JP2004349418A - Mounting structure, mounting method and repairing method of surface-mounted component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve soldering strength of a surface-mounted component to a substrate, to prevent floating of the surface-mounted component from the substrate, to improve soldering quality of a wiring electrode, to easily inspect the soldering state of the rear face of the surface-mounted component, and to easily repair the surface-mounted component. <P>SOLUTION: Leads 2 are installed on sides of the surface-mounted component 1, and a fixed pad 3 is arranged at the rear face. Wiring pads 4 are disposed in positions corresponding to tips of the leads 2 on a surface of a printed board 6. A land 5 is arranged in a position corresponding to the fixed pad 3, and a through hole 7 is made in the center of the land 5. In the surface-mounted part with lead 1 and the printed board 6, the leads 2 and the wiring pads 4 are soldered, and the fixed pad 3 and the land 5 are soldered through solder 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mounting structure, a mounting method, and a repair (repair) method of a surface mounting component, and more particularly, to a mounting structure of a surface mounting component in which the back surface of the surface mounting component is directly soldered to a substrate to increase the soldering strength, and the mounting structure. It relates to a mounting method and a repair method.
[0002]
[Prior art]
As shown in FIG. 5, a surface mount component is mounted on a substrate by mounting the lead 27 on the side surface of the component body in the QFP type surface mount component 25 in which the leads 27 extend in four directions from the side surface of the component body. In a leadless QFN type surface mount component 26 in which side electrodes 28 are formed along four side surfaces of the component body as shown in FIG. Was soldered.
[0003]
However, the mounting structure of such a surface mount component has a problem that the soldering strength is weak. In particular, a leadless type surface mount component for the purpose of miniaturization of components has no solder back fillet and has a small soldering area, and thus has low soldering strength.
[0004]
FIG. 7 is a cross-sectional view illustrating a mounting structure of a conventional surface mount component with improved soldering strength.
[0005]
7, a wiring pad 33 and a fixing pad 37 are provided on a printed board 31, a wiring side electrode 32 is provided along the side surface of the surface mount component 30, and a fixing pad 34 is provided at the center of the back surface. Have been. FIG. 7 shows a result of supplying a solder paste to the wiring pads 33 and the fixing pads 35 and performing solder reflow.
[0006]
In the mounting structure shown in FIG. 7, the soldering strength is increased by soldering the fixing pads 34 and 35 with the solder 36. However, the solder 37 between the fixing pads 34 and 35 causes the surface mount component 30 to float high from the printed circuit board 31, so that the side electrodes 32 and the wiring pads 33 are not soldered as shown in FIG. 7. Sometimes.
[0007]
Patent Document 1 discloses a mounting method in which a metal part provided on the back surface of a semiconductor device is soldered to a printed circuit board to ground the semiconductor device.
[0008]
[Patent Document 1]
JP-A-11-243268 (FIG. 1)
[0009]
[Problems to be solved by the invention]
In a conventional mounting structure in which the back surface of a surface-mounted component is soldered to a substrate, there is a problem that the solder on the back surface of the surface-mounted component floats over the entire component as shown in FIG. 7 and deteriorates the soldering quality of the wiring electrodes. Was.
[0010]
Further, since the back surface of the surface mount component is not visible from the outside, there is a problem that the appearance inspection of soldering cannot be performed. Furthermore, since the solder on the back surface of the surface-mounted component cannot be directly heated, there is also a problem that it is difficult to remove the surface-mounted component from the substrate by melting the solder and repair such as replacement.
[0011]
Further, the mounting method described in Patent Literature 1 solders a semiconductor device for grounding, and does not increase soldering strength.
[0012]
An object of the present invention is to solve the above problems and to provide a mounting structure, a mounting method, and a repair method by soldering high-strength, high-quality surface-mounted components.
[0013]
[Means for Solving the Problems]
The mounting structure of the surface mounting component according to the first aspect of the present invention is provided on a fixing pad (3 in FIG. 1) provided on the back surface of the surface mounting component (1 in FIG. 1) and on a substrate (6 in FIG. 1). The through hole (7 in FIG. 1), a land (5 in FIG. 1) provided around the through hole on the surface of the substrate, and a solder (FIG. 1) for fixing the fixing pad to the land. 8).
[0014]
The mounting structure for a surface-mounted component with leads according to the invention according to claim 2 includes a lead (2 in FIG. 1) provided around the surface-mounted component (1 in FIG. 1) and a lead (2 in FIG. 1) provided on the back surface of the surface-mounted component. The fixing pad (3 in FIG. 1), the wiring pad (4 in FIG. 1) provided on the substrate (6 in FIG. 1), and the through-hole (7 in FIG. 1) provided on the substrate. A land (7 in FIG. 1) provided around the through hole on the surface of the substrate, a wiring solder (8 in FIG. 1) for connecting the lead and the wiring pad, and the fixing pad And fixing solder (8 in FIG. 1) for fixing to the land.
[0015]
According to a third aspect of the present invention, there is provided a mounting structure of a leadless type surface mount component, wherein an electrode (10 in FIG. 2) provided around the surface mount component (9 in FIG. 2) and a back surface of the surface mount component. The provided fixing pads (12 in FIG. 2), the wiring pads (11 in FIG. 2) provided on the substrate (16 in FIG. 2), and the through holes (15 in FIG. 2) provided on the substrate. A land (13 in FIG. 2) provided around the through hole on the surface of the substrate; a wiring solder (14 in FIG. 2) for connecting the electrode to the wiring pad; And fixing solder (14 in FIG. 2) for fixing the pad to the land.
[0016]
According to a fourth aspect of the present invention, there is provided a method for mounting a surface-mounted component, wherein a fixing pad (3 in FIG. 1) is provided on a back surface of the surface-mounted component (1 in FIG. 1), and a substrate (FIG. In 1-6), a wiring pad (4 in FIG. 1) corresponding to the wiring electrode (2 in FIG. 1) of the surface mount component, and a through hole (7 in FIG. 1) corresponding to the fixing pad and The surrounding land (5 in FIG. 1) is provided, and after the solder paste (20, 21 in FIG. 3) is supplied on the wiring pad and the land, the wiring is provided at each position of the wiring pad and the land. The surface mounting component is mounted on the substrate by aligning the positions of the electrodes and the fixing pads, and thereafter, the solder paste is reflowed.
[0017]
According to the method for mounting a surface mount component of the invention according to claim 5, a fixing pad (3 in FIG. 1) is provided on the back surface of the surface mount component (1 in FIG. 1), and a substrate (FIG. 1) on which the surface mount component is mounted. In 1-6), a wiring pad (4 in FIG. 1) corresponding to the wiring electrode (2 in FIG. 1) of the surface mount component, and a through hole (7 in FIG. 1) corresponding to the fixing pad and The surrounding land (5 in FIG. 1) is provided, and after the solder paste (20, 21 in FIG. 3) is supplied on the wiring pad and the land, the wiring is provided at each position of the wiring pad and the land. After mounting the surface mount component on the substrate by aligning the positions of the electrodes for mounting and the fixing pads, the solder paste is reflowed, and excess solder paste supplied on the lands at the time of reflow of the solder paste is used. Characterized by suppressing the floating of the surface mounting component so as to flow into the through hole.
[0018]
According to the mounting method of the surface mounting component of the invention according to claim 6, a through hole (7 in FIG. 1) and a land (5 in FIG. 1) around the through hole (7 in FIG. 1) are provided on the substrate (6 in FIG. 1), and fixed on the back surface. A surface mounting component (1 in FIG. 1) is mounted on the substrate with the position of the pad for mounting (3 in FIG. 1) aligned with the land, and the land and the fixing pad are soldered. Further, the solder in the through hole is visually inspected.
[0019]
According to the method for repairing a surface mounted component of the invention according to claim 7, a through hole (7 in FIG. 1) is provided on a substrate (6 in FIG. 1) and a land (5 in FIG. 1) is provided around the through hole (7 in FIG. A surface mounting component (1 in FIG. 1) mounted on the substrate by soldering a pad for use (3 in FIG. 1) to the land and the through-hole from the back surface of the substrate by heating the through-hole (8 in FIG. 1) is melted and removed from the substrate.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 is a sectional view of a mounting structure of a lead-mounted surface mounting component according to an embodiment of the present invention.
[0022]
Leads 2 are provided on the side surface of the surface mount component 1, and fixing pads 3 are provided on the back surface. On the surface of the printed board 6, wiring pads 4 are provided at positions corresponding to the tips of the leads 2, lands 5 are provided at positions corresponding to the fixing pads 3, and a through hole 7 is provided at the center of the land 5. Is provided.
[0023]
The lead 2 and the wiring pad 4 are soldered to the lead-mounted surface mount component 1 and the printed board 6, and the fixing pad 3 and the land 5 are soldered via the solder 8. Thus, the soldering strength is greatly improved by soldering the fixing pad 3 and the land 5.
[0024]
FIG. 2 is a sectional view showing a mounting structure of a leadless type surface mount component according to another embodiment of the present invention.
[0025]
In FIG. 2, a side electrode 10 for wiring is provided along the side surface of the surface mount component 1, and a fixing pad 12 is provided on the back surface. On the surface of the printed circuit board 16, wiring pads 11 are provided at positions corresponding to the side electrodes 10, lands 13 are provided at positions corresponding to the fixing pads 12, and through holes 15 are provided at the centers of the lands 13. ing.
[0026]
In the leadless type surface mount component 9, the side electrode 10 and the substrate pad 11 are soldered, and the fixing pad 12 and the substrate land 13 are soldered via the solder 14.
[0027]
This embodiment has a new effect that the soldering quality of the side electrode 10 can be improved when the fixing pad 12 is soldered to the land 13.
[0028]
The reason is that the through holes 15 are provided in the lands 13 of the printing plate 16 and surplus solder at the time of soldering is filled in the through holes 15, so that floating of the surface mount component due to the surplus solder can be suppressed. is there.
[0029]
Next, a method of mounting the lead-mounted surface mount component 1 shown in FIG. 1 on the printed circuit board 6 will be described with reference to FIGS.
[0030]
In FIG. 3, solder pastes 20 and 21 are supplied to the board pads 4 and the lands 5 of the printed board 6, respectively. At this time, the solder paste 21 is supplied to the lands 5 in such a manner as to avoid the through holes 7.
[0031]
Next, as shown in FIG. 4, the surface mount component 1 is aligned and mounted, and reflow soldering is performed. At the time of reflow, the solder of the solder pastes 20 and 21 is melted, and the solder of the solder paste 21 spreads and spreads in the through holes 24, and after the soldering, the mounting state is as shown in FIG.
[0032]
Although the solder 8 between the fixing pad 3 and the land 5 cannot be seen from the surface of the printed circuit board 6 and cannot be visually inspected, the inside of the through hole 7 can be observed from the back side of the printed circuit board 6. If the solder 8 flowing into the through hole 7 is buried, it can be determined that the soldering condition of the fixing pad 3 is good. If the solder 8 is not sufficiently buried in the through hole 7, the soldering is defective. I can do it. Thus, by observing the inside of the through hole 7, a visual inspection of the soldering of the fixing pad 3 becomes possible.
[0033]
Further, the solder 8 between the fixing pad 3 and the land 5 cannot be directly heated with a soldering iron or the like from the front side of the printed circuit board 6. It is not easy to melt and remove the surface mount component 1 from the printed circuit board 6. However, if the through hole 7 is directly heated by a soldering iron or the like from the back surface of the printed circuit board 6, the solder 8 between the fixed pad 3 and the land 5 is heated and melted by the heat transfer through the through hole 7. Therefore, the surface mount component 1 can be easily removed from the printed circuit board 6 and the surface mount component 1 can be repaired.
[0034]
The heating of the through hole 7 is not limited to the soldering iron, and various methods such as laser irradiation can be used.
[0035]
【The invention's effect】
The first effect is that the soldering strength between the surface mount component and the substrate can be improved. Therefore, solder cracks due to thermal and mechanical stress can be prevented.
[0036]
The reason is that soldering to the board, which is usually done only with the lead part and wiring electrode, is soldered to the board even on the body side of the surface mount by soldering the fixing pad provided on the back of the surface mount component This is because the solder flows into the through hole on the substrate side and is soldered, so that an anchor effect is generated.
[0037]
A second effect is that a visual inspection of the soldering of the back surface of the surface mount component, which cannot be normally performed, can be performed. Therefore, the soldering state of the back surface of the surface-mounted component can be visually confirmed without using an expensive inspection machine such as an X-ray inspection machine.
[0038]
The reason for this is that the solder condition in the through-hole, which is soldered to the fixing pad on the back surface of the surface-mounted component, can be visually checked from the back surface of the board. This is because the quality of the soldering can be determined.
[0039]
A third effect is that even if the fixing pad on the back surface of the surface-mounted component is soldered to the substrate, it is easy to remove the surface-mounted component from the substrate for repair. Therefore, repair using a soldering iron or the like is possible without using a special repair device.
[0040]
The reason is that through holes are provided in the lands where the fixing pads are soldered to the board, so that the through holes are directly heated from the back of the board with a soldering iron etc. Can be melted.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a mounting structure of a surface-mounted component with leads 1 according to an embodiment of the present invention.
FIG. 2 is a sectional view of a mounting structure of a leadless type surface mount component 9 according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view of the printed circuit board 6 in which solder pastes 20 and 21 are supplied to the pads 4 and the lands 5 for showing a mounting method of the lead-mounted surface mounting component 1 whose mounting structure is shown in FIG.
FIG. 4 is a cross-sectional view showing a state where the surface mount component 1 is mounted on the printed board 6 shown in FIG.
FIG. 5 is a perspective view of a QFP type surface mount component 25 with leads extending in four directions from the side surface of the component body.
FIG. 6 is a perspective view of a leadless QFN type surface mount component 26 having electrodes formed along four side surfaces of the component body.
FIG. 7 is a cross-sectional view showing a mounting structure of a conventional surface mount component 30 with improved soldering strength.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 surface mount component 2 lead 3 fixing pad 4 wiring pad 5 land 6 printed board 7 through hole 8 solder 9 surface mount component 10 side electrode 11 wiring pad 12 fixing pad 13 land 14 solder 15 through hole 16 printed circuit board 20 Solder paste 21 Solder paste 25 Surface mount component 26 Surface mount component 27 Lead 28 Side electrode 30 Surface mount component 31 Printed circuit board 32 Side electrode 33 Wiring pad 34 Fixing pad 35 Fixing pad 36 Solder 37 Solder

Claims (7)

A fixing pad provided on the back surface of the surface mount component, a through hole provided on the substrate, a land provided around the through hole on the surface of the substrate, and the fixing pad is fixed to the land. A mounting structure of a surface mount component characterized by including solder. A lead provided around the surface mount component, a fixing pad provided on the back surface of the surface mount component, a wiring pad provided on the substrate, a through hole provided on the substrate, A land provided around the through hole on the surface, a wiring solder for connecting the lead and the wiring pad, and a fixing solder for fixing the fixing pad to the land. Mounting structure of surface mounted components with lead. An electrode provided around the surface mounted component, a fixing pad provided on the back surface of the surface mounted component, a wiring pad provided on the substrate, a through hole provided on the substrate, A land provided around the through hole on the surface, a wiring solder for connecting the electrode and the wiring pad, and a fixing solder for fixing the fixing pad to the land. Mounting structure for leadless surface mount components. A fixing pad is provided on the back surface of the surface mount component, and a wiring pad corresponding to the wiring electrode of the surface mount component and a through hole corresponding to the fixing pad are provided on the substrate on which the surface mount component is mounted. After providing a surrounding land and supplying a solder paste on the wiring pad and the land, the surface mounting is performed by adjusting the positions of the wiring electrode and the fixing pad to the respective positions of the wiring pad and the land. A method of mounting a surface mount component, comprising mounting a component on the substrate, and thereafter reflowing the solder paste. A fixing pad is provided on the back surface of the surface mount component, and a wiring pad corresponding to the wiring electrode of the surface mount component and a through hole corresponding to the fixing pad are provided on the substrate on which the surface mount component is mounted. After providing a surrounding land and supplying a solder paste on the wiring pad and the land, the surface mounting is performed by adjusting the positions of the wiring electrode and the fixing pad to the respective positions of the wiring pad and the land. After mounting the component on the board, the solder paste is reflowed, and at the time of reflow of the solder paste, the excess of the solder paste supplied on the land flows into the through hole to suppress the floating of the surface mount component. A method of mounting a surface mount component, comprising: After providing a through hole and a land around it on the substrate, mounting the surface mounting component on the substrate by matching the position of the fixing pad provided on the back surface to the land, and after soldering the land and the fixing pad And visually inspecting the solder in the through hole from the back surface of the substrate. By providing a through hole in the board and a land around the board, soldering a fixing pad provided on the back surface to the land, and mounting the surface mounted component mounted on the board, heating the through hole from the back surface of the board. A method for repairing a surface mounted component, wherein the solder for soldering is melted and removed from the substrate.

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