TW201838117A - Ball mounting process - Google Patents

Abstract

A ball mounting process including the following steps is provided. A chip package structure is provided, wherein the chip package structure has a plurality of pads at the surface thereof. A protection material is formed on each of the plurality of pads. A thermal evaporative cleaning material is formed on the surface of the chip package structure, such that the protection material is covered by the thermal evaporative cleaning material and reacted with the thermal evaporative cleaning material. A thermal process is performed to remove the thermal evaporative cleaning material and the protection material at the same time. Solder balls are formed respectively on the corresponding one of the pads.

Description

Ball planting process

This invention relates to a wafer packaging process, and more particularly to a planting ball process.

In the current chip packaging process, after the wafer is coated with a molding compound, the formed wafer package structure is subjected to a ball bonding process to bond the solder ball to the chip package structure. Pad) bonding.

Generally, after the wafer is coated with the encapsulant, the formed wafer package structure is not immediately implanted. In order to solve the above problems, a padding material is usually formed on the pad to prevent the pad from contacting the outside, and then the protective material is removed through the cleaning material, because the pad of the chip package structure is oxidized or damaged. And then perform the ball placement process.

In the existing process, the pin of the jig is firstly taken with the cleaning material, and then the pin to which the cleaning material is attached is brought into contact with the pad covering the protective material on the chip package structure, so that the cleaning material is attached to the pad. The cleaning material is reacted with the protective material, and the cleaning material and the protective material are simultaneously removed through the thermal process to facilitate the ball-planting operation. However, the above method often requires a lot of time, and the fixture needs to be cleaned regularly, thereby increasing the process time and production cost. Furthermore, contacting the pins to which the cleaning material is attached with the pads of the wafer package structure requires very precise alignment. Therefore, when the wafer package structure generates a warpage, the problem of alignment misalignment is apt to occur.

The present invention provides a planting ball process that uses a thermally volatile cleaning material to remove the protective material overlying the pads.

The ball placement process of the present invention comprises the steps of: providing a wafer package structure, wherein the surface of the chip package structure has a plurality of pads; forming a protective material on each of the pads; forming a thermal volatile cleaning material in the Surfacely, the thermal volatile cleaning material is covered and reacts with the protective material; heat treatment is performed to simultaneously remove the thermal volatile cleaning material and the protective material; Solder balls are each formed on a corresponding one of the plurality of pads.

In an embodiment of the ball placement process of the present invention, the thermal volatile cleaning material is, for example, an organic flux, and the protective material is, for example, an organic solderability preservative (OSP).

In an embodiment of the ball placement process of the present invention, the method of forming the thermally volatile cleaning material on the surface is, for example, spraying the thermally volatile cleaning material onto the surface using a spray device.

In an embodiment of the ball placement process of the present invention, the heat treatment is, for example, a reflow process or a bake process.

In an embodiment of the ball placement process of the present invention, after the forming of the thermally volatile cleaning material on the surface and prior to performing the heat treatment, the chip package structure is further disposed.

Based on the above, in the present invention, the thermal volatile cleaning material is formed on the surface of the wafer package structure, so that the thermal volatile cleaning material can effectively cover the protective material formed on the pad without the need of the alignment treatment. The problem of alignment misalignment caused by the warpage of the chip package structure in the prior art is avoided. Further, by the above-described manner, the steps of taking the cleaning material by the stitches and the steps of cleaning the stitches in the prior art can be omitted, thereby shortening the processing time and the production cost.

The above described features and advantages of the invention will be apparent from the following description.

1A to 1D are schematic cross-sectional views showing a process of a ball placement process according to an embodiment of the present invention. First, referring to FIG. 1A, a chip package structure 100 is provided. The chip package structure 100 has a wafer (not shown), a wafer carrier substrate (not shown), and a pad 100a electrically connected to the wafer. The pad 100a is used to electrically connect the chip package structure 100 with external components. In addition, in the embodiment, the chip package structure 100 may further have an under bump metal layer (UBM) 100b disposed on each of the pads 100a. Then, a protective material 101 is formed on each of the under bump metal layers 100b. In other embodiments, when the under bump metal layer 100b is absent, the protective material 101 is formed directly on the exposed surface of the pad 100b. The protective material 101 is, for example, an organic solder resist, and the method of forming the same is well known to those skilled in the art and will not be further described herein. The protective material 101 can prevent the under bump metal layer 100b (the pad 100a) from coming into contact with the external environment to cause oxidation or damage.

Then, referring to FIG. 1B, the thermal volatile cleaning material 102 is formed on the surface of the wafer package structure 100 such that the thermal volatile cleaning material 102 covers the protective material 101 formed on the under bump metal layer 100b (pad 100a). And reacting with the protective material 101. In the present embodiment, the thermally volatile cleaning material 102 is, for example, an organic flux, and the thermally volatile cleaning material 102 is sprayed onto the entire surface of the wafer package structure 100, for example, using a spray device 104. In this way, the thermally volatile cleaning material 102 can be easily and quickly covered to cover the surface of the entire wafer package structure 100, and thus the under bump metal layer 100b (pad 100a) can be easily and quickly covered, instead of the prior art. The cleaning material is first formed by using the pins to take the cleaning material, and then the pins to which the cleaning material is attached are brought into contact with the pads of the chip package structure to form the cleaning material on the pads. Thereby, the thermal volatile cleaning material 102 can completely cover the under bump metal layer 100b without the need of alignment processing (in other embodiments, when there is no under bump metal layer 100b, it is the pad 100b). Exposing the surface), avoiding the misalignment of the stitches or the warpage of the package structure of the wafer causes the alignment to be difficult to cause the cleaning material to completely cover the under bump metal layer 100b (pad 100a). In addition, the thermal volatile cleaning material 102 is directly formed on the surface of the chip package structure 100 by spraying, and the steps of the prior art to take the cleaning material by the stitches and the steps of cleaning the stitches can be omitted, thereby effectively Reduce process time.

Next, referring to FIG. 1C, when the wafer package structure 100 is to be implanted, the wafer package structure 100 is first heat treated to simultaneously remove the thermal volatile cleaning material 102 and the protective material 101 reacted therewith to expose the bumps. Lower metal layer 100b (pad 100a). In the present embodiment, since the thermally volatile cleaning material 102 has a property of being volatilized by heat, after the heat treatment, the thermal volatile cleaning material 102 and the protective material 101 reacted therewith can be completely removed from the wafer package structure 100 to be exposed. The under bump metal layer 100b is formed. The above heat treatment is, for example, a reflow treatment or a baking treatment.

Thereafter, referring to FIG. 1D, after the thermal volatile cleaning material 102 and the protective material 101 reacted therewith are removed to expose the under bump metal layer 100b, solder balls 106 are formed on the under bump metal layer 100b to complete the present. The ball placement process of the embodiment. Forming solder balls 106 on the under bump metal layer 100b can be performed using techniques well known in the art and will not be further described herein.

After the protective material 101 is formed on each of the under bump metal layers 100b (pads 100a), the thermally volatile cleaning material 102 can be formed on the surface of the wafer package structure 100 for subsequent heat treatment and ball processing. Alternatively, after the protective material 101 is formed on each under bump metal layer 100b (pad 100a), the wafer package structure 100 can be left idle without subsequent processing of the wafer package structure 100. In the case where the wafer package structure 100 is left idle, since the under bump metal layer 100b (pad 100a) has been covered by the protective material 102, the under bump metal layer 100b (pad 100a) can be prevented from coming into contact with the outside to cause oxidation. Phenomenon or damage.

While the present invention has been described above with reference to the embodiments of the present invention, it is not intended to limit the present invention, and it is possible to make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧ Chip package structure

100a‧‧‧ pads

100b‧‧‧ under bump metal layer

101‧‧‧Hot volatile cleaning materials

102‧‧‧Protective materials

104‧‧‧Spray device

106‧‧‧ solder balls

1A to 1D are schematic cross-sectional views showing a process of a ball placement process according to an embodiment of the present invention.

Claims (5)

a planting ball process, comprising: providing a chip package structure, wherein a surface of the chip package structure has a plurality of pads; forming a protective material on each of the pads; forming a thermal volatile cleaning material on the surface Having the thermally volatile cleaning material cover the protective material and react with the protective material; performing a heat treatment to simultaneously remove the thermally volatile cleaning material and the protective material; and each of the plurality of solder balls Formed on a corresponding one of the plurality of pads. The ball placement process of claim 1, wherein the thermally volatile cleaning material comprises an organic flux, and the protective material comprises an organic soldering flux. The ball placement process of claim 1, wherein the method of forming the thermally volatile cleaning material on the surface comprises spraying the thermal volatile protective material onto the surface using a spray device. The ball processing process of claim 1, wherein the heat treatment comprises a reflow process or a bake process. The ball placement process of claim 1, wherein the forming of the thermally volatile cleaning material on the surface and before performing the heat treatment further comprises idling the wafer package structure.