1. Field of the Invention
The present invention relates to a semiconductor device using a lead frame and a method of manufacturing the same.
2. Description of the Related Art
A portable electronic device has been downsized in recent years, and a semiconductor package to be used in a semiconductor device has accordingly been required to be downsized and thinned while securing a mounting strength. Employing a surface mount package has been known as a measure for downsizing the semiconductor package, in which an external terminal protrudes in parallel to a substrate mounting surface. Examples of this package type include a small outline non-lead package (SON) and a quad flat non-lead package (QFN).
Those packages have a feature in that an external electrode required for mounting the package on a substrate is smaller than that of a dual inline package (DIP) or a small outline package (SOP), and hence a small amount of solder fillet is formed after the package is mounted on the substrate, and a mounting strength is low. Further, those packages are often manufactured with use of a lead frame produced by using a stamping mold or etching process. As a material of the lead frame, a 194 alloy or a copper alloy is used in general.
In manufacturing of the semiconductor device using the lead frame, a semiconductor chip is mounted on the lead frame, and the semiconductor chip and the lead frame are electrically connected to each other via wires. The resultant structure is then subjected to resin encapsulation process and deburring process, and exterior plating process is carried out on the copper surface. After the exterior plating process, the semiconductor device is cut off from the lead frame so as to have a predetermined size.
As described above, the semiconductor device is cut off from the lead frame after the exterior plating process, and hence no exterior plated film is formed on a cut surface of an outer lead. Accordingly there arises a problem that the solder wetting is poor when the semiconductor device is mounted on the substrate. In order to improve the mounting strength of the semiconductor package produced under such conditions, it is proposed that the shape of an outer lead distal end portion be changed in plan view or cross-sectional view so that the solder wetting after the semiconductor device is mounted on the substrate is improved and a solder fillet is thus easily formed, to thereby increase the mounting strength (for example, see Japanese Patent Application Laid-open Nos. 2006-19465 and Hei 7-45769).
However, along with the progress in downsizing and thinning of a semiconductor device, it is required to further improve the substrate mounting strength of the semiconductor device.
The present invention provides a semiconductor device having improved solder bonding strength onto a substrate, and a method of manufacturing the same.
In order to solve the problem described above, the following measures are taken.
First, according to one embodiment of the present invention, there is provided a semiconductor device, including: an encapsulating resin for covering a semiconductor chip mounted on an island of a lead frame; an outer lead extending from a side surface of the encapsulating resin; an inner lead connected to the outer lead; an inner lead suspension lead that is connected to the inner lead and extends from the encapsulating resin; and a plated film formed on all of surfaces of the outer lead.
Further, in the semiconductor device, the inner lead suspension lead is exposed from the encapsulating resin.
Further, in the semiconductor device, the island and the inner lead are set higher with respect to the outer lead in the lead frame.
Further, in the semiconductor device, the lead frame, the island, and the outer lead have the same height, and only the inner lead is set higher.
Further, according to one embodiment of the present invention, there is provided a method of manufacturing a semiconductor device including: an encapsulating resin for covering a semiconductor chip mounted on an island of a lead frame; and an outer lead extending from a side surface of the encapsulating resin, the method including: preparing a lead frame including the island, an inner lead close to the island, an inner lead suspension lead and the outer lead that are connected to the inner lead, and an island suspension lead connected to the island; die-bonding, wire-bonding, and resin encapsulating the semiconductor chip; cutting a distal end of the outer lead; forming, by electrolytic plating, a plated film on a cut surface of the outer lead; and cutting the inner lead suspension lead and the island suspension lead.
Further, the method of manufacturing a semiconductor device further includes testing electrical characteristics between the cutting the inner lead suspension lead and the cutting the island suspension lead.
According to one embodiment of the present invention, when the semiconductor device is mounted on the substrate, a thick solder layer is formed on all of the surfaces of the outer lead exposed from the encapsulation resin, and hence the semiconductor device can be firmly bonded to the substrate.
Now, the present invention is described with reference to the drawings.
Next, a method of manufacturing the semiconductor device of the present invention is described.
A stepped portion is formed between the inner lead 2 and the outer lead 5, which are continuous with one another, so that the lower surface of the outer lead is lower than a lower surface of the inner lead. As shown in
In other words, the lead frame of this embodiment is a lead frame in which the island and the inner leads are set higher. The lead frame 1 described above can be formed by die stamping and embossing a plate that has a predetermined thickness and is made of a 194 alloy material or a copper alloy. In other words, the plate is stamped for determining planar shapes of the island 6, the inner lead 2, the outer lead 5, the inner lead suspension lead 3, and the island suspension lead 4. As shown in
Next, the plate is upwardly embossed so that the island 6, the inner lead 2, a portion of the inner lead suspension lead 3, and a portion of the island suspension lead 4 are relatively higher than other portions. At this time, a step is formed between the inner lead 2 and the outer lead 5. At the same time, a folded portion is formed to each of the inner lead suspension lead 3 and the island suspension lead 4.
Through the manufacturing method described above, the plated film is formed on all of the surfaces of the outer lead, and hence the semiconductor device capable of firmly connecting to the substrate can be obtained.
In the above description, the lead frame in which the island and the inner lead are set higher is exemplified, but a semiconductor device may be manufactured with use of a lead frame in which no stepped portion or folded portion is formed, and the island, the inner lead, the outer lead, and the lead frame rim have the same height. Further, a semiconductor device may be manufactured with use of a lead frame in which the island, the outer lead, and the lead frame rim have the same height and only the inner lead is set higher.
Number | Date | Country | Kind |
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2014-046883 | Mar 2014 | JP | national |
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