JP3300486B2 - Lead frame manufacturing 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 manufacturing a lead frame.
About the law.

[0002]

2. Description of the Related Art A resin-molded lead frame is generally provided with a dam bar so that molten resin does not leak from between leads during resin molding.
However, recently, with the increase in the number of pins in the lead frame and the extremely small lead spacing, some problems have arisen in processing when manufacturing a semiconductor device. That is, in the case of the conventional lead frame, after the resin molding, the resin burr remaining inside the dam bar must be dropped, and the dam bar between the outer leads must be deleted. And dam bar cut processing becomes extremely difficult.

[0003] Comb blades formed in accordance with the lead pitch are used in resin dropping and dam bar cutting, but the lead pitch has been narrowed to about 0.3 mm even at present, and there is a limit in mechanical processing using a dam bar cutting punch. Is approaching. If the fine pitch is further reduced in this state, mechanical processing becomes almost impossible due to the problem of mechanical strength and durability of the dam bar cut punch.

[0004] Therefore, as a method for solving these problems, the use of a dam frame without a lead frame has been studied. For example, a polyimide tape is attached to the dam bar part of the lead frame to give the function of the dam bar, and the resin is molded into the resin by integrating it into the resin, or the function of the dam bar by potting the resin to the lead frame without the dam bar It is a method of giving it.

[0005]

However, in the case of the above-mentioned dam-barless lead frame, there is a problem that high-precision machining cannot be performed. For example, in a lead frame to which a tape having electrical insulation properties is applied as a dam bar, it is difficult to reduce the bonding position accuracy to 0.1 mm or less when applying the tape with a taping machine. In the lead forming, deviation in the bonding position of the tape causes variations in the bending accuracy of the leads. Further, in this case, since the resin is molded with the tape interposed therebetween, there is a possibility that moisture may enter from an interface between the tape and the resin, and reliability of the semiconductor device becomes a problem.

[0006] Even when the resin is applied with a dispenser as described above, it is difficult to obtain a high degree of positional accuracy, and thus it is not possible to obtain the required processing accuracy.
Since the number of leads in a multi-pin lead frame is large, the bending accuracy of the leads is required to be higher than that of conventional products. Therefore, in the manufacture of such a semiconductor device, there is a background that extremely high accuracy is required for the position accuracy of the dam bar and the like.

The present invention has been made to solve these problems, and an object of the present invention is to enable a process such as a dam-bar-less and high-precision lead forming in response to a fine pitch of a lead frame. , it is intended to provide a method of <br/> manufacturing lead frames that can be obtained a highly reliable semiconductor device.

[0008]

The present invention has the following arrangement to achieve the above object. That is, the lead frame formed by connecting the distal ends of the inner leads to each other to form a dumb bar is extended from the base position of the outer leads of the lead frame to the distal end side position of the inner leads excluding the die pad and the bonding portion of the inner leads. using the same resin material as the resin used in the resin mold frame and the pre-molded to the frame shape that is packaged in outer shape and the same shape of the semiconductor device, up to the frame body shaped
A resin mold using a mold inside the remolded
The semiconductor chip is molded by filling with a resin by molding operation, and a pre-mold concave portion for molding the pre-mold resin , and adjacent to the inner and outer clamping surfaces of the pre-mold concave portion when the lead frame is clamped. After clamping between the leads by pre-molding the lead frame by filling the resin in the pre-molded recess, closing the space between the leads and providing an elastic body for preventing leakage of the resin from between the leads. this to obtain the lead frame which is premolded by independent inner leads disconnects the distal end connecting portion of said inner leads
And features. In addition, an electrically insulating tape that is formed without a dam bar and prevents leakage of resin at the time of pre-molding is retracted at least by the bonding range from the tip of the inner lead and is adhered along the pre-mold range on the inner lead side. From the base position of the outer leads of the lead frame to the position where the tape is adhered, using the same resin material as the resin used for the resin molding of the lead frame and the outer shape of the package of the semiconductor device. Pre- shaped into the same frame shape
Molded, motor inside which is pre-molded to the frame body shaped
A pre-mold recess for molding a pre-mold resin , and a clamp surface on the outer lead side of the pre-mold recess, wherein the semiconductor chip is filled and filled with resin by a resin molding operation using a mold. The tape portion and the base position of the outer lead are provided by a molding die provided with an elastic body that closes between adjacent leads when the lead frame is clamped to prevent leakage of resin from between the leads. And a pre-molded lead frame is obtained by filling the resin in the pre-mold concave portion while preventing the resin from leaking inside and outside the pre-mold concave portion.
Further, in the method for manufacturing a lead frame, a resin having an electrical insulating property is dispensed along a pre-molding range of the inner lead in place of the tape to be attached to the inner lead, and the dispensed portion and the base position of the outer lead are provided. Are clamped to prevent leakage of the resin inside and outside the pre-mold concave portion, and the resin is filled in the pre-mold concave portion to obtain a pre-molded lead frame.

[0009]

[ Function ] Resin mold for lead frame without dam bar
When packaging semiconductor devices using pre-molded resin
Pre-molded into a frame that has the same shape as the cage
Of the pre-mold recess to be loaded and
Resin leaks from between the leads during resin molding on the side and outside
Priming using a molding die equipped with an elastic body to prevent
The resin on the tip side of the inner lead.
Pre-mold easily without getting into
Thus, it is possible to prevent misalignment of the inner leads and to provide a highly accurate lead frame product.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The method for manufacturing a lead frame according to the present invention is characterized in that after forming a dam barless lead frame by pressing or etching, the lead frame is partially resin-molded (referred to as pre-molding). The pre-molding here is the operation of resin-molding the part except for the bonding part at the tip of the die pad and the inner lead in the area where the lead frame is to be finally resin-molded. The resin is molded in the same shape as the external shape.

FIG. 1 is an explanatory view showing a state in which the lead frame 10 is pre-molded by the above-mentioned pre-molding operation. 10a is a die pad, 10b is an inner lead, and 10c is an outer lead. Reference numeral 12 denotes a pre-molded resin, and as shown in FIG.
The area excluding the tip of the inner lead 10b from the base position of c is molded into a frame. That is, in the lead frame 10 after the pre-molding, the tips of the die pad 10a and the inner leads 10b are exposed, and the leads are held by the frame-shaped pre-mold resin 12.

FIG. 2 shows a state where the lead frame 10 is set in a molding die for pre-molding the lead frame 10. The portion A in the drawing is the range for pre-molding. Since the lead frame 10 is formed in a dam-barless shape, when resin is molded across the leads as shown in the figure, it is necessary to prevent the molten resin from leaking from the boundary clamped by the molding die.

In order to prevent the molten resin from leaking from between the leads, resin molding is performed. In this embodiment, as shown in FIG.
6a is provided and resin molding is performed. Lower mold 14
The upper mold 16 is provided with pre-mold recesses 14b, 16b for pre-molding at positions opposing the lower mold 14 and the upper mold 16, and the elastic bodies 14a, 16a are provided in the pre-mold recesses 14b, 16b. It is stuck on the outside of the boundary surface, that is, on the surface that clamps the lead frame 10.

The elastic bodies 14a and 16a are connected to the lead frame 1.
When the 0 is clamped, the elastic members 14a and 16a prevent the resin from leaking from between the leads by entering the gap between the leads. Therefore, the elastic members 14a and 16a need to have enough flexibility to close the leads when the lead frame 10 is clamped, and have durability enough to withstand a large number of clamping operations. Elastic body 1
As 4a and 16b, for example, urethane rubber, silicon rubber, or the like can be used. In the embodiment, these elastic bodies 1
4a and 16a were used by sticking them to a mold in a sheet shape.

In FIG. 3, reference numeral 18 denotes a pot and reference numeral 20 denotes a mold cull. When pre-molding the lead frame 10, as shown in FIG. 2, the ends of the inner leads 10b are connected to each other, and resin molding is performed so that the inner leads 10b are not displaced. The pre-molding method is the same as the conventional method of transfer-molding the lead frame. As shown in FIG. 3, the lead frame 10 is clamped by the lower mold 14 and the upper mold 16 and the pot
0. The cavity formed by the pre-mold concave portions 14b and 16b is filled with resin via the gate and molded.

The pre-mold concave portions 14b and 16b are formed in a shape that matches the final shape of the resin molded portion when the semiconductor chip is mounted on the lead frame 10 and finally molded. That is, the pre-mold resin 1
The two parts are parts that become part of the mold resin in the final product after the resin molding, and are therefore preliminarily molded into a shape corresponding to the package shape. For this reason, at the time of this pre-molding, the same resin as that used when resin molding the lead frame 10 is used.

As described above, resin molding is performed using a molding die provided with the elastic members 14b and 16b, so that leakage of resin from between the leads can be prevented, and the lead frame 10 can be molded with resin. After the pre-molding, the portion where the tip of the inner lead 10b is connected is cut off to make the inner lead 10b independent, and a pre-molded lead frame 10 as shown in FIG. 1 is obtained. When the lead frame 10 is pre-molded, necessary processing such as plating is performed in advance.

The lead frame 10 thus obtained can be resin-molded by the method shown in FIG. That is, the semiconductor chip 30 is attached to the lead frame 10.
Is mounted and wire-bonded, then set in a mold and resin molded. The wire bonding operation for connecting the semiconductor chip 30 and the inner lead 10b is performed in a space within a frame surrounded by the pre-mold resin 12. Since the pre-mold resin 12 is formed in a frame shape on the lead frame 10, in this resin molding operation, molding is performed by filling the inside of the pre-mold resin 12 with resin.

In the embodiment, a pot 32 is arranged above a cavity formed in a mold, and a tapered gate 34 is extended vertically below the pot 32 to communicate the cavity with the pot 32. Is molded by forcing the resin into the cavity. Thus, the mold resin is filled inside the pre-mold resin 12, and a resin mold type semiconductor device having a predetermined outer shape can be finally obtained.

Since the semiconductor device thus obtained is dam-bar-less, a process such as dam-bar cutting and resin dropping is not required, and a resin-molded semiconductor device can be easily formed on a lead frame having a large number of pins and a very fine lead pitch. Can be obtained. Further, in the resin molded product, the outer leads 10c are completely molded by the pre-mold resin 12, the tape or the like is not exposed on the outer surface, and the ingress of moisture can be effectively prevented, so that a highly reliable semiconductor device can be provided. become.

In this embodiment, the elastic members 14a, 14b
There is an advantage that a molding die can be easily manufactured since resin molding is performed using the above method. Further, since the pre-mold resin 12 is formed by resin molding using a molding die, it has high dimensional accuracy, and can be processed with high accuracy even when lead forming or the like is performed after resin molding. As a result, it is possible to suitably apply the present invention to a lead frame requiring a high number of pins and high processing accuracy. In addition, when the lead frame 10 is pre-molded, the resin is molded so that the resin does not enter the inner lead 10b side, so that there is an advantage that good wire bonding can be secured to the inner lead 10b. is there.

As a method of preventing leakage of the resin on the inner lead side during pre-molding, a tape having an electrically insulating property such as a polyimide tape is pasted on a boundary portion of the pre-mold, Dispensing resin with electrical insulation, clamp the lead frame with a molding die, clamp the lead frame with an elastic body on the outside of the pre-mold recess, and clamp the tape or dispense part on the inner lead side A method of pre-molding by preventing leakage of the resin is also possible. In this case, it is possible to prevent the displacement of the inner lead by attaching a tape to the inner lead, and perform pre-molding.

In the above embodiment, a quad-type lead frame has been described. However, the method for manufacturing a lead frame according to the present invention can be similarly applied to a dual-type product. Even in the case of the dual type, resin molding can be performed without dam bars by pre-molding, and after mounting a semiconductor chip, resin molding can be similarly performed to obtain a semiconductor device.

[0024]

According to the manufacturing method of the present invention leadframe according to the present invention, as described above, it can be suitably premolded targeting leadframes Damubaresu,
It can be provided as a lead frame product with excellent lead position accuracy. In addition, the inner lead
Can be pre-molded without entering the resin.
A good wire bond for the inner lead
Loading property can be obtained. In addition, of Dam Burles
By pre-molding the lead frame, it is obtained <br/> Rukoto to easily be dam bar cutting are difficult products outer leads at a narrow pitch as a semiconductor device by the resin molding. Also uses a molding die with an elastic body
By doing so, there is a remarkable effect that the lead frame can be easily and reliably pre-molded.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of a lead frame.

FIG. 2 is an explanatory diagram showing a state in which a lead frame is set in a molding die and pre-molded.

FIG. 3 is an explanatory diagram showing a configuration of a molding die for pre-molding a lead frame.

FIG. 4 is an explanatory view showing a state in which a semiconductor chip is mounted on a lead frame and resin molding is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Lead frame 10a Die pad 10b Inner lead 10c Outer lead 12 Premold resin 14 Lower mold 14a Elastic body 14b Premold concave part 16 Upper mold 16a Elastic body 16b Premold concave part 18 Pot 20 Mold cal 30 Semiconductor chip 32 Pot 34 Gate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/50 H01L 21/56

Claims (3)

(57) [Claims] 1. A lead frame formed by connecting the distal ends of inner leads to each other to form a dam bar is disposed between the base position of the outer leads of the lead frame and the distal end position of the inner leads excluding the die pad and the bonding portion of the inner leads. , pre molded to the frame shape that is packaged in outer shape and the same shape of the semiconductor device using the same resin material as the resin used in the resin mold of the lead frame, on the inside, which is pre-molded to the frame body shaped <br/> resin by resin molding operation using the molding die is a semiconductor chip is filled is molded, pre
A pre-mold concave portion for molding the mold resin , and a clamp surface inside and outside the pre-mold concave portion,
When the lead frame is clamped, the space between the adjacent leads is closed and clamped by a molding die provided with an elastic body for preventing leakage of the resin from between the leads. after premolded leadframe Te, method for fabricating a lead frame, characterized in that to obtain a lead frame that is premolded by independent inner leads disconnects the distal end connecting portion of the inner lead. 2. An electrically insulating tape, which is formed without a dam bar and prevents leakage of resin at the time of pre-molding, is retracted at least by a bonding range from the tip of the inner lead and extends along the pre-mold range on the inner lead side. The attached lead frame is moved from the base position of the outer lead of the lead frame to the position where the tape is attached, and a half of the same resin material as the resin used for the resin molding of the lead frame is used. pre molded to the frame shape that is packaged in outer shape and the same shape of the conductor arrangement, the resin is filled semiconductor chip by resin molding operation using the molding die inside which is pre-molded to the frame body shaped mold Primo
A pre-molded recess for molding a mold resin , and a clamp surface on the outer lead side of the pre-molded recess is closed between adjacent leads when the lead frame is clamped to prevent leakage of resin from between the leads. The tape portion and the base position of the outer lead are respectively clamped by a molding die provided with an elastic body to be formed, and leakage of the resin inside and outside of the pre-mold concave portion is prevented so that the inside of the pre-mold concave portion is prevented. A method for producing a lead frame, characterized in that a pre-molded lead frame is obtained by filling a resin into the lead frame. 3. The method of manufacturing a lead frame according to claim 2, wherein an electrically insulating resin is dispensed along a pre-molded area of the inner lead instead of the tape attached to the inner lead. A pre-molded lead frame is obtained by clamping the portion and the base position of the outer lead respectively, preventing leakage of the resin inside and outside the pre-mold concave portion and filling the resin into the pre-mold concave portion. A method for manufacturing a lead frame, comprising: