JP2001274307A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor device in which a masking jig is eliminated, and a partial plating of a lead frame is performed with superior productivity and further with profile precision even if a partial plating portion is fine, and a mounting of a semiconductor chip and an electric connection of the semiconductor chip with an inner lead are performed with superior workability and reliability, and further an adhesion of a sealing resin to the lead frame is excellent and the reliability is superior. SOLUTION: A lead frame 1 is coated with a resist 8, the resist 8 at a plating required portion of the lead frame 1 coated with the resist 8 is eliminated by a laser irradiation, a plating 9 is performed at the eliminated portion, a semiconductor chip 10 is mounted to a semiconductor chip mounted part 2, an inner lead 3 is electrically connected to the semiconductor chip 10 via a bonding wire 11, and the inside of the inner lead 3 in which the resist 8 except for the eliminated portion is still coated is sealed with a resin to manufacture a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In a semiconductor device using a lead frame, a semiconductor chip is mounted on a pad, electrodes of the semiconductor chip are electrically connected to inner leads by bonding wires, and the inner leads, pads, semiconductor chip, and bonding wires are connected. Is sealed with a resin or the like.

The pads are plated with a noble metal such as gold or silver in order to mount the semiconductor chip with high reliability. In addition, the noble metal is plated on the inner leads in order to facilitate the connection operation with the bonding wire and to enhance the reliability of the connection. These platings are performed only on necessary portions in order to eliminate wasteful use of precious metals and reduce costs.

In the conventional partial plating, a mask is manufactured, and a masking jig and a back plate cover portions other than the tip of the inner lead and the pad which need to be plated, and apply a plating solution or apply a plating solution. The plating is performed only at the necessary portions.

[0005]

Since the partial plating is performed as described above, the shape to be plated, that is, a masking jig such as a mask corresponding to the plating shape is used to change the shape of the lead frame to be plated or the plating. It has to be manufactured every time the shape changes, it takes time and requires a high level of skill. Further, as the size of the semiconductor device is reduced, the size of the lead frame becomes smaller, and the area of the inner lead that is partially plated becomes finer.

A semiconductor chip is mounted on a pad plated with a noble metal, the electrode of the semiconductor chip is connected to the tip of an inner lead by a bonding wire, and the inside of the inner lead is sealed with a resin or the like to manufacture a semiconductor device. . In the resin encapsulation process, after the resin encapsulation molding, a release agent is included in the resin to facilitate removal of the product from the encapsulation mold, thereby reducing the adhesion to the lead frame. Also, due to the difference in thermal expansion between the sealing resin and the lead frame,
A gap may be formed in the bonding interface due to the use of the semiconductor device, and the reliability of the semiconductor device is impaired.

[0007] Further, in the situation where semiconductor devices are becoming smaller and thinner, the problem of the adhesion between the sealing resin and the lead frame is a major problem to be solved.

According to the present invention, a masking jig such as a mask is unnecessary, and partial plating of a lead frame can be performed with high productivity.
Even if the partial plating part is fine, it can be performed with good shape accuracy,
The mounting of the semiconductor chip and the electrical connection between the semiconductor chip and the inner lead can be performed with good workability and reliability,
It is another object of the present invention to obtain a semiconductor device having good adhesion between a sealing resin and a lead frame and excellent reliability.

[0009]

SUMMARY OF THE INVENTION The gist of the present invention is to coat a resist on a lead frame, remove the resist at a required portion of the coated lead frame by laser irradiation, apply plating to the removed portion, and form a semiconductor chip. Is mounted on the semiconductor chip mounting portion of the lead frame, and the inner lead and the electrode of the semiconductor chip are electrically connected via a bonding wire. A method for manufacturing a semiconductor device, comprising sealing a part, a semiconductor chip, and a bonding wire with a resin.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; In the drawing, reference numeral 1 denotes a lead frame, an inner lead 3 is formed continuously with a pad 2 on which a semiconductor chip is mounted, and an outer lead 4 is formed continuously with the inner lead 3. Reference numeral 5 denotes a tie bar formed between the inner lead 3 and the outer lead 4 and used for resin sealing when sealing with resin. Reference numeral 6 denotes a support bar connected to the corner of the pad 2. 7 is a guide hole. These lead patterns are formed by a pressing method, an etching method, or a combination thereof.

The lead frame 1 is coated on the entire surface with a resist made of, for example, an epoxy-based or polyimide-based resist which does not dissolve even when wet with a plating solution. The coating is performed by roll coating, spray coating, film coating, or a combination thereof, and is also applied to the side surface of the lead.

The lead frame 1 coated with the resist 8 is irradiated with a laser, for example, a YAG laser, a carbon dioxide gas laser, or the like, at a portion requiring plating, in this embodiment, a surface of the inner lead tip 3a and a surface of the pad center 2a. Only the resist 8 on the surface is removed. The beam of the laser beam can be adjusted to a light diameter of, for example, 0.1 μm or less, and the resist can be removed only from the irradiated portion, so that the resist can be removed only from the portion requiring plating with high precision. Further, since the subsequent plating is not applied to the portion where the resist is still applied, a plating mask is unnecessary.

The lead frame 1 from which the resist 8 has been removed is passed through a plating bath, for example, a gold plating bath, a silver plating bath, an antimony plating bath, or a gold plating solution, a silver plating solution, or an antimony plating solution. Noble metal is plated 9 by spraying a plating solution such as a solution.

Since the plating 9 is provided with a resist 8 except for the portions where the plating is required at the tip 3a of the inner lead and the center portion 2a of the pad, the plating 9 is not plated, and the plating is not required without any side leakage. Only one is partially plated as shown in FIG.

In the partial plating, an appropriate metal such as Ni, Sn, or Cu is first plated on the lead frame 1 as a base,
Alternatively, it can be performed without applying a base plating.

After the partial plating, the portion where the tip of the inner lead 3 is connected to the pad 2 is cut off by a press or the like, separated from the pad 2 and the side surface of the pad 2 is formed. The semiconductor chip 10 is mounted on the formed pad 2 by ultrasonic welding or bonding with an adhesive or the like.

The mounted semiconductor chip 10 is electrically connected by a bonding wire 11 to its electrode and the portion of the tip of the inner lead 3 which is partially plated 9.
In this bonding, the noble metal is plated at the bonding portion at the tip of the inner lead 3, so that the bonding is performed with good reliability and workability.

Next, the inner leads 3, the pads 2, the semiconductor chip 10 mounted on the pads 2, and the bonding wires 11 are sealed with a resin except for the portions removed by the laser irradiation. Resin sealing is performed using, for example, polyimide resin, epoxy resin, or the like.
Even if the mold release material 2 is included, the interface between the inner lead 3 and the pad 2 is not adversely affected, and the sealing resin 12 is bonded to the resist 8 with good adhesion and sealed. Thereby, the semiconductor device 13 is manufactured.

In this embodiment, the resin sealing is performed such that the bottom surfaces of the inner leads 3 and the pads 2 are also included in the resin. However, the bottom surfaces of the inner leads 3 and the pads 2 are exposed from the resin sealing bottom surface. May be sealed.

In this embodiment, the inner lead 3 and the outer lead 4 are formed on the lead frame 1 as leads. However, the present invention is also applicable to a semiconductor device using the lead frame 1 on which only the inner lead 3 is formed. The present invention can also be applied to a semiconductor device 13 of a type in which leads are not exposed outside the semiconductor device as shown in FIG.

In the above embodiment, the removal of the resist 8 of the lead frame 1 by laser irradiation is performed on both the inner lead end portion 3a and the pad central portion 2a, but either one may be performed as necessary.

[0022]

According to the present invention, a lead frame is coated with a resist, the resist is removed from only the plating-required portions of the coated lead frame by laser irradiation, and the removed portion is plated with a noble metal to form a semiconductor chip. Mounted on the semiconductor chip mounting part of the lead frame,
The semiconductor device is manufactured by connecting the inner lead and the electrode of the semiconductor chip via a bonding wire, and sealing the resin in the inner lead except for the partially plated portion while the resist is still coated. Therefore, partial plating can be performed without manufacturing a masking jig, and even if a portion requiring plating is fine, the resist in that portion can be removed with high positional accuracy, and the noble metal can be partially plated. Further, since the resist is applied to portions other than the portions subjected to the partial plating, the adhesiveness with the sealing resin is strong, and there is an operational effect that a highly reliable semiconductor device is obtained without occurrence of resin peeling or the like. .

[Brief description of the drawings]

FIG. 1 is a diagram showing coating of a lead frame with a resist in one embodiment of the present invention.

FIG. 2 is a view showing a portion of the lead frame where plating is required removed by laser irradiation in one embodiment of the present invention.

FIG. 3 is a view showing a part of a lead frame in which plating is required in one embodiment of the present invention.

FIG. 4 is a diagram showing a state in which a tip of an inner lead and a pad are formed and a semiconductor chip is mounted in one embodiment of the present invention.

FIG. 5 is a diagram showing a semiconductor device manufactured in one embodiment of the present invention.

FIG. 6 is a diagram showing a semiconductor device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Pad 3 Inner lead 4 Outer lead 5 Tie bar 6 Support bar 7 Guide rail 8 Resist 9 Plating 10 Semiconductor chip 11 Bonding wire 12 Sealing resin 13 Semiconductor device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Yasunaga 2-10-1 Komine, Yawatanishi-ku, Kitakyushu F-term (reference) 4M109 AA01 BA01 CA21 FA06 FA07 5F067 AA01 DC00 DC13 DC14 DE06

Claims (2)

[Claims] 1. A method for coating a lead frame with a resist, removing the resist at a portion of the lead frame required for plating by laser irradiation, plating the removed portion, and mounting the semiconductor chip on a semiconductor chip mounting portion of the lead frame. And the inner lead and the electrode of the semiconductor chip are electrically connected via a bonding wire, and the inner lead, the semiconductor chip mounting portion, the semiconductor chip, and the bonding wire remain coated with the resist other than the removed portion. A method for manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein a portion of the resist coated on the lead frame removed by the laser irradiation is at least one of a tip portion of an inner lead and a semiconductor chip mounting portion.