Multi-media cards (MMC) are small-scale integrated circuit (IC) devices having control and memory chips for storing and processing digital video and audio data. Conventionally, MMC chips are packaged and accommodated on a chip carrier such as substrate or tape; however, this substrate-based or tape-based packaging technology is relatively cost-ineffective to implement.
Therefore, Taiwan Publication No. 484222 teaches a lead-frame-based semiconductor package in which a lead frame is employed as a chip carrier for MMC chips. As shown in FIG. 4, this semiconductor package 1 is provided with a lead frame 10 having a plurality of leads 11. Each of the leads 11 is defined with an inner lead portion 110, a middle lead portion 111 and an outer lead portion 112, wherein the middle lead portion 111 interconnects the inner and outer lead portions 110, 112. The inner lead portion 110 is used for chip-mounting purpose, and lower in elevation than the outer lead portion 112 by a predetermined height difference.
A chip 12, such as a MMC chip, is mounted on the inner lead portions 110, and electrically connected to the leads 11 by a plurality of bonding wires 13. Then, an encapsulant 14 is formed to encapsulate the leads 11, chip 12 and bonding wires 13, wherein the outer lead portions 112 are exposed to outside of the encapsulant 14 for mediating electrical connection between the semiconductor package 1 and an external device such as a printed circuit board (not shown). These components encapsulated by the encapsulant 14 can thus be protected against external moisture, contaminants and impact.
However, the above semiconductor package 1 has significant drawbacks. One is difficulty in obtaining desirable planarity of the leads; when the leads 11 are shaped or deformed to form inner lead portions 110, middle lead portions 111 and outer lead portions 112, it may easily lead to poor planarity of the outer lead portions 112, or a R angle (as circled in FIG. 4) at an interconnecting portion between an outer lead portion 112 and a corresponding middle lead portion 111. As such, during a molding process, a resin compound such as epoxy resin used for forming the encapsulant 14 may flash over the outer lead portions 112 that are to be exposed to outside of the encapsulant 14, thereby adversely affecting reliability and quality of electrical connection between the semiconductor package 1 and the external device.