Lead-frame structure, lead-frame, surface mount electronic device and methods of producing same
View Patent ↗A lead-frame structure having two faces and exposing a treated silver surface on at least one of said two faces, the treated silver surface(s) serving the wire bonding, which lead-frame structure has a surface which, after applying resin to it, has excellent adhesion even under severe testing conditions, such as the IPC/JEDEC J-STD-20 MSL standard, and a surface mount electronic device comprising a lead-frame or lead-frame entity and at least one semiconductor device mounted thereon, wherein the lead-frame or lead-frame entity exposes a treated silver surface on at least one of the two faces thereof, wherein the treated silver surface(s) serve(s) the wire bonding, and wherein a resin is applied to the lead-frame or lead-frame entity, and which surface mount electronic device has excellent adhesion of the surface of the lead-frame or lead-frame entity even under severe testing conditions.
1. A lead-frame structure having two faces and exposing a treatment layer comprising silver oxide on at least one of said two faces, wherein said lead-frame structure comprises at least two lead-frame entities each one having two faces and wherein said lead-frame structure is made of:
(i) a lead-frame body structure made of copper and having two main sides;
(ii) at least one of said main sides being coated with a silver coating, so that said at least one of said main sides at least partially exposes an untreated silver surface; and
(iii) said untreated silver surface on said at least one of said main sides further comprising a treatment layer comprising silver oxide, wherein thickness of the treatment layer is less than thickness of the silver coating;
characterized in that said at least one of said two faces of at least one of said at least two lead-frame entities either exclusively exposes said treatment layer comprising silver oxide or
that said at least one of said two faces of said at least one of said at least two lead-frame entities partially exposes said treatment layer comprising silver oxide and partially exposes said copper surface, wherein, on each one of said two faces of each one of said at least two lead-frame entities which partially exposes said treatment layer comprising silver oxide, the area of said copper surface is smaller than the area of said treatment layer comprising silver oxide;
wherein said silver coating is at most 0.5 μm thick.
2. The lead-frame structure according to claim 1 , wherein said at least one of said two faces of at least one of said at least two lead-frame entities exclusively exposes said treatment layer comprising silver oxide and no copper surface.
3. A lead-frame having two faces and exposing a treatment layer comprising silver oxide on at least one of said two faces and wherein said lead-frame is made of:
(i) a lead-frame body made of copper and having two main sides;
(ii) at least one of said main sides being coated with a silver coating, so that said at least one of said main sides at least partially exposes an untreated silver surface; and
(iii) said untreated silver surface on said at least one of said main sides further comprising a treatment layer comprising silver oxide, wherein thickness of the treatment layer is less than thickness of the silver coating;
characterized in that said at least one of said two faces of said lead-frame either exclusively exposes said treatment layer comprising silver oxide or that said at least one of said two faces of said lead-frame partially exposes said treatment layer comprising silver oxide and partially exposes said copper surface, wherein, on each one of said two faces of said lead-frame, the area of said copper surface is smaller than the area of said treatment layer comprising silver oxide;
wherein said silver coating is at most 0.5 μm thick.
4. A surface mount electronic device, comprising:
(A) a lead-frame having two faces and exposing a treatment layer comprising silver oxide on at least one of said two faces of said lead-frame, wherein said lead-frame is made of:
(i) a lead-frame body made of copper and having two main sides;
(ii) at least one of said main sides being coated with a silver coating, so that said at least one of said main sides at least partially exposes an untreated silver surface; and
(iii) said untreated silver surface on said at least one of said main sides further comprising a treatment layer comprising silver oxide, wherein thickness of the treatment layer is less than thickness of the silver coating; and
(B) at least one semiconductor device which is mounted on said at least one of said two faces of said lead-frame which exposes said treatment layer comprising silver oxide, wherein said at least one semiconductor device is bonded to said treatment layer comprising silver oxide on said at least one of said two faces of said lead-frame, wherein said bond creates an electrical connection between said lead-frame and said at least one semiconductor device,
wherein said at least one semiconductor device and said lead-frame are together encapsulated with a resin material,
characterized in that said at least one of said two faces of said lead-frame either exclusively exposes said treatment layer comprising silver oxide or that said at least one of said two faces of said lead-frame partially exposes said treatment layer comprising silver oxide and partially exposes said copper surface, wherein, on each one of said two faces of said lead-frame which partially exposes said treatment layer comprising silver oxide, the area of said copper surface is smaller than the area of said treatment layer comprising silver oxide;
wherein said silver coating is at most 0.5 μm thick.
5. The surface mount electronic device according to claim 4 , wherein said at least one of said two faces of said lead-frame exclusively exposes said treatment layer comprising silver oxide and no copper surface.
6. The lead-frame structure according to claim 1 , wherein said treatment layer has a thickness from 0.5 to 2 nm.
7. The lead-frame structure according to claim 3 , wherein said treatment layer has a thickness from 0.5 to 2 nm.
8. The surface mount electronic device according to claim 4 , wherein said treatment layer has a thickness from 0.5 to 2 nm.
9. The lead frame structure according to claim 1 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.
10. The lead frame structure according to claim 3 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.
11. The surface mount electronic device according to claim 4 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.
12. The lead frame structure according to claim 6 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.
13. The lead frame structure according to claim 7 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.
14. The surface mount electronic device according to claim 8 , wherein, when tested by applying a shear force at an angle of 90° at a rate of 50 mm/min over a distance of 100 mm, a shear force Fshear required to shear off from said treatment layer a cured epoxy button 3 mm diameter and 3 mm height is at least 11.611 MPa.