JP7468056B2 - Lead frame and manufacturing method thereof, and semiconductor device and manufacturing method thereof - Google Patents

Description

This disclosure relates to a lead frame and a manufacturing method thereof, and a semiconductor device and a manufacturing method thereof.

In recent years, there has been a demand for smaller and thinner semiconductor devices mounted on substrates. To meet this demand, various types of so-called QFN (Quad Flat Non-lead) type semiconductor devices have been proposed, which are conventionally constructed using a lead frame, with a semiconductor element mounted on the mounting surface sealed with sealing resin and with a portion of the leads exposed on the back side.

However, traditionally, as the lead frame becomes thinner, it becomes more difficult to maintain the strength of the lead frame, and the lead frame becomes deformed after etching, which is a problem.

In recent years, there has also been a demand to increase the number of leads (number of pins) without changing the chip size. In response to this, the conventional approach has been to narrow the width of the leads, but as the leads become thinner, they become more susceptible to deformation, which creates the problem of making it difficult to perform stable wire bonding.

JP 2019-57590 A

Patent Document 1 discloses a technique for providing a resin portion on the back surface of a lead frame and then removing unnecessary portions of the resin portion. When manufacturing a semiconductor device using a lead frame with such a resin portion on the back surface, there is a demand for improved adhesion between the sealing resin and the lead frame.

The present disclosure provides a lead frame and a manufacturing method thereof, as well as a semiconductor device and a manufacturing method thereof, that can improve adhesion between a sealing resin and a lead frame in a lead frame having a resin on the back side.

The lead frame according to the present disclosure comprises a die pad, a lead portion disposed around the die pad and having a terminal portion, and a back side resin disposed around the die pad and the lead portion on the back side of the lead frame, the terminal portion having a terminal surface located on the front side, a terminal back surface located on the back side, and a terminal side surface located between the terminal surface and the terminal back surface, the width of the terminal back surface of the terminal portion is wider than the width of the terminal surface of the terminal portion, the terminal side surface has a first terminal side surface located on the front side and a second terminal side surface located on the back side, the second terminal side surface is in close contact with the back side resin, and the first terminal side surface is exposed to the outside and is roughened.

In the lead frame according to the present disclosure, the die pad has a die pad surface located on the surface side, a die pad back surface located on the back side, a first die pad side surface facing the lead portion side and located on the die pad surface side, and a second die pad side surface facing the lead portion side and located on the die pad back side, the second die pad side surface being in close contact with the back side resin, and the die pad surface and the first die pad side surface may be exposed to the outside and roughened.

In the lead frame according to the present disclosure, the lead portion has an inner lead connected to the terminal portion, the inner lead is thinned from the back side, the inner lead has an inner lead surface located on the front side, an inner lead back surface located on the back side, and an inner lead side surface located between the inner lead surface and the inner lead back surface, the inner lead back surface is in close contact with the back side resin, and the inner lead surface and the inner lead side surface may be exposed to the outside and roughened.

In the lead frame according to the present disclosure, the terminal portion may have a lateral protrusion protruding laterally from the terminal side surface, the first terminal side surface being located closer to the front surface of the terminal than the lateral protrusion, and the second terminal side surface being located closer to the rear surface of the terminal than the lateral protrusion.

The semiconductor device according to the present disclosure is a semiconductor device comprising a die pad, a lead portion arranged around the die pad and having a terminal portion, a back side resin arranged around the die pad and the lead portion on the back side of the semiconductor device, a semiconductor element mounted on the die pad, a connection member electrically connecting the semiconductor element and the lead portion, and a sealing resin that seals the die pad, the lead portion, the semiconductor element, and the connection member, and the terminal portion has a terminal surface located on the front side, a terminal back surface located on the back side, and a terminal side surface located between the terminal surface and the terminal back surface, the width of the terminal back surface of the terminal portion is wider than the width of the terminal surface of the terminal portion, the terminal side surface has a first terminal side surface located on the front side and a second terminal side surface located on the back side, the second terminal side surface is in close contact with the back side resin, and the first terminal side surface is in close contact with the sealing resin and is roughened.

The method for manufacturing a lead frame according to the present disclosure includes the steps of: preparing a metal substrate; etching the metal substrate from the rear surface side to the middle of the thickness direction to form a rear surface recess; forming a rear surface resin on the rear surface side of the metal substrate and covering the rear surface recess with the rear surface resin; and etching the metal substrate from the front surface side to the middle of the thickness direction to expose the rear surface resin to the front surface side, forming a die pad and a lead portion disposed around the die pad and having a terminal portion. The method includes the steps of forming a surface of the metal substrate, removing the resin on the rear surface side by a predetermined thickness, and roughening the surface side of the metal substrate, and the terminal portion has a terminal surface located on the front surface side, a terminal rear surface located on the rear surface side, and a terminal side surface located between the terminal surface and the terminal rear surface, the width of the terminal rear surface of the terminal portion is wider than the width of the terminal surface of the terminal portion, the terminal side surface has a first terminal side surface located on the front surface side and a second terminal side surface located on the rear surface side, the second terminal side surface is in close contact with the resin on the rear surface side, and the first terminal side surface is exposed to the outside and is roughened.

The method for manufacturing a semiconductor device according to the present disclosure includes the steps of preparing a lead frame according to the present disclosure, mounting a semiconductor element on the die pad, electrically connecting the semiconductor element and the lead portion with a connecting member, and sealing the lead frame, the semiconductor element, and the connecting member with a sealing resin.

According to the present disclosure, in a lead frame having a backside resin, it is possible to improve the adhesion between the sealing resin and the lead frame.

FIG. 1 is a plan view showing a lead frame according to an embodiment. FIG. 2 is a bottom view showing a lead frame according to an embodiment. FIG. 3 is a cross-sectional view showing a lead frame according to one embodiment (a cross-sectional view taken along line III-III in FIG. 1). FIG. 4 is a cross-sectional view showing a lead frame according to one embodiment (a cross-sectional view taken along line IV-IV in FIG. 1). FIG. 5 is a plan view showing a semiconductor device according to an embodiment. FIG. 6 is a cross-sectional view showing the semiconductor device according to the embodiment (a cross-sectional view taken along line VI-VI in FIG. 5). 7(a) to (j) are cross-sectional views showing a method for manufacturing a lead frame according to one embodiment. 8A to 8E are cross-sectional views showing a method for manufacturing a semiconductor device according to one embodiment.

One embodiment will be described below with reference to Figures 1 to 8. Note that in the following figures, the same parts are given the same reference numerals, and some detailed descriptions may be omitted.

In this specification, the X direction and the Y direction are two directions parallel to each side of the lead frame 10, and the X direction and the Y direction are perpendicular to each other. The Z direction is perpendicular to both the X direction and the Y direction. The terms "inside" and "inner side" refer to the side facing the center of each package area 10a, and the terms "outside" and "outer side" refer to the side away from the center of each package area 10a. The term "front side" refers to the side on which the semiconductor element 21 is mounted (the positive side in the Z direction), and the term "back side" refers to the side opposite the "front side" (the negative side in the Z direction) that is connected to an external wiring board (not shown).

In addition, in this specification, half-etching refers to etching the material to be etched partway in the thickness direction. The thickness of the material to be etched after half-etching is, for example, 30% to 70%, preferably 40% to 60%, of the thickness of the material to be etched before half-etching.

(Lead frame configuration)
First, an outline of the lead frame according to the present embodiment will be described with reference to Figures 1 to 4. Figures 1 to 4 are diagrams showing the lead frame according to the present embodiment.

As shown in Figures 1 and 2, the lead frame 10 includes an outer frame 40 and a package area (unit lead frame) 10a arranged inside the outer frame 40.

In this case, multiple package areas 10a are arranged in multiple rows and columns (in a matrix). However, this is not limited to the above, and it is sufficient that there is one or more package areas 10a. Note that each package area 10a corresponds to a semiconductor device 20 (described below), and is an area located inside the imaginary lines in Figures 1 and 2. Also, the imaginary lines in Figures 1 and 2 correspond to the outer periphery of the semiconductor device 20.

Next, the configuration of the lead frame 10 will be further explained with reference to Figures 1 to 3.

As shown in Figures 1 to 3, each package area 10a of the lead frame 10 includes a die pad 11, a plurality of elongated lead portions 12A, 12B, and 12C that are provided around the die pad 11 and connect a semiconductor element 21 (described below) to an external circuit (not shown), and a back side resin 18 that is disposed around the die pad 11 and the lead portions 12A, 12B, and 12C and on the back side of the lead frame 10. The package areas 10a are connected to each other via support leads (support members) 13. The support leads 13 support the die pad 11 and the lead portions 12A, 12B, and 12C, and extend along the X and Y directions, respectively.

In this embodiment, the front surface side of the lead frame 10 is roughened. Specifically, the die pad 11, lead portion 12, support lead 13, and outer frame 40 of the lead frame 10, which are closer to the front surface than the back surface side resin 18 and are not in contact with the back surface side resin 18, are each roughened.

The roughened portion is formed by subjecting the surface of the metal substrate 31 to a roughening treatment (e.g., microetching treatment) as described below. That is, the roughness of the roughened portion of the lead frame 10 is rougher than the roughness of the non-roughened portion of the lead frame 10. The average roughness of the roughened portion can be, for example, Ra = 0.03 μm or more and 0.6 μm or less. The average roughness Ra is the arithmetic mean roughness defined in JIS B0601. Note that in Figures 1 and 2, the roughened portion is indicated by a shaded area (the same applies to Figure 5 described below). Also, in Figure 3, the roughened portion is indicated by a thick dashed line (the same applies to Figures 4, 6 to 8 described below).

The die pad 11 has a substantially square shape in plan view. In this case, the die pad 11 is not half-etched and has the same thickness as the metal substrate (metal substrate 31 described later) before processing. The planar shape of the die pad 11 is not limited to a square, but may be a polygon such as a rectangle. No suspension leads are connected to the die pad 11, and the die pad 11 is supported by the support leads 13 or the outer frame 40 only via the back side resin 18. In this case, for example, other lead parts not shown may be arranged in the areas near the corners of the die pad 11. This allows the areas near the corners of the die pad 11 to be effectively used. However, this is not limited to this, and the die pad 11 may be supported by the support leads 13 or the outer frame 40 via the suspension leads.

3, the die pad 11 has a die pad surface 11a located on the surface side and a die pad back surface 11b located on the back surface side. A semiconductor element 21 described later is mounted on the die pad surface 11a. The die pad back surface 11b is exposed to the outside from the lead frame 10. In addition, a first die pad side surface 11c and a second die pad side surface 11d are formed on the side of the die pad 11 facing the lead portions 12A, 12B, and 12C. The first die pad side surface 11c is located on the die pad surface 11a side and is exposed to the outside from the lead frame 10. The second die pad side surface 11d is located on the die pad back surface 11b side and is in close contact with the back surface resin 18. In this case, the die pad surface 11a and the first die pad side surface 11c of the die pad 11 are each roughened. On the other hand, the die pad back surface 11b and the second die pad side surface 11d of the die pad 11 are not roughened.

Next, the configuration of the lead portions 12A, 12B, and 12C will be described. Note that the lead portions 12A, 12B, and 12C are also referred to as the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C, respectively.

Each of the lead portions 12A, 12B, and 12C is connected to the semiconductor element 21 via a bonding wire 22, as described below, and is disposed with a space between it and the die pad 11. Each of the lead portions 12A, 12B, and 12C extends from the support lead 13 or the outer frame 40.

As shown in FIG. 1, each first lead portion 12A has a first terminal portion 53A and an inner lead 51A connected to the first terminal portion 53A. The inner lead 51A extends from the first terminal portion 53A toward the inside (the die pad 11 side), and its tip portion is disposed away from the die pad 11. The first terminal portion 53A is also directly connected to the support lead 13 or the outer frame 40.

The second lead portion 12B has a second terminal portion 53B, an inner lead 51B connected to the second terminal portion 53B, and a connection lead 52B connected to the second terminal portion 53B. Of these, the inner lead 51B extends from the second terminal portion 53B toward the inside (the die pad 11 side), and its tip is disposed away from the die pad 11. The connection lead 52B extends from the second terminal portion 53B toward the outside (the support lead 13 or outer frame 40 side), and is connected to the support lead 13 or the outer frame 40.

The third lead portion 12C has a third terminal portion 53C, an inner lead 51C connected to the third terminal portion 53C, and a connection lead 52C connected to the third terminal portion 53C. Of these, the inner lead 51C extends from the third terminal portion 53C toward the inside (the die pad 11 side), and its tip is disposed away from the die pad 11. The connection lead 52C extends from the third terminal portion 53C toward the outside (the support lead 13 or outer frame 40 side), and is connected to the support lead 13 or the outer frame 40.

An inner lead tip surface 51d is formed at the tip (end on the die pad 11 side) of each of the inner leads 51A, 51B, and 51C of the lead portions 12A, 12B, and 12C (FIG. 3). The inner lead tip surface 51d is disposed in a position facing the second die pad side surface 11d of the die pad 11. The inner lead tip surface 51d is not covered by the back surface side resin 18, and a space is formed between the inner lead tip surface 51d and the second die pad side surface 11d.

Also, an internal terminal 15 is formed on the surface of the tip end (die pad 11 side end) of the inner leads 51A, 51B, 51C of the lead portions 12A, 12B, 12C. This internal terminal 15 is an area that is electrically connected to the semiconductor element 21 via the bonding wire 22 as described below. For this reason, a plating layer 25 that improves adhesion with the bonding wire 22 is provided on the internal terminal 15. The plating layer 25 may be made of, for example, silver plating. Also, each internal terminal 15 of the lead portions 12A, 12B, 12C is arranged along a straight line parallel to the side of the die pad 11. This can increase the efficiency of the bonding work.

The mutually adjacent lead portions 12A, 12B, lead portions 12B, 12C, and lead portions 12C, 12A are shaped so as to be electrically insulated from each other after the semiconductor device 20 (described below) is manufactured. In addition, each of the lead portions 12A, 12B, and 12C is shaped so as to be electrically insulated from the die pad 11 after the semiconductor device 20 is manufactured.

As shown in FIG. 2, external terminals 17A, 17B, and 17C are formed on the back surfaces of terminal portions 53A, 53B, and 53C, respectively, to be electrically connected to an external mounting board (not shown). Each of external terminals 17A, 17B, and 17C is adapted to be exposed to the outside from semiconductor device 20 after semiconductor device 20 (described below) is manufactured.

The inner leads 51A, 51B, 51C and the connection leads 52B, 52C of the lead portions 12A, 12B, 12C are each thin-walled by half-etching from the back side. On the other hand, the terminal portions 53A, 53B, 53C have the same thickness as the die pad 11 without being half-etched. In this way, by making the thickness of the inner leads 51A, 51B, 51C and the connection leads 52B, 52C thinner than the thickness of the terminal portions 53A, 53B, 53C, the narrow lead portions 12A, 12B, 12C can be formed with high precision, and a small semiconductor device 20 with a large number of pins can be obtained. In this embodiment, the first lead portion 12A does not have a connection lead, but this is not limited to this, and the first lead portion 12A may have a connection lead thin-walled by half-etching from the back side.

As shown in FIG. 1, the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C are each supported by the support lead 13, and are repeatedly arranged in this order along the support lead 13. That is, in this embodiment, the third lead portion 12C, the second lead portion 12B, and the first lead portion 12A are repeatedly arranged in this order from the longitudinal end side of the support lead 13 toward the longitudinal center side. However, this is not limited to this, and the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C may be repeatedly arranged in this order from the longitudinal end side of the support lead 13 toward the longitudinal center side.

In addition, the first lead portion 12A is provided at the center of the length of the support lead 13. From the center first lead portion 12A toward both ends of the length of the support lead 13, the second lead portion 12B, the first lead portion 12A, and the third lead portion 12C are repeatedly arranged in this order. In this case, the multiple first lead portions 12A, the multiple second lead portions 12B, and the multiple third lead portions 12C supported by the support lead 13 are arranged line-symmetrically with the center of the length of the support lead 13 as the center. Specifically, with the center first lead portion 12A as the center, both the shapes and the arrangement of the lead portions 12A, 12B, and 12C on both sides are line-symmetric. This allows the terminal portions 53A, 53B, and 53C to be arranged in a well-balanced manner, making it easier to design and manufacture the semiconductor device 20.

As shown in Fig. 1, the terminals 53A, 53B, and 53C of the leads 12A, 12B, and 12C are arranged in a staggered pattern when viewed from above. In this case, the terminals 53A, 53B, and 53C are arranged in three rows along straight lines parallel to either the X direction or the Y direction. That is, the centers of the terminals 53A, 53B, and 53C are arranged along straight lines L _A , L _B , and L _C , respectively. The distance _D1 between the straight lines L _A and L _B and the distance _D2 between the straight lines L _B and L _C are equal to each other (D ₁ =D ₂ ).

The first terminal portion 53A of the first lead portion 12A is located outside (towards the support lead 13) the second terminal portion 53B of the second lead portion 12B. Also, the second terminal portion 53B of the second lead portion 12B is located outside (towards the support lead 13) the third terminal portion 53C of the third lead portion 12C. This ensures the pitch between the terminal portions 53A, 53B, and 53C, preventing the terminal portions 53A, 53B, and 53C from contacting the adjacent lead portions 12A, 12B, and 12C.

Note that the lead portions 12A, 12B, and 12C may not have the inner leads 51A, 51B, and 51C, respectively. In this case, the lead portions 12A, 12B, and 12C may extend from the support lead 13 toward the die pad 11 and terminate at the terminal portions 53A, 53B, and 53C, respectively.

Next, the cross-sectional shapes of the lead portions 12A, 12B, and 12C will be described with reference to Figure 4. Figure 4 shows the cross sections of the lead portions 12A, 12B, and 12C taken along line IV-IV in Figure 1.

As shown in FIG. 4, the inner lead 51A of the first lead portion 12A is thinned from the back surface side. The inner lead 51A of the first lead portion 12A has a shape that is approximately symmetrical in cross section. The inner lead 51A has an inner lead surface 51a located on the front surface side, an inner lead back surface 51b located on the back surface side, and a pair of inner lead side surfaces 51c located between the inner lead surface 51a and the inner lead back surface 51b. The inner lead surface 51a is located on the same plane as the die pad surface 11a of the die pad 11. The inner lead back surface 51b is a surface formed by half etching. The inner lead back surface 51b is located on the front surface side (positive side in the Z direction) of the die pad back surface 11b of the die pad 11, and is in close contact with the back surface resin 18. The pair of inner lead side surfaces 51c each have a shape that is recessed toward the inside in the width direction of the inner lead 51A. Each inner lead side surface 51c is exposed to the outside without being covered by the back surface resin 18.

In this case, the inner lead surface 51a and the inner lead side surface 51c of the inner lead 51A that are not covered with the plating layer 25 are each roughened. The inner lead tip surface 51d described above is also roughened (see FIG. 3). On the other hand, the inner lead surface 51a and the inner lead back surface 51b that are covered with the plating layer 25 are not roughened. However, this is not limited to the above, and the entire inner lead surface 51a other than the portion covered with the plating layer 25 may be roughened.

Although not shown, the cross-sectional shapes along the width direction of the inner lead 51B of the second lead portion 12B and the inner lead 51C of the third lead portion 12C are each substantially the same as the cross-sectional shape of the inner lead 51A of the first lead portion 12A shown in FIG. 4.

As shown in FIG. 4, the second terminal portion 53B of the second lead portion 12B has a shape symmetrical in the width direction in cross section. This second terminal portion 53B has a terminal surface 53a located on the surface side, a terminal back surface 53b located on the back surface side, a pair of terminal side surfaces 53c located between the terminal surface 53a and the terminal back surface 53b, and a pair of lateral projections 53f each protruding laterally from the terminal side surface 53c. This second terminal portion 53B has the same thickness as the die pad 11, and the terminal surface 53a and the terminal back surface 53b of the second terminal portion 53B are located on the same plane as the die pad surface 11a and the die pad back surface 11b of the die pad 11, respectively. An external terminal 17B is formed on the terminal back surface 53b of the second terminal portion 53B.

Each terminal side surface 53c has a first terminal side surface 53d located closer to the terminal surface 53a than the lateral protrusion 53f, and a second terminal side surface 53e located closer to the terminal back surface 53b than the lateral protrusion 53f. Each first terminal side surface 53d extends from the lateral protrusion 53f to the terminal surface 53a, and each second terminal side surface 53e extends from the lateral protrusion 53f to the terminal back surface 53b. The first terminal side surface 53d and the second terminal side surface 53e are each curved toward the inside in the width direction of the second lead portion 12B. Each first terminal side surface 53d is also inclined from the terminal surface 53a side toward the lateral protrusion 53f side so that the width of the second terminal portion 53B increases.

In this case, the width _wb of the terminal back surface 53b of the second terminal portion 53B is wider than the width _wa of the terminal front surface 53a of the second terminal portion 53B. As a result, even if the interval between the first lead portion 12A, the second lead portion 12B, and the third lead portion 12C adjacent to each other is narrowed, the area of the external terminal 17B can be secured wide, and the external terminal 17B can be reliably connected to an external mounting board (not shown). In addition, the width _wf between the lateral projections 53f of the second terminal portion 53B is wider than the width _wa of the terminal front surface 53a of the second terminal portion 53B. Note that the width _wf between the lateral projections 53f of the second terminal portion 53B may be wider or narrower than the width _wb of the terminal back surface 53b of the second terminal portion 53B.

In this case, the terminal surface 53a and the first terminal side surface 53d of the second terminal portion 53B are roughened. On the other hand, the terminal back surface 53b and the second terminal side surface 53e of the second terminal portion 53B are not roughened. In this way, the first terminal side surface 53d of the second terminal portion 53B is roughened, so that the adhesion between the second terminal portion 53B and the sealing resin 23 described later can be improved and the second lead portion 12B can be prevented from falling off from the sealing resin 23. In particular, even if the width w _b of the terminal back surface 53b of the second terminal portion 53B is wider than the width w _a of the terminal surface 53a and the second terminal portion 53B has a shape that is likely to fall off from the sealing resin 23 to the back surface side, the first terminal side surface 53d of the second terminal portion 53B is roughened, so that the second terminal portion 53B can be prevented from falling off.

Although not shown, the cross-sectional shapes along the width direction of the first terminal portion 53A of the first lead portion 12A and the third terminal portion 53C of the third lead portion 12C are each substantially the same as the cross-sectional shape of the second terminal portion 53B of the second lead portion 12B shown in FIG. 4.

As shown in FIG. 4, the connection lead 52C of the third lead portion 12C is thinned from the back surface side. The connection lead 52C of the third lead portion 12C has a shape that is approximately symmetrical in cross section. The connection lead 52C has a connection lead surface 52a located on the front surface side, a connection lead back surface 52b located on the back surface side, and a pair of connection lead side surfaces 52c located between the connection lead surface 52a and the connection lead back surface 52b. The connection lead surface 52a is located on the same plane as the die pad surface 11a of the die pad 11. The connection lead back surface 52b is a surface formed by half etching. The connection lead back surface 52b is located on the front surface side (positive side in the Z direction) of the die pad back surface 11b of the die pad 11, and is in close contact with the resin surface 18a of the back surface side resin 18. The pair of connection lead side surfaces 52c each have a shape that is recessed toward the inside in the width direction of the connection lead 52C. Each connection lead side surface 52c is exposed to the outside without being covered by the back surface side resin 18.

In this case, the connection lead surface 52a and the connection lead side surface 52c of the connection lead 52C are each roughened. On the other hand, the connection lead back surface 52b of the connection lead 52C is not roughened.

Although not shown, the cross-sectional shape along the width direction of the connection lead 52C of the third lead portion 12C is substantially the same as the cross-sectional shape of the connection lead 52B of the second lead portion 12B.

The back side resin 18 is disposed around the die pad 11 and the leads 12A, 12B, and 12C. That is, as shown in FIG. 1, when viewed from the front side, the back side resin 18 is located in an area surrounded by the four sides of the die pad 11, the multiple leads 12A, 12B, and 12C, and the support leads 13 or the outer frame 40. As shown in FIG. 2, when viewed from the back side, the back side resin 18 is located in an area surrounded by the four sides of the die pad 11, the external terminals 17A, 17B, and 17C of the leads 12A, 12B, and 12C, and the support leads 13 or the outer frame 40. Note that in FIG. 1 and FIG. 2, the back side resin 18 is shown in gray (the same applies to FIG. 5 described later).

The back surface side resin 18 is disposed on the back surface side of the lead frame 10. In other words, the back surface side resin 18 is not present on the front surface side (positive side in the Z direction) of the lead frame 10 relative to the middle position in the thickness direction (Z direction), but is present only on the back surface side (negative side in the Z direction) of the middle position in the thickness direction. Note that the middle position is not limited to the center in the thickness direction of the lead frame 10, and may be located on the front surface side or back surface side of the middle position in the thickness direction.

3, the back surface resin 18 is disposed in a region surrounded by the second terminal portion 53B, the inner lead back surface 51b, and the second die pad side surface 11d in a cross-sectional view along the length direction of the second lead portion 12B. The back surface resin 18 is also disposed in a region surrounded by the terminal portion 53B, the connection lead back surface 52b, and the support lead 13 or the outer frame 40 in a cross-sectional view along the length direction of the second lead portion 12B.

As shown in FIG. 4, the back surface side resin 18 is located on the back surface side of the inner lead back surface 51b of the inner lead 51A of the first lead portion 12A and is in close contact with the inner lead back surface 51b. The same is true for the inner lead 51B of the second lead portion 12B and the inner lead 51C of the third lead portion 12C.

The back surface side resin 18 is located on the back surface side of the lateral protrusion 53f of the second terminal portion 53B of the second lead portion 12B, and is in close contact with the second terminal side surface 53e. On the other hand, the back surface side resin 18 is not in contact with the first terminal side surface 53d. Therefore, the first terminal side surface 53d is exposed to the outside. The same is true for the first terminal portion 53A of the first lead portion 12A and the third terminal portion 53C of the third lead portion 12C.

Furthermore, the back surface side resin 18 is located on the back surface side of the connection lead back surface 52b of the connection lead 52C of the third lead portion 12C, and is in close contact with the connection lead back surface 52b. The same is true for the connection lead 52C of the third lead portion 12C.

As shown in FIG. 3, the back surface side resin 18 has a resin surface 18a located on the front surface side and a resin back surface 18b located on the back surface side. Of these, the resin surface 18a is exposed to the outside from the space between the first die pad side surface 11c and the inner lead tip surface 51d. The resin back surface 18b is exposed to the outside from the back surface side of the lead frame 10. In addition, the resin back surface 18b, the die pad back surface 11b, and the external terminals 17A, 17B, and 17C are located on the same plane.

The rear surface side resin 18 can be a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin. In order to improve adhesion between the rear surface side resin 18 and the sealing resin 23 described below, it is preferable to use the same material as the sealing resin 23 for the rear surface side resin 18.

The die pad 11 and lead portions 12A, 12B, and 12C of the lead frame 10 described above are made of metals such as copper, copper alloy, and 42 alloy (Fe alloy containing 42% Ni). The thickness of the lead frame 10 can be 80 μm or more and 250 μm or less, depending on the configuration of the semiconductor device 20 to be manufactured.

In this embodiment, the lead portions 12A, 12B, and 12C are arranged along all four sides of the die pad 11, but this is not limited thereto, and they may be arranged, for example, along only two opposing sides of the die pad 11.

In addition, in this embodiment, the external terminals 17A, 17B, and 17C of the lead portions 12A, 12B, and 12C are arranged in three rows in a staggered pattern, but this is not limiting, and the external terminals may be arranged in one or two rows, or four or more rows.

(Configuration of Semiconductor Device)
Next, the semiconductor device according to the present embodiment will be described with reference to Figures 5 and 6. Figures 5 and 6 are diagrams showing the semiconductor device (QFN type) according to the present embodiment.

As shown in Figures 5 and 6, the semiconductor device (semiconductor package) 20 includes a die pad 11, a number of lead portions 12A, 12B, and 12C arranged around the die pad 11, a semiconductor element 21 mounted on the die pad 11, and a number of bonding wires (connecting members) 22 that electrically connect the lead portions 12A, 12B, and 12C to the semiconductor element 21. In addition, a back side resin 18 is arranged around the die pad 11 and the lead portions 12A, 12B, and 12C on the back side of the semiconductor device 20. Furthermore, the die pad 11, the lead portions 12A, 12B, and 12C, the semiconductor element 21, and the bonding wires 22 are resin-sealed with sealing resin 23.

Of these, the die pad 11, the leads 12A, 12B, 12C, and the back surface side resin 18 are made from the lead frame 10 described above. The configurations of the die pad 11, the leads 12A, 12B, 12C, and the back surface side resin 18 are similar to those shown in Figures 1 to 4 described above, except for the areas not included in the semiconductor device 20, so detailed explanations will be omitted here.

In this embodiment, the die pad 11 and the lead portions 12A, 12B, and 12C are roughened at the front side of the back side resin 18 and at the portions that come into contact with the sealing resin 23. The roughened portions of the die pad 11 and the lead portions 12A, 12B, and 12C are similar to the portions shown in Figures 1 to 4 described above, except for the portions that are not included in the semiconductor device 20.

The semiconductor element 21 may be any of a variety of commonly used semiconductor elements, including, but not limited to, integrated circuits, large-scale integrated circuits, transistors, thyristors, and diodes. The semiconductor element 21 has a number of electrodes 21a to which bonding wires 22 are attached. The semiconductor element 21 is fixed to the surface of the die pad 11 by an adhesive 24, such as die bonding paste.

Each bonding wire 22 is made of a material with good conductivity, such as gold or copper. One end of each bonding wire 22 is connected to the electrode 21a of the semiconductor element 21, and the other end is connected to the plating layer 25 located on the internal terminal 15 of each lead portion 12A, 12B, 12C.

The sealing resin 23 may be a thermosetting resin such as silicone resin or epoxy resin, or a thermoplastic resin such as PPS resin. The thickness of the entire sealing resin 23 may be about 300 μm or more and 1200 μm or less. In addition, one side of the sealing resin 23 (one side of the semiconductor device 20) may be, for example, 1 mm or more and 16 mm or less. In the space between the die pad 11 and the lead portions 12A, 12B, and 12C, the sealing resin 23 is in close contact with the resin surface 18a of the back side resin 18. Note that in FIG. 5, the sealing resin 23 located on the front side of the die pad 11, the lead portions 12A, 12B, and 12C, and the back side resin 18 is omitted from the illustration.

(Lead frame manufacturing method)
Next, a method for manufacturing the lead frame 10 shown in FIGS. 1 to 4 will be described with reference to FIGS.

First, as shown in FIG. 7(a), a flat metal substrate 31 is prepared. This metal substrate 31 may be made of a metal such as copper, a copper alloy, or alloy 42 (a 42% Ni-Fe alloy). It is preferable to use a metal substrate 31 that has been degreased and cleaned on both sides.

Next, photosensitive resist is applied to the entire front and back surfaces of the metal substrate 31 and dried. The photosensitive resist on the metal substrate 31 is then exposed through a photomask and developed to form etching resist layers 32 and 33 having the desired openings 32b and 33b (FIG. 7(b)).

Next, the metal substrate 31 is thinned from the back side of the metal substrate 31 to the middle of the thickness direction by half etching. In this case, the back side etching resist layer 33 is used as a corrosion-resistant film, and the back side of the metal substrate 31 is etched with an etchant (FIG. 7(c)). At this time, the front side etching resist layer 32 may be covered with a film (not shown). This forms a back side recess 36, which is a non-penetrating recess, on the back side of the metal substrate 31. This back side recess 36 has a shape corresponding to the back side resin 18. The etchant can be appropriately selected depending on the material of the metal substrate 31 used. For example, when copper is used as the metal substrate 31, a ferric chloride aqueous solution is usually used, and this ferric chloride aqueous solution may be spray-etched from one side or both sides of the metal substrate 31.

Next, the etching resist layer 33 on the back side is peeled off and removed, leaving the etching resist layer 32 on the front side, and then the metal substrate 31 is washed with water and dried (Figure 7 (d)).

Next, the back side resin 18 is formed on the back side of the metal substrate 31, and the back side recess 36 is covered with the back side resin 18 (FIG. 7(e)). At this time, a thermosetting resin or a thermoplastic resin may be injection molded or transfer molded on the back side of the metal substrate 31. As a result, the back side resin 18 is filled into the back side recess 36. The thickness T1 of the back side resin 18 from the portion 11e corresponding to the die pad back side 11b may be 25 μm or more and 200 μm or less. In this case, the back side of the metal substrate 31, the portion 11e corresponding to the die pad back side 11b, and the portion 17a corresponding to the external terminals 17A, 17B, and 17C of the lead portions 12A, 12B, and 12C are covered with the back side resin 18. At this time, the entire back side of the metal substrate 31 may be covered with the back side resin 18.

Next, the metal substrate 31 is thinned from the front surface side to the middle of the thickness direction by half etching. In this case, the front surface side of the metal substrate 31 is etched with an etchant, using the etching resist layer 32 on the front surface side as a corrosion-resistant film (FIG. 7(f)). This forms the outlines of the die pad 11, the leads 12A, 12B, 12C, and the support leads 13. Furthermore, by half-etching the front surface side of the metal substrate 31, gaps are formed between the die pad 11 and the leads 12A, 12B, 12C, and the back surface side resin 18 is exposed to the front surface side. The etchant may be the same as that used when etching the back surface side of the metal substrate 31 (FIG. 7(c)).

Next, the back side resin 18 is removed by a predetermined thickness to expose the back side of the metal substrate 31 (FIG. 7(g)). Specifically, the back side resin 18 is polished from the back side, and when the back side of the metal substrate 31 appears, polishing of the back side resin 18 is completed. At this time, the die pad back side 11b of the die pad 11 and the metal surfaces constituting the external terminals 17A, 17B, 17C of the lead portions 12A, 12B, 12C are exposed on the back side. Note that, as a method for removing the back side resin 18, for example, back grinding, which is the most upstream process in manufacturing the semiconductor device 20, for finishing the semiconductor element 21 to a predetermined thickness, can be mentioned.

Next, the etching resist layer 32 is peeled off and the metal substrate 31 is washed with water and dried (Figure 7(h)).

Next, electrolytic plating is applied to the inner leads 51A, 51B, and 51C of the lead portions 12A, 12B, and 12C. This causes a metal (e.g., silver) to deposit on the inner leads 51A, 51B, and 51C of the lead portions 12A, 12B, and 12C, forming plating layers 25 (FIG. 7(i)).

Then, the front surface of the metal substrate 31 is roughened (FIG. 7(j)). At this time, the rear surface of the metal substrate 31 is covered with a film (not shown), and a micro-etching solution is supplied to the front surface of the metal substrate 31 to form a rough surface over the entire front surface of the metal substrate 31 except for the portion covered with the plating layer 25. The micro-etching solution is a surface treatment agent that slightly dissolves the metal surface to form a rough surface with fine irregularities. For example, when roughening the metal substrate 31 made of copper or a copper alloy, a micro-etching solution mainly composed of hydrogen peroxide and sulfuric acid may be used. In this way, the lead frame 10 shown in FIGS. 1 to 4 is obtained (FIG. 7(j)).

(Method of manufacturing a semiconductor device)
Next, a method for manufacturing the semiconductor device 20 shown in FIGS. 5 and 6 will be described with reference to FIGS.

First, the lead frame 10 is fabricated (Figure 8(a)) using, for example, the method shown in Figures 7(a)-(j).

Next, the semiconductor element 21 is mounted on the die pad 11 of the lead frame 10. In this case, the semiconductor element 21 is placed on the die pad 11 and fixed thereon using an adhesive 24 such as die bonding paste (die attachment process) (FIG. 8(b)).

Next, each electrode 21a of the semiconductor element 21 and the plating layer 25 formed on each lead portion 12A, 12B, 12C are electrically connected to each other by a bonding wire (connecting member) 22 (wire bonding process) (Figure 8 (c)).

Next, the sealing resin 23 is formed on the lead frame 10 by injection molding or transfer molding, for example, a thermosetting resin or a thermoplastic resin (FIG. 8(d)). In this way, the lead frame 10, the lead portions 12A, 12B, and 12C, the semiconductor element 21, and the bonding wires 22 are sealed.

Next, the sealing resin 23 and the support leads 13 between each semiconductor element 21 are diced to separate the lead frame 10 into each semiconductor device 20. At this time, the sealing resin 23 and the support leads 13 between each semiconductor device 20 may be cut while rotating a blade made of, for example, a diamond grindstone.

In this manner, the semiconductor device 20 shown in Figures 5 and 6 is obtained (Figure 8 (e)).

Thus, according to this embodiment, the terminal side surface 53c of the terminal portions 53A, 53B, and 53C are in close contact with the back surface resin 18, and the second terminal side surface 53e of the terminal portions 53A, 53B, and 53C are roughened without being covered by the back surface resin 18. As a result, after the semiconductor device 20 is manufactured, the roughened second terminal side surface 53e adheres to the sealing resin 23 with high adhesion strength, so that the terminal portions 53A, 53B, and 53C can be prevented from falling off the sealing resin 23. In particular, when the width of the terminal back surface 53b of the terminal portions 53A, 53B, and 53C is wider than the width of the terminal front surface 53a, and the terminal portions 53A, 53B, and 53C have a shape that is easily peeled off from the sealing resin 23, the roughened second terminal side surface 53e adheres to the sealing resin 23. Therefore, it is possible to prevent the terminal portions 53A, 53B, and 53C from falling off the sealing resin 23.

In addition, according to this embodiment, the second die pad side surface 11d of the die pad 11 is in close contact with the back surface resin 18, and the die pad surface 11a and the first die pad side surface 11c are exposed to the outside and are roughened. As a result, after the semiconductor device 20 is manufactured, the roughened die pad surface 11a and the first die pad side surface 11c are in close contact with the sealing resin 23 with high adhesion strength, so that the die pad 11 can be prevented from falling off the sealing resin 23.

In addition, according to this embodiment, the inner lead back surface 51b of the inner leads 51A, 51B, and 51C is in close contact with the back surface resin 18, and the inner lead surface 51a and the inner lead side surface 51c are exposed to the outside and are roughened. As a result, after the semiconductor device 20 is manufactured, the roughened inner lead surface 51a and the inner lead side surface 51c are in close contact with the sealing resin 23 with high adhesion strength, so that the inner leads 51A, 51B, and 51C can be prevented from falling off the sealing resin 23.

In addition, according to this embodiment, the terminals 53A, 53B, and 53C have lateral protrusions 53f that protrude laterally from the terminal surface 53a, and the first terminal side surface 53d is located closer to the terminal surface 53a than the lateral protrusions 53f, and the second terminal side surface 53e is located closer to the terminal back surface 53b than the lateral protrusions 53f. As a result, after the semiconductor device 20 is manufactured, the lateral protrusions 53f penetrate into the boundary between the sealing resin 23 and the back surface resin 18 and act as an anchor, preventing the terminals 53A, 53B, and 53C from falling off the sealing resin 23 and the back surface resin 18.

In addition, according to this embodiment, the process of exposing the back surface resin 18 to the front surface by etching (FIG. 7(f)) is performed before the process of removing a predetermined thickness of the back surface resin 18 (FIG. 7(g)). As a result, when the front surface side of the metal substrate 31 is etched, the back surface side of the metal substrate 31 is covered with the back surface resin 18, so that only the front surface side of the metal substrate 31 can be thinned without a separate process of covering the back surface of the metal substrate 31 with another member.

In addition, according to this embodiment, the photolithography process for forming the etching resist layers 32 and 33 can be performed only once (Figure 7 (b)), which simplifies the manufacturing process of the lead frame 10.

The components disclosed in each of the above embodiments and modifications may be combined as necessary. Alternatively, some components may be deleted from all the components shown in each of the above embodiments and modifications.

REFERENCE SIGNS LIST 10 Lead frame 10a Package area 11 Die pad 12A, 12B, 12C Lead portion 15 Internal terminal 17A, 17B, 17C External terminal 18 Back surface resin 20 Semiconductor device 21 Semiconductor element 22 Bonding wire (connecting member)
23 Sealing resin 25 Plating layer 51A, 51B, 51C Inner lead 52B, 52C Connection lead 53A, 53B, 53C Terminal portion 53a Terminal surface 53b Terminal back surface 53c Terminal side surface 53d First terminal side surface 53e Second terminal side surface 53f Lateral protrusion portion

Claims (8)

In the lead frame,
A die pad;
a lead portion disposed around the die pad and having a terminal portion;
a back surface side resin disposed around the die pad and the lead portion on a back surface side of the lead frame,
the terminal portion has a terminal front surface located on the front surface side, a terminal back surface located on the back surface side, and a terminal side surface located between the terminal front surface and the terminal back surface,
The terminal side surface includes a first terminal side surface located on the front surface side and a second terminal side surface located on the back surface side,
the second terminal side surface is in close contact with the rear surface side resin,
The first terminal side surface is exposed to the outside and is roughened,
A lead frame , wherein the roughness of the side surface of the first terminal is greater than the roughness of the side surface of the second terminal . In the lead frame,
A die pad;
a lead portion disposed around the die pad and having a terminal portion;
a back surface side resin disposed around the die pad and the lead portion on a back surface side of the lead frame,
the die pad has a die pad front surface located on the front surface side, a die pad back surface located on the back surface side, a first die pad side surface facing the lead portion side and located on the die pad front surface side, and a second die pad side surface facing the lead portion side and located on the die pad back surface side,
the second die pad side surface is in close contact with the rear surface side resin,
the die pad front surface and the first die pad side surface are exposed outward and are roughened;
A lead frame , wherein the roughness of the die pad surface and the first die pad side surface is rougher than the roughness of the second die pad side surface . In the lead frame,
A die pad;
a lead portion disposed around the die pad and having a terminal portion;
a back surface side resin disposed around the die pad and the lead portion on a back surface side of the lead frame,
the lead portion has an inner lead connected to the terminal portion, the inner lead being thinned from a rear surface side,
the inner lead has an inner lead surface located on the surface side, an inner lead back surface located on the back side, and an inner lead side surface located between the inner lead surface and the inner lead back surface,
The back surface of the inner lead is in close contact with the back surface side resin,
the inner lead surface and the inner lead side surface are exposed outward and are roughened;
A lead frame , wherein the roughness of the inner lead surface and the inner lead side surface is greater than the roughness of the inner lead back surface . The lead frame according to claim 1, wherein the terminal portion has a lateral protrusion protruding laterally from the terminal side surface, the first terminal side surface is located closer to the front surface of the terminal than the lateral protrusion, and the second terminal side surface is located closer to the rear surface of the terminal than the lateral protrusion. There are a plurality of the lead portions, and the plurality of lead portions include a first lead portion, a second lead portion, and a third lead portion;
the first lead portion, the second lead portion, and the third lead portion are repeatedly arranged in this order;
The lead frame according to claim 1 , wherein the terminal portion of the first lead portion is positioned outside the terminal portion of the second lead portion, and the terminal portion of the second lead portion is positioned outside the terminal portion of the third lead portion. In a method for manufacturing a lead frame,
Providing a metal substrate;
forming a back surface recess by etching the metal substrate from a back surface side to a middle of a thickness direction;
forming a back surface side resin on a back surface side of the metal substrate and covering the back surface side recess with the back surface side resin;
a step of etching the metal substrate from the front surface side to a middle of the thickness direction to expose the back surface side resin to the front surface side, and forming a die pad and a lead portion disposed around the die pad and having a terminal portion;
removing the back surface side resin by a predetermined thickness;
and roughening the front surface side of the metal substrate,
a step of forming the die pad and the lead portion disposed around the die pad and having the terminal portion is a step subsequent to a step of covering the rear surface side recess with the rear surface side resin and prior to a step of roughening the front surface side of the metal substrate,
the terminal portion has a terminal front surface located on the front surface side, a terminal back surface located on the back surface side, and a terminal side surface located between the terminal front surface and the terminal back surface,
The terminal side surface includes a first terminal side surface located on the front surface side and a second terminal side surface located on the back surface side,
the second terminal side surface is in close contact with the rear surface side resin,
A method for manufacturing a lead frame, wherein the first terminal side surface is exposed to the outside and is roughened. In a method for manufacturing a lead frame,
Providing a metal substrate;
forming a back surface recess by etching the metal substrate from a back surface side to a middle of a thickness direction;
forming a back surface side resin on a back surface side of the metal substrate and covering the back surface side recess with the back surface side resin;
a step of etching the metal substrate from the front surface side to a middle of the thickness direction to expose the back surface side resin to the front surface side, and forming a die pad and a lead portion disposed around the die pad and having a terminal portion;
removing the back surface side resin by a predetermined thickness;
and roughening the front surface side of the metal substrate,
a step of forming the die pad and the lead portion disposed around the die pad and having the terminal portion is a step subsequent to a step of covering the rear surface side recess with the rear surface side resin and prior to a step of roughening the front surface side of the metal substrate,
the die pad has a die pad front surface located on the front surface side, a die pad back surface located on the back surface side, a first die pad side surface facing the lead portion side and located on the die pad front surface side, and a second die pad side surface facing the lead portion side and located on the die pad back surface side,
the second die pad side surface is in close contact with the rear surface side resin,
A method for manufacturing a lead frame, wherein the die pad surface and the first die pad side surface are exposed to the outside and are roughened. In a method for manufacturing a lead frame,
Providing a metal substrate;
forming a back surface recess by etching the metal substrate from a back surface side to a middle of a thickness direction;
forming a back surface side resin on a back surface side of the metal substrate and covering the back surface side recess with the back surface side resin;
a step of etching the metal substrate from the front surface side to a middle of the thickness direction to expose the back surface side resin to the front surface side, and forming a die pad and a lead portion disposed around the die pad and having a terminal portion;
removing the back surface side resin by a predetermined thickness;
and roughening the front surface side of the metal substrate,
a step of forming the die pad and the lead portion disposed around the die pad and having the terminal portion is a step subsequent to a step of covering the rear surface side recess with the rear surface side resin and prior to a step of roughening the front surface side of the metal substrate,
the lead portion has an inner lead connected to the terminal portion, the inner lead being thinned from a rear surface side,
the inner lead has an inner lead surface located on the surface side, an inner lead back surface located on the back side, and an inner lead side surface located between the inner lead surface and the inner lead back surface,
The back surface of the inner lead is in close contact with the back surface side resin,
A method for manufacturing a lead frame, wherein the inner lead surface and the inner lead side surfaces are exposed to the outside and are roughened.