Leadframe, plastic-encapsulated semiconductor device, and method for fabricating the same
View Patent ↗An inventive leadframe includes an outer frame, a die pad, and a plurality of leads each having land portions and connections. The land portions each have an upper surface serving as a bonding pad to be connected with a metal wiring, and a lowermost part serving as an external terminal. The connections are each devoid of its lower part so as to be thinner than the land portion, and are provided between the outer frame and the land portions, between the land portions associated with each other in each lead, and between the land portions and the die pad. Furthermore, the inventive leadframe is provided with no member that functions as a suspension lead for connecting the outer frame and the die pad to each other during plastic encapsulation.
1. A method for fabricating a plastic-encapsulated semiconductor device, the method comprising the steps of:
a) preparing a leadframe comprising an outer frame with a plurality of sides surrounding a region of the leadframe on which a semiconductor chip is to be mounted, a die pad on which the semiconductor chip is to be mounted, and a plurality of leads each having land portions and connections, the land portions each having an upper surface serving as a bonding pad to be connected with a metal wiring and a lowermost part serving as an external terminal, the connections each being devoid of its lower part so as to be thinner than the land portion and being provided between the outer frame and the land portions, between the land portions associated with each other in each lead and between the land portions and the die pad, wherein the plurality of leads include no member that functions as a suspension lead during plastic encapsulation;
b) mounting the semiconductor chip on the die pad of the leadframe;
c) placing the leadframe on an adhesive sheet for encapsulation;
d) cutting the connections with the leadframe placed on the encapsulation sheet, thus detaching, from the outer frame, the isolated land portions and the die pad;
e) connecting, through a connecting member, a portion of the semiconductor chip to the associated bonding pad; and
f) carrying out plastic encapsulation with the leadframe placed on the encapsulation sheet,
wherein the step c) is carried out prior to or subsequent to the step b), and the steps d), e) and f) are carried out in this order after the step c) has been carried out.
2. The method according to claim 1 ,
wherein after the step f) has been carried out, there exists no member that is connected to the die pad and that has its end exposed at a surface of the plastic encapsulant.
3. The method according to claim 1 ,
wherein the plurality of leads of the leadframe prepared in the step a) include a lead that is connected to one side of the outer frame and is connected to the other lead that is connected to the other side of the outer frame adjacent to the one side thereof.
4. A method for fabricating a plastic-encapsulated semiconductor device, the method comprising the steps of:
a) preparing a leadframe comprising an outer frame with a plurality of sides surrounding a region of the leadframe on which a semiconductor chip is to be mounted, a die pad having a thin portion that is provided along the peripheral section of the main body of the die pad and that is devoid of its lower part and having a plurality of heat dissipating terminals each protruded downward from the lower surface of the thin portion, and a plurality of leads each having land portions and connections, the land portions each having an upper surface serving as a bonding pad to be connected with a metal wiring and a lowermost part serving as an external terminal, the connections each being devoid of its lower part so as to be thinner than the land portion and being provided between the outer frame and the land portions, between the land portions associated with each other in each lead, and between the land portions and the heat dissipating terminals;
b) mounting the semiconductor chip on the die pad of the leadframe;
c) placing the leadframe on an adhesive sheet for encapsulation;
d) cutting the connections with the leadframe placed on the encapsulation sheet, thus detaching the isolated land portions from the outer frame;
e) connecting, through a connecting member, a portion of the semiconductor chip to the associated bonding pad; and
f) carrying out plastic encapsulation with the leadframe placed on the encapsulation sheet,
wherein the step c) is carried out prior to or subsequent to the step b), and the steps d), e) and f) are carried out in this order after the step c) has been carried out.
5. The method according to claim 4 ,
wherein in the step a), the leadframe prepared is provided with no member that functions as a suspension lead during the plastic encapsulation, and
wherein in the step d), the die pad is also detached from the outer frame.
6. The method according to claim 4 ,
wherein the plurality of leads of the leadframe prepared in the step a) include a lead that is connected to one side of the outer frame and is connected to the other lead that is connected to the other side of the outer frame adjacent to the one side thereof.