JPH02306692A - Mounting method for component on circuit substrate - Google Patents

Abstract

PURPOSE:To effectively and accurately mount components on upper and lower surfaces in one step by connecting electrodes of an upper surface mounting component with solder to be guided from the lower surface side to the upper surface side via a through hole in the case of dip soldering, and connecting the electrodes of a lower surface mounting component. CONSTITUTION:A through hole 4 is formed at a position opposed to the electrode of an upper surface mounting component 1, a lower surface mounting component is secured to the lower surface, and dip soldered from the lower surface of a circuit substrate 3. In this case, the electrode of the component 1 is solder-connected with solder to be guided from the lower surface side to the upper surface side via the hole 4, and the electrode of the lower surface mounting component is simultaneously solder-connected. Thus, the electrodes of the upper and lower surface mounting components can be effectively solder- connected once in a dip soldering step.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of mounting surface-mounted components on a double-sided circuit board in electronic circuit equipment by soldering.

(Prior Art) In recent years, with the miniaturization of electronic devices, the density of component mounting has also increased, and methods of surface mounting on double-sided boards have been widely used. Furthermore, as the size of IC component packages has progressed, high-frequency IC components have become widespread, and there has been a need to mount IC components having electrodes that take high-frequency characteristics into consideration, as shown in FIG.

That is, in FIG. 11, 1 is an IC component, 1a is the bottom surface of the IC component, and 2 is an electrode (lead). By shortening the length of electrode 2, the inductance of the electrode portion at high frequency is reduced. It became necessary to mount an IC component 1 that prevents the IC component 1 from becoming large and causing problems.

A conventional example in which such IC components are surface-mounted on a double-sided board to achieve high-density mounting is shown in FIGS. 9 and 10.

That is, FIG. 9 is a side cross-sectional view after components are mounted, and FIG. 10 is a perspective view showing a situation in which components to be mounted are aligned on a circuit board.

In FIG. 10, it will be understood that upon mounting, the electrodes (leads) 2 of the IC component 1 are first aligned with the copper foil pattern 6 and then placed thereon.

After mounting, the structure will be as shown in Figure 9.

That is, the electrode 2 of the tC component 1 is soldered to the copper foil pattern 6 using the solder 5, and the chip component 7a as a top-mounted component is once fixed on the circuit board 3 using the adhesive 10a, and then the chip component 7a is also soldered to the copper foil pattern 6 using the solder 5. Connected by soldering. The leaded insertion component 8 has its long lead inserted into the through hole and is soldered to the bottom surface of the circuit board 3 using the solder 5, and the chip component 7b as a bottom surface mounting component is also attached to the bottom surface of the circuit board 3 using the adhesive 10b. After being fixed on top, it is also soldered and connected using solder 5.

Note that when mounting the chip components 7a and IC components 1 as top-mount components on the top surface of the circuit board 3, reflow soldering is performed, and the chip components 7b and IC components as bottom-mount components are mounted on the bottom surface of the circuit board 3. When mounting the insertion component 8, dip soldering is performed.

FIG. 12 is a diagram illustrating the conventional mounting component mounting process described above in an organized manner. As shown in FIG. 12, the conventional mounting component mounting process includes a reflow soldering process in which the top-mounted component is attached to the top surface of the circuit board, and a chip component 7b is attached to the bottom surface of the circuit board using an adhesive 10b. The process consists of a mounting process, an insertion process of inserting the leaded insertion component 8 into the through hole, and a dip soldering process of soldering the bottom-mounted component.

Another conventional example is that when the number of top-mounted components is small, and for equipment reasons, IC components 1 are manually attached to the circuit pattern as shown in FIG. 11 instead of using the adhesive flow soldering process in FIG. 12. In some cases, the process of aligning the parts by hand and soldering them by hand has been adopted.

Documents describing this type of component mounting method include, for example, Japanese Unexamined Patent Publication No. 59-28998 and Japanese Utility Model Application No. 42-20.
Examples include Publication No. 22, Japanese Utility Model Application No. 5O=7t174, and the like.

[Problem to be solved by the invention]

When surface mounting components on both sides of a one-way board using the conventional technology as described above, (1) dip soldering on the top and bottom surfaces (2) reflow soldering on the top surface and dip soldering on the bottom surface (3)
There are methods such as manual soldering on the top surface and dip soldering on the bottom surface, but both require two soldering processes, resulting in increased number of work steps, complicated processes, and the need for a large amount of equipment.

Furthermore, in the case of mounting using method (1) above, there is a problem in that in IC parts having electrodes in four directions (see FIG. 11), solder bridging occurs depending on the dipping direction, which is inconvenient. Furthermore, in the case of mounting using the methods (2) and (3) above, there was a problem in terms of accuracy and reliability, as the reliability of soldering was lowered due to positional deviation and the like.

Furthermore, for IC parts in large packages, it may be prohibited to apply multiple thermal shocks to the element body for reliability reasons, so mounting using methods (1) and (2) above is not possible. This is difficult because thermal shock is applied twice.

An object of the present invention is to provide a mounting method that can accurately and reliably attach components to the top and bottom surfaces in a single soldering process in a surface mount circuit board that can be mounted on both the top and bottom surfaces for high-density mounting. It is about providing.

(Means for Solving the Problems) In order to achieve the above object, the mounting method according to the present invention provides a method for mounting components on a double-sided circuit board in which components can be mounted on the top and bottom surfaces of the circuit board. When attaching bottom-mounted components, there is a step of fixing the components to the bottom surface.Dip soldering is performed from the bottom surface of the circuit board, and at that time, soldering is performed from the bottom side through the through-holes. The method includes the steps of soldering and connecting the electrode portions of the top surface mount component with the solder guided to the top surface side, and also soldering and connecting the electrode portions of the bottom surface mount component together.

Further, in this case, the through hole can be used for positioning the top surface mounted component with respect to the circuit board, and the electrode of the mounted component can be inserted halfway into the through hole.

[Effect]

By inserting the lead of the IC component halfway into the through hole, the IC component can be accurately positioned with respect to the circuit board. Furthermore, for general surface-mounted components, they are fixed to the circuit board using an adhesive prior to soldering connection. Through-hole holes are made on the circuit board at positions corresponding to the electrode positions of the components to be mounted, and when dip soldering is performed on the bottom side,
It acts to guide the solder to the upper surface pattern, and can reliably solder connect to the leads of the IC component and the electrodes of the surface mount component fixed with the adhesive in a single dip soldering process.

Furthermore, since this method enables solder connection by guiding the solder to the upper surface through the through-hole, no solder bridges will occur in the lead portions of IC components due to the dipping direction.

Furthermore, by controlling the immersion depth and through-hole diameter during dip soldering, it is possible to solder with an appropriate amount of solder.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a perspective view showing how an IC component 1 is placed and positioned on a circuit board 3 according to the present invention. That is,
In the circuit board 3, through holes 4 are installed at positions on the copper foil pattern 6 corresponding to the leads (electrodes) 2 of the IC component 1.

FIG. 2 is a sectional view of the IC component 1 inserted into the through hole 4 on the circuit board 3 according to the present invention. I
Lead 2 of C component 1 is inserted into through hole 4,
The IC component 1 is positioned and arranged on the circuit board 3 in such a manner that the wire 2 does not penetrate through the through hole 4 from the lower surface of the circuit board 3.

Next, FIG. 3 is a sectional view showing a soldered connection state when dip soldering is performed from the bottom surface of the circuit board 3 in the position as shown in FIG. 2.

It will be seen that the electrodes (leads) 2 are reliably soldered and connected by the solder 5 guided to the upper surface via the through hole 4 by dip soldering from the lower surface of the circuit board 3.

FIG. 4 is a sectional view showing an overall view of the soldered connection state made according to the present invention, in which the chip component 7b, the leaded insertion component 8, the IC component 1, etc. are soldered to the circuit board 3 by one dip soldering. It shows the connected state.

To supplement the explanation, the IC component 1 is positioned as described with reference to FIG. 2, and at the same time, in FIG. 4, the chip component 7b is fixed to the lower surface of the circuit board 3 by the adhesive 10b. Also, regarding the leaded insertion part 8, the lead V is inserted into the through hole and penetrated. After that, once dip soldering is performed on the bottom surface of the circuit board 3, the chip component 7b is soldered by the solder 5 as shown in FIG.
The solder is connected to the bottom surface of the circuit board 3 by the solder, and the IC component 1 is also soldered to the top surface of the circuit board by guiding the solder into the through hole as explained earlier with reference to FIG. The component 8 is also soldered and connected to the circuit board 3 by the solder 5, as shown in FIG.

FIG. 5 is a sectional view showing another embodiment of the present invention. In the figure, 7 is a chip component, 2 is its electrode (lead),
3 is a circuit board, 4 is a through hole, 5 is solder, 6 is a copper foil pattern, 9 is an overcoat, and 10 is an adhesive.

In this embodiment, adhesive IO is first applied to the circuit board 3, and the chip component 7 is positioned and bonded so that the tip of the electrode 2 of the chip component 7 to be mounted is approximately in the center of the upper surface of the through hole 4. After bonding with the adhesive 10, the adhesive l
It is fixed by curing O. Next, by performing dip soldering on the lower surface of the substrate 3, the solder 5 is guided to the upper surface through the through hole 4, and the electrode 2 can be connected to the copper foil pattern 6 by soldering.

The embodiments described above with reference to FIGS. 1 to 4 are as follows:
Since the electrode shapes are different, it is not possible to position the parts to be installed by inserting the electrode halfway into the through hole as in the previous example, so we used adhesive to position and fix the part. The difference is in what they do.

It will be easily understood that according to this embodiment as well, components can be mounted on both sides of the circuit board in a single dip soldering process.

6 and 7 are cross-sectional views showing still other embodiments of the present invention, but both differ only in the shape of the electrode 2 from the embodiment shown in FIG. 5, and in other respects. There is no difference from the embodiment shown in FIG.

Since FIG. 8 is a top view of the embodiment shown in FIGS. 6 and 7, no further explanation is necessary.

〔Effect of the invention〕

According to the present invention, components can be surface-mounted on the upper and lower surfaces of a circuit board simultaneously with one dip soldering process, and the number of man-hours can be significantly reduced by eliminating the need for a reflow soldering process or a manual soldering process.

In addition, by soldering with solder guided from the bottom surface of the board to the top surface through through holes, a stable solder fillet can be formed, and there is no solder bridge even in high-density patterns, allowing for highly reliable soldering. .

In addition, (1) the soldering pattern and through hole can be used together, resulting in high area efficiency and high density, (2) the terminals of IC components can be connected at the shortest distance, making it possible to form a good high-frequency circuit; (3) There is no need for a cleaning process after reflow soldering, and (4) heat is not applied directly to the IC element, so thermal shock is small and reliability is improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a situation when IC components are placed on a board according to the present invention, FIG. 2 is a side sectional view showing a situation where IC components are mounted on a board according to the invention, and FIG. 4 is a side sectional view showing the overall situation when the present invention is implemented, and FIGS. A side sectional view for explaining the embodiment, Fig. 8 is Fig. 6,
A top view of the embodiment shown in Fig. i7, Fig. 9 is a side sectional view showing the state in which parts are mounted by the conventional method, Fig. 10 is a perspective view showing the situation when positioning the parts by the conventional method, and Fig. 11 The figure is an outline drawing showing the two sides of the IC component, No. 12.
The figure is an explanatory diagram showing the conventional method of mounting components on a circuit board.
It is. Explanation of symbols 1...IC component, 1a...bottom of IC component, 2...
・Electrode (lead), 3... Circuit board, 4... Through hole, 5... Solder, 6... Copper foil pattern, 7...
・Chip parts, 8... Insert parts with leads, 9... Overcoat, 10... Adhesive Ll Figure 2 Figure 3 Figure @ 4 ■ Chi21 parts 1X5 Figure 6 Figure C Iten 7 Figure zS Illustrated 9 ■ Answer 10 Prisoner Figure 11 Figure 412

Claims (2)

[Claims] 1. In a double-sided circuit board that allows components to be mounted on the top and bottom surfaces of the circuit board, there is a step in which through-holes are formed at positions facing the electrodes of top-mounted components, and a step in which the components are mounted on the bottom surface when mounting bottom-mounted components. a step of fixing the
Dip soldering is performed from the bottom of the circuit board, and at that time,
The method is characterized by comprising the step of soldering and connecting the electrode portions of the top surface mount component with the solder guided from the bottom surface side to the top surface side through the through hole, and also connecting the electrode portions of the bottom surface mount component by soldering. How to mount components on a circuit board. 2. In the method of mounting a component on a circuit board according to claim 1, the through hole is used for positioning the top surface mounted component with respect to the circuit board, and the electrode of the mounted component is inserted halfway into the through hole. How to mount featured components onto a circuit board.