JPH0319229Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is applicable to resin-sealed electronic components, such as
Regarding the improvement of lead frames used for resin sealing of semiconductor devices such as ICs and LSIs, in particular, the structure of the tie bars provided at least between each lead of the lead frame has been improved, and the manufacturing technology of this type of lead frame is disclosed. It is used in the industrial field.

(Prior Art) As a method for resin-sealing semiconductor devices, the transfer molding method, which is excellent in molding efficiency, is widely used today.

In this transfer molding method, as shown in FIG. 10, a lead frame 3 is set at a predetermined position in cavities 1a and 2a facing the parting line (P and L) surfaces of both upper and lower molds 1 and 2. In this state, molten resin material 4 is injected under pressure into the cavities 1a and 2a from the gate 2b, thereby sealing the semiconductor device 5 on the lead frame with the resin material filled into the cavities. It is. Therefore, as shown in FIG. 11, a resin molded body 4a encapsulating a semiconductor device 5 is fixed to the lead frame 3 taken out between the molds 1 and 2. Resin molded bodies 4b and 4c, which are cured within the gate 2b provided in the lower mold and the air vent 1b provided in the upper mold, are fixed to the edge frames 3a and 3b. Furthermore, the dams 6...6 are made up of a space between the edge frames 3a, 3b, a required plurality of leads 3c...3c provided between the edge frames, and tie bars 3d...3d that connect the respective leads. As shown in FIGS. 11 and 12, a part of the molten resin material injected under pressure into the cavities 1a and 2a has penetrated and hardened resin moldings 4d are fixed therein. The above-mentioned air vents 1b and dams 6...6 are cured within the cavities by discharging the air inside the cavities to the outside using the filling action of the molten resin material 4 injected under pressure into the cavities 1a and 2a. The purpose is to prevent voids or defects caused by residual air from occurring inside or on the surface of the resin molded body 4a, and therefore, this type of resin sealing is essential. This is one of the important molding conditions that cannot be achieved. However, each resin molded body 4 hardens within the gate 2b, air vent 1b, and dam 6...6.
b, 4c, and 4d are unnecessary parts for the product, so the edge frames 3a and 4d are unnecessary parts of the lead frame.
3b and tie bars 3d...3d may be cut and removed simultaneously in the cutting process (tie bar cutting process) or separately in separate processes.

By the way, since the above-mentioned resin material 4 usually contains an epoxy resin or the like containing a large amount of filler such as fused silica (for example, about 70 to 75% in the material), the tie bar is particularly During the cutting process and the process of cutting and removing the resin molded body 4d of the dam 6 portion (resin cutting process), the following problems occur.

That is, as shown in FIGS. 12 to 14, each of the tie bars 3d...3d and the resin molded body 4d are cut using a cutting machine 7 consisting of a punch 7a and a die 7b.
When cutting is performed, both the punch 7a and the die 7b are subject to significant wear, so there is a problem in that they must be replaced in a short period of time. In addition, in the case where the cutting machine 7 is equipped with a punch for cutting tie bars and a punch for cutting resin (resin molded body 4d) separately (not shown),
The life of the punch for resin cutting is extremely short, and in the case of the punch 7a that serves both as a tie bar and as a resin cutter as shown in FIG. The same applies to the contact surface of the die 7b.

Further, when the punch 7a and die 7b are worn out, the tie bar cut surface 8 of the lead frame and the cut surface of the resin molded body 4d become uneven, resulting in a problem that the appearance of the product is impaired.

Further, the tie bar cut surface 8, that is, the tie bar cut surface remaining as both sides of the lead 3c, has a burr 8a as shown in FIGS. 13 and 14.
will occur. This burr 8a is usually generated on the lower surface side of the tie bar 3d because the punch 7a is lowered from the upper surface side to cut and remove the tie bar 3d when the tie bar 3d is cut.

Therefore, burrs of equal height are generated at both positions on the lower surfaces of both sides of each lead 3c...3c, or burrs of different heights _h1 and _h2 are generated at both positions as shown in FIG. burrs 8a, 8a are generated, but these burrs are removed from each lead 3c in the next process...
A serious problem will occur during the bending process (bending process) of 3c. That is, as shown in FIG. 15, the bending process of each lead 3c...3c involves a fitting support member 9a of a resin molded body 4a in which a semiconductor device is sealed, and the molded body 4a set in the support member 9a. This is performed by a bending machine 9 comprising a bending roller 9b for bending each lead 3c...3c to a predetermined angle. It is bent along a predetermined bending surface 9c.

Therefore, when the above-mentioned burrs 8a are formed on the lower surfaces of both sides of each lead 3c...3c, each lead 3c...3c after bending is bent in a predetermined manner as shown by the chain line in FIG. The position of the burr 8a is raised according to the height of the burr 8a, or due to the burrs 8a and 8a of different heights _h1 and _h2 , the bending position is It becomes tilted. This means that when assembling the product to a chassis (not shown), etc., it becomes difficult to fit each lead into the mounting hole, etc., resulting in poor assembly workability or damage to each lead. There are various serious problems such as the product may become unreliable and its appearance may be damaged.

(Problems to be Solved by the Invention) The present invention provides a lead frame for resin sealing of electronic components that allows easy cutting and removal of the resin molded body at the tie bar portion of the lead frame and the dam portion of the lead frame. The purpose is to provide the following.

In addition, the present invention provides the ability to form an amount of resin molded body that is cured in the dam portion without reducing the air vent function of the dam portion in the lead frame;
By reducing the amount of resin film (flash) that adheres to the surface of each lead around the dam, we aim to improve the overall effective utilization of resin materials and create highly reliable, high-quality products. The purpose is to provide this kind of lead frame from which a product can be obtained.

Furthermore, the present invention provides a lead frame of this type in which, even if burrs are generated on the tie bar cut surface when cutting the tie bars of a lead frame, the burrs do not interfere with the bending process of each lead. The purpose is to provide a frame.

(Means for Solving the Problems) As a means for solving the above problems and achieving the objective, the present invention provides a plurality of leads, a frame for supporting the leads, and at least a space between each lead. A lead frame for resin sealing of an electronic component, comprising a tie bar connected to the tie bar, and a thin cutting part formed at a predetermined cutting location of the tie bar along the cutting direction, the lead frame having a thin cutting part in the tie bar. For resin sealing of electronic components, the tie bar is formed by a groove of a required depth that communicates between both end positions in the cutting direction, and partition-like shallow grooves are formed at required locations of the groove. Developed and adopted a lead frame.

In addition, in the present invention, in the lead frame for resin sealing of electronic components configured as described above, the grooves are formed in the same corresponding locations on both the front and back sides of the tie bar. , developed and adopted a lead frame with a large number of holes.

(Function) According to the configuration of the present invention, when a semiconductor device is sealed with resin, the air in the cavity on the mold side that is pushed into the dam part is discharged to the outside through the thin cutting part of the tie bar in the lead frame. Therefore, the thin part can maintain its function as an air vent.

Further, since the thin cutting portion described above is formed by a groove that communicates between both ends of the tie bar in the cutting direction, the tie bar can be cut more accurately and easily.

Furthermore, since the above-mentioned grooves are provided with partition-like shallow grooves, the strength of the grooves can be maintained and the molten resin material can be prevented from flowing out from the grooves. There is.

(Example) Next, the present invention will be explained based on the embodiment diagrams shown in FIGS. 1 to 9.

FIG. 1 shows a lead frame 12 in which a semiconductor device 10 is sealed within a resin molded body 11. The lead frame 12 includes two long edge frames 13 and 14 arranged in parallel, and a required plurality of leads 16...16 integrally connected between the edge frames via tie bars 15...15. , the semiconductor device 10
Tab leads 17, 17 with attached tab leads are provided. Also, between the periphery of the resin molded body 11, which is molded in accordance with the position and shape of the cavity in a resin sealing mold (not shown), and the edge frames 13 and 14, and the The space formed between the periphery and the leads 16 and the tie bars 15 is a dam 18 . be.

The dams 18...18 utilize the filling action of the molten resin material injected into the cavity under pressure,
By infiltrating a portion of the filled resin material into the dam 18, it also functions as an air vent for discharging the air inside the cavity to the outside. Further, the tie bars 15...15 have a storage function to prevent the molten resin material that has entered the dams 18...18 from flowing out from the dams. Furthermore, as shown in an enlarged view in FIG. 2, one end edge of the tie bars 15...15 is formed to have a wide width W extending to a position close to the cavity of the mold. , the tie bar 15, the lead 16 and the cavity part (i.e.
The dams 18 . . . 18 formed between the dams 18 and the periphery of the resin molded body 11 are formed to have a width W ₁ as narrow as possible within a range that can maintain the above-mentioned air vent function. Further, the predetermined cutting points of each tie bar 15...15, that is, each tie bar and each lead 16...16
Thin cutting portions 19 . . . 19 having shapes to be described later are formed at the boundary portions where the two are continuous. The thin cutting portions 19 are formed along the cutting direction parallel to the longitudinal direction of each lead 16, and the positions where the thin cutting portions are formed, that is, the predetermined cutting locations of the tie bars 15 are as follows: As shown in Figure 2,
Two locations on the left and right within the width W ₂ between the leads 16 and 16 are sufficient. Further, the shape of the thin cutting portion 19 may be any shape as long as it can improve the cutting efficiency when cutting the tie bar 15 portion from the thin portion.

By the way, as described above, each of the tie bars 15...15 is necessary to prevent voids or missing parts from occurring inside or on the surface of the resin molded body 11, but they are unnecessary parts as a product. Therefore, after the semiconductor device 10 is sealed with resin, each tie bar is punched with a punch 2 as shown in FIG. 3, for example.
The material is cut and removed by a cutting machine 22 consisting of a 0 and a die 21. Therefore, the thin cutting portion 19 of the tie bar 15 is located at the tie bar 1 corresponding to the position of the left and right tip portions 20a, 20a of the punch.
It is preferable that the cutters be formed at two locations on the left and right sides of the cutter 5, respectively, in order to increase the cutting efficiency.

Further, as shown in FIG. 4, the thin cutting portion 19 is a groove 19 of a required depth that communicates between both end positions of the tie bar 15 in the cutting direction on at least one side of the front or back side of the tie bar 15.
It is formed from a.

In addition, for the purpose of preventing the molten resin material that has entered the dam 18 from flowing out from the groove 19a to the outside at the end portion or the intermediate portion of the groove 19a,
Alternatively, for the purpose of maintaining the strength of the groove 19a, a partition wall-like shallow groove 19b as shown in FIGS. A partition wall-like shallow groove portion 19b is provided which projects from the partition wall and is formed by the end portion of the partition wall.

In addition, as shown in FIG. 7, the groove 19a is
They may be formed at the same corresponding locations on both the front and back sides of the tie bar 15, respectively.

Furthermore, as shown in FIG. 8, for example, a large number of holes 19c...19c are formed in each of the grooves 19a for the purpose of facilitating cutting of the grooves 19a.

Note that numerals 23, 24, and 25 in the figure indicate resin molded bodies that have been cured at the gate, air vent, and dam 18 portions of the resin sealing mold.

In the above configuration, when cutting each tie bar 15...15 in the lead frame, as shown in FIG. Two thin sections for cutting on the left and right 19, 19
When the right and left end portions 20a, 20a of the punch are brought into contact with the left and right ends 20a, 20a, and then the punch 20 is pressed toward the die 21, the tie bar 15 will be moved to its both thinner portions 19, 1.
At the same time, the two cut surfaces (tie bar cut surfaces) 15a, 15a remain as left and right side surfaces of the lead 16. At this time, the thin cutting portion 19 of the tie bar 15 is
As shown in FIGS. 4 to 6, when the tie bar is formed only on one side, the side where the thin cutting portion 19 is formed is shown in FIG. 3 when cutting the tie bar 15. As shown, it may be set on the die 21 side, that is, facing downward on the opposite side from the punch 20. Therefore, the thin section for cutting 1
On the tie bar cut surfaces 15a, 15a at 9,
As shown in FIG. 9, even if a downward burr 15b is generated, the burr 15b can be accommodated in the groove 19a constituting the thin cutting portion, so that when bending each lead 16...16, , the burr 1
5b can be reliably prevented from interfering with the bending action on each lead 16...16. In addition,
If the thin cutting portions 19 are formed on both the front and back surfaces of the tie bar 15 as shown in FIGS. 7 and 8, the above-described restrictions regarding setting the tie bar 15 on the front and back sides during the cutting process can be eliminated. It is something.

Further, the lead frame 12 of the above embodiment is used in the same manner as conventional lead frames of this type, but when the structure of this embodiment is used, when the semiconductor device 10 is sealed with resin,
The air in the mold side cavity pushed into the dam 18 is transferred to the tie bar 15 in the lead frame.
Since the air is discharged to the outside through the thin cutting portion 19, the thin portion 19 can maintain its function as an air vent.

Furthermore, since the space constituting the dam 18 is formed to have a narrow width W ₁ , the molten resin material is prevented from entering the surface of the lead 16 inside the dam 18 and around the dam 18, and The amount of molded resin body 25 and the amount of resin film attached to the surface of lead 16 can be reduced.

In addition, the tie bar 15 part of the lead frame is
As mentioned above, since cutting is performed extremely easily and reliably along the thin cutting portion 19 formed on the tie bar, the cutting area for the resin molded body that hardens at the dam 18 portion is reduced. , the overall durability of the cutting machine 22 can be improved.

Although not shown, the configuration of the above embodiment can be substantially the same in a lead frame for a transistor or a lead frame for a light emitting diode, which has a tie bar portion, for example. .

(Effects of the invention) When the configuration of the invention is used, the tie bar portion of the lead frame and the resin molded body that hardens within the dam portion can be cut and removed more easily and reliably than with conventional methods. This makes it possible to simplify the cutting process and save labor, as well as to perform appropriate bending on each lead, making it easy to form high-quality products with excellent reliability. A suitable lead frame for resin sealing of electronic components can be provided.

In particular, since the thin cutting portion of the tie bar of the present application is formed by a groove that communicates between both end positions of the tie bar in the cutting direction, the tie bar can be cut more accurately and easily. In addition, since the groove is provided with a partition-like shallow groove, it is possible to maintain the strength of the groove, and to effectively prevent the molten resin material from flowing out from the groove. can be prevented.

Furthermore, by forming the grooves at the same corresponding locations on both the front and back sides of the tie bar, restrictions regarding the front and back set of the tie bar can be eliminated. Furthermore, by forming a large number of holes in the grooves, excellent practical effects such as the ability to easily cut the tie bars can be achieved.

[Brief explanation of the drawing]

1 to 9 show embodiments of the present invention. FIG. 1 is a partially cutaway plan view of a lead frame showing a state in which a semiconductor device is sealed with resin, and FIG. 2 is a partially cutaway plan view of the lead frame. A partially cutaway enlarged bottom view showing the main parts, Fig. 3 is an explanatory diagram regarding the cutting process of the tie bar part, Fig. 4 is an enlarged sectional view taken along the - line in Fig. 3, and Figs. 5 to 8 are all cutaways. FIG. 9 is a cross-sectional view showing another example of the shape of the thin portion, and FIG. 9 is a partially cutaway enlarged perspective view showing an example of the tie bar cut surface. 10 to 16 show conventional examples, FIG. 10 is an explanatory diagram of the resin sealing effect of a semiconductor device when a conventional lead frame is used, and FIG. 11 shows the resin sealing state. 12 to 14 are explanatory diagrams for cutting the tie bar portion and the resin molded body in the dam, and FIG. 15 is an explanatory diagram for bending the lead portion, FIG. 16 is a front view showing the product. 12...Lead frame, 13...Edge frame, 14
...Edge frame, 15...Tie bar, 16...Lead,
18...Dam, 19...Thin section for cutting, 19a...
...Groove, 19b...Partition-like shallow groove, 19c...
Hole.

Claims (1)

[Claims for Utility Model Registration] (1) A device comprising a required plurality of leads, an edge frame for supporting the leads, and a tie bar connecting at least the leads, and at a predetermined cutting point of the tie bar. A lead frame for resin sealing of an electronic component in which a thin section for cutting along the cutting direction is formed, wherein the thin section for cutting in the tie bar is
A resin for an electronic component, characterized in that the tie bar is formed by grooves of a required depth that communicate between both end positions in the cutting direction, and partition-like shallow grooves are formed at required locations of the grooves. Sealing frame. (2) A lead frame for resin-sealing electronic components as set forth in claim (1) of the utility model registration claim, characterized in that grooves are formed at the same corresponding locations on both the front and back sides of the tie bar. . (3) A lead for resin sealing of an electronic component according to claim 1 or 2 of the utility model registration claim, characterized in that the lead is formed by forming a large number of holes in a groove. flame.