Method for Filling Holes in Glass Through-Hole Substrate

Abstract

The present invention provides a method for filling holes in a glass via substrate. Metal balls are used to fill a plurality of through holes in the glass via substrate, and then a heating process is carried out to melt the plurality of metal balls to generate liquid metal. Finally, the liquid metal is cooled to form solid metal in the plurality of through holes. Since no solvent or flux is used, the solid metal in the plurality of through holes has better electrical conductivity.

Description

Technical Field

[0001] The present invention relates to a through-glass via (TGV) substrate, and more particularly to a method for filling vias in a through-glass via substrate. Background Art

[0002] In recent years, three-dimensional (3D) packaging has been widely developed. In 3D packaging, a through-glass via substrate is often used as an interposer to electrically connect a chip above the through-glass via substrate to a chip below the through-glass via substrate. The interposer is also referred to as an insertion layer or an intermediate layer. The upper chip and the lower chip are electrically connected to each other through solid metals in a plurality of vias of the through-glass via substrate. Currently, the method for filling vias in a through-glass via substrate includes filling metal paste into a plurality of vias of the through-glass via substrate by printing, and then curing the metal paste by a sintering process to form solid metals in the plurality of vias. In order to facilitate the filling of the metal paste during printing in the traditional via filling method, a solvent or a soldering agent must be added to the metal paste to keep the metal paste fluid. However, it is not easy for the added solvent or soldering agent to volatilize, so holes may appear inside the solid metals formed by the sintering process, resulting in poor electrical conductivity. Summary of the Invention

[0003] The present invention relates to a method for filling vias in a through-glass via substrate.

[0004] According to the present invention, a method for filling vias in a through-glass via substrate includes the following steps:

[0005] A. Coating a release agent on the upper surface of a jig;

[0006] B. Placing the through-glass via substrate on the upper surface of the jig, wherein the through-glass via substrate has a plurality of vias;

[0007] C. Filling a plurality of metal balls into the plurality of vias;

[0008] D. Melting the plurality of metal balls to form liquid metal;

[0009] E. Cooling the liquid metal in the plurality of vias to produce solid metal;

[0010] F. Repeating steps C to E until the solid metal fills the plurality of vias; and

[0011] G. Cleaning the surface of the through-glass via substrate and removing the through-glass via substrate from the jig.

[0012] Preferably, step D includes melting the plurality of metal balls by a reflow process.

[0013] Preferably, the reflow process includes:

[0014] In the first heating stage, the temperature of the glass via substrate is increased from a first temperature to a second temperature at a rate of 1 - 2 degrees per second; and

[0015] In the second heating stage, the temperature of the glass via substrate is increased from the second temperature to a third temperature at a rate of 1 - 2 degrees per second.

[0016] Preferably, the reflow process further includes an isothermal stage between the first heating stage and the second heating stage, wherein during the isothermal stage, the temperature of the glass via substrate is maintained at the second temperature.

[0017] Preferably, the first temperature is 25 degrees, the second temperature is 180 degrees, and the third temperature is 230 degrees.

[0018] Preferably, step D includes melting a plurality of the metal balls by a laser heating process.

[0019] Preferably, the laser heating process includes sequentially irradiating a plurality of regions of the glass via substrate with a laser beam having a power of 6 - 8 watts to melt a plurality of the metal balls, wherein the irradiation time for each region is 5 - 9 seconds.

[0020] Preferably, the volume of each via is an integer multiple of the volume of each metal ball.

[0021] Preferably, the height and diameter of each via are 200 μm and 125 μm respectively, and the diameter of each metal ball is 105 μm.

[0022] Compared with the prior art method of filling holes with metal paste, the present invention does not require a solvent or a soldering aid, so there will be no holes inside the solid metal in the plurality of vias, and it has better electrical conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0024] Figure 1 An upper view showing the glass via substrate without filled holes;

[0025] Figure 2 An upper view and a cross-sectional view showing the jig;

[0026] Figure 3 An embodiment showing a glass via substrate placed on a jig;

[0027] Figure 4 An embodiment showing metal balls poured onto a glass via substrate;

[0028] Figure 5 An upper view and a sectional view showing the metal balls filled into the vias of the glass via substrate.

[0029] Figure 6 Showing the solid metal formed after melting and cooling the metal balls.

[0030] Figure 7 An embodiment showing the vias filled with solid metal.

[0031] Figure 8 An upper view and a sectional view showing the glass via substrate with the via filling completed.

[0032] Figure 9 Showing the method for filling vias in the glass via substrate of the present invention.

[0033] In the figure: 10 - glass via substrate, 12 - via, 20 - jig, 22 - release agent, 30 - metal ball, 32 - solid metal, H - height, R1 - radius, R2 - radius. Detailed Description of the Invention

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Figures 1 to 8 To illustrate the method for filling vias in the glass via substrate of the present invention. First, as Figure 1 shown, a glass via substrate 10 is obtained, and the glass via substrate 10 has a plurality of vias 12 communicating the upper surface and the lower surface of the glass via substrate 10. Next, as Figure 2 shown, a high-temperature resistant release agent 22 is coated on the upper surface of a jig 20, wherein the function of the release agent 22 is to make it easier to remove the glass via substrate 10 from the jig 20 after the via filling process is completed. In Figure 2 , the upper diagram is the upper view of the jig 20, and the lower diagram is the sectional view of the jig 20. After coating the release agent 22, the glass via substrate 10 is placed on the upper surface of the jig 20, as Figure 3 shown.

[0036] After placing the glass through-hole substrate 10 on the jig 20, a plurality of metal balls 30 are filled into a plurality of through-holes 12 of the glass through-hole substrate 10, as Figure 4 and Figure 5 shown. First, a plurality of metal balls 30 are poured onto the glass through-hole substrate 10, as Figure 4 shown, and then the jig 20 is gently vibrated or shaken to make the metal balls 30 roll and fall into the through-holes 12, as Figure 5 shown. In Figure 5 , the upper side is a top view of the glass through-hole substrate 10 and the jig 20, and the lower side is a cross-sectional view in the AA' direction of the top view on the upper side. There are many ways to fill the metal balls 30 into the through-holes 12, Figure 4 and Figure 5 shown is just one of them. In Figure 4 and Figure 5 embodiment, the height and radius of each through-hole 12 of the glass through-hole substrate 10 are H and R1 respectively, and the radius of each metal ball is R2, where the height H of the through-hole 12 is the thickness of the glass through-hole substrate 10, and the radius R1 of the through-hole 12 is greater than or equal to the radius R2 of the metal ball. The volume of each through-hole 12 is H×π×R12, and the volume of each metal ball 30 is (4 / 3)×π×R23, where π is the pi. In the present invention, the remainder obtained by dividing the volume of the through-hole 12 by the volume of the metal ball 30 is preferably as close to 0 as possible. In other words, in the best case, the volume of the through-hole 12 is an integer multiple of the volume of the metal ball 30. Therefore, when the height H and radius R1 of the through-hole 12 are known, metal balls with an appropriate radius R2 can be designed. In one embodiment, the height H and diameter D1 = 2×R1 of the through-hole 12 are 200 μm and 125 μm respectively, and the diameter D2 = 2×R2 of the metal ball 30 is 105 μm.

[0037] After filling a plurality of metal balls 30 into a plurality of through-holes 12 of the glass through-hole substrate 10, a heating process is performed on the plurality of metal balls 30 in the through-holes 12 to melt the plurality of metal balls 30 to form liquid metal. After all the plurality of metal balls 30 are completely liquefied, a cooling process is performed to cool the liquid metal in the plurality of through-holes 12 to produce solid metal 32, as Figure 6 shown.

[0038] In one embodiment, the heating process includes a reflow soldering process. The reflow soldering process includes a first heating stage, an isothermal stage, and a second heating stage. The reflow soldering process can heat the entire glass via substrate 10. In the first heating stage, the temperature of the glass via substrate 10 is increased from a first temperature to a second temperature at a rate of 1 - 2 degrees per second. After heating to the second temperature, the first heating stage ends and the isothermal stage is entered. In the isothermal stage, the temperature of the glass via substrate 10 is maintained at the second temperature. After the isothermal stage ends, the second heating stage is entered. In the second heating stage, the temperature of the glass via substrate 10 is increased from the second temperature to a third temperature at a rate of 1 - 2 degrees per second. After heating to the second temperature, the reflow soldering process ends. In one embodiment, the first temperature can be, but is not limited to, 25 degrees, the second temperature can be, but is not limited to, 180 degrees, and the third temperature can be, but is not limited to, 230 degrees.

[0039] In one embodiment, the heating process includes a laser heating process. The laser heating process uses a laser beam to irradiate a plurality of metal balls 30 to melt the plurality of metal balls 30. Generally, the laser beam can only irradiate a part of the area of the glass via substrate 10 at a time. Therefore, the laser heating process sequentially irradiates the laser beam on a plurality of areas of the glass via substrate 10 to melt the metal balls 30 in all the vias 12. In one embodiment, the laser heating process uses a laser beam with a power of 6 - 8 watts, and the irradiation time for each area of the glass via substrate 10 is about 5 - 9 seconds.

[0040] Compared with the sintering process of the prior art, the reflow soldering process or the laser heating process used in the present invention can reduce the heating time, thereby reducing the possibility of breakage of the glass via substrate 10 during the heating process.

[0041] As Figure 6 shown, in the case where the solid metal 32 in the via 12 of the glass via substrate 10 does not completely fill the via 12, repeat the Figures 4 to 6 steps until all the vias 12 of the glass via substrate 10 are filled with solid metal, as Figure 7 shown. After all the vias 12 of the glass via substrate 10 are filled with solid metal, first clean the surface of the glass via substrate 10 using, but not limited to, alcohol. After the cleaning is completed, remove the glass via substrate 10 from the fixture 20 to end the via filling process of the glass via substrate 10, as Figure 8 shown. Compared with the prior art method of filling vias with metal paste, the present invention uses solid metal balls to fill the vias 12 and then heats and melts the metal balls. Therefore, the present invention does not require a solvent or a flux, and there will be no holes inside the solid metal 32, having better electrical conductivity.

[0042] From the above description, the method for filling holes in the glass via substrate of the present invention can be understood and can be expressed as Figure 9 shown, including the following steps:

[0043] Step S10: Apply a release agent on the upper surface of a jig.

[0044] Step S11: Place the glass via substrate on the upper surface of the jig.

[0045] Step S12: Fill a plurality of metal balls into a plurality of through holes of the glass via substrate.

[0046] Step S13: Melt the plurality of metal balls to form liquid metal.

[0047] Step S14: Cool the liquid metal in the plurality of through holes to produce solid metal.

[0048] Step S15: Determine whether the plurality of through holes are filled with solid metal. If not, repeat steps S12 to S14. If so, proceed to step S16; and

[0049] Step S16: Clean the surface of the glass via substrate and remove the glass via substrate from the jig.

[0050] The above is only an embodiment of the present invention and does not impose any formal limitations on the present invention. Although the present invention has been disclosed as above by way of examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field can, without departing from the technical solution of the present invention, make some changes or modifications using the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for filling vias in a glass via substrate, characterized in that, Including the following steps: A. Coat a release agent on the upper surface of a jig; B. Place the glass via substrate on the upper surface of the jig, wherein the glass via substrate has a plurality of vias; C. Fill a plurality of metal balls into the plurality of vias; D. Melt the plurality of metal balls to form liquid metal; E. Cool the liquid metal in the plurality of vias to produce solid metal; F. Repeat steps C to E until the solid metal fills the plurality of vias; and G. Clean the surface of the glass via substrate and remove the glass via substrate from the jig.

2. The method for filling vias of a glass via substrate according to claim 1, characterized in that, Step D includes melting the plurality of metal balls by a reflow soldering process.

3. The method for filling holes in the glass through-hole substrate according to claim 2, characterized in that, The reflow soldering process includes: In a first heating stage, increasing the temperature of the glass via substrate from a first temperature to a second temperature at a rate of 1 to 2 degrees per second; and In a second heating stage, increasing the temperature of the glass via substrate from the second temperature to a third temperature at a rate of 1 to 2 degrees per second.

4. The method for filling vias of the glass via substrate according to claim 3, wherein, The reflow soldering process further includes an isothermal stage between the first heating stage and the second heating stage, wherein during the isothermal stage, the temperature of the glass via substrate is maintained at the second temperature.

5. The method for filling holes in the glass through-hole substrate according to claim 3, wherein, The first temperature is 25 degrees, the second temperature is 180 degrees, and the third temperature is 230 degrees.

6. The method for filling holes in the glass through-hole substrate according to claim 1, wherein, Step D includes melting the plurality of metal balls by a laser heating process.

7. The method for filling vias of the glass via substrate according to claim 6, wherein, The laser heating process includes sequentially irradiating a plurality of regions of the glass via substrate with a laser beam having a power of 6 to 8 watts to melt the plurality of metal balls, wherein the irradiation time for each region is 5 to 9 seconds.

8. The method for filling vias of the glass via substrate according to claim 1, wherein, The volume of each via is an integer multiple of the volume of each metal ball.

9. The method for filling vias of the glass via substrate according to claim 1, wherein The height and diameter of each via are 200 μm and 125 μm respectively, and the diameter of each metal ball is 105 μm.

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