JP4207133B2 - Resin-sealed semiconductor device - Google Patents

Description

  The present invention relates to a lead frame of a resin-encapsulated semiconductor device intended for a multichip power device as a control device applied to, for example, a power supply circuit (switching power supply).

  First, taking a control device applied to the head power supply circuit as an example, a conventional structure of a single-ended resin-encapsulated semiconductor device and a lead frame used for assembling the semiconductor device is shown in FIGS. Shown in 2A is a development view of the lead frame alone, FIG. 2B is an assembly state diagram in which the semiconductor element is mounted on the lead frame and wire bonding is performed, and FIG. 2C is a semiconductor device in which the lead is cut after sealing with resin. 1 is a lead frame, 2 and 3 are power elements (switching elements) mounted on the lead frame 1, 4 is a control IC for the power elements 2 and 3, and 5 is an internal part. A bonding wire 6 for wiring is a resin package in which the peripheral area of the power element 2, the control IC 4, and the bonding wire 5 is sealed with resin.

  That is, (a) the conventional lead frame 1 shown in FIG. 1 is arranged between the side rails 1a and 1b serving as tie bars that extend to both sides of the lead frame to feed the lead frame in accordance with the external size of the single semiconductor device. , All the leads are arranged in a line on one side at a constant pitch interval, and the terminal pads 10 of the main circuit, control power supply, and signal circuit (each of which is separated from the die pads 7 and 9 and pulled out to the side rail 1b side) The numbers 1, 2,... Attached to the leads are terminal numbers), and the dam bars 11 connecting the leads are patterned. The side rail 1a is connected to the die pad 7 via a tie bar 1a-1.

  In the assembly process of the semiconductor device, the lead frame 1 is sequentially transferred between the processes, and in the first process, the power semiconductor elements 2, 3 and the chip of the control IC 4 are mounted on the die pads 7, 8, 9 of the lead frame 1. In the subsequent wiring process, the wires 5 are bonded between the power semiconductor elements 2 and 3 and the control IC 4 and the terminal leads 10 for internal wiring. Next, in the molding (transfer molding) process, the lead frame is set on a mold die (not shown), and the resin package 6 is formed by resin-sealing the inside of the mold line area indicated by a chain line in FIG. After molding, the side rails 1a and 1b and the dam bar 11 are cut to complete the device product shown in FIG.

  Incidentally, the resin-encapsulated semiconductor device assembled using the conventional lead frame shown in FIG. 2 (a) has the following problems in terms of assembly and cost.

  (1) In a series of assembly steps of die bonding, wire bonding, and resin molding performed on the lead frame, the die pad patterned on the lead frame 1 and the terminal pad portion to which the wire bonding is performed are not warped and misalignment does not occur. In order to ensure the strength, in the conventional lead frame, as shown in FIG. 2 (a), the pattern area is supported by two rows of side rails 1a and 1b extending on both sides, and is sequentially fed. .

  For this reason, in addition to increasing the number of tie bar cuts to be performed after resin molding, the amount of frame breakage (parts discarded such as side rails and dam bars) generated by the tie bar cut also increases and the material cost of the lead frame increases. Moreover, in the completed state in which the tie bar 1a-1 connecting the side rail 1a and the die pad 7 is cut after resin sealing, the resin is formed on the side opposite to the lead-out side of the terminal lead 10 as shown in FIG. 2 (c). Since the cut remainder of the tie bar 1a-1 protrudes from the outer surface of the package 6 and the internal potential is exposed, post-processing for insulating this portion is required.

  (2) In addition, when a semiconductor device is upgraded by adding a new function such as a protection function, the number of terminals to be pulled out increases as the circuit of the semiconductor device is changed. In order to manufacture products, not only the lead frame pattern changes, but also the number of terminal leads pulled out from the package increases, so it is necessary to recreate a mold mold for resin sealing in accordance with the number of leads. There is. For this reason, the investment amount of the production equipment to be added increases and the price of the semiconductor device increases.

  The present invention has been made in view of the above points, and in addition to reducing the lead frame material cost, even when a new function is added to a semiconductor device and upgraded, the investment amount of the added production equipment is kept low. An object of the present invention is to provide a lead frame for a resin-encapsulated semiconductor device which is improved so as to improve cost performance.

To achieve the above object, according to the present invention, die pads (7, 8, 9) for individually mounting the chips of the first and second power elements (2, 3) and the control IC (4) are provided. In a resin-encapsulated semiconductor device using a lead frame (1) in which a plurality of leads (10) arranged in a line on one side and a dam bar (11) connecting the leads are patterned, The frame (1) has a die pad (9) for mounting the control IC between a first die pad (7) and a second die pad (8) for mounting the first and second power elements, respectively. Among the plurality of leads, at least first and second power elements, a main circuit terminal corresponding to the control IC, and a control power supply terminal include a plurality of leads drawn out corresponding to each terminal. It is one, before Symbol plurality of lead Of over de previous SL plurality of leads (1,2,18,19) part of which corresponds to the first die pad (18, 19), said second die pad for mounting the control IC Connected to the first die pad (7) from between the die pads, the first and second power elements mounted on each die pad, the control IC and the internal wiring were applied, and the peripheral area was sealed with resin In the state, an unnecessary lead is selected from the leads, and the outer lead is cut and removed together with the dam bar.

  As described above, by forming more leads on the lead frame than the required number of terminals of the semiconductor device in advance, each lead plays the role of a beam and the mechanical strength (bending rigidity) of the lead frame itself. ). Accordingly, it is possible to effectively prevent the lead frame from being warped and displaced in a series of assembly steps of the semiconductor device such as die bonding, wire bonding, and resin sealing performed on the lead frame.

  In addition, even when new protection functions are added to the semiconductor device to upgrade the version, the inner lead and die pad patterns are partially changed without changing the outer lead arrangement with respect to the basic pattern of the lead frame described above. Since it becomes possible to cope with the new version only by changing, it is not necessary to make a new mold, and the conventional mold can be used as it is to mold the resin package.

  Further, in the invention of claim 2 of the present invention, in addition to the above configuration, dummy leads are formed by being arranged between leads of different potentials of the main circuit terminals, and the dummy leads are removed together with the dam bar after sealing with resin. Furthermore, the inner end of the dummy lead is cut at a position in front of it in accordance with the mold line of the resin package.

  With this configuration, in the completed state of the semiconductor device, a sufficient insulation creepage distance is formed between the terminal leads arranged on both sides of the portion where the dummy lead is removed, thereby providing a dielectric strength corresponding to the main circuit voltage. It can be secured.

  In this case, the inner end of the dummy lead is extended to the mold line of the resin package, so that the inner end of the dummy lead is placed in the mold when resin sealing is performed by setting the lead frame on the mold. In addition to preventing resin leakage from the mold, the dummy leads can be removed by cutting the dam bar because the inner ends of the dummy leads are not connected to the resin package in the state after resin sealing.

  According to a third aspect of the present invention, the side rails of the lead frame are formed in only one row on the basis of the above configuration, and the side rails are formed to be connected to the tip ends of the terminal leads. That is, increasing the number of leads increases the strength of the lead frame itself, so even if the die pad side rail 1a shown in FIG. 2 (a) is omitted, one side of the side connected to the tip of the terminal lead The die pad and each terminal lead are supported by the rail, and the lead frame can be sequentially transferred in the assembly process of the semiconductor device without any trouble. As a result, the material cost of the lead frame can be reduced by omitting the side rail 1a on one side, the tie bar cutting man-hours to be performed after resin sealing can be reduced, and the tie bar remaining on the outer surface of the resin package after tie bar cutting. Since it is not exposed, the insulation process of that part is also unnecessary.

  As described above, according to the present invention, on the lead frame, the die pad for individually mounting each chip of the power element and the control IC, all the leads are arranged in one row and separated from each die pad and the die pad. Main circuit terminals corresponding to at least power elements and control ICs in the lead frame of the resin-encapsulated semiconductor device in which the drawn main circuit, control power supply, signal circuit terminal leads, and dam bars connecting the leads are patterned , For the control power supply terminals, pull out multiple leads from each terminal, select the unnecessary leads with the power element mounted on the die pad, control IC and internal wiring, and the surrounding area sealed with resin The outer lead is cut and removed together with the dam bar so that a conventional lead frame can be used. Compared with the semiconductor device assembled Te, kill is possible to achieve the effect of the following SL.

  (1) Increasing the number of leads increases the strength (bending rigidity) of the lead frame itself, and warps the lead frame in a series of assembly processes such as die bonding, wire bonding, and resin sealing performed on the lead frame. , It is possible to assemble the semiconductor device without any defects by suppressing displacement. In addition, the increase in the number of leads reduces the number of times the inner lead pattern is routed and reduces the wiring space, thereby enabling a reduction in the size of the package.

  (2) In addition, even when new protection functions are added to the semiconductor device to upgrade the version, the inner lead and die pad patterns are partially changed without changing the number of lead leads and the basic layout of the lead frame. This makes it possible to accommodate a new version of the product by accommodating a number of leads formed in advance in the lead frame. Therefore, an existing mold can be used as it is without re-creating a new mold, so that it is possible to make a product with excellent cost performance while keeping newly added equipment costs low.

  In addition, a dummy lead is formed by juxtaposing between leads of different potentials on the main circuit terminal, and the dummy lead is cut off with a dam bar after sealing with a resin, so that the main circuit drawn on both sides of the dummy lead is removed. By increasing the pitch interval between the terminal leads, the insulation creepage distance necessary for the withstand voltage of the main circuit voltage can be secured.

  In addition, by cutting the dummy lead in front of the lead with the inner end of the lead aligned with the mold line of the resin package, the dummy lead prevents resin leakage from the mold die in the resin sealing process. The dummy lead can be easily removed afterwards.

  Furthermore, the lead frame side rails are formed in one row on one side and connected to the tip of each terminal lead, so that the material cost of the lead frame is reduced by the amount of omitting one side rail compared to the conventional lead frame. In addition to reducing the cost, the tie bar cut residue is not exposed on the surface of the resin package in the state after the resin sealing, and the insulation treatment is unnecessary.

  Embodiments of the present invention will be described below based on the examples shown in FIGS. 1 (a) to 1 (c). Fig. 1 (a) is a development view of the lead frame alone, (b) is an assembly state where a semiconductor element is mounted on the lead frame and wire bonding is performed, and (c) is a completed state where the lead is cut after sealing with resin. 2 is an external view (plan view) of the semiconductor device in FIG. 1. In the drawing of the embodiment, members corresponding to those in FIG.

  That is, in the illustrated embodiment, the die pads 7, 8, and 9 for mounting the power elements 2 and 3 and the control IC 4 are formed on the lead frame 1 in the same pattern as in FIG. ˜9, the terminal leads 10 arranged in a line on one side and drawn out are provided with a plurality of leads corresponding to the main circuit and the control power supply from each terminal as shown in the drawing in accordance with the external size of the semiconductor device (2 in the illustrated example). Dummy leads 10a (three leads represented by terminal numbers 3, 17, and 21 in FIG. 1 (b)) are added between the leads that are drawn out one by one and connected to different potentials of the main circuit. The dam bars 11 are formed at the boundary between the inner leads and the outer leads after the leads 10 having the terminal numbers 1 to 23 are arranged at a constant pitch interval (for example, 1.27 mm). The Also for the side rails of the lead frame 1, the side rails 1a on the die pad side in the conventional structure of FIG. 2A are omitted, and the side frames 1b extending from the end of each terminal lead 10 are used. 1 is pitch-fed. Further, the inner end of the dummy lead 10a is cut at the front position in accordance with the mold line of the resin package 6 represented by a chain line in FIG.

  In order to assemble a semiconductor device using the lead frame 1 having the above configuration, the power elements 2 and 3 and the control IC 4 are mounted on the die pads 7, 8, and 9 of the lead frame 1 (die bonding) as shown in FIG. In the subsequent resin sealing step, the lead frame 1 is set in a mold, and the inside of the mold line is sealed with a resin to form a resin package 6. To do. The mold used is one that is manufactured according to the terminal lead arrangement shown in FIG. 1 (b). In the lead cutting process after resin sealing, as shown in FIG. 1 (c), only the terminal lead 10 used as the external lead terminal is left, and other unnecessary leads and dummy leads 10a are replaced with the dam bar 11 and side rails. The device product is completed by cutting together with 1b and removing it. The minute protrusions 6a remaining on the surface of the resin package 6 represent the resin protruding from the cavity of the mold die toward the end surface of the dummy lead 10a during resin sealing.

  Here, the semiconductor device assembled using the lead frame 1 of the above embodiment has the following advantages over the semiconductor device assembled using the conventional lead frame shown in FIG. It is done.

  First, the material cost of the lead frame can be reduced by omitting one of the side rails 1a, and the cost can be reduced. In the state after resin sealing, the tie bar is placed on the surface of the resin package 6 as shown in FIG. 2 (c). The cut residue of 1a-1 is not exposed and the insulation treatment is not necessary. In addition, increasing the number of leads 10 increases the strength (bending rigidity) of the lead frame itself, and the lead frame is deformed through a series of assembly processes such as die bonding, wire bonding, and resin sealing performed on the lead frame. , It is possible to assemble the semiconductor device without any defects by suppressing displacement. Further, by removing the dummy leads 10a after resin sealing, the pitch interval between the main circuit terminal leads arranged on both sides of the dummy leads 10a is widened, and the insulation creepage distance necessary for the withstand voltage of the main circuit voltage can be secured.

  Even when a protection function or the like is newly added to the semiconductor device to upgrade the version, in the illustrated embodiment, the number and arrangement of the terminal leads 10 with respect to the basic pattern of the lead frame 1 are not changed. The number of leads 10 formed in advance on the lead frame can be accommodated simply by changing the design of the inner lead, die pad, and the above-mentioned dummy lead to the inside and using it as a terminal lead. To support the new version. Therefore, it is not necessary to make a new mold, and the existing mold can be used as it is and the resin can be sealed without any trouble. As a result, the equipment cost to be newly added can be reduced.

In the configuration diagram of the lead frame and the semiconductor device according to the embodiment of the present invention, (a) is a development view of a single lead frame, (b) is an assembly state diagram in which a semiconductor element is mounted on the lead frame and wire bonding is performed. c) is an external plan view of the semiconductor device in the completed state with lead cut after resin sealing. 1 is a configuration diagram of a conventional example corresponding to FIG. 1, (a) is a development view of a lead frame alone, (b) is an assembly state diagram in which a semiconductor element is mounted on a lead frame and wire bonding is performed, and (c) is a resin state. External plan view of the semiconductor device in the completed state with lead cut after sealing

Explanation of symbols

1 Lead frame 1b Side rail 2, 3 Power element 4 Control IC
5 Bonding wire 6 Resin package 7-9 Die pad 10 Terminal lead 10a Dummy lead 11 Dam bar

Claims (3)

A lead frame in which a die pad for individually mounting each chip of the first and second power elements and the control IC, a plurality of leads arranged in a row on one side, and a dam bar connecting each lead is patterned. In the resin-encapsulated semiconductor device used,
The lead frame is
A die pad for mounting the control IC is provided between a first die pad and a second die pad for mounting the first and second power elements, respectively, and at least the first and second of the plurality of leads are provided. The power element, the main circuit terminal corresponding to the control IC, and the control power supply terminal are provided with a plurality of leads drawn corresponding to each terminal,
Before SL plurality of lead sac Chi, before Symbol some of the plurality of leads corresponding to the first die pad, from between the second die pad and the die pad for mounting the control IC said first Connected to the die pad,
In the state where the first and second power elements mounted on each die pad, the control IC and the internal wiring are provided and the peripheral area thereof is resin-sealed, an unnecessary lead is selected from the leads and the outer A resin-encapsulated semiconductor device in which a lead is cut and removed together with a dam bar. Dummy leads are formed in parallel between leads of different potentials on the main circuit terminals,
The dummy lead has its inner end cut in accordance with the mold line of the resin package,
2. The resin-encapsulated semiconductor device according to claim 1, wherein the dummy lead is removed together with a dam bar after resin encapsulation. 3. The resin-encapsulated semiconductor device according to claim 1, wherein the side rails of the lead frame are formed to be connected to the tip ends of the terminal leads only in one row on one side.

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