JP2018041956A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method using stamping, which can ensure an island with the size equivalent to the size in the past even when a thickness of a lead frame is increased.SOLUTION: A semiconductor device manufacturing method comprises the steps of: punching a clearance between an island and inner leads by a punch having a width either equaling or surpassing a minimum required board thickness in stamping; and subsequently, crushing a circumference of the island from a rear face of the island. By making the clearance between the island and the inner leads smaller than a thickness of the lead frame and making a thickness of the lead frame to be the circumference of the island thinner than the original thickness of the lead frame at the same time, a required area of the island is obtained.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for manufacturing a semiconductor device mounted on a resin-encapsulated semiconductor package. In particular, the present invention relates to a method for manufacturing a semiconductor device mounted on a resin-encapsulated semiconductor package using a lead frame manufactured by stamping press processing.

  With the recent miniaturization of portable electronic devices, semiconductor packages that are used in smaller and thinner semiconductor packages are also required. In the semiconductor package, it is necessary to seal the semiconductor element with a resin in order to protect the mounted semiconductor element from the environment.

  There is a need to reduce the size and thickness of a semiconductor package, but it may be necessary to use a thick lead frame for a semiconductor package that requires high voltage and high current to flow.

  As a result, in order to suppress the thickness in the packaged state, the resin sealing thickness is thin, but the lead frame used is thicker than the resin sealing thickness. ing. For example, a pin insertion type semiconductor package having a lead frame thickness of 0.4 mm or more with respect to a resin sealing thickness of 1.5 mm has been commercialized.

  As a lead frame material, a 194 alloy material or a copper alloy is generally used. Further, the lead frame is processed by etching and stamping using a stamping press die, and an invention that minimizes the gap between the island and the inner lead by etching is proposed (see, for example, Patent Document 1). ). However, the lead frame produced by the etching process does not require the production of a mold as compared with the stamping press process, but the etching lead frame needs to be masked with a dry film using a photoresist during the etching process. A dry film that has been used once cannot be reused and is discarded. Therefore, when a lead frame is continuously manufactured, it is necessary to continuously prepare a dry film. In addition, the etching process is a process using a chemical solution, and the shape accuracy is inferior to the press process using a stamping press die.

  When processing a lead frame with a stamping press die, the lead frame is punched with a cutter called a punch. The punch material is generally made of super hard material. Carbide materials are hard but fragile. In order to avoid buckling due to the brittleness of the cemented carbide, the punch for punching needs to secure a width that can secure the strength against the lead frame to be processed. Therefore, the punching punch width is determined by the minimum punching width that can be processed depending on the thickness of the lead frame. Usually, when punching the shape with a stamping press die, it is common to set the punch width to be equal to or greater than the thickness of the lead frame in order to ensure punch strength. As a result, the punch for punching between the inner lead and the island also requires a width greater than the plate thickness, and at least a gap greater than the plate thickness is required.

  When a thick lead frame is used, it is necessary to reduce the size of the inner lead or the island in order to secure a gap larger than the plate thickness between the inner lead and the island. The inner lead requires at least a wire connection region to be electrically connected from the mounted semiconductor element. In addition, semiconductor packages that require a high current need to adopt a thick wire diameter for electrically connecting the semiconductor element and the inner lead. If the inner lead is reduced, the wire connection area decreases and the intended wire cannot be connected. It leads to. As a result, it is necessary to reduce the island size. The semiconductor element mounted on the island is generally fixed to the island with a die attach material, but in order to secure the bonding strength between the semiconductor element and the island, the die attach material is crawled up to the side of the semiconductor element to fillet. Need to form. For this reason, it is necessary that the semiconductor element mounted for the island size has a size capable of forming a fillet of the die attach material. That is, to reduce the island size, it is necessary to reduce the size of the semiconductor element that can be mounted.

  In general, a semiconductor product has a larger chip size when its function is increased or the current to be controlled is increased. As a result, it is necessary to reduce the size of a semiconductor element that can be mounted as the island size decreases, and there is a possibility that a semiconductor element having a target function cannot be mounted.

  As already mentioned, it is necessary to use a thick lead frame for a semiconductor package that requires high voltage and high current to flow, but the thickness of the lead frame relative to the thickness of the resin encapsulation If it is 1/4 or more, the flow of the resin will be hindered, and the resin will not flow to the end of the product, and internal voids that will harden with air entrained in the middle of the product will lead to product reliability. May decrease.

JP 2002-208664 A

  Therefore, an object of the present invention is to provide a method for manufacturing a semiconductor device using stamping press processing, which can secure an island of the same size as the conventional one even if the lead frame is thickened.

  In the present invention, first, punching is performed between the island and the inner lead with a punch having a width equal to or larger than the minimum required for stamping press processing, and then processing for crushing the periphery of the island from the back surface of the island is performed. By making the gap between the island and the inner lead smaller than the thickness of the lead frame, and at the same time making the thickness of the lead frame surrounding the island thinner than the thickness of the original lead frame, the surface of the island is enlarged and necessary Get an island area.

  By crushing the backside of the island, the island size is expanded and the size limit of the semiconductor elements that can be mounted is relaxed. Moreover, by crushing the island back surface, the inflow path at the time of resin sealing is expanded, obstruction by the lead frame at the time of resin filling is reduced, and unfilled and internal voids are eliminated.

It is a table | surface top view which shows the shape after the stamping press punching process of the lead frame which is the 1st Example of this invention. It is a side view which shows the shape after the stamping press punching process of the lead frame which is the 1st Example of this invention. It is a table | surface top view which shows the shape after the island back surface crushing process of the lead frame which is the 1st Example of this invention. It is a back view which shows the shape after the island back surface crushing process of the lead frame which is the 1st Example of this invention. It is a figure for explaining crushing processing. FIG. 3 is a cross-sectional instruction view for explaining an embodiment of the island backside crushing processing of the lead frame according to the first embodiment of the present invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a table | surface top view after resin sealing using the lead frame which is the 1st Example of this invention. It is a side view after resin sealing using the lead frame which is the 1st example of the present invention. It is sectional drawing which shows the resin inflow path | route at the time of resin sealing in the conventional lead frame. It is sectional drawing which shows the resin inflow path | route at the time of resin sealing in the lead frame which is the 1st Example of this invention. It is a figure which shows the state cut | disconnected from the lead frame and divided | segmented into an individual semiconductor device. It is a table | surface top view which shows the shape after the island back surface crushing process of the lead frame which is the 2nd Example of this invention. It is CC sectional drawing of FIG. It is DD sectional drawing of FIG. It is a table | surface top view which shows the shape after the island back surface crushing process of the lead frame which is the 3rd Example of this invention. It is EE sectional drawing of FIG. It is FF sectional drawing of FIG.

Embodiments of the present invention will be described below with reference to the drawings. First, a case of a pin insertion type semiconductor package will be described.
FIG. 1 is a front plan view showing a shape of a lead frame according to a first embodiment of the present invention after stamping press processing, and FIG. 2 is a side view showing the thickness of the lead frame according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line YY of FIG.

  First, the prepared lead frame material is punched using a stamping press die, and an island 2 for mounting a semiconductor element, an inner lead 3 and an inner lead electrically connected to the electrode of the semiconductor element by a wire 3 is formed. A gap 4 equivalent to the plate thickness T of the lead frame shown in FIG. 2 is formed between the island and the inner lead. The lead composed of the inner lead 3 and the outer lead 23 is fixed by a tie bar 24. FIG. 1 shows only a lead frame for one semiconductor product. A lead frame shown in FIG. 1 is repeatedly formed two-dimensionally vertically and horizontally on a lead frame in the middle of manufacture.

The gap 4 is punched using a punch (blade) in a stamping press mold, but the punch may be damaged if it is not strong due to resistance when punching the lead frame. Since the damaged blade may be scattered in the mold and other parts in the mold may be damaged, the width of the lead frame plate is usually secured to maintain the punch strength.
Therefore, when punching with a stamping press die, the island 2 and the inner lead 3 need to have a width equal to or greater than the lead frame thickness T.

  For islands 5 and 6 (X-direction island size 5 and Y-direction island size 6), the gap 4 between the island 2 and the inner lead 3 is punched so that the punching strength of the stamping press mold can be maintained. It is essential to secure a width greater than the thickness, and the sizes 5 and 6 of the island 2 cannot be enlarged. The inner lead 3 is a wire connection region that is electrically connected to a semiconductor element to be mounted. The wire connection area needs to be enlarged in proportion to increasing the wire diameter. Reducing the area limits the diameter of the wire to be connected, or when using multiple wires in a semiconductor package that requires a large current to flow, reducing the inner leads will reduce the target number of wires. There is a possibility that the target semiconductor device performance cannot be achieved. For this reason, the inner lead is not reduced and the wire connection is not forced.

  FIG. 3 is a front plan view of a lead frame according to an embodiment of the present invention in which crushing processing is performed along the periphery of the back surface of the island 2 after stamping press punching to form crushing portions 7a, 7b, 7c, 7d, and 7e. is there. The gap 8 between the island 2 and the inner lead 3 can be made smaller than half the gap 4 shown in FIG. 1 by providing the crushing portions 7c and 7d on the rear surface of the island.

  Further, by providing the crushing portions 7a, 7c, and 7d, the Y-direction island size 10 can be enlarged with respect to the Y-direction island size 6 in FIG. This makes it possible to increase the size Y of the semiconductor element that can be mounted.

  Further, by providing the crushing portions 7b and 7e, the X-direction island size 9 can be enlarged with respect to the X-direction island size 5 in FIG. The crushing portions 7b and 7e can be enlarged by simply changing the punching shape with a stamping press instead of the crushing processing. However, the crushing processing is preferably performed because the filling of the resin is affected. This will be described later.

  FIG. 4 is a back view showing an embodiment in which the crushing process of the present invention is performed on the back surface of the island. Crushing portions 7a, 7b, 7c, 7d, and 7e are formed on the back surface of the island 2. After the crushing process, the semiconductor element is mounted on the island by bonding with a die attach material, and the electrode provided on the surface of the semiconductor element and the inner lead are electrically connected by a wire mainly made of gold or aluminum. Connecting.

  FIG. 5 is a diagram for explaining the crushing process. As shown in FIG. 5A, in the state processed by the stamping press, the gap 4 between the island 2 and the inner lead 3 is at least as large as the plate thickness T of the lead frame. Therefore, as shown in FIG. 5B, in order to perform the crushing process, the tip of the punch is pressed along the edge of the eye and the lead frame material where the punch hits is moved toward the surface of the lead frame. Although not shown in the drawing, the lead frame is fixed to a flat surface with the surface facing down, so that the moved lead frame material is plastically deformed along the surface. As a result, as shown in the figure after the crushing process in FIG. 5C, a crushed region extending in an eaves shape is formed around the island surface, and a gap 4 between the island 2 and the inner lead 3 is formed. It becomes small and it becomes the clearance gap 8 newly, and can increase the area of an island.

  FIG. 6 is a cross-sectional view of the island back side crushing shape of the present invention. The state where the semiconductor element 16 is mounted on the surface of the island 2 is shown. A wire 20 connects an electrode (not shown) of the semiconductor element 16 and the inner lead 3.

  FIG. 7 is a detailed sectional view taken along the line AA shown in FIG. Crushing portions 7 b and 7 e are formed at a depth of 11 and a width of 12 from the back surface of the island 2. The semiconductor element 16 is omitted.

  FIG. 8 is a detailed sectional view taken along the line BB shown in the figure. The crushing portions 7a and 7c are formed on the back surface of the island 2 with a depth of 11 and a width of 121. Even if the crushing depth 11 is more than half of the plate thickness, it can be processed without any problem. The island size can be further increased by increasing the crushing depth. The crushed width 12 can be equal to the lead frame thickness 4.

  FIG. 9 is a front plan view showing the semiconductor package of the present invention after resin filling. The lead frame sealing resin 13 is filled from a resin injection port (gate) 14. In the embodiment of FIG. 9, the resin inlet is provided on the + X side, but this may be provided at any position on the resin body.

  FIG. 10 is a side view showing the semiconductor package after resin filling of the present invention. A sealing resin 13 is formed on the front surface and the back surface side with a required thickness so as to seal the island and inner lead connected to the lead frame 1 and the semiconductor element fixed to the island by a die attach material. Yes.

  FIG. 11 is a cross-sectional view showing, for comparison, the resin filling state when using a lead frame that is not subjected to island backside crushing after punching with the stamping press of the present invention. The sealing resin 13 is filled from the resin injection port 14 through the resin inflow path 17. When the lead frame is relatively thick with respect to the thickness of the sealing resin, for example, when the thickness is 1/4 or more, the resin injection port When the sealing resin 13 flows from the resin 14 into the resin body 13, the lead frame 1 may be obstructed and the resin may not be sufficiently filled.

  FIG. 12 is a cross-sectional view showing a resin filling state when the lead frame of the present invention is used. The resin inflow path 18 is filled from the resin injection port 14, but the island end is thinner than the resin filling in the case of using the lead frame which is not subjected to the processing of the present invention shown in FIG. The resin filling path in the section is secured. As a result, it is possible to reduce the occurrence of internal voids in which resin is not filled or air remains in the resin seal 13.

  FIG. 13 shows a state in which the semiconductor device is cut from the lead frame to be separated into individual pieces after being sealed with a resin to form individual semiconductor devices. In this embodiment, the semiconductor device is resin-sealed in a semiconductor package having a lead shape in which the outer lead 23 protrudes from the sealing resin 13 in parallel in one direction.

  The case of the pin insertion type semiconductor package as an embodiment of the present invention has been described above. The embodiment of the present invention is not limited to the case of a pin insertion type semiconductor package. Next, an embodiment in the case of a gull wing type semiconductor package in which pins are extended relatively long from the side of the semiconductor package to the outside will be described.

  FIG. 14 is a front plan view of a lead frame used in a gull wing type semiconductor package according to the second embodiment of the present invention, and after the stamping press punching process, the crushing process is performed along the periphery of the back surface of the island 2. Portions 7a, 7b, 7c, 7d, 7e, and 7f are formed. The gap 8 between the island 2 and the inner lead 3 can be reduced by providing the crushing portions 7a to 7f on the rear surface of the island, thereby reducing the initial gap provided by stamping press punching. Depending on the initial size of the gap, the size can be reduced to less than half by crushing. For this reason, the island is expanded vertically and horizontally.

  In FIG. 14, the suspension leads 18 for supporting the island 2 are extended and arranged from both ends of the island 2 that is above and below, and therefore, a crushing portion cannot be provided on the back surface in this portion. The crushing portions 7 a and 7 f and 7 c and 7 d are divided by the suspension leads 18. Each inner lead 3 is connected to an outer lead 23 extending outside the semiconductor package.

  FIG. 15 is a detailed sectional view taken along the line CC of FIG. On the back surface of the island 2, crushing portions 7 b and 7 e having a depth of 11 and a width of 121 are formed. Even if the crushing depth 11 is more than half of the plate thickness, it can be processed without any problem. The island size can be further increased by increasing the crushing depth. The crushed width 12 can be equal to the plate thickness T of the lead frame.

  FIG. 16 is a detailed cross-sectional view taken along the line DD shown in FIG. On the back surface of the island 2, crushing portions 7 b and 7 e having a depth of 11 and a width of 121 are formed. Even if the crushing depth 11 is more than half of the plate thickness, it can be processed without any problem. The island size can be further increased by increasing the crushing depth. The crushed width 12 can be equal to the plate thickness T of the lead frame.

  The suspension lead 18 is formed by sealing the island 2, the inner lead 3, a semiconductor element (not shown) mounted on the island 2, and a wire (not shown) connecting the semiconductor element and the inner lead with a sealing resin. Since it is cut later, the end face after being cut is exposed from the sealing resin.

  FIG. 17 is a front plan view of a lead frame used in a non-lead type semiconductor package according to a third embodiment of the present invention, and after the stamping press punching process, the crushing process is performed along the periphery of the back surface of the island 2. Portions 7a, 7b, 7c, 7d, 7e, and 7f are formed. The gap 8 between the island 2 and the inner lead 3 can be reduced by providing the crushing portions 7a to 7f on the back surface of the island, thereby reducing the initial gap provided by stamping press punching. Depending on the initial size of the gap, the size can be reduced to less than half by crushing. For this reason, the island is expanded vertically and horizontally.

  In FIG. 17, the suspension leads 18 for supporting the island 2 are extended and arranged from both ends of the island 2 on the left and right sides. Can not. The crushing portions 7b and 7c, 7e and 7f are divided by the suspension leads 18. Each inner lead 3 is connected to an outer lead 23 that is slightly exposed outside the semiconductor package.

  18 is a detailed cross-sectional view taken along the line EE shown in FIG. On the back surface of the island 2, crushing portions 7 c and 7 e having a depth of 11 and a width of 12 are formed. Even if the crushing depth 11 is more than half of the plate thickness, it can be processed without any problem. The island size can be further increased by increasing the crushing depth. The crushed width 12 can be equal to the plate thickness T of the lead frame.

  FIG. 19 is a detailed cross-sectional view taken along the line FF shown in FIG. On the back surface of the island 2, crushing portions 7 a and 7 d having a depth of 11 and a width of 12 are formed. Even if the crushing depth 11 is more than half of the plate thickness, it can be processed without any problem. The island size can be further increased by increasing the crushing depth. The crushed width 12 can be equal to the plate thickness T of the lead frame.

  The suspension lead 18 is formed by sealing the island 2, the inner lead 3, a semiconductor element (not shown) mounted on the island 2, and a wire (not shown) connecting the semiconductor element and the inner lead with a sealing resin. Since it is cut later, the end face after being cut is exposed from the sealing resin.

  As described above, the invention according to the present application can be implemented regardless of the shape of the package as long as it is a semiconductor package using a lead frame.

1 Lead frame 2 Island 3 Inner lead 4 Inner lead, gap between islands 5 X direction island size 6 Y direction island size 7 Island back side crushing part 8 Inner lead after island back side crushing, gap between islands 9 Island size after island crushing
10 Island size Y after island crushing
11 Island back side crushing depth 1
12 Island back side crushing depth 2
13 Sealing resin 14 Sealing resin inlet (gate)
15 Die attach agent 16 Semiconductor element 17 Resin inflow path 18 Hanging lead 20 Wire 23 Outer lead T Lead frame plate thickness

Claims (4)

Preparing the lead frame material;
A step of manufacturing a lead frame having a certain plate thickness having a semiconductor element mounting island, an inner lead, and an outer lead connected to the inner lead by punching using a stamping press die from the lead frame material;
After the punching process, applying a crushing process from the back surface around the island, and expanding the area of the island;
Fixing the semiconductor element to the surface of the island with a die attach material;
Sealing the semiconductor element, the island, and the inner lead with a sealing resin without exposing the back surface of the island;
The outer lead protrudes from the sealing resin, the semiconductor element, the island, and the inner lead are sealed by the sealing resin, and the semiconductor device supported by the lead frame is cut from the lead frame; ,
A method for manufacturing a semiconductor device comprising:   2. The semiconductor device according to claim 1, wherein a size of a gap between the island and the inner lead is smaller than the certain plate thickness of the lead frame after the crushing process. Production method.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the constant plate thickness of the lead frame is ¼ or more of the thickness of the sealing resin that has passed through the sealing step.   4. The method of manufacturing a semiconductor device according to claim 1, wherein the cutting step includes cutting a suspension lead extending from the island.

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