JPH087655Y2 - Mounting structure for surface mount components - Google Patents

Description

[Detailed Description of the Invention] (b) Industrial field of application The present invention relates to a mounting structure of surface mounting parts by soldering surface mounting parts to a mounting land of a printed circuit board, and particularly reflow soldering using cream solder. The present invention relates to a surface mounting component mounting structure suitable for mounting.

(B) Problems to be Solved by Prior Art and Invention Conventionally, many mounting structures of surface mounting components having a mounting bottom surface on the bottom of the component are provided as shown in FIGS. 3 to 5. It was

FIG. 3 (A) is a perspective view when cream solder is applied to the entire mounting land of the printed circuit board to attach the surface mounting component, and FIG. 3 (B) is a diagram after mounting the surface mounting component of FIG. 3 (A). FIG. 4 (A) is a cross-sectional view, FIG. 4 (A) is a perspective view when cream solder is applied to approximately half of the mounting land of the printed circuit board to mount the surface mount component, and FIG. 4 (B) is the surface of FIG. 4 (A). FIG. 5 (A) is a cross-sectional view after mounting the mounting components, FIG. 5 (A) is a perspective view when the surface mounting components are mounted by applying cream solder to the small mounting land, and FIG. 5 (B) is the surface of FIG. 5 (A). It is sectional drawing after mounting component mounting.

In the figure, 1 is a printed circuit board on which surface mounting components are mounted, 4 is cream solder 4 applied to mounting lands, 4a is a solder fillet generated when the surface mounting components are mounted on the printed circuit board 1, and 6 is a surface mounted on the printed circuit board 1. Mounting component, 6a is a bottom electrode provided on the bottom of the surface mounting component 6,
6b is an end surface electrode provided at the end of the surface mounting component 6, 7 is another copper foil pattern provided between the mounting lands at the bottom of the surface mounting component 6, 10 is a mounting land of the printed circuit board 1, 11 is a soldering The generated solder balls, 12 are small mounting lands of the printed circuit board 1.

For example, as shown in the figure, electrodes 6a and 6b are provided at two locations, both bottom and both ends, of the surface mount component 6 having a substantially square shape, and the bottom electrodes 6a are the bottom electrodes 6a. Are attached to two mounting lands 10 provided at predetermined positions by soldering.

As shown in FIG. 3 (A), this soldering is performed by applying the cream solder 4 to the entire mounting land 10, contacting the bottom electrode 6a of the surface mounting component 6 on the cream solder 4, and applying heat treatment to the solder. I was attached.

However, as shown in FIG. 3 (B), the above-mentioned soldering has a large amount of solder and can be firmly attached, but as shown in the figure, a solder ball 11 is generated between the mounting lands 10 at the bottom of the surface mount component 6. However, if there is another copper foil pattern between the mounting lands, there is a risk that it may short-circuit with this copper foil pattern, or this solder ball may come off later and cause abnormal noise or short-circuit with other circuits. It was

In addition, in order to prevent the above-mentioned solder balls 11 from being generated, the fourth
As shown in FIGS. (A) and (B), cream solder 4 was applied to approximately half of the mounting land 10 for soldering.

However, the soldering of the surface mount component 6 can prevent the generation of the solder balls 11, but
Cannot be firmly attached to the printed circuit board 1, and the solder fillet 4a becomes small as shown in FIG. 4 (B).
There is a drawback that the surface mount component 6 is detached due to the vibration or dropping of the device.

In addition, as shown in FIGS. 5A and 5B, the surface mount component 6
If a small mounting land 12 having a length shorter than the length of the bottom electrode 6a is provided and the cream solder 4 is applied to the small mounting land 12 and soldered, the drawbacks of FIGS. 3 and 4 can be solved. For example, when there is another copper foil pattern 7 between the small mounting lands 12 as shown in FIG. 5 (B), the cream solder 4 is short-circuited with the copper foil pattern 7 via the bottom electrode 6a due to the solder heat processing. The disadvantage occurs.

This invention was made in view of the above points,
The purpose is to eliminate the drawbacks of the conventional example, and to divide the mounting land of the printed circuit board 1 and solder the bottom electrode of the surface mounting component on the outer side of the division to mount the surface mounting component. It is in the area of providing structure.

(C) Means for Solving the Problem The mounting structure of the surface mounting component of the present invention is such that the mounting land of the printed circuit board is mounted on the surface in the mounting structure of the surface mounting component having the mounting electrode at the bottom of the component mounted on the printed circuit board. It is configured to be divided into an outer mounting land and an inner mounting land when viewed from the mounting component, and solder is applied to only the divided outer mounting land to solder the mounting electrodes of the surface mounting component. .

(D) Function According to this invention, the mounting land of the printed circuit board is divided into the outer mounting land and the inner mounting land when viewed from the surface mounting component, and the cream solder is applied only to the divided outer mounting land, Mounting Mounted component's bottom electrode is brought into contact with the whole of the divided outer and inner mounting lands and subjected to soldering heat processing to firmly mount the surface mounted component to the printed circuit board and maintain the mechanical strength of solder mounting. it can.

Even if the cream solder applied to the outer mounting land flows by heat processing, this flowing solder will flow into the gap between the split mounting lands and prevent it from flowing out, and also prevent the generation of solder balls. it can.

(E) Embodiment First Embodiment of the mounting structure for surface mount components according to the present invention
A description will be given with reference to FIGS.

The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a perspective view of a surface mounting component mounting land formed on a printed circuit board, and FIG. 2 is a cross-sectional view of the surface mounting component mounted and subjected to solder heat processing for mounting.

In the figure, 2 is a first mounting land formed on the printed circuit board 1, 3 is a second device land, and 5 is a gap formed between the first mounting land 2 and the second mounting land 3. .

The mounting lands 2 and 3 for mounting the surface mount component 6 formed on the printed circuit board 1 are divided into an outer first mounting land 2 and an inner second mounting land 3 as shown in FIG.
And the second mounting lands 2 and 3 form a gap 5 therebetween.

The cream solder 4 is applied to the entire divided first mounting land 2 on the outer side, and the cream solder 4 is not applied to the second mounting land 3 on the inner side. The bottom electrode 6a is brought into contact with the first and second mounting lands 2 and 3 and subjected to solder heat processing for soldering.

The cream solder 4 applied to the first mounting land 2 is melted by heat processing, and the surface mount component 6 can be firmly attached to the printed board 1.

In this solder heat processing, the first mounting land 2 is divided into a smaller area than in the conventional example, so that the heat capacity is small and the heat efficiency of the solder heat processing is improved, so that the mounting work becomes easy.

Cream solder 4 melted by this solder heat processing
Flows out between the first mounting land 2 and the end surface electrode 6b of the surface mounting component 6 to generate a solder fillet 4a, which rises as shown in the figure to firmly solder the surface mounting component 6.

On the other hand, the cream solder 4 on the bottom electrode 6a side is the bottom electrode 6a.
Flow toward the second mounting land 3 through the first and second
It falls into the gap 5 formed between the mounting lands 2 and 3 of.

That is, the cream solder 4 at the bottom of the surface mount component 6 does not flow out to the outside, and there are problems such as the generation of solder balls and a short-circuit with another copper foil pattern formed at the bottom of the surface mount component 6 as in the conventional example. Can be prevented.

As described above, the mounting land on the printed circuit board 1 is divided into the first and second mounting lands 2 and 3 in a substantially linear manner as shown in the drawing. It may be divided by a curved line other than a straight line depending on the shape of 6a.

(F) Effect of the Invention In the mounting structure for surface mount components according to the present invention, as described above, the mounting lands on the printed circuit board are divided, and a gap is provided between the divisions. Therefore, reflow soldering using cream solder is used. There is an effect that it is possible to prevent the generation of unnecessary solder balls by attaching.

Further, in this soldering, the solder can be sufficiently raised up to the end surface electrodes of the surface mount component to form the solder fillet, and the mechanical strength of the solder can be secured.

Further, since the area of the divided first mounting land is small, the heat capacity becomes small, the melting speed of the solder increases, and good soldering can be performed.

Furthermore, since the split mounting land on the printed circuit board is formed to have almost the same size as the bottom surface electrode of the surface mount component,
Another copper foil pattern cannot be formed immediately under the vicinity of the bottom electrode, and it is possible to prevent a problem such as a short circuit between the another copper foil pattern and the soldering portion of the bottom electrode.

Moreover, it has excellent features such as a simple structure and easy implementation because it can be constructed at low cost.

[Brief description of drawings]

1 and 2 show an embodiment of a mounting structure for surface mounting components according to the present invention. FIG. 1 is a perspective view of a surface mounting component mounting land formed on a printed circuit board, and FIG. 2 is a surface mounting component. FIG. 4 is a cross-sectional view when the is mounted and subjected to solder heat processing and mounted. 3 to 5 show a conventional example, FIG. 3 (A) is a perspective view when cream solder is applied to the entire mounting land of a printed circuit board and surface mounting components are mounted, and FIG. 3 (B) is FIG. 3 (A) is a cross-sectional view after mounting the surface mount component, and FIG. 4 (A) is a perspective view when mounting the surface mount component by applying cream solder to substantially half of the mounting land of the printed circuit board,
FIG. 4 (B) is a cross-sectional view after mounting the surface mounting components of FIG. 4 (A), and FIG. 5 (A) is a perspective view when mounting the surface mounting components by applying cream solder to a small mounting land. 5 (B) is a cross-sectional view after mounting the surface mount component of FIG. 5 (A). Explanation of main symbols 1: Printed circuit board for mounting surface mounting components, 2: First mounting land on printed circuit board, 3: Second mounting land on printed circuit board, 4: Cream solder applied to mounting land, 4
a: solder fillet, 5: gap between the first and second mounting lands, 6: surface mounting component, 6a: bottom electrode of surface mounting component, 6b: end face electrode of surface mounting component,

Claims (1)

[Scope of utility model registration request] 1. In a surface mounting component mounting structure for mounting a surface mounting component having a mounting electrode on the bottom of the component to a printed circuit board, a mounting land of the printed circuit board is divided into an outer mounting land and an inner mounting land when viewed from the surface mounting component. The surface mounting component mounting structure is characterized in that the mounting electrodes of the surface mounting component are soldered by applying solder only to the divided outer mounting lands.