Patent Application
20050275090
The present invention relates to a chip-component-mounted device and semiconductor device in which a chip component is mounted on a print wiring board or lead frame, and, particularly, to a chip-component-mounted device and semiconductor device which can prevent a short circuit with an adjacent pad (or lead) and component.
In recent years, a semiconductor device in which a semiconductor element is mounted on a print wiring board (or lead frame) is becoming higher in density, and there is an increasing importance of a semiconductor device of a module type, in which a chip component is mounted. The chip component, such as a bypass condenser for stabilization of power source, a condenser for stabilization of circuit operation, a load resistance, an inductance or the like, is disposed around the semiconductor element. In most of the semiconductor devices of the module type, the semiconductor element and chip component are mounted on the print wiring board (or lead frame) and sealed by a resin collectively. Solder or an electrically conductive adhesive is used for electrical connection between the semiconductor element and chip component and the print wiring board.
When the semiconductor device in which solder such as SnPb, SnAgCu and so like is used is mounted on a mother board, heat generated in the mounting may fuse the solder in the semiconductor device. If the solder in the semiconductor device is fused, thermal expansion of the fused solder may cause a crack in the sealing resin, and outflow of the solder along the crack may cause a short circuit between pad (or leads). The electrically conductive adhesive is therefore being used widely.
A conventional example in which the electrically conductive adhesive is used is explained below using drawings.
When the electrically conductive adhesive 103 is used, it is necessary to pay sufficient attention to the connection reliability because of its weaker connection strength than the solder. If the connection strength is weak, impact during an assembly process (for example, a wire bonding step or resin sealing step) after mounting the chip component 102 or a temperature change (for example, reflowing) around a product after finishing the assembly may break off the electrical connection of the electrode part 102a of the chip component 102 with the pad 101a of the print wiring board 101 (or a lead on a lead frame) or may bring about a greater electrical resistance because of deterioration of the strength of the connected part.
Since the connection strength of the electrically conductive adhesive 103 is weaker than the connection strength of the solder, the connection reliability of the electrically conductive adhesive 103 decreases as compared with the connection reliability of the solder. In order to improve the connection strength, it is necessary to increase the quantity of the electrically conductive adhesive 103 to enlarge the contact area of the chip component 102 with the electrically conductive adhesive 103.
JP Patent Kokai Publication No. P2002-25801A
When the quantity of the electrically conductive adhesive is increased to enlarge the contact area of the chip component with the electrically conductive adhesive, the following problems arise.
A first problem resides in that the area of application of the electrically conductive adhesive is enlarged and that there is therefore a probability that the electrically conductive adhesive short-circuits with the adjacent pad (or lead) or component.
A second problem resides in that the area of application of the electrically adhesive is enlarged and that there is therefore a probability that the electrically conductive adhesive flows over the lead to reach the back side of the lead when the chip component is mounted on a lead frame. If the electrically conductive adhesive goes to the back side of the lead, a conveyor for a component mounting apparatus is contaminated, and there is a therefore probability that the electrically conductive adhesive adheres to the back side of a product carried later and to an area where a mold presses down upon resin sealing with a mold. Moreover, if the electrically conductive adhesive adhered to the back side of the lead frame is hardened, a bonding face becomes out of the horizontal in a later bonding step, and thus there is a probability of a poor bonding. Further, if the electrically conductive adhesive adhered to the area where the mold presses down during the resin sealing with the mold is hardened, a gap is formed between the mold and the lead frame, and thus there is a probability that the sealing resin leaks out and that the mold or sealing apparatus is damaged.
Therefore, there is much to be desired in the art for a chip-component-mounted device and semiconductor device which can prevent a short circuit between an electrically conductive adhesive and an adjacent pad (or lead) or component even if the quantity of the electrically conductive adhesive is increased and the contact area of the chip component with the electrically conductive adhesive is enlarged.
Also, there is much to be desired in the art for a chip-component-mounted device and semiconductor device which can prevent the electrically conductive adhesive from going to the back side of the lead even if the contact area of the chip component with the electrically conductive adhesive is enlarged.
In a first aspect of the present invention, a chip-component-mounted device comprises a print wiring board or lead frame, an electrically conductive adhesive and a chip component. The chip component is mounted on the print wiring board or lead frame through the electrically conductive adhesive. The chip component has a corner part. A ridgeline of the corner part faces to a connected part side of the print wiring board or lead frame. An angle made by a face adjacent to the ridgeline and a face of the connected part is acute.
In a second aspect of the present invention, a chip-component-mounted device comprises a print wiring board or lead frame, an electrically conductive adhesive and a chip component. The chip component is mounted on the print wiring board or lead frame through the electrically conductive adhesive. The chip component has a corner part. A ridgeline of the corner part faces to a connected part side of the print wiring board or lead frame. An angle made by a face adjacent to the ridgeline and a face of the connected part is acute. The face of the connected part has a groove along a direction of the ridgeline. The corner part of the chip component is put in the groove.
In a third aspect of the present invention, a semiconductor device comprises a chip-component-mounted device and a semiconductor element. The chip-component-mounted device comprises a print wiring board or lead frame, an electrically conductive adhesive and a chip component. The chip component is mounted on the print wiring board or lead frame through the electrically conductive adhesive. The chip component has a corner part. A ridgeline of the corner part faces to a connected part side of the print wiring board or lead frame. An angle made by a face adjacent to the ridgeline and a face of the connected part is acute. The semiconductor element is mounted on the chip-component-mounted device.
In a fourth aspect of the present invention, a semiconductor device comprises a chip-component-mounted device and a semiconductor element. The chip-component-mounted device comprises a print wiring board or lead frame, an electrically conductive adhesive and a chip component. The chip component is mounted on the print wiring board or lead frame through the electrically conductive adhesive. The chip component has a corner part. A contour (ridgeline) of the corner part faces a connected part side of the print wiring board or lead frame. An angle generated by a face adjacent to the ridgeline and a face of the connected part is acute. The face of the connected part has a groove along a direction of the edge (ridgeline). The corner part of the chip component is disposed in the groove. The semiconductor element is mounted on the chip-component-mounted device.
The meritorious effects of the present invention are summarized as follows.
According to the present invention (claims 1 to 4), a possibility that the electrically conductive adhesive short-circuits with an adjacent pad or component could reduce because the electrically conductive adhesive is prevented from extending toward the perpendicular direction to the ridgeline of the corner part of the chip member even if the quantity of the electrically conductive adhesive is increased as compared with a conventional structure to enlarge the contact area of the chip component with the electrically conductive adhesive and therefore to increase the connection strength.
According to the present invention (claims 1 to 4), similarly, when the chip component is mounted on a lead frame, a possibility that the electrically conductive adhesive flows over the lead and goes to the back side of the lead also could reduce because the electrically conductive adhesive is prevented from extending toward the perpendicular direction to the ridgeline of the corner part of the chip member.
According to the present invention (claim 2), the connection strength could increase further because the groove part increases the contact area of the electrically conductive adhesive with a connected part (the pad of the print wiring board, the lead of the lead frame) and generates an anchor effect. Moreover, the position and inclination of the chip component could be stabilized and the connection strength therefore could be stabilized because the groove part also keeps the angle formed by the connected part and the chip component even if the strength to keep a form before hardening of the electrically conductive adhesive is insufficient.
A chip-component-mounted device according to a first embodiment of the present invention is explained below with reference to drawings.
In the first embodiment, a chip component 2 is arranged on two pads 1a (connected parts) of a print wiring board 1, on which a semiconductor element (not shown) is mounted, so as to bridge between two pads 1a, a corner part 2b of the chip component 2 facing toward the pad 1a side. The pad 1a and an electrode part 2a corresponding to the pad 1a are connected each other through an electrically conductive adhesive 3 physically and electrically. The pad 1a of the print wiring board 1 is an electrically conductive pad formed on a surface of a wiring (not shown) in the print wiring board 1 and comprises plating of noble metal such as Au. The other (corresponding) pad 1a is arranged leaving a predetermined space from the pad 14 shown on the front side. The chip component 2 is an electronic component, such as a condenser, a resistance, an inductance or the like, like a chip, comprising at least the corner part (or edge) 2b and also comprises the electrode parts 2a on both the ends. The electrode 2a of the chip component 2 comprises plating of noble metal such as AgPd, Ag or the like. Most of the electrically conductive adhesives 3 include metal filler such as Ag in an epoxy resin adhesive. An angle a made by a face of the pad 1a and a face adjacent to a ridgeline of the corner part 2b of the chip component 2 is acute (see
The electrically conductive adhesive 3 is filled at least between the pad 1a and the electrode part 2a. The contact area of the chip component 2 with the electrically conductive adhesive 3 amounts to about 50% of a length L of the circumference of the chip component 2 as viewed in the cross section, which is considered to be sufficient to secure connection reliability of the pad 1a of the print wiring board 1 with the chip component 2 (see
According to the first embodiment, the connection strength of the pad 1a of the print wiring board with the chip component 2 becomes sufficiently large, and the electrically conductive adhesive 3 does not cause the short-circuit with the adjacent pad and component at all. The reason is that the electrically conductive adhesive 3 is filled between the pad 1a of the print wiring board 1 and the electrode part 2a of the chip component 2 and is therefore prevented from extending toward a perpendicular direction to the ridgeline of the corner part 2b of the chip component 2 even if the quantity of the electrically conductive adhesive 3 is increased and accounts for about 50% of the length L of the circumference of the chip component 2.
Next, a chip-component-mounted device according to a second embodiment of the present invention is explained below using drawings.
In the second embodiment, as the first embodiment, the chip component 2 is mounted on two pads 1a (connected parts) of the print wiring board 1, on which the semiconductor element (not shown) is mounted, such that the chip component 2 bridges between two pads 1a and that the corner part 2b of the chip component 2 faces toward the pad 1a side. The pad 1a and the corresponding electrode part 2a are connected each other through the electrically conductive adhesive 3 physically and electrically. The pad 1a of the print wiring board 1 is an electrically conductive pad formed on the surface of the wiring (not shown) of the print wiring board 1 and comprises the plating of noble metal such as Au. The other (corresponding) pad 1a is arranged leaving from the pad 1a. The chip component 2 is an electronic component, such as a condenser, a resistance, an inductance or the like, like a chip (for example, a rectangular parallelepiped or a cube), comprising at least the corner part 2b and also comprises the electrode parts 2a on both the ends. The electrode 2a of the chip component 2 comprises a plating of noble metal such as AgPd, Ag or the like. An adhesive, for example, including a metal filler, such as Ag, in an epoxy resin adhesive is used as the electrically conductive adhesive 3. An angle made by the face of the pad 1a and the face adjacent to the ridgeline of the corner part 2b of the chip component 2 is acute (see
The difference between the second embodiment and the first embodiment is that a groove part 1b is formed along the ridgeline direction of the corner part 2b of the chip component 2 on the face of the pad 1a of the print wiring board 1. The groove part 1b shown in
The electrically conductive adhesive 3 is filled at least between the pad 1a and the electrode part 2a. The contact area of the chip component 2 with the electrically conductive adhesive 3 accounts for about 50% of the length L of the circumference of the chip component 2 in view of the sectional direction, which is considered to be sufficient to secure connection reliability of the pad 1a of the print wiring board 1 with the chip component 2 (see
According to the second embodiment, the connection of the pad 1a of the print wiring board 1 with the chip component 2 is sufficiently strong, and the electrically conductive adhesive 3 does not short-circuit with the adjacent pad and component at all. The reason is that the electrically conductive adhesive 3 is filled between the pad 1a of the print wiring board 1 and the electrode part 2a of the chip component 2 and is therefore prevented from extending toward a perpendicular direction to the ridgeline of the corner part 2b of the chip component 2 even if the quantity of the electrically conductive adhesive 3 is increased and amounts to about 50% of the length L of the circumference of the chip component 2. In addition, the groove 1b increases the contact area of the electrically conductive adhesive 3 with the pad 1a of the print wiring board 1 and generates an anchor effect, thereby making the connection stronger than the first embodiment. Even if the strength to keep the form before hardening of the electrically conductive adhesive 3 is insufficient, the groove 1b can keep the angle made by the pad 1a of the print wiring board 1 and the chip component 2, the position and inclination of the chip component 2 is therefore stabilized, and the connection strength is also stabilized.
Next, a third embodiment is explained. In the first and second embodiments, the chip component mounted on the print wiring board is explained, whereas, in the third embodiment, a lead frame is used in place of the print wiring board. When the chip component is mounted on the lead frame, the ridgeline of the corner part (corresponding to 2b in
It should be noted that other objects, features and aspects of the present invention will become apparent in the entire disclosure and that modifications may be done without departing the gist and scope of the present invention as disclosed herein and claimed as appended herewith.
Also it should be noted that any combination of the disclosed and/or claimed elements, matters and/or items may fall under the modifications aforementioned.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-171049 | Jun 2004 | JP | national |
