KR100673953B1 - Lead frame - Google Patents

Abstract

A lead frame is provided to restrain the generation of short between adjacent leads and to prevent an incomplete formation of the leads by restraining a bevel portion generated between the leads from being grown to a package line. A semiconductor chip is mounted on a chip pad(210). At least one or more lead columns are formed on the resultant structure in order to connect the semiconductor chip with an external substrate. A dam bar(240) has one side for being connected with leads of the lead columns. The dam bar is used for connecting arbitrarily the leads with each other and supporting the leads. The one side of the dam bar has connection portions. At least one out of the connection portions is inserted into the dam bar. The inserted connection portion is more spaced apart from the lead than a package line.

Description

Lead frame

1 is a plan view illustrating a conventional multi-row lead type lead frame.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.

3 is a plan view illustrating another conventional multi-row lead type lead frame.

4 is a cross-sectional view taken along line IV-IV of FIG. 3.

5 is a plan view showing a lead frame according to a first embodiment of the present invention.

6 is an enlarged plan view of a portion A of FIG. 5.

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6.

8 is a plan view illustrating a lead frame according to a second embodiment of the present invention as a modification of FIG. 6.

Explanation of symbols on the main parts of the drawings

200, 300: lead frame 210: chip pad

220, 320: lead 221, 321: first row lead

222, 322: lead body 223, 323: connection bar

231, 331: Second row lead 240, 340: Dam bar

242, 342: Dam bar one side 243, 343: Lead engaging surface

244, 344: connection surface 244_a: incoming connection surface

250; Pad support 260, 360: opening

B: Bevel PL: Package Line

DL: Dambar Line

The present invention relates to a lead frame, and more particularly, to a lead frame formed by mounting a semiconductor chip and electrically connecting the semiconductor needle to an external substrate.

In general, the semiconductor chip itself cannot receive electric power from the outside to transmit an electric signal. Therefore, the semiconductor package is packaged to easily transmit various electrical signals of the semiconductor chip to the outside. In recent years, the semiconductor package is various in consideration of chip size reduction, heat dissipation ability and electrical performance, reliability, manufacturing cost, and the like. It is manufactured in a structure.

Recently, in accordance with the trend of higher integration of semiconductor chips, it is necessary to increase the number of leads, which are electrical input and output terminals, between the semiconductor chip and the external substrate. Accordingly, a multi-row lead frame having leads having two or more rows of arrays connecting the chip and the external substrate to each other has been in the spotlight.

1 shows a conventional two-row lead frame 10. The lead frame includes a chip pad 20 to which a semiconductor chip is bonded and a plurality of rows of leads 30.

The chip pad 20 is connected to the dam bar 40 by the pad support 50 and has a function of supporting the semiconductor chip.

The leads 30 are arranged in a plurality of rows, for example, arranged in the first row of leads 31 and the second row of leads 32 in the order close to the chip pad 20 in FIG. The input and output terminals serve to electrically connect the semiconductor chip and the external substrate. In this case, the first column lead 31 and the second column lead 32 are connected to each other by the connection part 35 and formed side by side. The second row leads 32 directly connected to the dam bars 40 are non-functional portions 32b that are removed together with the dam bars 40 during the lead row individual process, and are not substantially removed after the lead row individual processes. It can be divided into a functional part 32a serving as a lead function. In this case, the functional unit 32a and the non-functional unit 32b are divided based on the virtual package line PL.

The dam bar 40 functions to support the leads 30 and the chip pads 20. In this case, the dam bar 24 is removed through the lead individualization process when the assembly of the semiconductor package is completed. The lead individualization process refers to a process of separating neighboring leads connected to each other by a damper through sawing or trimming.

In order to manufacture a semiconductor package having such a multi-row lead type lead frame, first, a plurality of rows of leads 30 are supported by the dam bar 40 by an etching process, and the openings are formed between the leads of the same row. 60) first go through the shape machining step to form. At this time, as shown in Figure 2, the opening 60, after coating the photo resist sheet 3 on both sides of the lead 30, and spraying the etching solution from both sides, thereby openings 60 between the leads 30 ) By etching at the same time above and below the position.

However, according to the etching method on both the upper and lower sides, etching starts from the upper and lower sides of the lid and proceeds to the center portion. The bevel B which protrudes bulging because the etching is made less at the center of the side of the lid 30 is formed. Is formed. The bevel B grows at the point where the dam bar 40 and the lead 30 meet, where the etching solution cannot reach smoothly.

A die attach step of adhering the semiconductor chip to the chip pad 20 after the shape processing; a wire bonding step of wire-bonding between the terminal portion of the semiconductor chip and the plurality of rows of leads 30; and an insulator such as a thermosetting resin. By going through a molding process to seal the wire and the inner lead portion, the semiconductor chip and lead frame are semiconductor packaged, and then the lead individualization step of removing the dam bar of the molded lead frame is performed.

In the lead individualization step, the connecting portion 35 connecting the first row lead 31 and the second row lead 32 is further cut and removed by sawing or trimming. . Through the lead individualization step, the first column lead 31 and the second column lead 32 each have independent input / output terminals. That is, in order to manufacture the semiconductor package, it is necessary to go through the individualization step such as the sawing or trimming process together with the removal of the dam bar 40 in the lead individualization step, thereby increasing the manufacturing cost of the semiconductor package. In addition, sawing cutting may cause a quality problem of the lead frame in the process, thereby causing a reliability problem of the semiconductor package.

3 is a view showing another conventional lead frame. Referring to FIG. 3, another conventional lead frame 100 includes a plurality of rows of leads 130 in one dam bar in order to omit a sawing cutting process of separating the leads 130 between adjacent rows of adjacent leads in a lead individualization process. To be supported at 140. In this case, the leads 131 of the first row and the leads 132 of the second row are alternately positioned, and the leads 131 of the first row that are relatively far from the dam bar 140 than the leads 132 of the second row. ) Includes a lead body 131a that is an input / output terminal and a connection bar 131b that connects the lead body and the dam bar 140. On the contrary, the second row of leads 132 relatively close to the dam bar 140 are directly connected to and supported by the dam bar. In this case, the connecting bar 132b is typically half etched so as not to be exposed to the outside after the package. Meanwhile, reference numeral 120, which is not described, denotes a chip pad.

In the lead frame 100 having such a structure, the lead line 131 of the first row and the lead 132 of the second row are separated by cutting the package line PL in the lead individualization process, so that no separate sawing step is required. Therefore, there is an advantage that the manufacturing cost is reduced and the semiconductor package quality is improved compared to the structure of FIG.

However, the connection bar 131b supporting the lead bodies 131a in the first row should have a minimum width, and the first and second leads 131 and 132 may be wire bonding and external exposed areas. Is standardized, the opening 60 between the connection bar 131b and the leads 132 in the second row is narrowed. This results in a lack of space for etching, resulting in the problem of lead shorting or unforming in the shape machining step.

That is, as shown in FIG. 4, the bevel B generated in the etching process starts from the dam bar line DL connected to the lead 130 and extends up to the package line PL. The adjacent second lead 132 and the connection bar 131b are contacted or unmolded in the PL), which is later left after the lead individualization process of removing the dam bar 140 and adjacent to each other. There is a problem that lead short occurs due to liver contact.

Meanwhile, the problem may not only occur between the leads 130, but may also occur between the leads 130 and the pad support 150 adjacent thereto. In addition, even if the lead 130 or the pad support 150 is not extended from the dam bar, the problem also occurs when the gap between them is narrow.

The present invention is to solve the various problems, including the above problems, to provide a lead frame having a structure having a predetermined gap or more in the package line between adjacent leads or between the lead and the special functional unit. The purpose.

It is another object of the present invention to provide a lead frame that prevents a short from occurring between leads of the separate rows in a package line as a multi-row lead frame.

The present invention provides a chip pad on which a semiconductor chip is mounted; At least one row of leads connecting the semiconductor chip and an external substrate; And a dam bar for temporarily interconnecting and supporting the leads, the side having one side in contact with the leads, the one side including lead coupling surfaces in direct contact with the leads and the neighboring lead coupling surface. Connecting surfaces connecting the two surfaces, and at least one of the connecting surfaces provides a lead frame drawn into the dam bar rather than another connecting surface.

In this case, each of the leads is divided into a non-functional part that is scraped and removed after packaging with the semiconductor chip based on a virtual package line, and a remaining functional part after the packaging, and the drawn connection surface is larger than the package line. Preferably at least 10% spaced apart relative to the material thickness of the lead.

The leads may be arranged in two or more rows to connect the semiconductor chip and the external substrate, and the drawn connection surface may be formed between lead coupling surfaces in contact with leads of different rows.

On the other hand, another aspect of the invention: a chip pad on which the semiconductor chip is mounted; Leads connected between the semiconductor chip and the external substrate, each of which is divided into a non-functional part removed after packaging based on a virtual package line, and a remaining functional part after the packaging, and arranged in at least two rows; And one side surface in contact with the non-functional portion of the leads, wherein the lead surface is spaced apart from the package line by at least 10% relative to the material thickness of the lead.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 is a plan view of the lead frame 200 according to the first embodiment of the present invention, and FIG. 6 is an enlarged plan view of part A of FIG. 5. 5 and 6, the lead frame 200 according to the first embodiment of the present invention includes a chip pad 210, leads 220, and a dam bar 240.

The chip pad 210 is connected to the dam bar 240 by the pad support 250 and has a function of supporting the semiconductor chip.

The lead 220 connects the semiconductor chip and the external substrate. That is, one side of the lead 220 is electrically connected to the semiconductor chip, and the other side is electrically connected to the external substrate. The leads 220 may be formed in one row formed side by side, or alternatively, may be formed in a plurality of rows as shown in FIG. 5.

The dam bar 240 is coupled to the pad support 250 to support the chip pad 210 and is excluded after the semiconductor package is packaged. The dam bar 240 may be disposed to surround the outermost of the lead frame, in which case the dam bar may be referred to as a rail. In this case, at least some of the leads 220 and the like supported by the dam bar 240 may include a lead body 222 connecting between an external substrate and a semiconductor chip, and a connection bar 223 connecting between the lead body and the dam bar. ) May be provided.

In this case, in particular, as shown in FIG. 6, the dam bar 240 includes one side 242 connected to the leads 220. One side surface 242 may include a lead coupling surface 243 and a connection surface 244. The lead coupling surface 243 refers to a surface directly contacting the leads 220, and the connection surface 244 refers to a surface connecting between adjacent lead coupling surfaces 243.

At least one of the connection surfaces 244 is formed to be drawn toward the center of the dam bar 240 than the other connection surfaces. Due to the inlet connecting surface 244_a, the separation distance K between the virtual dambar line DL connecting the neighboring connecting surface 244 and the package line becomes large.

As a result, even when the bevel B is formed and grown from the dam bar line DL in the shape machining process, as shown in FIGS. 6 and 7, it does not reach the package line PL. There is no short circuit between the 220 or failure due to unmolding. In this case, it is preferable that the opening 260 between the leads is disposed at a position narrower than that of the other openings.

5 and 6, each of the leads 220 may be divided into a non-functional part 220b and a functional part 220a based on the virtual package line PL. The non-functional part 220b is a part that is scrapped and removed during a lead individualization process after packaging with a semiconductor chip, and the functional part 220a is a part that remains without scraping during a lead individualization process.

In this case, the drawn connection surface 244_a preferably has a gap K with the package line PL of at least 0.02 mm or more. When the gap K between the drawn connection surface 244_a and the package line PL is less than 0.02 mm, the bevel B started at the drawn connection surface 244_a is the functional part 220a in the package line. This is because growth may occur and unmolding or shorting may occur between adjacent leads 220. In this case, the drawn connection surface 244_a may have a distance K of the package line PL and 0.03 mm.

In this case, the drawn connection surface 244_a is more preferably spaced apart from the package line PL by a distance of at least 10% of the lead thickness, which is formed by the formation of the bevel B during etching. This is because the distance is proportional to the lead thickness. Therefore, when the lead thickness is 0.25 mm, the drawn connection surface 244_a is preferably spaced at least 0.025 mm from the package line PL.

In addition, the drawn connection surface 244_a should be spaced apart from the package line PL by a predetermined distance, and in this embodiment of individualizing the package by sawing after the entire molding, it is preferable to be spaced apart by 0.07 mm or less. This is because if the separation distance is exceeded, the strength of the dam bar 240 becomes small, and thus the function of supporting the lead may not be smoothly performed. Of course, if the method of individualizing the package after the entire molding is a punching form, the separation distance is less limited.

On the other hand, the lead frame, although not shown, may be provided with a specific functional portion coupled to one end of the side of the dam bar 242. This particular functional unit may be a pad support unit 250 supporting the chip pad 210, or a function different from that of the pad pad unit. The specific function unit may be disposed to have a predetermined gap with adjacent leads. In this case, the lead and the specific functional portion are narrower than between the leads 220, so that the inlet connecting surface 244_a is formed between the functional mating surface in contact with the specific functional portion and the lead mating surface adjacent thereto. It is preferable.

In addition, the lead frame 200 is a multi-row lead type lead frame in which two or more leads 220 are provided, and the number coupled to one side of the dam bar 240 may be different for each lead row. . For example, the first row leads 221 far from one side of the dam bar 240 and the second row leads 231 close to one side of the dam bar may be provided. In this case, the first row leads 221 may be provided. The width of the connection surface 244 formed between the second row leads 231 is smaller than the connection surface formed between the adjacent first row leads. Therefore, in this case, the opening 260 in which the connection surface 244_a drawn from the lead coupling surface 243 is formed is an opening between the second column lead 231 and the first column lead 221.

8 is a plan view illustrating a lead frame 300 according to a second embodiment of the present invention. The entire connecting surface 343 of the dam bar 340 provided in the lead frame 300 according to the second embodiment of the present invention is formed to have a distance K between the package line PL and 0.2 mm or more. That is, each of the leads 320 may be divided into a non-functional part 320b that is removed during the read individualization process based on the virtual package line PL, and a functional part 320a that remains during the read individualization process. In this case, one side surface 342 of the dam bar 340 is a connection surface 344 connecting between the lead coupling surface 343 and the adjacent lead coupling surface 343 in contact with the non-functional portion 320b of the leads. ).

In this case, the coupling surface 343 and the connection surface 344 are spaced apart from the package line PL by at least 0.02 mm or more. As a result, even if the slung bevel B is formed from the connection surface 344 and grows, it is not formed until the functional portion 320a in the package line PL. In other words, the width of the opening 360 between the functional portions 320a in the package line is appropriate.

This is more useful when a plurality of rows of leads are alternately connected to one side of one dam bar 340. For example, referring to FIG. 8, the leads 321 of the first row and the leads 331 of the second row are alternately positioned, and are relatively far from the dam bar 340 than the leads 331 of the second row. The lead bodies 322 of the leads 321 of the first row are connected to and supported by the dam bar 340 through the connection bar 323, and the leads 331 of the second row that are relatively close to the dam bar 340 are the dam bars. 340 may be connected to and supported.

In this case, the connection bar 323 supporting the lead body 322 of the leads of the first row should have a minimum width, and the leads 320 are standardized as wire bonding and external exposure areas. As a result, the gap between the connection bar 323 and the leads 331 in the second row is narrowed so that the width of the opening 360 is small. Therefore, the connecting surface 344 is separated from the package line PL by maintaining the distance K more than a predetermined distance, so that the bevel B stops growing in a non-functional part other than the package line, and the neighboring lead after the lead individualization process. Short or a short formed between the 320 may be solved.

In this case, it is preferable that the one side surface 342 has a spacing K of at least 0.02 mm or more with the package line, and more preferably, the one side surface 342 is at least with the package line PL. It is more preferable to be spaced apart by a distance of 10% or more of the thickness of the lead, which will not be described in detail as described in the lead frame of the first embodiment of the present invention.

According to the present invention having the above structure, even if bevel occurs between the leads by the etching process, the bevel does not grow to the package line. This can prevent shorting or unmolding between adjacent leads after the package process and the lead individualization process.

In addition, since a separate sawing process is unnecessary in the lead individualization process after the package process, a separate sawing process is unnecessary, thereby simplifying the manufacturing process, reducing the manufacturing cost, and not causing quality problems in the lead frame, resulting in reliability of the semiconductor package. This 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 (4)

A chip pad on which a semiconductor chip is mounted; At least one or more rows of leads connecting the semiconductor chip and the external substrate; And A dam bar having one side in contact with the leads and temporarily interconnecting and supporting the leads; The one side may include lead coupling surfaces directly contacting the leads and connection surfaces connecting the neighboring lead coupling surfaces, and at least one of the connection surfaces may be led into the dam bar rather than another connection surface. The lead frame characterized in that. The method of claim 1, Each of the leads is divided into a non-functional part that is scraped and removed after packaging with the semiconductor chip based on a virtual package line, and a remaining functional part after the packaging. The lead connecting surface is at least 10% spaced apart from the package line relative to the material thickness of the lead. The method of claim 1, The leads are arranged in two or more rows to connect between the semiconductor chip and the external substrate, The lead connecting surface is formed between the lead engaging surfaces in contact with the leads of different rows. A chip pad on which a semiconductor chip is mounted; Leads connected between the semiconductor chip and the external substrate, each of which is divided into a non-functional part removed after packaging based on a virtual package line and a functional part remaining after the packaging, and arranged in at least two rows; And It has a side surface in contact with the non-functional portion of the leads, The lead surface is at least 10% spaced apart from the package line relative to the material thickness of the lead.

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