Via-filling method of through-glass via substrate
A via-filling method of a TGV substrate includes steps: filling a plurality of metal balls into a plurality of vias of the TGV substrate; using a heating process to melt the plurality of metal balls to form a liquid-state metal; and cooling down the liquid-state metal to form a solid-state metal inside the plurality of vias. Because the method needn't use solvents or fluxes, the solid-state metal inside the plurality of vias have better electric conductivity.
1. A via-filling method of a Through-Glass Via (TGV) substrate, comprising:
Step A: coating a release agent on an upper surface of a fixture;
Step B: placing the TGV substrate on the upper surface of the fixture, wherein the TGV substrate has a plurality of vias;
Step C: filling a plurality of metal balls into the plurality of vias;
Step D: melting heating the plurality of metal balls to melt the plurality of metal balls to form a liquid-state metal;
Step E: cooling the liquid-state metal inside the plurality of vias to generate a solid-state metal;
Step F: repeating Steps C-E until the plurality of vias is fully filled by the solid-state metal; and
Step G: cleaning a surface of the TGV substrate, and removing the TGV substrate from the fixture;
wherein in Step D the heating includes a reflow process comprises a first heating stage, a second heating stage to raise a temperature of the TGV substrate and an isothermal stage, arranged between the first heating stage and the second heating stage to maintain the temperature of the TGV substrate.
2. The via-filling method according to claim 1 , wherein the reflow process further comprises:
a first heating stage: raising the temperature of the TGV substrate from a first temperature to a second temperature at a rate of 1 to 2 degrees per second in the first temperature stage; and
a second heating stage: raising the temperature of the TGV substrate from the second temperature to a third temperature at a rate of 1 to 2 degrees per second in the second temperature stage.
3. The via-filling method according to claim 2 , wherein the reflow process further comprises: an isothermal stage, arranged between the first heating stage and the second heating stage, wherein in the isothermal stage, the temperature of the TGV substrate is maintained at the second temperature.
4. The via-filling method according to claim 2 , wherein the first temperature is 25° C., the second temperature is 180° C., and the third temperature is 230° C.
5. The via-filling method according to claim 1 , wherein in Step D the heating further comprises a step: using a laser heating process to melt the plurality of metal balls.
6. The via-filling method according to claim 5 , wherein the laser heating process uses a laser beam with a power of 6-8 W to irradiate a plurality regions of the TGV substrate in sequence to melt the plurality of metal balls, wherein each of the plurality of regions is irradiated by the laser beam for 5-9 seconds.
7. The via-filling method according to claim 1 , wherein a volume of each of the plurality of vias is an integer multiple of a volume of each of the plurality of metal balls.
8. The via-filling method according to claim 1 , wherein a height of each of the plurality of vias and a diameter of each of the plurality of vias are respectively 200 μm and 125 μm, and a diameter of each of the plurality of metal balls is 105 μm.