KR20060112307A - Method for manufacturing a lead frame and press system for the same - Google Patents

Abstract

A method for fabricating a leadframe is provided to decrease the number of processes and shorten an interval of work time by performing a cavity cutting process and a setting process in a single step. A plurality of leads are formed in a leadframe, separated from each other by a predetermined interval. The plurality of leads and a cavity for interconnecting the front ends of the leads are incorporated in a prepared base material by a patterning process(S12). The leadframe is pressed by using a mold of a predetermined type. A cutting process for cutting the cavity and a setting process for forming a vertical step with respect to a part of the leadframe are simultaneously performed in a leadframe blanking mold process in which the leadframe is disposed between upper and lower molds having mutually corresponding types such that the upper and lower molds are pressed to each other(S16).

Description

Method for manufacturing a lead frame and a press working apparatus for a lead frame applied thereto {Method for manufacturing a lead frame and press system for the same}

1 is a flowchart illustrating a method of manufacturing a lead frame according to a preferred embodiment of the present invention according to a process sequence;

FIG. 2 is a perspective view illustrating a lead frame subjected to the patterning process of FIG. 1;

3 is a plan view illustrating a lead frame that has undergone the plating layer forming process of FIG. 1;

4 is a plan view illustrating a lead frame that has been subjected to the tape attaching process of FIG. 1;

5 is a cross-sectional view showing a press working apparatus for a lead frame of the present invention;

6 is a plan view showing the upper mold and the lower mold,

7 and 8 are a perspective view showing a part of the upper mold and the lower mold shown in Figure 6,

9 is a plan view illustrating a lead frame that has undergone the lead frame punching forming process of FIG. 1,

10 is a perspective view showing in more detail the portion A shown in FIG.

<Description of Symbols for Major Parts of Drawings>

110: lead frame 111: cavity

112: wing bar 114: inner lead

115: lead 116: external lead

117: Dam Bar 118: Side Rails

141: shuttle 142: punch holder

143: punch 143a: first bias

143b: second deviation 145: drive shaft

146: guide shaft 147: lower holder

148: base 210: upper mold

220: lower mold 211: first punch hole

212: second punch hole 214: pressure strip

218,228 base 221 through hole

The present invention relates to a manufacturing method of a lead frame for electrically connecting a semiconductor chip and an external circuit, and a press working apparatus for a lead frame applied thereto, and more particularly, to an improved lead frame in which the number of processes is reduced and the processing precision is improved. It relates to a manufacturing method and a press working apparatus for a lead frame applied thereto.

The lead frame constitutes a semiconductor package together with a semiconductor chip. The lead frame supports a semiconductor chip and electrically connects the semiconductor chip and an external circuit. In general, a lead frame includes a side rail constituting a skeleton and a plurality of leads integrally formed with the side rails, the leads having inner and outer leads formed corresponding to the inner and outer sides. do. Dam bars are formed between the inner leads and the outer leads to maintain a constant gap between the leads and support them. When the assembly of the semiconductor package is completed, the side rails and the dam bar are removed. Wing bars may be integrally formed on one side and the other side of the side rails, and the wing bars may be down-set or up-set to be at a lower level than side rails and leads. Or high levels. After the semiconductor chip is mounted on the lead frame, a molding process of encapsulating a predetermined region of the lead frame with a molding resin such as an EMC (Epoxy Molding Compound) is performed, wherein the wing bars are disposed at upper and lower sides thereof. It performs a function to make the molding smoothly by adjusting the flow rate of the injection molding resin.

In manufacturing a lead frame according to the prior art, first, a lead frame base material is prepared, and the lead frame is patterned into a predetermined shape to form a plurality of leads integrally. Next, a lead lock tape or a chip attaching tape is attached over a plurality of leads, and the leads are mutually supported by the tape, thereby suppressing bending deformation due to the weight of the leads and the like. Such a tape may be attached over a portion of the cavity connecting the tip of the leads and a portion of the lead tip. Subsequently, a cavity cutting process is performed, whereby the leads are individually separated from each other, and in this process, a part of the tape is also cut together with the cavity, so that the front end of the inner lead and the cut surface of the tape coincide. Subsequently, the down-set (or up-set) process is performed. The down-set (or up-set) process is a process of forming a predetermined portion of the lead frame lower (or higher) than the surface on which the leads are formed. In order to improve the wiring characteristics between the semiconductor chips, the die pad is up-set processed or the wing bar is up-set processed to control the flow rate of the molding resin.

However, according to the related art, although the cavity cutting process and the down-set process are both processes of cutting using a mold or forming a step, there is a problem in that the number of processes is increased by proceeding individually. In addition, since these processes are performed by separate equipment, the standard alignment of the equipment and the lead frame is repeatedly required, and there is a problem in that a product defect rate increases due to misalignment and cumulative tolerances.

The present invention is to solve a number of problems, including the above problems, improved production method by reducing the number of processes and reducing the accumulated tolerance, manufacturing cost improved manufacturing method of the lead frame and lead applied thereto It is an object of the present invention to provide a frame press working apparatus.

Another object of the present invention is to provide a method of manufacturing a lead frame in which machining accuracy is improved while achieving the above object and a press working apparatus for a lead frame applied thereto.

In order to achieve the above object, a method of manufacturing a lead press arbitrary according to an aspect of the present invention,

 A method of manufacturing a lead frame in which a plurality of leads are formed with a predetermined interval therebetween,

A patterning process of integrally forming a plurality of leads and a cavity interconnecting the ends of the leads to the prepared base material; And

And a lead frame punching molding step of pressing the lead frame using a mold having a predetermined shape, and simultaneously performing a cutting process of cutting the cavity and a setting process of forming a step up and down with respect to a part of the lead frame. .

In the present invention, preferably, in the punching-molding process of the lead frame, the lead frame is disposed between the upper mold and the lower mold having a shape corresponding to each other, and pressed against each other. Preferably, the upper mold is formed with a first punch hole into which a first punch contributing to the cutting process is inserted, and a second bias hole into which a second bias to contribute to the setting machining is inserted, and the lower mold has the first punch hole. Through-holes and set blocks are formed to correspond to the first punch hole and the second punch hole, respectively.

In the setting process, a part of the lead frame may be up-set to a higher level than the leads or up-set to a lower level than the leads.

The lead frame may have a wing bar for distributing an inflow amount of the molding resin. In this case, the wing bar may be set in the punching process of the lead frame.

A die pad on which the semiconductor chip is mounted may be formed in the lead frame. In this case, it is preferable that the die pad is up-set in the punch molding process of the lead frame.

In the present invention, preferably, the tape attaching process may further include attaching a lead lock tape or a chip attaching tape to one end surface of the leads between the patterning process of the lead frame and the punch forming process of the lead frame. In this case, in the lead frame punching molding process, it is preferable that a portion of the tape is cut together with the cavity so that the tape is aligned with the ends of the leads.

Preferably, the lead frame punching molding process is performed in a reel form in which a plurality of lead frames are formed together. In this case, a cut-off process of cutting and individualizing each lead frame is performed after the punching molding process.

 On the other hand, the press working apparatus for a lead frame according to another aspect of the present invention,

A press working apparatus for a lead frame for press molding a lead frame seated between an upper mold and a lower mold,

A first punch for cutting a cavity connecting the leads of the lead frame; And

And a second punch forming a step in a part of the lead frame.

 In the present invention, preferably, the upper mold is formed with a first punch hole into which the first punch is inserted and a second biasing hole into which the second punch is inserted, and the first and second punch holes are formed in the lower mold. The through holes and the set blocks are formed to correspond to the punch holes, respectively.

Next, a method of manufacturing a lead frame according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is a process flowchart of a method for manufacturing a lead frame according to an embodiment of the present invention. As can be seen in the figure, first, to prepare a base material for the lead frame (S11), as such a base material, all conventional lead frame materials can be used, for example, copper and copper alloy or iron and nickel An alloy thin plate containing as a main component may be used.

Next, the lead frame patterning step (S12) is passed. In the patterning process, a plurality of inner leads and outer leads are integrally formed on the base material, through which a lead frame as shown in FIG. 2 is formed. Referring to the same figure, the lead frame 110 includes a side rail 118 forming a skeleton, and a plurality of leads 115 formed integrally with the side rail 118. Here, the leads 115 have an inner lead 114 and an outer lead 116 formed to correspond to the inner and outer sides, and each lead 115 has an inner lead 114 and an outer lead 116. Dam bars 117 are formed to maintain a constant distance between the leads 115 and support them. When the assembly of the semiconductor package is completed, the side rail 118 and the dam bar 117 are removed. A cavity 111 that interconnects the inner leads 114 is formed along the tip of the inner lead 114, which protects the tip of the inner lead 114, and the inner leads 114 support each other. To function.

Wing bars 112 are integrally formed on one side and the other side of the side rails 118, respectively. In the lead frame punching molding process described later, the wing bars 112 are down-set or up-set. It may be up-set and formed at a lower level or higher level than the surface on which the leads 115 are formed. This will be described later. After the semiconductor chip is mounted on the lead frame 110, a molding process of enclosing a predetermined region of the lead frame with a molding resin such as an EMC (Epoxy Molding Compound) is performed, wherein the wing bar 112 is It performs a function to make the molding smoothly by adjusting the inflow of the molding resin flowing into the upper side and the lower side.

The patterning process S12 described above may be performed by a stamping method or an etching method. According to the said stamping method, a predetermined shape is formed by punching, while conveying a base material sequentially by the conveyance type press die apparatus. According to the said etching method, a predetermined shape is formed by forming a photosensitive layer on a base material, irradiating light, exposing, and developing through the photomask which has a predetermined pattern. After the lead frame patterning process S12, a heat treatment process S13 may be performed to remove residual stress in the lead frame, if necessary.

Subsequently, a plating layer forming process S14 is performed. In order to improve coupling characteristics of the leads 115, as shown in the example illustrated in FIG. 3, the first plating layer 121 is formed at an inner end of the inner lead 114. ) And the second plating layer 122 is formed on the outer lead 116. That is, the semiconductor chip (not shown) and the inner lead 114 are electrically coupled to each other by a conductive wire (not shown). Here, the conductive wire is formed by forming the first plating layer 121 at the tip of the inner lead 114. Can be firmly coupled to the tip of the lead 114. The first plating layer 121 may be generally formed by silver (Ag) plating, but is not limited thereto, and may be plated with a component having a predetermined similar property.

On the other hand, when the semiconductor package assembly process is completed, the external lead 116 is exposed to the outside of the molding resin to function to connect the internal semiconductor chip and the external circuit. At this time, the second plating layer 122 is formed on the outer lead 116 in order to prevent corrosion of the outer lead 116 exposed to the outside and to improve soldering characteristics (solder wettability, solder wettability) with the external circuit. do. The second plating layer 122 may be formed by plating tin (Sn) or tin (Sn) alloy. After the second plating layer 122 is formed, a reflow process may be additionally performed, which is referred to as a beard crystal when the tin (Sn) or tin (Sn) alloy is plated with the second plating layer 122. whiskers) to inhibit growth. This reflow process may be performed by a known method of heating the second plating layer 122 by heating above the recrystallization temperature.

Next, a tape attaching process S15 is performed. More specifically, as shown in FIG. 4, a lead lock tape or a chip attaching tape (for example, a lower surface thereof) is formed along the front end of the inner leads 114. 130). Since the tape 130 is attached, the inner leads 114 may be mutually supported even after the cavity 111 is cut, thereby preventing bending deformation or shaking due to its own weight.

Next, the lead frame punching forming process S16 is performed, in which the cavity cutting process and the down-set (or up-set) process of the lead frame are simultaneously performed. This punching forming process (S16) can be made collectively by the press working apparatus for lead frame shown in FIG. As can be seen in the drawing, the press working apparatus has a carriage 141 reciprocating in the vertical direction, the carriage 141 is moved up and down while sliding the drive shaft 145, a pair of guide shaft Guided by 146. The punch holder 142 is supported below the carriage 141, and a plurality of punches 143 spaced at predetermined intervals are mounted on the punch holder 142.

An upper mold 210 and a lower mold 220 are disposed to face each other between the carriage 141 and the lower holder 147, and a lead frame 110 seated between the upper mold 210 and the lower mold 220. ) Is pressed or released in the vertical direction according to the driving of the carriage 141. When the carriage 141 is driven downward so that the lead frame 110 is pressed, the punch holes 143 supported on the carriage 141 are formed in the upper mold 210 and the lower mold 220. The lead frame 110 is processed while passing through the 211 and the through holes 221. When the carriage 141 is driven upward to release the pressure, the molds 210 and 220 are spaced apart from each other by the elastic means 144 interposed between the upper mold 210 and the lower mold 220. The lower mold 220 is seated on the lower holder 147, the discharge hole 147` for discharging the scrap generated after the press molding operation is formed in the lower holder 147 to correspond to the punch 143. Meanwhile, reference numeral 148 denotes a base for supporting the lower holder 147.

In FIG. 6, opposing surfaces of the upper mold and the lower mold formed to correspond to each other are unfolded from side to side. In the illustrated upper mold 210 and the lower mold 220, a plurality of molding tools 210a are formed in a matrix pattern. Since 220a is formed together, the lead frame punching molding may be performed in a reel-to-reel state in which a plurality of lead frames are formed together. Here, the molding tools 210a and 220a mean a part of a mold that is responsible for molding the unit lead frame in the upper mold 210 and the lower mold 220, respectively.

7 and 8 are perspective views illustrating the upper mold and the lower mold, respectively. Here, only the mold part for molding the lead frame of one unit is shown for convenience of description. Referring to FIG. 7, an upper protrusion 215 is formed at a center of the upper mold 210 to form a predetermined step, and a first punch having a first punch 143a inserted at an approximately center of the protrusion 215. The hole 211 is formed. Second punch holes 212 are formed at both sides of the upper protrusion 215, and second punch holes 143b are inserted into each second punch hole 212. Pressing strips 214 are symmetrically formed at the inlet end of the second punch hole 212. These press strips 214 firmly fix the inner leads 114 connected to the wing bars 112, thereby adjoining the wing bars. The inner lead 114 is not deformed by the step machining of 112.

Meanwhile, a lower protrusion 225 protruding to a predetermined height is formed at an approximately center of the lower mold 220 illustrated in FIG. 8, and a first punch 143a of the upper mold 210 is formed at an approximately center of the protrusion 225. The through hole 221 penetrates through is formed. On both sides of the lower protrusion 225, the set block 222 protruding at a predetermined height h corresponding to the second punch 143b is symmetrically formed. As shown in FIG. 7 and FIG. 8, the protrusion 215 of the upper mold 210 and the protrusion 225 of the lower mold 220 are formed to correspond to each other to firmly secure the inner leads 114 disposed therebetween. To be fixed. Thus, in spite of the punching process described below, bending deformation or damage of the inner leads 114 does not occur. In addition, the outer portions of the upper mold 210 and the outer mold 220, the base portion 218, 228 forming a smooth surface are formed, respectively, these are the side rail 118 and the outer lead (shown in Figure 4 during the pressing process) 116) and firmly support them therebetween, thereby preventing their deformation or damage that may occur in the pressing process.

 The first punch 143a and the second punch 143b are mounted on the punch holder 142 shown in FIG. 5 and reciprocated in the vertical direction. The first punch 143a presses and punches the ends of the inner leads 114 shown in FIG. 4 to remove the cavity 111 connecting the ends with each other to separate the leads 115 from each other and to separate them. A portion of the 130 is removed to align the cross section of the tape 130 with the tip of the inner leads 114. On the other hand, the second punch 143b by pressing the wing bar (112) shown in Figure 4 against the set block 222 of the lower mold 220, it is down-set or up (up) -Set up-set. The pressed wing bar 112 is down-set or up-set according to the height h of the set block 222 and is placed at a different level than the leads 115.

9 illustrates a lead frame formed through the above-described punching molding process. As shown in the drawing, the cavity is removed to separate the inner leads 114 from each other, and the front end of the inner leads 114 and the tape ( It can be seen that the cross section of 130) is aligned. On the other hand, Figure 10 shows a partially enlarged perspective view of the portion indicated by 'A' in Figure 9, the wing bar 112 is down-set to a level lower than the side rail 118 or the inner lead 114 You can see that it is arranged.

Next, a cut-off process (S17) for separating the lead frame of one unit from the reel state in which a plurality of lead frames are formed is performed. Through the cut-off process (S17), the lead frame is individualized in a predetermined package unit. Finally, it is delivered to the package company through visual inspection and packing process (S18).

In the drawings attached to this specification, a lead-on-chip (LOC) type lead frame in which a semiconductor chip is assembled to be positioned under an inner lead is shown. However, the substantial features of the present invention are described in the accompanying drawings. The present invention is not limited to the illustrated lead frame structure, and may be similarly applied to lead frames of other deformable structures. For example, in the case of a lead frame having a die pad on which a semiconductor chip is mounted, since the die pad is disposed at a lower level than the lead, it is more advantageous for the wiring between the semiconductor chip and the lead, so that the die pad is down-set. Preferably, the shapes of the upper mold and the lower mold shown in Figs. 7 and 8 can be changed accordingly.

According to the manufacturing method of the lead frame of the present invention having the above structure and the press working apparatus for lead frame applied thereto, the following effects can be obtained.

First, product yield can be improved by reducing the working time. According to the present invention, the cavity cutting process and the setting process, which are conventionally performed separately, are performed in a single process, thereby reducing the number of processes, thereby shortening the working time. Particularly, when the process is performed in a separate process, since the installation and setting of the lead frame processing equipment are repeatedly performed, the time and effort required for this process are wasted, but only one installation is required in the present invention. Workability is improved and working time is shortened.

Second, the machining precision of the lead frame is improved. As described above, according to the prior art, since the setting for the equipment of the lead frame has to be made repeatedly, machining errors generated therefrom are also accumulated. In the present invention, since only one setting is required, the accumulation of errors can be prevented at the source and the processing accuracy is improved.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and any person skilled in the art to which the present invention pertains may have various modifications and equivalent other embodiments. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (8)

A method of manufacturing a lead frame in which a plurality of leads are formed with a predetermined interval therebetween, A patterning process of integrally forming a plurality of leads and a cavity interconnecting the ends of the leads to the prepared base material; And A lead frame punching molding step of pressing the lead frame using a mold having a predetermined shape and simultaneously performing a cutting process of cutting the cavity and a setting process of forming a step up and down with respect to a part of the lead frame; Manufacturing method of lead frame. The method of claim 1, In the punching molding step of the lead frame, the lead frame is disposed between an upper mold and a lower mold having shapes corresponding to each other, and pressed against each other. The method of claim 2, The upper mold is formed with a first punch hole into which a first punch contributing to the cutting process is inserted, and a second bias hole into which a second bias to contribute to the setting machining is inserted, and the lower mold has a first punch hole. And a through hole and a set block are formed to correspond to the second punch hole, respectively. The method of claim 1, And a lead lock tape attaching step of attaching a tape having an adhesive formed on at least one surface to one end surface of the leads between the patterning process of the lead frame and the punching molding process of the lead frame. The method of claim 4, wherein In the lead frame punching forming process, a part of the tape is cut together with the cavity so that the tape is aligned with the ends of the leads. The method of claim 1, The lead frame punching forming process is performed in a reel form in which a plurality of lead frames are formed together, and after the punch forming process, a cut-off process of cutting and individualizing each lead frame is performed. . A press working apparatus for a lead frame for press molding a lead frame seated between an upper mold and a lower mold, A first punch for cutting a cavity connecting the leads of the lead frame; And And a second punch for forming a step in a part of the lead frame. The method of claim 7, wherein  The upper mold is formed with a first punch hole into which the first punch is inserted and a second shift hole into which the second punch is inserted, and the lower mold penetrates corresponding to the first punch hole and the second punch hole, respectively. Press processing apparatus for a lead frame, characterized in that the hole and the set block is formed.

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