Pre-cut plating lines on lead frames and laminate substrates for saw singulation
Described herein is a technology or a method for pre-fabricating pre-cut plating lines on a lead frame with use of a pre-cut etchback process to minimize burrs during a semiconductor package singulation process. A package includes: a chip, and a lead frame that mounts the chip. The lead frame further includes pre-fabricated pre-cut plating lines that are etched back on the lead frame to form an opening slot on a periphery of the lead frame. The opening slot allows a saw blade to cut through a prepreg material, without touching or cutting a conductive material of the lead frame.
1. A method of forming a semiconductor package comprising:
an etchback process on a lead frame that comprises:
forming a stack including a prepreg material, a conductive layer, and a solder mask on a lead frame;
exposing a top surface of the prepreg material; and
creating pre-cut plating lines;
mounting a chip on the lead frame;
making electrical connections from the chip to leads on the lead frame; and
cutting through the pre-cut plating lines, wherein an edge of the semiconductor package after cutting, includes a portion of the prepreg material exposed in a slot between an edge of the lead and the edge of the semiconductor package.
2. The method of claim 1 , wherein the etchback process further comprises:
patterning a masking layer on the stack; and
forming a mask opening on the masking layer.
3. The method of claim 1 , wherein creating pre-cut plating lines comprises etching back the solder mask and the conductive layer within the formed mask opening.
4. The method of claim 2 , wherein exposing a top surface of the prepreg material comprises dissolving the masking layer.
5. The method of claim 1 , wherein the conductive layer includes a copper layer that is laminated on an insulating material.
6. The method of claim 1 , wherein each of the pre-fabricated pre-cut plating lines includes a “U” shaped opening slot.
7. The method of claim 6 , wherein the opening slot includes a width wider than a width of a saw blade that is used for cutting.
8. The method of claim 5 , wherein the conductive layer includes plating lines that extend bonding wires of the electrical connection from the chip.
9. The method of claim 1 , wherein each of the pre-fabricated pre-cut plating lines includes the conductive layer etched completely until the top surface of the prepreg material.
10. A method of forming a semiconductor package comprising:
an etchback process on a lead frame that comprises:
forming a stack of prepreg material, a conductive layer, and a solder mask;
patterning a masking layer on the stack;
forming a mask opening on the masking layer;
etching back the solder mask and the conductive layer within the formed mask opening to expose a top surface of the prepreg material; and
dissolving the masking layer, thereby creating pre-cut plating lines;
mounting a chip on the lead frame;
making electrical connections from the chip to leads on the lead frame; and
cutting through the etched back pre-fabricated pre-cut plating lines.
11. The method of claim 10 , wherein the conductive layer includes a copper layer that is laminated on an insulating material.
12. The method of claim 10 , wherein each of the pre-fabricated pre-cut plating lines includes a “U” shaped opening slot.
13. The method of claim 12 , wherein the opening slot includes a width wider than a width of a saw blade that is used for cutting.
14. The method of claim 10 , wherein each of the pre-fabricated pre-cut plating lines includes a length that traverses the conductive layer on the lead frame.
15. The method of claim 14 , wherein the conductive layer includes plating lines that extend bonding wires of the electrical connection from the chip.
16. The method of claim 10 , wherein each of the pre-fabricated pre-cut plating lines includes the conductive layer etched completely until the top surface of the prepreg material.
17. The method of claim 10 , wherein each of the pre-fabricated pre-cut plating lines includes a longitudinal opening slot that includes trench sidewalls and a surface of a prepreg material.