Method and package for circuit chip packaging
View Patent ↗A method of assembling a bent circuit chip package and a circuit chip package having a bent structure. The circuit chip package includes: a substrate having a first coefficient of thermal expansion (CTE); a circuit chip, having a second CTE, mounted onto the substrate; a metal foil disposed on the circuit chip in thermal contact with the chip; a metal lid having (i) a third CTE that is different from the first CTE and (ii) a bottom edge region, where the metal lid is disposed on the metal foil in thermal contact with the metal foil; and an adhesive layer along the bottom edge of the metal lid, cured at a first temperature, bonding the lid to the substrate, producing an assembly which, at a second temperature, is transformed to a bent circuit chip package.
1. A method of assembling a bent circuit chip package, comprising:
providing a substrate having a first coefficient of thermal expansion (CTE);
mounting onto the substrate a circuit chip having a second CTE;
placing a metal foil on the circuit chip to establish thermal contact therewith;
dispensing an adhesive onto a metal lid having a bottom edge region and a third CTE that is different from the first CTE, wherein the dispensing is along the bottom edge of the metal lid;
placing the metal lid onto the metal foil to establish thermal contact therewith so that the bottom edge region having adhesive thereon is in contact with the substrate forming an assembly;
compressing the assembly at a first temperature and at a pressure and length of time sufficient to cure the adhesive and bond the lid to the substrate; and
changing temperature of the assembly to a second temperature causing the assembly to bend, thereby reducing thermal resistance of the thermal contacts and producing the bent circuit chip package.
2. The method according to claim 1 , wherein reducing the thermal resistance of the thermal contacts reduces the thermal resistance of the circuit chip package.
3. The method according to claim 1 , wherein the first CTE is greater than the third CTE when the first temperature is greater than the second temperature.
4. The method of claim 1 , wherein the first CTE is less than the third CTE when the first temperature is less than the second temperature.
5. The method of claim 1 , further comprising patterning a lid surface that is in thermal contact with the metal foil.
6. The method according to claim 1 , wherein the metal foil has a metal selected from the group consisting of: indium, lead (Pb), gold, silver, bismuth, antimony, tin, thallium, gallium, and an alloy thereof.
7. The method according to claim 6 , wherein the alloy is selected from the group consisting of: indium-tin, indium-silver, and lead-tin (Pb—Sn).
8. The method of claim 1 , further comprising:
coating a circuit chip surface that is in thermal contact with the metal foil with a metal selected from the group consisting of: gold, copper, nickel, chromium, Cr—Cu, Ni—V, titanium, and aluminum.
9. The method of claim 1 , further comprising:
coating a lid surface that is in thermal contact with the metal foil with a metal selected from the group consisting of: gold, nickel, tin, chromium, titanium, and copper.
10. The method according to claim 1 , further comprising:
patterning the metal foil.
11. The method according to claim 1 , wherein the first temperature is the adhesive curing temperature.
12. The method according to claim 1 , wherein the second temperature is room temperature or the operating temperature of the package.