Die bonding method to prevent die warpage

Abstract

A die bonding method is provided that prevents warping of the die 30. The method includes contacting a die bonding device with a glass carrier plate, heating the substrate with a temperature lower than the melting point of the solder balls between the wiring layer and the substrate, and the die bonding device heats the glass carrier plate with a temperature lower than the melting point of the solder balls, making one of the substrate and the glass carrier plate with a first material and the other of the substrate and the glass carrier plate with a second material. The thermal expansion coefficient of the first material is smaller than that of the second material, and the temperature of the first material is higher than that of the second material. Thus, the length L1 of the substrate and the length L2 of the glass carrier plate are maintained equal during the heating. The method further includes heating the solder balls with a light source to a temperature above the melting point of the solder balls, and fixing the wiring layer to the substrate after the liquid solder is hardened. The length of the substrate and the length of the glass carrier plate are maintained equal during the cooling process to room temperature.

Description

[Technical field]

[0001] The present invention relates to a die bonding method, and more particularly to a die bonding method that prevents warping of the die. [Background technology]

[0002] Die bonding is a very important step in the packaging of semiconductor back-end processes. Die bonding by applying heat and pressure is one of the die bonding methods.

[0003] A known die bonding method includes placing a substrate on a heating tray, placing a die on the substrate, and having a plurality of solder balls between the wiring layer of the die and the substrate, and a die bonding machine contacting the glass carrier plate of the die, and the heating tray heats the substrate, and the substrate transfers the heat to the plurality of solder balls. Tell The heating temperature of the heating tray exceeds the melting point of the plurality of solder balls, and the die bonding device pressurizes and heats the glass carrier plate, and the glass carrier plate transfers heat to the plurality of solder balls through the wiring layer. Tell The heating temperature of the die bonding device exceeds the melting point of the plurality of solder balls, the plurality of solder balls melt into the liquid solder and penetrate onto the substrate, and after the liquid solder hardens, the wiring layer is completely fixed to the substrate.

[0004] However, since the thermal expansion coefficients of the substrate and the glass carrier plate are different, and the heating temperature of the heating tray and the heating temperature of the die bonding device both exceed the melting points of the multiple solder balls, under the same temperature change conditions, the substrate and the glass carrier plate with a larger thermal expansion coefficient will be longer in length, and the substrate and the glass carrier plate with a smaller thermal expansion coefficient will be shorter in length. As the temperature increases or decreases, the difference in the change in length between the substrate and the glass carrier plate will become more significant, and eventually the die will warp. Summary of the Invention [Problem to be solved by the invention]

[0005] The main objective of the present invention is to provide a die bonding method to prevent die warpage, which achieves the purpose of preventing die warpage by controlling the temperature of the substrate and the glass carrier plate according to the difference in thermal expansion coefficient. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a die bonding method for preventing die warpage, which includes the following steps:

[0007] A substrate is placed on a heating tray, a die is placed on the substrate, there are a number of solder balls between the wiring layer of the die and the substrate, a die bonding device contacts the glass carrier plate of the die, both the die bonding device and the glass carrier plate are light transmissive, and the length of the substrate and the length of the glass carrier plate are equal at room temperature.

[0008] The heating tray heats the substrate, and the substrate transfers the heat to the plurality of solder balls. Tell and the heating temperature of the heating tray is lower than the melting point of the plurality of solder balls; the die bonding device pressurizes and heats the glass carrier plate, and the glass carrier plate transfers heat to the plurality of solder balls through the wiring layer. Tell and the heating temperature of the die bonding apparatus is lower than the melting point of the plurality of solder balls; and one of the substrate and the glass carrier plate is made of a first material, and the other of the substrate and the glass carrier plate is made of a second material, and the thermal expansion coefficient of the first material is smaller than the thermal expansion coefficient of the second material, and the temperature of the first material is higher than the temperature of the second material, so that the length of the substrate and the length of the glass carrier plate are maintained equal during heating.

[0009] The light projected from the light source passes through the die bonding device and the glass carrier plate to heat the wiring layer, and the wiring layer transfers the heat to the plurality of solder balls. TellSince the heating temperature of the light source exceeds the melting point of the solder balls, the solder balls melt into liquid solder and permeate onto the substrate.

[0010] By stopping the heating of the wiring layer by the projection of light from the light source, After the liquid solder hardens, the wiring layer is completely fixed to the substrate; and By controlling the temperature of the substrate and the glass carrier plate according to the difference in thermal expansion coefficient, During the process of lowering the temperature to room temperature, the length of the substrate and the length of the glass carrier plate are maintained equal.

[0011] In some embodiments, the light source includes a quartz lamp, and infrared light projected from the quartz lamp passes through the die bonding device and the glass carrier plate to heat the wiring layer.

[0012] In some embodiments, the light source further includes a reflective cover, and the quartz lamp is disposed within the reflective cover to project infrared light into an opening in the reflective cover.

[0013] In some embodiments, the light source further includes a convex lens, the convex lens being disposed between the quartz lamp and the die bonding device, the quartz lamp projecting infrared light onto the convex lens, and the convex lens converging the infrared light.

[0014] In some embodiments, the light source further includes a laser module, and a laser beam projected from the laser module passes through the die bonding device and the glass carrier plate to heat the wiring layer.

[0015] In some embodiments, the heating temperature of the die bonding apparatus is between 140°C and 270°C, and the heating temperature of the heating tray is between 140°C and 270°C.

[0016] In some embodiments, the size of the die bonding apparatus is larger than the size of the die. Effect of the Invention

[0017] According to the present invention, in the process of preheating the solder balls, by controlling the temperatures of the first material and the second material according to the difference in thermal expansion coefficients, the length of the substrate and the length of the glass carrier plate can always be maintained equal under different temperature change conditions, regardless of whether the temperature is rising or falling, and the warping of the die and residual internal stress can be avoided. [Brief description of the drawings]

[0018] [Figure 1] 2 is a flowchart of a die bonding method for preventing die warpage according to the present invention. [Diagram 2] 2 is a schematic diagram of step S10 of the die bonding method for preventing die warpage according to the present invention. FIG. [Diagram 3] 2 is a schematic diagram of step S20 of the die bonding method for preventing die warpage according to the present invention. FIG. [Figure 4] 1 is a schematic diagram of step S30 of a first embodiment of a die bonding method for preventing die warpage according to the present invention. FIG. [Diagram 5] 1 is a schematic diagram of step S40 of the die bonding method for preventing die warpage according to the present invention. FIG. [Figure 6] 4 is a graph showing the thermal expansion coefficients of a first material and a second material in the die bonding method for preventing die warpage according to the present invention. [Figure 7] 11 is a schematic diagram of step S30 of a second embodiment of a die bonding method for preventing die warpage according to the present invention. FIG. [Figure 8] 11 is a schematic diagram of step S30 of a third embodiment of a die bonding method for preventing die warpage according to the present invention. FIG. [Figure 9] 13 is a schematic diagram of step S30 of a fourth embodiment of a die bonding method for preventing die warpage according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings and reference numerals.

[0020] FIG. 1 is a flow chart of the die bonding method for preventing die warpage according to the present invention. FIG. 2 is a schematic diagram of step S10 of the die bonding method for preventing die warpage according to the present invention. FIG. 3 is a schematic diagram of step S20 of the die bonding method for preventing die warpage according to the present invention. FIG. 4 is a schematic diagram of step S30 of a first embodiment of the die bonding method for preventing die warpage according to the present invention. FIG. 5 is a schematic diagram of step S40 of the die bonding method for preventing die warpage according to the present invention. FIG. 6 is a graph of the thermal expansion coefficients of a first material and a second material of the die bonding method for preventing die warpage according to the present invention. The present invention provides a die bonding method for preventing die warpage, which includes the following steps:

[0021] In step S10, as shown in Figures 1, 2 and 6, a substrate 10 is placed on a heating tray 20, a die 30 is placed on the substrate 10, there are a plurality of solder balls 40 between the wiring layer 31 of the die 30 and the substrate 10, a die bonding device 50 contacts the glass carrier plate 32 of the die 30, both the die bonding device 50 and the glass carrier plate 32 are light transmissive, and the length L1 of the substrate 10 and the length L2 of the glass carrier plate 32 are equal at room temperature.

[0022] In step S20, as shown in FIG. 1 and FIG. 3, the heating tray 20 heats the substrate 10, and the substrate 10 transfers the heat to the plurality of solder balls 40. Tell 1 and 3, the die bonding device 50 pressurizes and heats the glass carrier plate 32, and the glass carrier plate 32 transfers heat to the solder balls 40 through the wiring layer 31. Tell and the heating temperature of the die bonding apparatus 50 is lower than the melting point of the multiple solder balls 40; and, as shown in Figures 1, 3 and 6, one of the substrate 10 and the glass carrier plate 32 is made of a first material, and the other of the substrate 10 and the glass carrier plate 32 is made of a second material, the thermal expansion coefficient of the first material is smaller than the thermal expansion coefficient of the second material, and the temperature T1 of the first material is higher than the temperature T2 of the second material, so that the length L1A of the substrate 10 and the length L2A of the glass carrier plate 32 are maintained equal during heating.

[0023] In step S30, as shown in FIG. 1 and FIG. 4, light projected from a light source 60 passes through a die bonding device 50 and a glass carrier plate 32 to heat the wiring layer 31, and the wiring layer 31 transfers the heat to the plurality of solder balls 40. Tell Furthermore, since the heating temperature of the light source 60 exceeds the melting point of the plurality of solder balls 40 , the plurality of solder balls 40 melt into liquid solder and permeate onto the substrate 10 .

[0024] In step S40, as shown in FIGS. By stopping the heating of the wiring layer 31 by the projection of light from the light source 60, After the liquid solder hardens, the wiring layer 31 is completely fixed to the substrate 10, and By controlling the temperatures of the substrate 10 and the glass carrier plate 32 according to the difference in thermal expansion coefficients, During the process of lowering the temperature to room temperature, the length L1 of the substrate 10 and the length L2 of the glass carrier plate 32 are maintained equal.

[0025] As a result, in the present invention, in the process of preheating the solder balls 40, by controlling the temperatures of the first material and the second material according to the difference in thermal expansion coefficients, the lengths of the substrate 10 and the glass carrier plate 32 can always be maintained equal under different temperature change conditions, regardless of whether the temperature is rising or falling, and warping of the die 30 and residual internal stress can be avoided.

[0026] In the first embodiment, the heating temperature of the die bonding device 50 is between 140°C and 270°C, and the heating temperature of the heating tray 20 is between 140°C and 270°C. More specifically, the melting point of the solder balls 40 varies depending on the amount of the solder balls 40. Since the melting point of the solder balls 40 of the amount used during die bonding is usually above 270°C, the heating temperature of the die bonding device 50 and the heating tray 20 must be below 270°C, thereby preventing the solder balls 40 from melting into liquid solder. If the heating temperature is less than 140°C, the preheating temperature of the solder balls 40 becomes too low, and the heating time of the light source 60 for melting the solder balls 40 into liquid solder becomes longer, thereby reducing the welding efficiency. Therefore, the method according to the present invention can sufficiently ensure the preheating temperature of the solder balls 40 by controlling the heating temperature between 140°C and 270°C, and improve the welding efficiency without melting the solder balls 40 into liquid solder.

[0027] In the first embodiment, the size of the die bonding apparatus 50 is larger than the size of the die 30. Therefore, the die bonding apparatus 50 can apply pressure and heat to the die 30 with uniform pressure and temperature, and warping of the die 30 is prevented.

[0028] Preferably, in step S30, a light source 60 The die bonding apparatus further includes a quartz lamp 61 , and infrared rays projected from the quartz lamp 61 pass through the die bonding apparatus 50 and the glass carrier plate 32 to heat the wiring layer 31 .

[0029] 7 is a schematic diagram of step S30 of the second embodiment of the die bonding method for preventing die warpage according to the present invention. As shown in FIG. 7, the difference between the second embodiment and the first embodiment is that in step S30, the light source 60A further includes a reflective cover 62, and a quartz lamp 61 is installed in the reflective cover 62 to project infrared rays into the opening of the reflective cover 62.

[0030] 8 is a schematic diagram of step S30 of the third embodiment of the die bonding method for preventing die warpage according to the present invention. As shown in FIG. 8, the difference between the third embodiment and the first embodiment is that in step S30, the light source 60B further includes a convex lens 63, which is disposed between the quartz lamp 61 and the die bonding device 50, and the quartz lamp 61 projects infrared rays onto the convex lens 63, which then converges the infrared rays.

[0031] 9 is a schematic diagram of step S30 of the fourth embodiment of the die bonding method for preventing warpage of a die according to the present invention. As shown in FIG. 9, the difference between the fourth embodiment and the first embodiment is that in step S30, the light source 60C is a laser module 64, and the laser beam projected from the laser module 64 passes through the die bonding device 50 and the glass carrier plate 32 to heat the wiring layer 31.

[0032] The above-mentioned are merely preferred embodiments for explaining the present invention, and are not intended to limit the present invention. Therefore, any modifications or alterations made to the present invention without departing from the spirit of the present invention are not intended to be construed as limiting the present invention. too All of these are within the scope of protection of the present invention. [Explanation of symbols]

[0033] 10 Substrate 20 Heating Tray 30 Die 31 Wiring layer 32 Glass carrier plate 40 solder balls 50 Die bonding equipment 60, 60A, 60B, 60C light source 61 Quartz Lamp 62 Reflective cover 63 Convex Lens 64 Laser Module L1, L1A, L2, L2A Length S10~S40 process T1, T2 temperature

Claims

1. A die bonding method for preventing die warpage, comprising the steps of: A substrate is placed on a heating tray, a die is placed on the substrate, and there are a number of solder balls between the wiring layer of the die and the substrate, a die bonding device contacts the glass carrier plate of the die, the die bonding device and the glass carrier plate are both light-transmitting, and the length of the substrate and the length of the glass carrier plate are equal at room temperature; the heating tray heats the substrate, the substrate transfers its heat to the solder balls, and the heating temperature of the heating tray is lower than the melting point of the solder balls; the die bonding device pressurizes and heats the glass carrier plate, the glass carrier plate transfers heat to the solder balls through the wiring layer, and the heating temperature of the die bonding device is lower than the melting point of the solder balls; and one of the substrate and the glass carrier plate is made of a first material, and the other of the substrate and the glass carrier plate is made of a second material, and the thermal expansion coefficient of the first material is smaller than the thermal expansion coefficient of the second material, and the temperature of the first material is higher than the temperature of the second material, so that the length of the substrate and the length of the glass carrier plate are maintained equal during heating. light projected from a light source passes through the die bonding device and the glass carrier plate to heat the wiring layer, the wiring layer transfers the heat to the plurality of solder balls, and the heating temperature of the light source exceeds the melting point of the plurality of solder balls, so that the plurality of solder balls melt into liquid solder and permeate onto the substrate; After the liquid solder is cured by stopping the heating of the wiring layer by the projection of light from the light source, the wiring layer is completely fixed to the substrate, and the lengths of the substrate and the glass carrier plate are maintained equal during the process of lowering the temperature to room temperature by controlling the temperatures of the substrate and the glass carrier plate according to the difference in thermal expansion coefficient. A die bonding method for preventing warpage of a die, comprising:

2. the light source includes a quartz lamp; 2. The die bonding method for preventing warpage of a die according to claim 1, wherein infrared rays projected from said quartz lamp pass through said die bonding device and said glass carrier plate to heat said wiring layer.

3. The light source further includes a reflective cover; 3. The die bonding method for preventing warpage of a die according to claim 2, wherein the quartz lamp is installed inside the reflective cover to project infrared rays to the opening of the reflective cover.

4. the light source further comprises a convex lens; the convex lens is disposed between the quartz lamp and the die bonding device; 3. The die bonding method for preventing die warpage according to claim 2, wherein the quartz lamp projects infrared rays onto the convex lens, and the convex lens converges the infrared rays.

5. The light source further includes a laser module; 2. The die bonding method for preventing warpage of a die according to claim 1, wherein the laser beam projected from the laser module passes through the die bonding device and the glass carrier plate to heat the wiring layer.

6. The heating temperature of the die bonding device is between 140° C. and 270° C.

2. The die bonding method for preventing warpage of a die according to claim 1, wherein the heating temperature of the heating tray is between 140° C. and 270° C.

7. 2. The die bonding method for preventing warpage of a die according to claim 1, wherein the size of the die bonding apparatus is larger than the size of the die.

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