Source: https://patents.google.com/patent/US20060255438A1/en
Timestamp: 2018-07-18 11:07:16
Document Index: 168484156

Matched Legal Cases: ['art 2', 'arts 1', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art.\n3', 'art.\n4', 'art.\n5', 'art.\n6', 'art.\n14']

US20060255438A1 - Lead frame and resin-encapsulated semiconductor device - Google Patents
Lead frame and resin-encapsulated semiconductor device Download PDF
US20060255438A1
US20060255438A1 US11414374 US41437406A US2006255438A1 US 20060255438 A1 US20060255438 A1 US 20060255438A1 US 11414374 US11414374 US 11414374 US 41437406 A US41437406 A US 41437406A US 2006255438 A1 US2006255438 A1 US 2006255438A1
US11414374
US7728414B2 (en )
Kouji Omori
Hideki Sakoda
Fabrication Method for Power QFN Package
Next, as illustrated in FIG. 2B, the lead frame 20 is partly etched to pass through the lead frame 20, thereby forming a generally rectangular die pad 2, a plurality of leads 31 and support leads 3 (not shown). In this process step, the thin part 2 e is formed into thin parts 1 a of the leads 31 and a thin part 2 c of the die pad 2. In this case, approximately 0.2-mm-diameter through holes 11 are formed in the thin part 2 c.
Subsequently, as illustrated in FIG. 2C, the die pad 2 is processed by a half blanking presswork such that a circular middle part 2 a of the die pad 2 is located at a higher level than part thereof around the middle part 2 a (peripheral part 2 b). In this half blanking presswork step, a pressing process for stamping a middle circular part of the die pad 2 of the lead frame 20 is stopped in progress so that the circular part is partly joined to the lead frame 20 while being stamped partway. A level difference is formed between the middle part 2 a and the peripheral part 2 b at each of the top and back faces of the die pad 2 due to the upward pressure produced by the presswork. In this process step, the middle part 2 a of the die pad 2 can be located at a higher level than the peripheral part 2 b thereof and the leads 31 by half etching instead of the half blanking presswork. In this case, parts of the upper part of the lead frame 20 that will be the peripheral part 2 b of the die pad 2 and the leads 31 are removed, and a part of the lower part thereof that will be the middle part 2 a of the die pad 2 is removed. This allows formation of a thinner resin-encapsulated semiconductor device. In the above-mentioned process steps, the lead frame 20 is processed. In this stage, the leads 31 remains joined to a framework (not shown).
Next, as illustrated in FIG. 4A, the lead frame 20 is enclosed with a molding die 30 such that the semiconductor chip 4, the die pad 2, the leads 31, and other components are located inside a cavity of the molding die 30. In this state, a liquid resin encapsulant 6 (for example, epoxy resin) is injected into the cavity through a port through which a resin is injected thereinto, and the cavity is filled with a resin. If through holes 11 were formed in the part of the die pad 2 other than the thin part 2 c thereof, the resin encapsulant 6 would reach the back face of the lead frame 20 in this process step. Therefore, through holes 11 needs to be formed in the thin part 2 c.
Subsequently, as illustrated in FIG. 4B, the molding die 30 is removed after the solidification of the resin encapsulant 6. Since the through holes 11 are also filled with the resin encapsulant 6, the adhesion level between the resin encapsulant 6 and the die pad 2 is enhanced as compared with the known QFN package. The lower faces of the middle part 2 a and peripheral part 2 b of the die pad 2 and the lower faces of the leads 31 are exposed without being encapsulated with a resin.
A first characteristic of the power QFN package of this embodiment is that an outer edge portion of a peripheral part 2 b of the die pad 2 is formed with a thin part 2 c and the outer edge of the thin part 2 c is formed with recesses 11 a.
Therefore, in the power QFN package of this embodiment, an anchor effect is exhibited by allowing the resin encapsulant 6 to enter into the recesses 11 a formed in the thin part 2 c, resulting in the more effectively enhanced adhesion level between the die pad 2 and the resin encapsulant 6. As a result, it is less likely that moisture will enter from the back face of the package, resulting in the suppressed production of cracks. Furthermore, it is less likely that the resin encapsulant 6 will be separated from the die pad 2. This allows prevention of breaks in the thin metal wires 5. The adhesion level between the resin encapsulant 6 and the die pad 2 is enhanced with an increase in the number of recesses Ha formed in the outer edge of the die pad 2. However, the number of recesses 11 a is not particularly limited.
In the power QFN package of this embodiment, an outer edge portion of a peripheral part 2 b of the die pad 2 is formed with a thin part 2 c.
In the power QFN package of this embodiment, like that of the second embodiment, while the lower part of the die pad 2 forms a generally rectangular planar shape as in the first embodiment, the upper part of the die pad 2 forms a generally octagonal planar shape. More particularly, the planar shape of the upper part of the die pad 2 is the shape of an octagon obtained by cutting away corner portions of the upper part of the rectangular die pad 2. Furthermore, as illustrated in FIG. 7A, approximately 0.2-mm-wide grooves 12 are formed in the top faces of parts of the die pad 2 to which the support leads 3 are connected, respectively. Each groove 12 extends in a direction that crosses or is orthogonal to the direction in which the corresponding support lead 3 extends. In the example illustrated in FIG. 7A, the grooves 12 are formed along four edges among the eight edges of the octagon forming the upper part of the die pad 2, respectively. However, since the upper part of the die pad 2 is encapsulated with the resin encapsulant 6, the bottom of the power QFN package of this embodiment has the same shape as the known QFN package.
1. A lead frame for use in the packaging of a semiconductor chip, said lead frame comprising: a framework; a die pad placed in the framework and having a middle part and a peripheral part surrounding the middle part; a plurality of signal leads placed around the die pad and connected to the framework; and a plurality of support leads for supporting the die pad,
wherein the top face of the middle part is formed at a higher level than the top face of the peripheral part, and
an outer edge portion of the peripheral part is formed with a thin part which forms part of the upper part of the die pad projecting laterally beyond the lower part thereof and is formed with a to-be-filled portion.
2. The lead frame of claim 1, wherein
the to-be-filled portion is a through hole formed in the thin part.
3. The lead frame of claim 1, wherein
the to-be-filled portion is a recess formed in the outer edge of the thin part.
4. The lead frame of claim 1, wherein
the to-be-filled portion is at least one groove formed in at least one of the top and back faces of the thin part.
5. The lead frame of claim 1, wherein
a groove is further formed in the top face of the part of the peripheral part other than the thin part.
6. The lead frame of claim 1, wherein
the lower part of the die pad forms a rectangular planar shape and the upper part thereof forms the shape of an n-gon (where n is an integer of 4 or more) whose corner portions are placed apart from corner portions of the lower part of the die pad or a circle.
7. The lead frame of claim 6, wherein
the top face of part of the die pad to which each said support lead is connected is formed with a groove.
8. A resin-encapsulated semiconductor device comprising: a die pad; a semiconductor chip formed with an electrode pad and a semiconductor element; a plurality of signal leads placed around the die pad and extending toward the die pad; a plurality of connection members through which the electrode pad is connected to the signal leads; a plurality of support leads for supporting the die pad; and a resin encapsulant with which the top face of the die pad, the connection members, the support leads, and the top face of the signal leads are encapsulated with the back face of the die pad and the back faces of the signal leads exposed;
wherein the top face of a middle part of the die pad is formed at a higher level than the top face of a peripheral part of the die pad surrounding the middle part,
the semiconductor chip is placed on the top face of the middle part of the die pad, and
an outer edge portion of the peripheral part is formed with a thin part which forms part of the upper part of the die pad projecting laterally beyond the lower part thereof and is formed with a to-be-filled portion filled with the resin encapsulant.
9. The resin-encapsulated semiconductor device of claim 8, wherein
10. The resin-encapsulated semiconductor device of claim 8, wherein
11. The resin-encapsulated semiconductor device of claim 8, wherein
12. The resin-encapsulated semiconductor device of claim 8, wherein
the to-be-filled portion and the semiconductor chip overlap each other when viewed in plane.
13. The resin-encapsulated semiconductor device of claim 8, wherein
a groove is further formed in the top face of part of the peripheral part other than the thin part.
14. The resin-encapsulated semiconductor device of claim 8, wherein
15. The resin-encapsulated semiconductor device of claim 14, wherein
US11414374 2005-05-10 2006-05-01 Lead frame and resin-encapsulated semiconductor device Active 2026-06-13 US7728414B2 (en)
JP2005-137707 2005-05-10
JP2005137707A JP2006318996A (en) 2005-05-10 2005-05-10 Lead frame and resin sealed semiconductor device
US20060255438A1 true true US20060255438A1 (en) 2006-11-16
US7728414B2 US7728414B2 (en) 2010-06-01
ID=37390175
US11414374 Active 2026-06-13 US7728414B2 (en) 2005-05-10 2006-05-01 Lead frame and resin-encapsulated semiconductor device
US (1) US7728414B2 (en)
JP (1) JP2006318996A (en)
KR (1) KR20060116696A (en)
CN (2) CN1862797A (en)
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OMORI, KOUJI;SAKODA, HIDEKI;REEL/FRAME:018240/0099