Lasing to attach die to lead frame
An example method includes placing a semiconductor die on a bonding surface of metal substrate. The die includes metal pillars extending from a surface of the die aligned with respective bonding locations on the bonding surface of the substrate. The pillars and the substrate can be formed of a common type of metal. The method also includes controlling a laser to emit laser light to heat the substrate at respective bonding locations to bond the metal pillars with the substrate at the respective bonding locations.
1 . A method comprising:
placing a semiconductor die on a bonding surface of metal substrate, the die including metal pillars extending from a surface of the die aligned with respective bonding locations on the bonding surface of the substrate, the metal pillars and the substrate being formed of a common type of metal; and
controlling a laser to emit laser light to heat the substrate at respective bonding locations to bond the metal pillars with the substrate at the respective bonding locations without solder or other interface material.
2 . The method of claim 1 , further comprising: forming localized melt regions in the substrate at the respective bonding locations responsive to the laser.
3 . The method of claim 2 , wherein the placing further comprises applying pressure to urge the metal pillars into engagement with the respective bonding locations where localized metal pools are formed for bonding the metal pillars directly with the substrate at the respective bonding locations.
4 . The method of claim 3 , wherein:
the substrate comprises a lead frame, and
the bond between the lead frame and the metal pillars is without solder or other interface.
5 . The method of claim 2 , wherein controlling the laser comprises controlling laser parameters of the laser light that include at least two of average power, wavelength, peak power, pulse width and spot size.
6 . The method of claim 5 , wherein the common type of metal has an absorption for the wavelength of greater than 50%.
7 . The method of claim 6 , wherein the common type of metal is copper or a copper alloy, and the laser is a blue laser configured to provide the laser light having a wavelength ranging from 400 nm to 500 nm.
8 . The method of claim 2 , wherein the die includes a flip chip interconnect that includes the metal pillars.
9 . The method of claim 2 , wherein the laser includes an array of independently controllable laser diodes arranged along a surface of a bonding tool, the surface of the bonding tool configured to support a second surface of the substrate, which is opposite the bonding surface, during the placing and the controlling.
10 . The method of claim 2 , wherein the laser is emitted onto a second surface of the substrate, which is opposite the bonding surface, at locations aligned with the respective bonding locations.
11 . The method of claim 2 , wherein prior to die placement, the method comprises planarizing a distal end of the respective pillars.
12 . The method of claim 2 , further comprising encapsulating the die in a molding compound to provide a packaged semiconductor device.
13 . A method comprising:
placing a semiconductor die on a bonding surface of metal substrate, the die including metal pillars extending from a surface of the die aligned with respective bonding locations on the bonding surface of the substrate, the metal pillars and the substrate being formed of a common type of metal; and
controlling a laser to emit laser light to heat the substrate at respective bonding locations to form localized melt regions in the substrate at the respective bonding locations to bond the metal pillars with the substrate at the respective bonding locations.
14 . The method of claim 13 , wherein the placing further comprises applying pressure to urge the metal pillars into engagement with the respective bonding locations where localized metal pools are formed for bonding the metal pillars directly with the substrate at the respective bonding locations.
15 . The method of claim 14 , wherein:
the substrate comprises a lead frame, and
the bond between the lead frame and the metal pillars is without solder or other interface.
16 . The method of claim 13 , wherein controlling the laser comprises controlling laser parameters of the laser light that include at least two of average power, wavelength, peak power, pulse width and spot size.
17 . The method of claim 16 , wherein the common type of metal has an absorption for the wavelength of greater than 50%.
18 . The method of claim 17 , wherein the common type of metal is copper or a copper alloy, and the laser is a blue laser configured to provide the laser light having a wavelength ranging from 400 nm to 500 nm.
19 . The method of claim 13 , wherein the die includes a flip chip interconnect that includes the metal pillars.
20 . The method of claim 13 , wherein the laser is emitted onto a second surface of the substrate, which is opposite the bonding surface, at locations aligned with the respective bonding locations.
21 . The method of claim 13 , wherein prior to die placement, the method comprises planarizing a distal end of the respective pillars.
22 . The method of claim 13 , further comprising encapsulating the die in a molding compound to provide a packaged semiconductor device.
23 . A method comprising:
placing a semiconductor die on a bonding surface of metal substrate, the die including metal pillars extending from a surface of the die aligned with respective bonding locations on the bonding surface of the substrate, the metal pillars and the substrate being formed of a common type of metal; and
controlling a laser to emit laser light to heat the substrate at respective bonding locations to bond the metal pillars with the substrate at the respective bonding locations, wherein the laser includes an array of independently controllable laser diodes arranged along a surface of a bonding tool, the surface of the bonding tool configured to support a second surface of the substrate, which is opposite the bonding surface, during the placing and the controlling.
24 . A method comprising:
placing a semiconductor die on a bonding surface of metal substrate, the die including metal pillars extending from a surface of the die aligned with respective bonding locations on the bonding surface of the substrate, the metal pillars and the substrate being formed of a common type of metal; and
heating the substrate at respective bonding locations to bond the metal pillars with the substrate at the respective bonding locations without solder or other interface material.