 109.
Since the alloy composition described above contains lead, it has good wettability. By blowing up, the solder 119 can pass through the through hole 109 to the land 117 of the component surface 105. In the soldering state, the solder 121 is bonded to the lands 117 of the component surface 105 and the solder surface 107 from both sides (see FIG. 8).

Patent Document 1 describes a technique for adjusting the amount of solder in order to prevent the cream solder from dropping when the electronic component 103 is mounted.
Patent Document 2 describes a technique for fixing a mounting component with a nail.
JP2002-026502 JP 07-312473

However, in recent years, the use of lead has been regulated due to environmental problems, and lead-free solder that does not contain lead is often used. A typical solder developed with lead-free solder has an alloy composition of 96.5% tin, 3% silver, 0.5% copper, and a melting temperature of 220 ° C, an increase of 37 ° C. Further, the wettability is inferior to that of conventional solder, and only the portion where the molten solder has spread is soldered. For this reason,
(1) When the solder melted by the conventional manufacturing method is blown up, the solder filled in the through hole can only go to the portion filled with the blowing pressure, so that the defective product shown in FIG. That is, the solder hole 121 is not sufficiently filled in the through hole 109, and the strength of the attached electronic component is inferior.

(2) Moreover, as shown in FIG. 14, the printed circuit board 101 manufactured by blowing up is always in an unsoldered state because the solder 121 does not reach the land on the component surface.
(3) And, as shown in FIG. 15, if the blowing pressure is increased for sufficient filling, the molten solder is connected to the adjacent pattern (the electronic component on the left in the figure).
(4) Accidents such as soldering failure (electronic parts on the right in the figure) occur due to blowing up and down.
(5) Also, since the melting temperature has risen, when the printed circuit board is cold, if the molten solder is blown up, the solder will be cured immediately. For this reason, it is necessary to heat and heat the printed circuit board in advance.
(6) Without using the solder blowing technique as described above, it may be possible to fill the through hole with soft solder in advance, but in that case, when inserting the lead of the electronic component into the through hole, There is a high possibility that the filled solder will fall out of the through hole and the applied solder amount cannot be maintained.

In order to solve the above problems, the present invention
(1) Solder sufficient for mounting electronic parts can be filled in the component mounting through hole on the printed circuit board. (2) Soldered on the solder surface land and through hole, and part of the land on the component surface is also soldered. 3) (4) No erroneous connection or un-soldering accident, (5) No need to heat printed circuit board in advance, (6) Solder filled when electronic component leads are inserted into through holes An object of the present invention is to provide an electronic component soldering method in which the amount of applied solder is maintained without falling off from a through hole or the like.

  In order to solve the above-mentioned problems, the first invention is a solder on the upper side, with a component surface being one side of the printed circuit board facing downward, a predetermined gap being formed, and being aligned with the solder pressing plate. A step of aligning a metal mask on the surface without gaps, a step of applying cream solder from above the metal mask, and an electronic component in the through hole filled with the cream solder by the application with the component surface of the printed circuit board facing upward And mounting the electronic component, and heating the printed circuit board from the lower solder surface side after the mounting. Is the method.

  The second invention includes a step of arranging a plurality of brush-shaped protrusions upward on a lower side of a through hole filled with cream solder with a component surface being one side of the printed circuit board as an upper side, and an electron in the through hole. Inserting a component lead and mounting the electronic component; and removing the plurality of brush-like protrusions after the mounting and heating the printed circuit board from a lower solder surface. The electronic component soldering method is characterized.

  According to the first invention, the printed circuit board is sandwiched between the metal mask and the solder pressing plate from above and below, and the cream solder is applied from above the metal mask, so that it can be applied at an accurate position, and the solder is sufficiently passed through the through hole to the back side. Since it can be filled, (1) Solder sufficient for mounting electronic parts can be filled in the component mounting through hole on the printed circuit board. (2) Soldered on the land and through hole on the solder surface, and part of the land on the component surface is also soldered. Attached.

  Also, since it is not necessary to blow up the molten solder at high pressure by filling it up as in the past, (4) there is no erroneous connection due to the solder being blown up, and (3) unsoldering accident due to failure in adjustment of blowing up and down. Does not occur. Furthermore, both the printed circuit board and the cream solder can be heated from room temperature, and it is not necessary to warm the printed circuit board in advance as in the prior art ((5)).

  According to the second aspect of the present invention, the plurality of brush-like protrusions are disposed upward on the lower side of the through hole filled with the cream solder so that the lead can pass through the gaps between the plurality of brush protrusions. The applied cream solder is held at the tips of the plurality of protrusions of the brush and does not come off, so that the applied solder amount is maintained ((6)).

An embodiment of the present invention is shown in FIGS.
[Step of filling through hole 109 with solder]
As shown in FIG. 1, the printed circuit board 1 is turned upside down, and the component surface 3 on the lower side is aligned with the solder pressing plate 7 with a predetermined gap 5, and further on the upper side of the printed circuit board 1. The metal mask 11 is aligned with the solder surface 9 without a gap 5. The solder pressing plate 7 is made of a material to which the cream solder 13 does not adhere.

As shown in FIGS. 1 and 2, cream solder 13 is applied to the solder surface 9 on the upper side of the printed circuit board 1 with a squeegee 15.
That is, the cream solder 13 is mixed with flux in a fine particle state. Stir the cream solder 13 to make it soft. In this state, the land 117 on the solder surface 9 is applied. The cream solder 13 passed through the metal mask 11 is filled in the through hole 109. At this time, the cream solder 13 that has flowed through the through hole 109 due to the pressure of the squeegee 15 is pressed by the solder pressing plate 7, and is repelled and filled into the gap 5 with the component surface 3. As a result, a thickness corresponding to the gap is applied to the land 117 side of the component surface 3.

  As shown in FIG. 3, when the metal mask 11 is removed, the land on the solder surface 9 coincides with the land 117 on the component surface 3 and is applied in a uniform state. The entire surface of the through hole 109 is filled. When the solder holding plate 7 is removed, a part of the land is applied to the land 117 of the component surface 3 in a uniform state.

[Attaching electronic parts to the through hole 109 filled with solder]
Next, as shown in FIG. 4, the lead 19 of the electronic component 17 is processed in advance so as to have an appropriate length when attached.
Then, as shown in FIG. 5, the printed circuit board 1 is changed from the inverted state to the correct state, and the component surface 3 is set to the upper side. The electronic component 17 is mounted on the component surface 3. That is, the lead 19 of the electronic component 17 is inserted and attached to the through hole filled with the solder 13. At this time, the insertion of the lead 19 may cause the cream solder 13 filled in the through hole to be pushed out and fall off. In order to prevent this, a brush-like article 21 is prepared on the lower solder surface 9 side.

  Since the lead 19 is a single wire, it can pass through the gaps 5 between the plurality of protrusions 23 of the brush as shown in FIG. The filled cream solder 13 may fall off due to the pressure of the component lead 19 at the time of insertion. However, the cream solder 13 is held at the tips of the plurality of protrusions 23 of the brush and does not fall off.

As shown in FIG. 7, the mounted electronic component 17 holds the lead 19 inserted by the flexibility of the cream solder 13, so that the mounted electronic component 17 is kept in a mounted state and does not collapse or fall down.
[Process of soldering by heating]
Further, by heating the printed circuit board 1 from the solder surface 9 side in the state of FIG. 7, the cream solder 13 is dissolved in the component lead 19 together with the land of the solder surface 9, the through hole and the land of the component surface 3. The entire land of the solder surface 9 is covered with the solder 25 (FIG. 8). The lands on the component surface 3 are partially covered with solder and connected. The mounting strength is maintained by the solder 25 of both lands and through holes.

Furthermore, since both the printed circuit board 1 and the cream solder 13 are heated from room temperature (the printed circuit board 1 does not need to be heated and heated in advance), it is possible to manufacture by soldering once.
Except for through holes and lands, no extra processing is added, so there is no dirt. For example, unlike the conventional case, the molten solder is blown from the solder surface side of the printed circuit board with a high pressure, and the solder does not adhere to the adjacent pattern with the molten solder.

"Effect of the embodiment"
According to this embodiment, as shown in FIGS. 1 to 3, the printed circuit board 1 is sandwiched between the metal mask 11 from above and the solder pressing plate 7 from below, and the cream solder 13 from above the metal mask 11. Since it is applied, it can be applied to an accurate position from a hole or the like made in the metal mask 11. Further, the solder pressing plate 7 can prevent the solder from dropping off through the through hole, and the gap 5 between the solder pressing plate 7 can sufficiently fill the solder through the through hole 109 to the back side.

Therefore, (1) the component mounting through hole 109 of the printed circuit board 1 can be filled with sufficient solder for mounting the electronic component 17, and (2) the land 117 and through hole 109 of the solder surface 9 are all soldered. A part of the third land 117 is also soldered.
Further, since it is not necessary to blow up the melted solder at a high pressure to fill the through hole 109 as in the prior art, (4) no erroneous connection due to the solder that is blown up. Conversely, (3) no unsoldering accident due to failure in adjustment of blowing up or down does not occur.
Furthermore, both the printed circuit board 1 and the cream solder 13 can be heated from room temperature. Therefore, it is not necessary to heat the printed circuit board 1 in advance and raise the temperature as in the prior art ((5)). Therefore, no stress due to heat is applied to the electronic component 17.
Further, by arranging a plurality of brush-like projections 23 on the lower side of the through hole 109 filled with the cream solder 13, the lead 19 is inserted into the through hole 109 and then between the plurality of projections 23 of the brush. On the other hand, the filled cream solder 13 is held at the tips of the plurality of protrusions 23 of the brush and does not fall off. Therefore, the amount of solder applied to the through hole or the like is maintained ((6)).
"Other embodiments"
In the above embodiment, the brush-like protrusion is used in order to prevent the cream solder filled in the through hole from falling off. However, in other embodiments, the cream solder can be used without using the brush-like protrusion. Although the work efficiency is reduced by adjusting the viscosity of the product, mounting the components from the bottom with the component side down, and mounting the electronic components from the horizontal with the printed circuit board in the vertical direction, It can prevent omission.
In the above embodiment, the solder pressing plate is used in order to sufficiently fill the cream solder to the back side through the through hole. However, in other embodiments, for example, both sides of the printed circuit board can be used without using the solder pressing plate. By applying the cream solder from above the metal mask, the working efficiency is lowered, but the cream solder can be sufficiently filled.

It is a longitudinal cross-sectional view of the printed circuit board by which cream solder is shown which shows one Embodiment of this invention. It is a longitudinal cross-sectional view just after application | coating of FIG. It is a longitudinal cross-sectional view of the printed circuit board after application | coating of FIG. It is a longitudinal cross-sectional view of the concept which processes the lead of an electronic component into appropriate length. The printed circuit board of FIG. 3 is turned over to the original state, and a cross-sectional view showing a state in which a plurality of brush-like protrusions are arranged upward and a lead of an electronic component is inserted below the through hole filled with cream solder. It is. It is a figure which shows the effect | action of the brush-shaped protrusion of FIG. FIG. 7 is a vertical cross-sectional view of a printed circuit board on which electronic components are mounted by inserting leads of FIGS. 5 and 6. It is a longitudinal cross-sectional view of the printed circuit board after the soldering by heating was made from the state of FIG. It is a figure of a mode that an electronic component is mounted in the printed circuit board which shows a prior art. FIG. 10 is a longitudinal sectional view showing a state in which a lead of an electronic component is inserted into the through hole of FIG. 9 and soldered. (A) is a view of the through hole in FIG. 10, and (B) is a perspective view of a land formed around the through hole. It is a figure which shows a mode that the molten solder is directly blown up to a solder surface by the conventional printed circuit board manufacturing method, and a through hole is filled. It is a longitudinal cross-sectional view which shows the defective product of the soldering produced by the conventional printed circuit board manufacturing method of FIG. FIG. 13 is a longitudinal sectional view showing defective soldering similarly produced in the conventional printed circuit board manufacturing method of FIG. 12. FIG. 13 is a longitudinal sectional view showing defective soldering similarly produced in the conventional printed circuit board manufacturing method of FIG. 12.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printed circuit board, 3 ... Component surface, 5 ... Gap, 7 ... Solder pressing board, 9 ... Solder surface, 11 ... Metal mask, 13 ... Cream solder, 15 ... Squeegee, 17 ... Electronic component, 19 ... Lead, 21 ... Brush-like article, 23 ... projection, 25 ... solder, 101 ... printed circuit board, 103 ... electronic component, 105 ... component surface, 107 ... solder surface, 109 ... through hole, 111 ... component lead, 113 ... pattern, 115 ... Resist film, 117... Land, 119.

Claims (2)

  A step of arranging a plurality of brush-like protrusions upward on the bottom side of the through hole filled with cream solder, with the component surface, which is one side of the printed circuit board, facing upward, and inserting electronic component leads into the through hole And mounting the electronic component, and removing the plurality of brush-like protrusions after the mounting and heating the printed circuit board from a lower solder surface. Soldering method. A step of aligning a metal mask with no gap on the solder surface on the upper side of the solder holding plate with a predetermined gap with the component surface being one side of the printed circuit board facing down, and the metal A step of applying cream solder from above the mask, and a step of arranging a plurality of brush-like protrusions upward on the lower side of the through hole filled with the cream solder by the application with the component surface of the printed circuit board facing upward Inserting a lead of an electronic component into the through hole filled with the cream solder and mounting the electronic component; and heating the printed circuit board from the solder side facing down after the mounting A soldering method for an electronic component comprising the steps of:

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