JPS5992597A - Method of soldering electronic part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an electronic component in which an electrode part of a leadless electronic component is connected to a board circuit electrode of a printed circuit board by a solder refill port, and the electronic component is mounted on a printed circuit board. This relates to a soldering method.

When mounting leadless electronic components on a printed circuit board, apply cream solder in advance to the circuit electrodes of the printed circuit board at positions where the electrodes of the electronic components and the circuit electrodes of the printed circuit board can be connected. and place the electronic components there.

Then, the connection between the electrode part of the electronic component and the board circuit electrode of the printed circuit board is fixed using a solder reflow method in which the cream solder is heated and melted. To prevent soldering failure, it is necessary to use a thermosetting adhesive to fix the electronic component to the printed circuit board before the solder refrigeration opening, and the adhesive has a large interaction with the cream solder. have.

(Conventional technology) The conventional example will be explained below based on the drawings.

Figure 1 (a) is a plan view showing a conventional example in which electronic components are fixed to a printed circuit board with adhesive, Figure 1 (b) is a cross-sectional view of the same side, and Figure 1 (c) is after solder reflow. It is a sectional view of the same side.

In the figure, 1 is a printed circuit board, 2 is the printed circuit board 1
a board circuit electrode formed on the board circuit electrode; 3, cream solder applied by a mold at predetermined intervals on the board circuit electrode 2; 4, a thermosetting adhesive applied to the middle of the cream solder 3; 5 is a leadless small electronic component, and 6 is an electrode portion of the small electronic component 5. Since the small electronic component 5 is placed with the bottom surface of the electrode portion 6 in contact with the cream solder 3, the predetermined interval of the cream solder 3 is the distance between both electrode portions 6 of the small electronic component 5. Refers to the interval.

Soldering during mounting of the small electronic component 5 in the conventional example configured as described above will be described below.

First, cream solder 3 is applied onto the board circuit electrodes 2 formed on the printed circuit board 1 at the predetermined intervals described above using a mold.

Next, a thermosetting adhesive 4 is applied to the middle of both cream solders 3, and a small electronic component 5 is placed on the electrode portion 6.
using a mounter so that its bottom surface is in contact with the cream solder 3.

Then, the adhesive 4 is heated and solidified to fix the small electronic component 5 to the printed circuit board 1.

This is to prevent the small electronic component 5 from moving during the next solder reflow.

After that, the cream solder 3 is heated and melted to form the printed circuit board 1.
The substrate circuit electrode 2 and the electrode part 6 of the small electronic component 5 are connected and fixed.

However, the use of the cream solder 3 and the adhesive 4 in such a method is limited to the thickness of the cream solder 3 applied between the electrodeposition part 6 of the small electronic component 5 and the board circuit electrode 2 of the printed circuit board 1. , the distance between the printed circuit board 1 and the small electronic component 5 becomes large, and therefore the adhesive 3 applied there must be applied to a thickness higher than the thickness of the cream solder 3. Moreover, the small electronic components 5 are required to be mounted with high density, and the smaller the electronic components, the narrower the area in which the adhesive 4 can be applied.

In such a situation, if you apply an appropriate amount of ream solder 3, the amount of adhesive 4 applied may be large depending on its thickness, and some of it may stick to the cream solder 3, or a short circuit may occur due to the cream solder 3 protruding. Alternatively, there have been drawbacks such as poor soldering such as a gap forming between the electrode portion 6 of the small electronic component 5 and the cream solder 3, and components being damaged by repeated stress due to thermal shock tests after soldering. .

(Purpose of the Invention) Therefore, by changing the method of applying cream solder from the conventional method, the present invention makes it possible to reduce the distance between the printed circuit board and small electronic components, and when using an appropriate amount of cream solder, it is possible to The purpose of this invention is to solve the drawbacks of the conventional method by using an appropriate amount of the agent.

(Structure of the invention) Its detailed characteristics are as follows.

Apply cream solder to the board circuit electrodes of the printed circuit board so that there is a very small gap between the electrodes of the small electronic components to be mounted, or Apply a thin layer of cream solder once on the board circuit electrode of the printed circuit board so that it is in contact with the bottom of the electrode section, and then apply cream solder to compensate for this on both sides of the electrode section of the small electronic component as described above. Furthermore, by applying cream solder to form a small gap, the distance between the printed circuit board and small electronic components can be further reduced when using an appropriate amount of cream solder, and therefore the adhesive used can also be reduced. The reason is that it can be used in an appropriate amount without causing any harm to others.

(Example) The method of the present invention will be specifically explained below based on the drawings of the example. Note that since the parts and materials used are the same as in the conventional example, the same reference numerals are also used.

FIG. 2(a) shows a first embodiment of the present invention, and is a plan view of a small electronic component fixed to a printed circuit board with adhesive;
FIG. 2(b) is a sectional view of the same side, and FIG. 2(C) is a sectional view of the same side after solder reflow.

In the figure, 1 is a printed circuit board, 2 is the printed circuit board 1
The board circuit electrodes 3 formed on the board circuit electrodes 2 are cream solder, 4 applied by a mold at predetermined intervals on the board circuit electrodes 2.
5 is a thermosetting adhesive applied to the middle of both cream solders 3, 5 is a small leadless electronic component, and 6 is an electrode portion of the small electronic component 5. Since the small electronic component 5 is arranged with the outer ends of the electrode portions 6 facing the cream solder 3, the predetermined interval of the cream solder 3 means the outer ends of both electrode portions 6 of the small electronic component 5. An interval that is very slightly longer than the length from the outer edge to the outer edge. In other words, the distance from one end of the small electronic component 5 to the other is very slightly larger than that of the other end.

The soldering process when mounting the small electronic component 5 in the first embodiment configured as described above is as follows.

First, cream solder 3 is applied with a mold onto the board circuit electrodes 2 formed on the printed circuit board 1 at the predetermined intervals described above.

Next, apply thermosetting adhesive 4 to the middle of the cream solder 3.
Then, apply cream solder 3 to the outer edge of the electrode section 6 of the small electronic component 5 between the cream solder 3.
The small electronic component 5 is placed using a mounter so as to face the small electronic component 5.

Then, the small electronic component 5 is adhesively fixed to the printed circuit board 1 by heating and curing the adhesive 4 by opening or the like. This is to prevent the small electronic component 5 from moving during the next solder reflow as in the conventional case.

After doing this, the cream solder 3 is heated and melted in a conveyor furnace or the like to form the electrode part 6 of the small electronic component 5 and the printed circuit board 1.
This is to connect and fix the 0-substrate circuit electrode 2.

As explained above, in the first embodiment, the cream solder 3 is not applied between the electrode section 6 of the small electronic component 5 and the circuit board circuit electrode 2 of the printed circuit board 1, so that the printed circuit board 1
The distance between the small electronic component 5 and the small electronic component 5 is minimized. Therefore, there is an advantage that the amount of adhesive 4 used therein can also be minimized. Further, since the amount of cream solder 3 applied is not related to the distance between the printed circuit board 1 and the small electronic component 5, there is an advantage that a sufficient appropriate amount can be supplied.

Next, a second embodiment will be explained.

FIG. 3(a) shows a second embodiment of the present invention; FIG. 3(b) is a plan view of a small electronic component fixed to a printed circuit board with adhesive; FIG. 3(b) is a sectional view of the same side; Figure (C) is a sectional view of the same side after solder reflow.

In the figure, 1 is a printed circuit board, 2 is the printed circuit board 1
The substrate circuit electrode 3a formed on the substrate circuit electrode 2
Cream solder applied at predetermined intervals on top; 3b is cream solder that is dried or melted by heating, cooled and solidified, and then further applied at predetermined intervals on top; 4 is the cream solder. A thermosetting adhesive is applied to the middle of 3a and 3b, 5 is a small electronic component, and 6 is both electrode portions of the small electronic component 5. The small electronic component 5 is placed on a mounter so that the bottom surfaces of both electrode portions 6 are in contact with the cream solder 3a, and the side surfaces are opposed to the cream solder 3b with an extremely small gap. Therefore, the cream solder 3
The predetermined distance a is the distance between the bottom surfaces of both electrode portions 6 of the small electronic component 5, and the predetermined distance of the cream solder 3b is the distance between the electrode portions 6 of the small electronic component 5, as in the first embodiment. A very small gap is formed with the side surface, that is, a slightly large gap between the electrodes from one end of the small electronic component 5 to the other.

Soldering when mounting small electronic components in this second embodiment first begins with soldering the circuit board electrodes 2 formed on the printed circuit board 1.
Cream solder 3a is applied on top using a mold at the predetermined intervals described above. After drying or heating and melting this cream solder 3a, it is cooled or solidified. Cream solder 3b to supplement the cream solder 3a is applied onto the cream solder 3a at the above-mentioned predetermined intervals using a mold.

Solidification of the cream solder 3a, this cream solder 3b
This is to prevent the cream solder 3a from collapsing during application using the mold.

A thermosetting adhesive 4 is applied to the middle of both cream solders 3a and 3b, and the bottom surface of the electrode section 6 of the small electronic component 5 is brought into contact with the cream solder 3a, and the side surface is placed with a mounter so as to face the cream solder 3b.

After this, as in the first embodiment, the adhesive 4 is heated and solidified by opening, etc., and then cream solder 3a, 3b is applied in a conveyor furnace.
The substrate circuit electrodes 2 of the printed circuit board 1 and the electrode portions 6 of the small electronic components 5 are connected and fixed by heating and melting.

In this way, in the second embodiment, since the cream solder 3a is applied thinly, the distance between the printed circuit board 1 and the small electronic component 5 can be made smaller than in the past, and the adhesive 4 used can also be used to prevent contamination of other parts. At the same time, if the amount of cream solder 3a only needs to be used depending on the type of small electronic component 5, it is better not to apply cream solder 3b. There is an advantage in that the amount of solder supplied can be adjusted by applying cream solder 3b to compensate for it if it is less.

It also has the advantage of being able to apply the cream solders 3a and 3b, the amount of adhesive applied, the mounting height of the mounter, etc. under the same conditions.

(Effects of the Invention) As described in detail above, in the present invention, cream solder is applied to both sides of a small electronic component so as to form an extremely small gap with the electrode portion of the small electronic component to be mounted. In Example 1, a thin layer of cream solder is once applied to the position where it contacts the bottom surface of the electrode part of the small electronic component, and cream solder to supplement this is applied on both sides of the electrode part of the small electronic component in the same manner as in the 16th embodiment. In the second embodiment, cream solder is further applied on top of the cream solder so as to form a slight gap, so that even if an appropriate amount of cream solder is always supplied, the space between the printed circuit board and the small electronic component is not the same as that of the first embodiment. In the embodiment, the amount of adhesive can be minimized, and in the second embodiment, it can be made much smaller than before, so you can apply an appropriate amount of adhesive without worrying about having to apply too much adhesive that will stain others. There are advantages that can be used.

The second embodiment also has the advantage that the amount of cream solder supplied can be adjusted depending on the type of small electronic component.

In this way, it has the advantage of being able to use an appropriate amount of cream solder and adhesive, which reduces soldering defects and provides reliable electronic components. It is very effective when used as a soldering method in high-density mounting.

[Brief explanation of the drawing]

Fig. 1(a) is a plan view showing a conventional example in which small electronic components are fixed to a printed circuit board with adhesive, Fig. 1(b) is a sectional view of the same side, and Fig. 1(C) is the same after soldering reflow. A sectional side view, FIG. 2(a) shows a first embodiment of the present invention, and a plan view showing a small electronic component fixed to a printed circuit board with an adhesive. FIG. 2(b) is a sectional view of the same side, and FIG. Figure (C) is a sectional view of the same side after soldering reflow, Figure 3 (a) is a plan view showing the second embodiment, in which a small electronic component is fixed to a printed circuit board with adhesive, and Figure 3 (b) is a top view of the second embodiment. 3(C) is a sectional view of the same side after solder reflow. 1... Printed circuit board 2... Board circuit electrode 3.3
&. 3b... Cream half 1) 4... Adhesive 5... Small electronic component 6... Electrode part Patent applicant Oki Electric Industry Co., Ltd. agent Patent attorney Takashi Kanakura @1 b(a) ( b) (C) 42 cill 1 m 31 m (a) (a) (C) (C) Procedural amendment axis) September 1, 1980 Mr. Kazuo Wakasugi, Commissioner of the Patent Office 1, Indication of the case 1981 Patent Application No. 201991 2. Title of the invention Method for soldering electronic components 3. Relationship with the amended case Patent applicant address 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Hashimoto Nankai O 4, Agent 7, Contents of amendment 1, Specification page 2, line 1θ, page 4, line 8, page 8, line 7
line, page 9, line 8, page 10, line 7, and page 11, line 1
In line 2, "heat melting" should be corrected to "heat melting." 2. Delete “by mold” on page 3, line 6 of the specification.0 3. Correct “by mold” to “by screen printing” on page 3, line 19 of the specification. do. 4. In the first line of page 7 of the specification, the words "depending on the model" should be deleted. 5. Delete "by type" from line 6 on page 10 of the specification. 6. In the 10th line of page 10 of the specification, delete the phrase "Use r-type." 7. In the 10th page, line 12 of the specification, delete the phrase "in type".

Claims (1)

[Claims] 1. Apply cream solder on the circuit electrodes of the printed circuit board, and bond and fix the leadless electronic components to the printed circuit board with a thermosetting adhesive.The circuit electrodes of the printed circuit board and the electronic components are bonded by reflowing the second half of the mold. In the method of soldering electronic components to connect and fix the electrode parts, cream solder is applied onto the board circuit electrodes of the printed circuit board so as to form a very small gap between the electrode parts of the electronic parts, or
Alternatively, apply a thin layer of cream solder so that it comes into contact with the bottom surface of the electrode section of the electronic component, and if necessary, apply cream solder to supplement this cream solder on top of it, leaving a very small gap between it and the electrode section of the electronic component. A method for soldering electronic components, characterized in that the soldering method is applied so as to form a .