JPH1187405A - Manufacture of external terminal of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of a quality external terminal of a semiconductor device. SOLUTION: In a ball bonding process, a ball 2 is bonded to the terminal face 1 of the package of a semiconductor device. In a plating process, a wet plating is applied onto the ball 2 to form a plating layer 3. Also, as a final plating, plating is applied using, for example, Sn/Pb alloy or Sn to form a plating layer 4. In a reflow process, a heat at the melting temperature or higher of the material of the plating layer 4 is applied for reflowing. Then, the plating layer 4 is shaped in a ball by its own surface tension to form a plating layer 5 for covering the entire surface of the ball 2 and the terminal face 1 around the ball 2. Thus, an external terminal is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing external terminals of a semiconductor device formed in a ball shape, such as a ball grid array (BGA).

[0002]

2. Description of the Related Art Conventionally, external terminals of a semiconductor device are in the form of leads or pins, but with the trend of increasing the number of pins in recent years, ball terminals such as BGA have come out.
As a method of manufacturing a ball-shaped external terminal such as a BGA, there is a method of pressing a ball-shaped Sn / Pb alloy or Sn on a terminal surface of a semiconductor device, or a method of printing using a metal mask.

[0003]

However, in the conventional method of manufacturing a ball-shaped external terminal, in the step of forming the ball-shaped terminal on the terminal surface of the semiconductor device, the yield is reduced due to the ball-shaped terminal falling off. In addition to the variation in the flatness (coplanarity) of each ball-shaped terminal,
There was a problem such as high cost. Also, it has been difficult to manufacture external terminals having a very narrow pitch between terminals.

[0004]

According to a first aspect of the present invention, there is provided a method of manufacturing an external terminal of a semiconductor device, comprising the steps of: providing a predetermined conductive material on a terminal surface of a package of the semiconductor device; A ball bonding step of bonding a ball of a desired size, a plating step of performing a plating process for forming a plating layer of a desired thickness on the ball using a predetermined material for a predetermined time, and a material of the plating layer. And a reflow process of manufacturing an external terminal by applying heat equal to or higher than the melting temperature of the above. According to the first aspect, in the ball bonding step, a ball having a desired size is bonded to the terminal surface of the package. In the plating step, the plating time is appropriately set, and a plating layer having a desired thickness is formed on the ball. In the reflow step, reflow is performed by heating at a temperature higher than the melting temperature of the material of the plating layer, and the external terminal is completed.

According to a second aspect of the present invention, a ball bonding step of bonding a ball of a predetermined size to a predetermined conductive material to a terminal surface of a package of a semiconductor device, and applying a flux to the entire surface of the terminal surface to which the ball is bonded. Flux coating step, a coating step of immersing the terminal surface in a metal of a predetermined material melted at a predetermined temperature for a predetermined time to form a coating layer, and applying heat above the melting temperature of the material of the coating layer. And a reflow step of manufacturing external terminals by performing reflow. According to the second aspect, in the ball bonding step, a ball having a desired size is bonded to the terminal surface of the package. In the flux applying step, a flux is applied to the entire surface of the terminal to which the ball is bonded. In the coating process, the terminal surface is coated with a metal of a predetermined material to form a coating layer. At this time, by adjusting the temperature of the molten metal, the immersion time, and the pulling speed,
The coating amount is adjusted. In the reflow process,
Reflow is performed on the coating layer to complete an external terminal.

According to a third aspect of the present invention, a ball bonding step of bonding a ball of a predetermined size to a predetermined conductive material to a terminal surface of a package of a semiconductor device, and applying a flux to the entire surface of the terminal surface to which the ball is bonded. Flux coating step, a potting step of forming a metal lump by potting a metal of a predetermined material melted at a predetermined temperature to a tip portion of the ball by a desired amount, and applying a heat equal to or higher than the melting temperature of the material of the metal lump. And a reflow process of forming a metal crown and manufacturing an external terminal. According to the third aspect, in the ball bonding step, a ball having a desired size is bonded to the terminal surface of the package. In the flux applying step, a flux is applied to the entire surface of the terminal to which the ball is bonded. In the potting step, a metal of a predetermined material is potted on the tip of the ball to form a metal lump one by one. In the reflow step, the metal block is reflowed to form a metal crown and complete the external terminal.

According to a fourth aspect of the present invention, the external terminal manufactured by the manufacturing method of the first, second, or third aspect is provided with a second plating layer of the first aspect and a second plating layer of the second aspect. A shaping step of setting the height of the external terminal to a desired value by applying pressure using shaping means set at a temperature lower than and close to the melting point of the coating layer or the metal crown of the third invention. I'm trying to do it. According to the fourth aspect, in the shaping step, the shaping means is set to a temperature lower than and near the melting point of the second plating layer, the second coating layer, or the metal crown. Therefore, when the second plating layer, the second coating layer, or the metal crown is pressed by using the shaping means, these are softened, and the external terminal having a desired height is completed at one time. Therefore, the above problem can be solved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIGS. 1A to 1D are process diagrams showing a method for manufacturing an external terminal of a semiconductor device according to a first embodiment of the present invention.
The steps (1) to (4) of manufacturing the external terminal will be described with reference to FIGS. (1) Ball bonding step of FIG. 1A A ball 2 of a desired size is bonded to a terminal surface 1 of a package of a semiconductor device. The material of the terminal surface 1 is generally Cu, and the material of the ball 2 is, for example, Au. The diameter of the ball 2 is about 50 to 150 μm, and an optimum diameter is selected from information such as a ball terminal interval. Further, the height of the ball 2 is set to be about 70 to 80% of a target value of a height of an external terminal to be finally formed. (2) Plating Step of FIGS. 1B and 1C A wet plating is performed on the ball 2 to form a plating layer 3. Since the plating layer 3 needs to consider compatibility with the material of the ball 2 as the base plating and needs a certain degree of hardness, a material such as Ni is used. However, ball 2
When the material is Sn, Sn / Pb alloy or the like, the base plating may not be performed in some cases. Then, as the final plating,
For example, the plating layer 4 is formed by performing a plating process with a reliable bonding to another substrate using an Sn / Pb alloy or Sn. In this case, the plating time is set appropriately, and the thickness of the plating layer 4 is set to about 50 to 100 μm.

(3) Reflow Step in FIG. 1D Reflow is performed by applying heat equal to or higher than the melting temperature of the material of the plating layer 4. The plating layer 4 is formed into a ball shape by its own surface tension, and becomes a plating layer 5 covering the entire surface of the ball 2 and the terminal surface 1 around the ball 2 to complete the external terminal. As described above, in the first embodiment, the type and thickness of the deposited metal of the base plating in the plating step are appropriately set, so that the hardness of the external terminal can be freely adjusted. Further, since the plating time is appropriately set and the thickness of the plating layer 4 is adjusted, the height of the external terminals can be freely adjusted, and the terminal interval is 500 μm.
Very narrow pitch external terminals can be manufactured.
In addition, since the plating layer 5 covers the entire surface of the ball 2 and the terminal surface 1 around the ball 2, falling off of the external terminal is reduced as compared with the related art, and the yield is improved.

Second Embodiment FIGS. 2A to 2D are process diagrams showing a method of manufacturing an external terminal of a semiconductor device according to a second embodiment of the present invention.
Elements common to those in FIG. 1 showing the first embodiment are denoted by common reference numerals. The manufacturing steps (1) to (4) of the external terminal will be described with reference to FIGS. 2 (a) to 2 (d). (1) Ball bonding step of FIG. 2A This is the same as in the first embodiment. (2) Flux application step of FIG. 2B A flux 6 is applied to the entire surface of the terminal surface 1 to which the ball 2 has been bonded. The method of applying the flux 6 includes a method of immersing the flux 6 with the bonding surface facing down, a method of applying the flux 6 using a brush, or the like.

(3) Coating Step of FIG. 2 (c) The terminal surface 1 with the ball 2 bonded to a molten Sn / Pb alloy, Sn or other metal is immersed, and the first coating layer 7 is coated. In this immersion, the coating amount is adjusted by adjusting the temperature of the molten metal, the immersion time, and the pulling speed. Thereby, the height of the external terminal finally formed is adjusted. (4) Reflow Step in FIG. 2D Heat is applied at a temperature higher than the melting temperature of the material of the coating layer 7 to perform reflow. The coating layer 7 is shaped into a ball by its own surface tension, and becomes the second coating layer 8 covering the entire surface of the ball 2 and the terminal surface 1 around the ball 2 to complete the external terminal.

As described above, in the second embodiment,
In the coating process, the coating surface 7 is coated at a time by immersing the terminal surface 1 to which the ball 2 has been bonded in the molten metal, so that a very short processing time is possible. Furthermore, in the coating process, the coating amount is adjusted by adjusting the temperature of the molten metal, the immersion time, and the pulling speed, so that the height of the external terminals can be freely adjusted, and the terminal interval is about 500 μm. It is possible to manufacture external terminals with a very narrow pitch up to. In addition, since the coating layer 8 covers the entire surface of the ball 2 and the terminal surface 1 around the ball 2, falling off of the external terminal is reduced as compared with the related art, and the yield is improved.

Third Embodiment FIGS. 3A to 3D are process diagrams showing a method of manufacturing an external terminal of a semiconductor device according to a third embodiment of the present invention.
Elements common to those in FIG. 2 showing the second embodiment are denoted by the same reference numerals. The manufacturing steps (1) to (4) of the external terminal will be described with reference to FIGS. (1) Ball bonding step of FIG. 3A This is the same as in the first embodiment. (2) Flux application step of FIG. 3B This is the same as the second embodiment. (3) Potting step of FIG. 3 (c) The molten Sn / Pb alloy, Sn and other metals are potted at an appropriate amount to the tip of the ball 2 using, for example, a syringe or the like to form a metal lump 9 one by one. The amount of potting is adjusted by the syringe temperature, pressure, and dispense time. (4) Reflow Step in FIG. 3D Reflow is performed by applying heat equal to or higher than the melting temperature of the material of the metal lump 9. The metal lump 9 is shaped into a ball shape by its own surface tension to become a metal crown 10 covering the tip of the ball 2, and the external terminal is completed. As described above, in the third embodiment, since each external terminal is formed one by one, the height of each terminal can be freely changed. Therefore, even if the package of the semiconductor device is warped or the like, it is possible to prevent variations in terminal height.

Fourth Embodiment FIGS. 4 (a) to (i) and FIGS. 5 (a) to (c) show steps of a method of manufacturing an external terminal of a semiconductor device according to a fourth embodiment of the present invention. FIG. 4 (a) to 4 (i) and FIGS. 5 (a) to 5 (c), the flatness (coplanarity) of the external terminals manufactured in the first to third embodiments is adjusted to obtain a desired value. Manufacturing process (1) to manufacture terminals of height
(4) will be described. (1) In order to adjust the flatness (coplanarity) of the height of the external terminal manufactured in the first embodiment shown in FIG. 4A, in the shaping step shown in FIG. ) Press P against the external terminal, and adjust the height of the external terminal to a desired value. At this time, plate P
Is to keep the temperature lower than and close to the melting point of the plating layer 5 to soften the plating layer 5. Thereafter, as shown in FIG. 4C, an external terminal whose height is set to a target value is completed. (2) In order to adjust the flatness (coplanarity) of the height of the external terminal manufactured in the second embodiment shown in FIG. 4D, the plate P is removed from the external terminal in the shaping step shown in FIG. To adjust the height of the external terminal to a desired value. At this time, the plate P is kept at a temperature lower than and near the melting point of the coating layer 8 to soften the coating layer 8. Then, FIG.
As shown in (2), an external terminal whose height is set to the target value is completed.

(3) Flatness (coplanarity) of the height of the external terminal manufactured in the third embodiment shown in FIG.
In the shaping step shown in FIG. 4H, the plate P is pressed against the external terminal to adjust the height of the external terminal. At this time, the plate P is kept at a temperature lower than and near the melting point of the metal crown 10 so as to soften the metal crown 10. Thereafter, as shown in FIG. 4 (i), the external terminal whose height is set to the target value is completed. (4) As shown in FIG. 5A, for example, when the height of each plating layer 5 of each external terminal manufactured in the first embodiment varies, as shown in FIG. P is pressed against each of the external terminals, and the height of each of the external terminals is adjusted to a desired value. At this time, the plate P is kept at a temperature lower than and near the melting point of the plating layer 5 so as to soften the plating layer 5. Thereafter, as shown in FIG. 5 (c), each external terminal whose height is set to the target value is completed. Thereby, the variation in the flatness (coplanarity) of each external terminal is suppressed to, for example, 5 μm or less.

As described above, in the fourth embodiment,
The plate P is kept at a temperature lower than and near the melting point of the plating layers 5, 8 and the metal crown 10, and the plating layers 5, 8 or the metal crown 10 are softened and pressed against the external terminals. External terminals set to the desired value can be manufactured at one time. Furthermore, the variation in flatness (coplanarity) of the external terminals manufactured in the first to third embodiments is reduced by, for example, 5%.
μm or less. Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications. (A) The material of the ball 2 is Al, Cu, S in addition to Au.
n, Sn / Pb alloy or the like may be used. (B) FIG. 5 illustrates an example in which the variation in the flatness of each external terminal manufactured in the first embodiment is adjusted.
Also, for each external terminal manufactured in the third embodiment,
Similarly, variation in flatness can be adjusted.

[0017]

As described above in detail, according to the first aspect, the plating time in the plating step is appropriately set and the thickness of the plating layer is adjusted.
The height of the external terminals can be freely adjusted, and external terminals having a very narrow pitch between terminals can be manufactured. In addition, since the plating layer covers the entire surface of the ball and the terminal surface around the ball, falling off of the external terminal is reduced as compared with the related art, and the yield can be improved. According to the second aspect, in the coating step, the coating surface is coated at once by immersing the terminal surface to which the ball is bonded in the molten metal, so that the processing can be performed in a very short time. Further, in this coating process, the amount of coating is adjusted by adjusting the temperature of the molten metal, the immersion time, and the pulling speed, so that the height of the external terminals can be freely adjusted, and the terminal spacing can be extremely small. An external terminal with a narrow pitch can be manufactured. In addition, since the coating layer covers the entire surface of the ball and the terminal surface 1 around the ball, falling off of the external terminal is reduced as compared with the related art, and the yield can be improved.

According to the third aspect, since each external terminal is formed one by one, the height of each terminal can be freely changed. Therefore, even if the package of the semiconductor device is warped or the like, it is possible to prevent variations in terminal height. According to the fourth aspect, the shaping means is the first type.
The second plating layer of the invention, the second coating layer of the second invention, or the metal crown of the third invention is kept at a temperature lower than and close to the melting point of the metal crown, the plating layer, the coating layer, or the metal crown. Is softened and pressed against the external terminal, so that the external terminal whose height is set to the target value can be manufactured at one time. Further, the variation in flatness of the external terminals manufactured by the manufacturing method according to the first to third aspects of the present invention can be reduced.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing an external terminal according to a first embodiment of the present invention.

FIG. 2 is a process chart showing a method for manufacturing an external terminal according to a second embodiment of the present invention.

FIG. 3 is a process chart showing a method for manufacturing an external terminal according to a third embodiment of the present invention.

FIG. 4 is a process chart showing a method for manufacturing an external terminal according to a fourth embodiment of the present invention.

FIG. 5 is a process chart showing a method for manufacturing an external terminal according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Terminal surface 2 Ball 4,5 Plating layer 6 Flux 7,8 Coating layer 9 Metal lump 10 Metal crown P plate

Claims (4)

[Claims] A ball bonding step of bonding a ball having a predetermined size to a predetermined conductive material to a terminal surface of a package of a semiconductor device; and forming a plating layer having a predetermined thickness on the ball by using a predetermined material. A semiconductor device comprising: a plating step of performing a plating process for a predetermined time; and a reflow step of producing an external terminal by performing reflow by applying heat at a temperature equal to or higher than the melting temperature of the material of the plating layer. Terminal manufacturing method. 2. A ball bonding step of bonding a ball of a predetermined conductive material and a desired size to a terminal surface of a package of a semiconductor device, and a flux applying step of applying a flux to the entire surface of the terminal surface to which the ball is bonded. A coating step of immersing the terminal surface in a metal of a predetermined material melted at a predetermined temperature for a predetermined time to form a coating layer; and performing reflow by applying heat above the melting temperature of the material of the coating layer. And a reflow step of manufacturing an external terminal by performing the method of manufacturing the external terminal of the semiconductor device. 3. A ball bonding step of bonding a ball of a predetermined conductive material and a desired size to a terminal surface of a package of a semiconductor device; and a flux applying step of applying a flux to the entire surface of the terminal surface to which the ball is bonded. A potting step of potting a metal of a predetermined material melted at a predetermined temperature to a tip of the ball by a desired amount to form a metal lump; reflowing by applying heat equal to or higher than the melting temperature of the metal lump material And forming a metal crown to manufacture an external terminal. 4. The external terminal according to claim 1, 2 or 3, the second plating layer according to claim 1, the second coating layer according to claim 2, or the metal according to claim 3. A shaping step of setting the height of the external terminal to a desired value by applying pressure using shaping means set to a temperature lower than and close to the melting point of the crown. Manufacturing method of external terminals.