JPH08241910A - Mounting structure of electronic parts - Google Patents

Abstract

PURPOSE: To provide a structure for mounting electronic parts where they can be mounted at a small mounting area on a substrate and no electrical short- circuiting occurs between a lead frame and a land. CONSTITUTION: After a bump 6a of a bare chip IC6 is joined to a lead frame 7 of a TAB tape, the bare chip IC6 is separated from the TAB tape along with only the lead frame 7 while leaving a carrier film and an IC package 8 is formed. An insulation spacer 5 is formed on a land 3a of a circuit substrate 1 and the lead frame 7 of the IC package 8 is supported by the insulation spacer 5 and the tip of the lead frame 7 is joined to the land 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for electronic parts. More specifically, the present invention relates to an electronic component mounting structure in which electronic components are TAB mounted on a substrate.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional electronic component mounting structure. This is generally TAB (Tape A
utomated Bonding) This is called the mounting structure. The TAB mounting structure will be described according to a mounting procedure. After the bare chip IC 31 is bonded to the lead frame 33 of the TAB tape, the TAB is removed while leaving a part of the carrier film 32.
The lead frame 33 is punched out of the tape, the lead frame 33 is formed, and the bare chip IC 31, the carrier film 32, and the lead frame 33 are formed.
A C package 34 is formed.

The IC package 34 is mounted face down on a circuit board 35 to form a land 3 of a wiring pattern 36.
The lead frame 33 is aligned with 6a, and the end of the lead frame 33 and the land 36a are joined with the solder 37. The carrier film 32 left on the lead frame 33 is interposed between the lead frame 33 and the circuit board 35.

However, in such an electronic component mounting structure, the lead frame 33 becomes longer by the length of the carrier film 32, and the distance between the bare chip IC 31 and the land 36a is increased by the width of the carrier film 32. And the mounting area on the circuit board 35 becomes large.

Further, since the carrier film 32 is fixed to the lead frame 33, for example,
A material having excellent heat resistance must be used so as to withstand the heat when soldering 3 to the land 36a, and there is a problem that the film material is limited and the film cost is high.

In order to avoid such a drawback, a structure in which the carrier film 32 is mounted on a lead frame which does not take on the carrier film 32 can be considered. That is, the bare chip IC 31
Is mounted on the lead frame 33 of the TAB tape, and only the lead frame 33 on which the bare chip IC 31 is mounted is cut out from the TAB tape while leaving the carrier film.
If this filmless IC package is mounted on the circuit board 35, the lead frame 33 can be shortened as much as there is no carrier film, and the mounting area of the bare chip IC 31 can be reduced. Also, a material having low heat resistance can be used for the carrier film.

However, when the carrier film 32 is removed from the conventional mounting structure as shown in FIG.
Since 3 is no longer supported on the circuit board 35, the lead frame 33 is easily bent downward, and the lead frame 33 may contact the adjacent land 36a as shown in FIG. It was In order to prevent this, it is necessary to devise the wiring pattern of the circuit board, and there is a disadvantage that the wiring pattern design near the IC is restricted.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the above conventional examples, and an object of the present invention is to mount electronic parts in a small mounting area and to reduce the mounting cost. Another object of the present invention is to provide a mounting structure for electronic components that can prevent a lead frame short circuit accident.

[0009]

An electronic component mounting structure according to the present invention is an electronic component mounted on a substrate by TAB mounting, wherein an electronic component separated from a TAB tape together with only a lead frame while leaving a carrier film. The component is placed on a substrate, and an insulating spacer is formed between the lead frame joined to the land of the substrate and the substrate.

[0010]

According to the present invention, since electronic components are mounted without using a TAB tape carrier film,
The lead frame can be shortened by the amount of the carrier film, and the distance between the electronic component and the land of the substrate can be shortened. As a result, the mounting area of the electronic component can be reduced as much as the lead frame can be shortened as compared with the conventional TAB mounting structure.

Since the carrier film is not used after being mounted on the substrate, the carrier film is not required to have high heat resistance, the range of choice of the film material is widened, and the film cost can be reduced.

In addition, since the insulating spacer is formed between the lead frame and the substrate even though the carrier film is not used for mounting on the substrate, the lead frame is supported by the insulating spacer, Even if the pitch between the lands is narrow, there is no possibility that the lead frame will contact the adjacent lead frame or land and short-circuit. Further, it becomes easy to design a wiring pattern near the electronic component.

[0013]

1 is a sectional view showing an IC mounting structure according to an embodiment of the present invention, and FIG. 2 is a partially cutaway plan view showing a circuit board for mounting the IC.

As shown in FIG. 2, a plurality of lands 3a located at the ends of the wiring pattern 3 are arranged on the four circumferences of the IC mounting position 2 on the circuit board 1, and these land areas are opened. The surface of the circuit board 1 is covered with the resist film 4, and each land 3 is opened from the opening 4a of the resist film 4.
a is exposed. Lead frame 7 of each land 3a
The insulating spacer 5 is formed on the circuit board 1 so as to traverse the inner peripheral side from the portion to be joined. The insulating spacer 5 is formed in a square frame shape so as to surround the IC mounting position 2 as a whole. The insulating spacer 5 may be formed into a square frame and adhered to the circuit board 1 or may be formed on the circuit board 1 by printing.
The insulating spacer 5 may not protrude from the inner peripheral end of the land 3a as shown in FIG. 1, or may protrude from the inner peripheral end of the land 3a as shown in FIG. No problem.

On the other hand, in the IC package 8 mounted on the circuit board 1, after the bumps 6a of the bare chip IC 6 are bonded to the lead frame 7 of the TAB tape and the bare chip IC 6 is mounted on the TAB tape, the lead is left with the carrier film left. TAB bare chip IC6 with frame 7 only
It is separated from the tape and the lead frame 7 is formed by forming.

As shown in FIG. 1, the IC package 8 without the carrier film is mounted face down on the circuit board 1, and the end of the lead frame 7 is aligned with the land 3a of the circuit board 1. The lead frame 7 is joined to the land 3a by solder 9. When mounted on the circuit board 1 in this manner, the insulating spacer 5 is interposed between the land 3a and the lead frame 7, and is supported by the insulating spacer 5 so that each lead frame 7 does not contact the land 3a except at the joint. Have been. Accordingly, it is possible to prevent the lead frame 7 from being bent by the external force or the own weight applied to the bare chip IC 6 and coming into contact with the wiring pattern 3 or the like of the circuit board 1 to cause an electrical short circuit.

Further, since the insulating spacer 5 does not function as a carrier film for holding the lead frame 7, the insulating spacer 5 is provided without being restricted by the position and the width with respect to the lead frame 7. This does not make the lead frame 7 longer. Accordingly, the mounting area of the bare chip IC 6 can be reduced by supporting the lead frame 7 with the insulating spacer 5 without using a carrier film.
Further, the material of the insulating spacer 5 is unlikely to be restricted by the material like the carrier film, and does not need to be a film, and may be resin or paint as long as it has an insulating property and an appropriate thickness. Therefore, the mounting cost is also low.

The material of the insulating spacer 5 is not particularly limited as long as it is an insulating material such as a resin. Further, the shape of the insulating spacer 5 is not limited to the rectangular frame shape, and may be a planar shape that also covers the IC mounting position 2, or may be divided into a plurality of land areas.

[0019]

According to the present invention, since the lead frame can be shortened by the amount of the carrier film, the lead frame can be shortened as compared with the conventional TAB mounting structure, the mounting area of electronic components can be reduced, and the circuit can be highly integrated. Can contribute to Also, since the carrier film is not used at the time of mounting on a substrate, the carrier film is not required to have high heat resistance,
The film cost can be reduced.

Further, since the insulating spacer is formed between the lead frame and the substrate even though the carrier film is not used for mounting on the substrate, the lead frame is supported by the insulating spacer, Even if the pitch between the lands is narrow, there is no possibility that the lead frame will contact the adjacent lead frame or land and short-circuit. Furthermore, since the possibility of short-circuiting of the circuit is reduced, the wiring pattern design in the vicinity of the electronic component becomes easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing a mounting structure of an electronic component according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view showing a circuit board used in the above embodiment.

FIG. 3 is a cross-sectional view illustrating a mounting structure of an electronic component according to a conventional example.

FIG. 4 is a partially omitted explanatory view showing a problem of another electronic component mounting structure according to a conventional example.

[Explanation of symbols]

 1 Circuit Board 3 Wiring Pattern 3a Land 4 Resist Film 5 Insulating Spacer 6 Bare Chip IC 7 Lead Frame 8 IC Package

Claims (1)

[Claims] 1. In a mounting structure in which electronic components are mounted on a substrate by TAB, the carrier film is left and only the lead frame and T are mounted.
The electronic components separated from the AB tape are placed on the substrate,
An electronic component mounting structure in which an insulating spacer is formed between the substrate and the lead frame joined to a land of the substrate.