JP2556204B2 - Film carrier semiconductor device mounting method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor integrated circuit, which is ILB (inner lead bonding) on a film carrier tape, on a substrate.

[0002]

2. Description of the Related Art Conventionally, a structure in which a semiconductor integrated circuit element (hereinafter referred to as an IC element) is mounted using a film carrier tape has been used. A conventional film carrier tape uses an insulating film such as polyimide as a base film, and a sprocket hole for transporting and positioning and a device hole into which an IC element is inserted are formed in the base film, and a metal foil such as Cu is bonded onto the insulating film. Then, this is etched to form leads of a desired shape and pads for electrical selection. Then, the metal protrusions (bumps) formed on the electrode terminals of the IC element are connected to the leads by a thermocompression bonding method or the like to perform the ILB.

After mounting, the selection pad is electrically connected to the selection pad from the outside in the state of the film carrier tape to perform the electric selection and the BT test, and then the lead is cut into a desired length. At this time, in the case of a large number of leads having a large number of leads, in order to prevent the outer lead bonding portions of the leads from being separated, as shown in FIGS.
A method of leaving 6b on the outer end of the outer lead is often used. The OLB leads of the film carrier semiconductor device thus formed are subjected to OLB (outer lead bonding) on a bonding pad on a printed board or a general lead frame to complete the mounting.
However, as shown in FIG. 3, there are a method in which the base film is not brought into contact with the substrate 5a and a method in which it is brought into contact with the substrate 5b as shown in FIG. In the case of mounting by such a film carrier tape, the ILB and OLB can be performed at one time regardless of the number of leads, so that the bonding speed can be increased, and the assembly such as bonding and the electric selection work can be automated and the mass productivity can be improved. It has advantages such as being excellent.

[0004]

In recent years, the number of input / output terminals has increased as the IC elements have become more highly integrated and multifunctional.
Some have ~ 600 pin input / output terminals. Considering an IC element having an input / output terminal of 300 pins, the outer size of the film carrier package greatly changes depending on the pitch of outer lead bonding (hereinafter abbreviated as OLB) of the mounting substrate. For example, the OLB pitch is 100 μm. At this time, the size of the film carrier package is about 10 mm, but when the OLB pitch becomes 500 μm, it becomes about 40 mm and becomes large.

In this case, the lead distance from the IC element connecting portion to the OLB lead becomes abnormally long, and therefore,
The wiring resistance R, the capacitance C, and the inductance L on the film carrier tape become large, and matching of characteristic impedance becomes difficult, so that there is a problem that the electrical characteristics cannot be satisfied in a high-speed logic IC or memory IC.

Particularly in a logic IC having a large number of gates, a large current flows through a power supply and an earth line at the time of signal switching, so that the inductance of leads on a film carrier tape as a package cannot be ignored. This is because if the inductance of this lead is large, power supply / earth noise will be generated and the IC will malfunction. Specifically, the OLB pitch is 100 μm and 300 μm, which is 500 μm.
For pin ICs, the required lead length is about 3-4 mm and about 22-
At 24 mm, the inductance L of the lead at this time is about 2 to 3 nH and about 25 to 27 nH, and the inductance L remarkably increases as the OLB pitch increases. Therefore, it is sufficient to reduce the OLB pitch in order to improve the electrical characteristics of the IC element, but in the actual mass production level, the OLB pitch of 100 μm is poor in productivity and cannot be applied at present.

Therefore, as a countermeasure for this problem, a film carrier tape called a double-sided film carrier tape (2-metal structure), which is an improvement of the conventional single-sided film carrier tape (1-metal structure), is being developed. This double-sided film carrier tape is provided with a metal layer such as Cu foil on the front surface and the back surface of the base film respectively, and the surface is a lead for signal and power supply system and the back surface is a pattern for grounding, and the through hole is used for electrical connection with the surface By forming a so-called microstripline structure, the inductance of the surface pattern of the leads is reduced. However, there is a problem that the versatility is insufficient due to a complicated manufacturing method of the film carrier tape, an extremely high price, and a very small number of suppliers.

[0008]

According to a method of mounting a film carrier semiconductor device of the present invention, a surface terminal portion provided at a position corresponding to a base film portion of a film carrier tape and a peripheral portion of the surface terminal portion are provided. Using the mounting board with the pads provided at the positions corresponding to the outer leads, the surface terminals of this mounting board and the base film of the film carrier tape are mounted in close contact, and The part is a mounting method that is electrically set to the ground potential.

[0009]

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

FIG. 1 is a sectional view for explaining a first embodiment of the present invention. 3c is an OLB lead, 5c is a mounting substrate, and 4c is a pad corresponding to the OLB lead 3c. Reference numeral 6c is a base film of the film carrier tape, and 8c is a surface terminal provided on the mounting substrate 5c.
Conductive or insulating adhesive 7 is applied on the surface terminals 8c.
The base film 6c is closely attached by c. As this method, for example, an adhesive (7c) is dropped on the surface terminal 8c by a potting method or the like, the pad 4c on the substrate and the OLB lead 3c are aligned with an OLB bonder or the like, and OLB is performed by a pulse method or a constant heat method. ,
After that, the adhesive (7c) is heat-cured in an oven or the like and joined with the adhesive 7c to complete the mounting.

The surface terminal 8c is designed by the substrate 5c so as to be electrically at the ground potential, and by adopting such a mounting method, the lead 11c, the base film 6c, and the surface terminal 8c are formed into a microstrip line structure. It is possible to improve the inductance L of the lead among the electrical characteristics.

In FIG. 1, the structure of the film carrier tape is as follows: lead 11c-adhesive 10c-base film 6c.
A double-layer film carrier tape having a two-layer structure of a lead-base film that does not use an adhesive 10c may be used as a conventional double-sided film carrier tape and is currently under development. It is said that the electrical characteristics can be improved to the same level as above, and if the OLB pitch is 100 μm in an extreme case, it cannot be applied in mass production, but the OLB pitch is increased to 0.3 to 0.4 mm and the workability of the OLB is not deteriorated. It is also effective in terms.

FIG. 2 is a sectional view for explaining the second embodiment of the present invention. The structure of the film carrier tape is as follows: lead 11d-adhesive 10d-base film 6d-
A five-layer structure of adhesive material 10d-metal layer 9d is used. The metal layer 9d and the surface terminals 8d are mechanically pressed by the adhesive force of the OLB lead 3d and the pad 4d without an adhesive agent or the like interposed. This is a mounting method that takes a structure and is also electrically connected. Since this mounting method does not use an adhesive such as a conductive paste, the mounting man-hours are the same as the conventional OLB process, and the mounting apparatus is the same as the conventional one. There is an advantage that it can be used and the electrical characteristics of the film carrier tape can be improved when mounted on a substrate.

[0014]

As described above, according to the present invention, in mounting a film carrier semiconductor device having a semiconductor integrated circuit element, a microstrip line is formed between the lead of the film carrier tape, the base film and the surface terminal on the mounting substrate. Since it is a mounting method configured, it reduces the inductance of the lead of the film carrier tape,
There is an effect that electrical characteristics for a high speed IC can be easily improved at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view used for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view used for explaining a second embodiment of the present invention.

FIG. 3 is a cross-sectional view used to describe a conventional technique.

FIG. 4 is a cross-sectional view used to describe a conventional technique.

[Explanation of symbols]

 1a, 1b, 1c, 1d IC element 2a, 2b, 2c, 2d bump 3a, 3b, 3c, 3d OLB lead 4a, 4b, 4c, 4d pad 5a, 5b, 5c, 5d substrate 6a, 6b, 6c, 6d base Film 7c Adhesives 8c, 8d Surface terminals 9d Metal layers 10a, 10b, 10c, 10d Adhesives 11c, 11d Leads

Claims (1)

(57) [Claims] 1. When mounting a film carrier semiconductor device in which a semiconductor integrated circuit element is mounted on a film carrier tape having inner leads, a surface terminal portion and the surface provided at a position corresponding to a base film portion of the film carrier tape. Using a mounting substrate on which pads corresponding to outer leads provided in the peripheral portion of the terminal portion are formed, mounting is performed in a state where the surface terminal portion of the mounting substrate and the base film portion of the film carrier tape are in close contact with each other. The method for mounting a film carrier semiconductor device, wherein the surface terminal portion is electrically set to a ground potential.