JPH08102596A - Method for mounting surface-mounting parts - Google Patents

Abstract

PURPOSE: To improve the reliability and quality of the mounting state of surface mounting parts even when parts having different terminal pitches are mounted in a mixed state. CONSTITUTION: At the time of mounting a plurality of surface-mounting chip parts 3a and 3b having different terminal pitches on a printed board 1, the printing thickness of solder is controlled to an appropriate value and the numbers of solder opens, solder bridges, etc., are reduced by dividing the parts 3a and 3b into groups based on the size ranges of their terminal pitches and respectively mounting the groups on different surfaces of the board 1 in such a way the group of parts 3a is mounted on the front surface 1a of the board 1 and the group of parts 3b is mounted on the rear surface 1b of the board 1. In addition, other chip parts 4a and 4b are also mounted on a sub-printed board 2 provided to increase the mounting surface by dividing the parts 4a and 4b into groups in the same way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting component mounting method for mounting a surface mounting component on a printed circuit board.

[0002]

2. Description of the Related Art As a means for achieving high-density mounting on a printed circuit board on which electronic components are mounted, chip components (surface mounting components) in which lead wires are miniaturized (or lead wires are eliminated) are used as electronic components. There is a method of directly mounting on the surface of the substrate.

The terminal pitch of such surface mount components is
2.54mm, 1.27mm, 1.08mm, 0.8m
m, 0.65mm, 0.5mm, 0.4mm, 0.3m
There are various types such as m, etc., and conventionally, these terminal pitches are mixed and mounted on a printed circuit board.

[0004]

However, at the time of mounting, the proper coating thickness of the solder paste supplied to the footprint of the printed board differs depending on the terminal pitch. Therefore, when components with wide terminal pitch and components with narrow terminal pitch are mixed, if solder paste coating thickness is increased and reflow soldering is performed, solder bridges between terminals frequently occur in components with narrow terminal pitch, and conversely, solder When the paste application thickness is made thin, there is a problem that solder end joints (solder open) frequently occur between the footprint of the printed circuit board and the terminals of the chip component in a component having a wide terminal pitch.

Further, the printed circuit board is limited to the two mounting surfaces, that is, the front surface and the back surface, of the surface mounting component, for example, SOP (Small).
The terminal (electrode) pitches of Outline Package), QFP (Quad Flat Package), etc. are various as described above, and mixing is inevitable. Therefore, although measures such as half-etching the solder paste printing plate (stencil) to adjust the solder printing amount are taken, there is a problem that the solder paste remains in the half-etched portion.

An object of the present invention is to provide a mounting method of surface mounting components which can improve the reliability and quality of mounting even when surface mounting components having different terminal pitches are mixedly used.

[0007]

In order to achieve the above object, the present invention, when mounting a plurality of surface mount components having different terminal pitches on a printed circuit board, measures the size of the terminal pitch of the surface mount components to be mounted. Divide into groups according to range,
Each group is mounted on a different board surface.

The printed circuit board is composed of a main printed circuit board and a sub-printed circuit board, and both of them can be integrated in a multi-layered state.

In this case, there are various methods for integrating the main printed circuit board and the sub printed circuit board. Specifically, surface mounting components are mounted on both sides of the sub-printed board, and the main printed-circuit board is connected with through holes and pins. Mounting components are not provided, and both are connected via the footprint provided in the joining area.
A portion of the main printed circuit board facing the sub printed circuit board is opened, and the main printed circuit board and the sub printed circuit board are coupled to each other through a footprint provided at a joint portion around the opening of each board. There are three methods.

[0010]

According to the above-described means, focusing on the fact that the solder failure is caused by the mismatch between the thickness of the solder printing plate and the terminal pitch, avoiding the mixed mounting of surface-mounted components having greatly different terminal dimensions, the solder printing plate thickness When a certain value is set to a certain value, the surface mount components up to the terminal pitch such that solder failure does not occur due to this are grouped together, and these are mounted on mutually different board surfaces. As a result, solder defects such as solder open and solder bridge can be reduced, and product quality and reliability can be improved.

With a single printed circuit board, only two mounting surfaces can be secured. Therefore, if a sub-printed circuit board is provided and connected to the main printed circuit board, the two surfaces can be further covered and the number of types of surface-mountable components that can be mounted can be increased.

The connection between the main printed circuit board and the sub printed circuit board can be fixed by soldering by using through holes and pins, or by using a footprint when surface mounting components need not be mounted in the joint area. Can be fixed. It is also possible to provide an opening on the side of the main printed circuit board and stack the surface mount components on one side of the sub printed circuit board so as to be embedded in the opening and connect them by a footprint. Any of the coupling (fixing) means is structurally simple, but the main printed circuit board and the sub printed circuit board can be reliably integrated.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is an exploded view showing a mounting situation of a surface mounting component based on a mounting method of the surface mounting component according to the present invention.

The printed circuit board in this embodiment is composed of a main printed circuit board 1 and a sub printed circuit board 2 in order to increase the mounting surface. The sub printed circuit board 2 is mounted on the main printed circuit board 1 in a stacked state. A plurality of chip components 3 are provided on the front surface 1a and the back surface 1b of the main printed circuit board 1.
a and 3b (surface mount components) are mounted. Similarly, a plurality of chip components 4a and 4b (surface mount components) are mounted on the front surface 2a and the back surface 2b of the sub-printed board 2.

FIG. 2 is a characteristic diagram showing the relationship between the terminal pitch of the chip component, the footprint width formed on the printed board, and the appropriate solder paste coating thickness. As is clear from FIG. 2, if the proper area shown by the diagonal lines is not reached, solder open or solder failure such as solder bridge occurs. Therefore, it is necessary to strictly regulate the relationship between the solder printing plate thickness and the terminal pitch (and footprint width).

Therefore, in the present invention, the chip parts whose terminal pitches are close to each other are grouped into one group,
This is collectively mounted on one board surface. That is, the chip component 3a having a terminal pitch of 1.27 mm or more is mounted on the surface 1a of the main printed circuit board 1, and
On the back surface 1b, chip components 3b having a size of less than 1.27 mm and 0.8 mm or more are mounted. Further, a chip component 4a having a terminal pitch of 0.5 mm or less is mounted on the front surface 2a of the sub-printed board 2, and a back surface 2b has a thickness of less than 0.8 mm and less than 0.65 m.
Chip components 4b of m or more are mounted.

By such a mounting method, it is possible to significantly reduce solder open and solder bridge. As a result, the solder repair work can be reduced, the footprint part is peeled off due to the heat of the soldering iron due to the solder repair, and the diffusion layer of copper and solder in the terminal (electrode part) and the footprint part is increased, resulting in the solder joint part. Becomes brittle,
It is possible to prevent the reliability of the solder joint from being significantly deteriorated. In addition, the repair prevents deterioration of the insulation between the footprints, thereby improving the quality and reliability.

Through holes 5 are provided at both ends of the sub-printed circuit board 2, and the upper ends of the pins 6 are fitted into the through holes 5. On the other hand, on the main printed circuit board 1 side, through holes 7 are provided at positions facing the pins 6.

When the component mounting of the main printed circuit board 1 and the sub printed circuit board 2 is completed, the pin 6 of the sub printed circuit board 2 is positioned in the through hole 7 of the main printed circuit board 1, and the pin 6 is left in the through hole 7 in this state. The main printed circuit board 1 and the sub printed circuit board 2 are integrated by inserting and soldering (using infrared rays, a solder bath or the like for this).

[Embodiment 2] FIG. 3 is an exploded view showing a mounting situation of a surface mount component based on a second example of the method for mounting a surface mount component according to the present invention. Note that, in FIG. 3, the same reference numerals are used for the same elements as those in FIG. 1, and thus duplicated description will be omitted below.

In this embodiment, no chip component (surface mounting component) is mounted on the surface (bonding region) where the main printed circuit board 1 and the sub printed circuit board 2 face each other, and a solder bonding footprint is mounted on this part. 8 and 9 are provided, and through holes 10 and 11 are provided instead of the through holes 5 and 7. A positioning pin 12 is inserted into the through holes 10 and 11 and is used as a positioning member when joining the main printed board 1 and the sub printed board 2.

In this case, the main printed circuit board 1 and the sub printed circuit board 2 have chip parts 3 depending on the terminal pitch.
The allocation of a, 3b and the chip parts 4a, 4b is the same as in the above embodiment.

In the structure of FIG. 3, after mounting the chip parts 3a, 3b and the chip parts 4a, 4b on the other parts of the main printed circuit board 1 and the sub printed circuit board 2 excluding the joints, the through holes 10, A positioning pin 12 is inserted into each of the positions 11 to temporarily position the main printed circuit board 1 and the sub printed circuit board 2. After that, if the footprint 8 and the footprint 9 are soldered while the temporary positioning is performed, the main printed board 1 and the sub printed board 2 are integrated.

This embodiment is different only in the method of integrating the main printed circuit board 1 and the sub printed circuit board 2 with no change in the obtained effect, and can improve the quality and reliability of the solder joint.

[Embodiment 3] FIG. 4 is an exploded view showing a mounting state of surface mount components based on a third example of the method of mounting surface mount components according to the present invention. Note that, in FIG. 4, the same reference numerals are used for the same elements as those in each of the above-described embodiments, and thus duplicated description will be omitted below.

In the present embodiment, in the configuration of FIG. 1, the portion of the main printed circuit board 1 facing the sub printed circuit board 2 is cut out (the inside size opening is smaller than the outer shape of the sub printed circuit board 2 by about 2.5 mm). ), The main printed circuit board 1 and the sub printed circuit board 2 are joined by using a footprint.

That is, the footprint 13 is provided around the sub printed circuit board 2, and the footprint 1 is provided around the upper surface (joint surface) of the opening of the main printed circuit board 1.
The sub-printed circuit board 2 can be integrated with the main printed circuit board 1 by providing 4 and directly soldering the footprints 13 and 14. Since the chip component 4b on the back surface (bottom surface) of the sub-printed board 2 enters into the opening of the main printed board 1, the front surface of the main printed board 1 and the back surface of the sub-printed board 2 can be brought into close contact with each other.

Also in this embodiment, the chip components 3a and 3b and the chip components 4a and 4b are distributed to the main printed circuit board 1 and the sub printed circuit board 2 according to the terminal pitch, which is the same as the above-described embodiment. The effect obtained by this embodiment is the same as that of the above embodiment, and the quality and reliability of solder joint can be improved.

In the above embodiment, one sub-printed circuit board is connected to the main printed circuit board. However, the number of sub-printed circuit boards is not limited to one, and three or more sub-printed circuits may be used. Good. Then, each coupling means can adopt the configuration shown in FIGS. 1, 3 and 4.

Although the printed circuit board is composed of the main printed circuit board and the sub printed circuit board, it does not necessarily have to be formed in a multi-layered structure and may be a single printed circuit board.

[0032]

As described above, according to the present invention, when mounting a plurality of surface mount components having different terminal pitches on a printed circuit board, the surface mount components to be mounted are grouped according to the dimensional range of the terminal pitch, Since it is mounted on a different board surface for each group, solder defects such as solder open and solder bridge can be reduced, and product quality and reliability can be improved.

[Brief description of drawings]

FIG. 1 is an exploded view showing a mounting state of a surface mount component based on a method of mounting a surface mount component according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a terminal pitch of a chip component and an appropriate solder paste coating thickness.

FIG. 3 is an exploded view showing a mounting state of surface mount components based on a second example of the method of mounting surface mount components according to the present invention.

FIG. 4 is an exploded view showing a mounting state of surface mount components based on a third example of the method of mounting surface mount components according to the present invention.

[Explanation of symbols]

 1 Main Printed Circuit Board 2 Sub Printed Circuit Board 3a, 3b, 4a, 4b Chip Components 5, 7 Through Hole 6 Pins 8, 9 Footprint 12 Positioning Pins 13, 14 Footprint

Claims (5)

[Claims] 1. When mounting a plurality of surface mount components having different terminal pitches on a printed circuit board, the surface mount components to be mounted are divided into groups according to the dimensional range of the terminal pitch, and each group is mounted on a different board surface. A method of mounting a surface mount component, which is characterized by the following. 2. The mounting method for surface mounting components, wherein the printed circuit board comprises a main printed circuit board and at least one sub-printed circuit board, and the both are integrated in a multi-layered state. 3. The mounting method for surface-mounting components according to claim 2, wherein surface-mounting components are mounted on both sides of the sub-printed circuit board, and the main printed circuit board is coupled by using through holes and pins. . 4. The surface mount component is not provided on the joint surface of the main printed circuit board and the sub printed circuit board, and the two are connected through a footprint provided in the joint area. Mounting method for surface mount components. 5. An opening is formed in a portion of the main printed circuit board facing the sub printed circuit board, and the main printed circuit board and the sub printed circuit board are coupled to each other by a footprint provided at a joint portion around the opening of each board. The mounting method of the surface mount component according to claim 2, wherein the mounting is performed via