JPH0783081B2 - Method for manufacturing lead frame used in semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead frame used in a semiconductor device, and more particularly, to forming a half-etching separation groove on an inner lead of a lead frame by an etching method. The present invention relates to a method for manufacturing a lead frame that can be easily separated into a bonding area and a stage.

[Conventional technology]

2. Description of the Related Art Conventionally, a semiconductor device has a structure in which a lead frame having a circuit pattern connected to the outside is resin-sealed with a semiconductor element. The lead frame used for this semiconductor device is manufactured as a circuit pattern in which a thin metal plate is separated into a wire bonding area and a stage on which the semiconductor device is mounted in advance by press punching or etching.

In recent years, with the progress of semiconductor integrated circuit technology, circuit elements have become more sophisticated and formed, and accordingly, the number of lead pins of a lead frame also tends to increase.
At the same time, the dimensions of semiconductor devices are increasing.

However, since the dimensions of the semiconductor package are standardized, the width of the package is required to be within a certain range. Therefore, as the number of lead pins increases, the space between the lead pins and the pin width must be reduced accordingly. Further, as the size of the semiconductor element increases, the stage of the semiconductor element also increases.

[Problems to be Solved by the Invention]

When the number of lead pins is increased in this way, when the wire bonding area and the stage are formed in advance with a molding pattern, the lead frame is manufactured through a plurality of processes, and therefore the inner lead is twisted or deformed by bending or scratches due to external force. Was likely to occur and was a cause of poor quality. On the other hand, for example, Japanese Patent Laid-Open Nos. 54-61874 and 61
As disclosed in Japanese Patent Laid-Open No. 216354, a method of integrating a wire bonding area and a stage, performing various steps and then separating them is currently adopted.

However, in the former method, a V notch is cut at the connection position by press working. In this method, processing distortion occurs at the tip of the lead or bulging occurs due to crushed meat being pushed to the periphery. , The lead extends, and the tip of the lead floats, sinks, is unbalanced, or the like. Therefore, there are problems that the flatness in the thickness direction is deteriorated and the depth of the V notch is not stable.

The latter is based on an etching method, in which a required portion of the lead frame is masked and then separated and removed by etching. However, since the wire bonding and the like are masked and etched, peeling of the plated portion in the wire bonding area and the problem of pinholes occur, and there is a cost disadvantage.

Therefore, it is an object of the present invention to provide a method of manufacturing a high quality lead frame, which can easily separate the wire bonding area of the inner lead surface and the stage by using a groove obtained by etching.

[Means for Solving the Problems]

A method of manufacturing a lead frame used for a semiconductor device according to the present invention is a method of manufacturing a lead frame in which tips of inner leads arranged toward a stage on which a semiconductor element is mounted are connected to an outer edge of the stage and are integrated by an etching method of a lead frame. In the artwork process of forming a glass mask pattern for etching, a separation groove for separating a wire bonding area and the stage is formed on the inner lead of the glass mask pattern, and then a baking / developing process and unnecessary portions are formed. Is subjected to an etching step to remove the, to form a separation groove on the surface of the inner lead, by pushing and bending the support bar connected to the stage, while displacing the stage downward, along the separation groove, It is characterized in that the tip of the inner lead and the stage are separated.

〔Example〕

Hereinafter, the features of the present invention will be specifically described with reference to the embodiments shown in the drawings.

FIG. 1 is a plan view showing an essential part of a lead frame structure manufactured according to the present invention, and FIG. 5 is an overall plan view of the lead frame.

In the lead frame A, as shown in FIG. 5, a stage 1 for mounting a semiconductor element is formed in the center of an outer frame 20, an outer lead 21 is provided on the outer side, and an inner lead 2 is provided on the inner side. A tie bar 22 is formed between the outer lead 21 and the inner lead 2, and a support lead 3 is provided between the outer frame 20 and the stage 1.

The lead frame A is made of a thin metal plate as in the conventional manufacturing method, and is an artwork process of forming a glass mask pattern of the lead frame A, a baking and developing process of forming a mask pattern on both sides of the material, and an unnecessary portion of the mask pattern. It is formed by an etching process for removing.

In the artwork process, the separation pattern is formed on the upper one or two upper and lower glass mask patterns so as to correspond to the quadrangle line L shown by the alternate long and short dash line in FIG. The quadrangle line L runs on the front surface or both front and back surfaces of the inner lead 2, and its position is separated from the outer edge of the stage 1 and extends along the inner side of a wire bonding area described later. The line L does not pass through the support lead 3, but only the inner lead 2 corresponds to it.

When the separation pattern corresponding to such a line L is formed on the upper and lower two glass mask patterns, the half etching groove 4 is formed on the upper and lower surfaces of the lead frame A as shown in FIG. In the manufacturing process for this purpose, a glass mask pattern is first adhered to the upper and lower surfaces of a thin Fe-Ni alloy plate coated with a photosensitive solution and dried, and then baked and developed. Next, after forming the resist pattern of the lead frame A, an etching solution (60C ferric chloride) is sprayed.
By this etching treatment with the etching solution, the half etching groove 4 is formed on the upper and lower surfaces of the lead frame A at the same time when the pattern of each lead shown in FIG. 5 is formed. Then, the half-etched groove 4 is formed so as to run along the inside of the wire bonding area 5, and a product before resin sealing is obtained.

In the structure shown in FIG. 1, the half etching groove 4 is formed only on the upper surface of the lead frame A. The half etching groove 4 is formed inside the wire bonding area 5 as in the case of FIG. 4, and is formed at a position apart from the outer edge 1 a of the stage 1.

After the half etching groove 4 is formed in the inner lead 2 of the lead frame A, the step of separating the inner lead 2 from the stage 1 is performed. In this step, first, the wire bonding area 5 is partially plated by using a spot plating apparatus, and further, an insulating thermosetting resin for fixing the inner lead 2 in the vicinity of the wire bonding area 5 is injected in a ring shape. Then, when the support lead 3 portion is bent and the stage 1 is depressed, the half etching groove 4 is bent as shown in FIG. 3, and the inner lead 2 and the stage 1 are separated.

After this separation step, the wire bonding area 5
A wire 7 is connected to the semiconductor element 6 bonded onto the stage 1 via a resin tape 6a. Therefore, each inner lead 2 is connected to each electrode of the semiconductor element 6,
When an electric signal is passed through each inner lead 2 through the circuit pattern, this signal can be transmitted from each wire 7 to each electrode to operate the semiconductor element 6. Then, in the final stage, the resin is sealed with the resin sealing body 8 excluding the outer leads 21.

In this way, since the inner lead 2 is separated from the stage 1 after performing various processes, it is possible to bend the inner lead 2 at the time of manufacturing as compared with the case where the inner lead 2 is separated at the time of pattern formation of the lead frame A as in the related art. Unaffected by twisting. Therefore, even if the width of the inner lead 2 is narrow, it is possible to perform favorable processing, and as a result, the inner lead 2
The number of can be increased. Therefore, even if the semiconductor element 6 is highly integrated, the number of pins can be increased, and the semiconductor element 6 can be sufficiently dealt with.

Further, in the case where the half etching groove 4 is provided on the upper and lower surfaces of the lead frame A as shown in FIG. 4, the separation can be performed by a gentle press compared with the case where the half etching groove 4 is formed only on the upper surface. Therefore, the deformation of each inner lead 2 is prevented even more effectively.

〔The invention's effect〕

As described above, according to the present invention, for each inner lead, a half etching groove is formed in a portion inside the wire bonding area and surrounding the stage, and after performing various steps, shearing of the half etching groove portion is performed. The inner lead and the stage are separated by. Therefore, the inner leads are less affected by twisting or bending as compared with the case where the inner leads are previously formed as a pattern separated from the stage. Therefore, even if the width of each inner lead is small, molding can be performed without twisting or bending, and the number of inner leads can be increased. As a result, high integration of semiconductor elements can be dealt with, and packaging density can be improved. Further, even when the number of pins is the same and the size of the semiconductor element is large, there is an advantage that it can be easily dealt with by changing the separation groove position of the glass mask pattern.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of a lead frame manufactured according to the present invention, FIG. 2 is a sectional view taken along the line II of FIG. 1, and FIG. 3 is a stage and inner leads after resin sealing. FIG. 4 is a schematic vertical sectional view showing separation of the lead frame, FIG. 4 is a sectional view when half etching grooves are formed on the upper and lower surfaces of the lead frame, and FIG. 5 is a plan view showing the entire lead frame. 1: Stage, 1a: Outer edge 2: Inner lead, 3: Support lead 4: Half etching groove 5: Wire bonding area 6: Semiconductor element, 6a: Resin tape 7: Wire, 8: Resin encapsulant 20: Outer frame, 21: Outer lead 22: Tie bar A: Lead frame

Claims (1)

[Claims] 1. A method for manufacturing a lead frame, wherein a tip of inner leads arranged toward a stage on which a semiconductor element is mounted is connected to an outer edge of the stage to be integrated by an etching method, and a glass mask pattern for etching is used. In the artwork step of forming the step, a separation groove for separating the wire bonding area and the stage is formed on the inner lead of the glass mask pattern, and then a baking / developing step and an etching step for removing unnecessary portions are performed, A separation groove is formed on the surface of the inner lead, and the support bar connected to the stage is pressed and bent to displace the stage downward, and the tip of the inner lead is separated from the stage along the separation groove. A method of manufacturing a lead frame, comprising: