POP welding method

Abstract

The invention discloses a POP welding method which can ensure that the surface of a bonding pad of an adapter plate is complete and reliable, simplify the technological process and reduce the manufacturing cost. The method comprises the following steps: S1, pasting an adapter plate above a multi-layer chip, and then carrying out plastic package on the adapter plate and the multi-layer chip in a plastic package body; s2, a TMV technology is used to carry out trepanning on the plastic package body above the PAD on the surface of the adapter plate, so that the PAD is exposed; s3, plating a copper layer on the side wall of the opening and the surface of the PAD through EMI sputtering; and S4, removing the oxide on the surface of the copper layer, and then carrying out POP welding on another BGA device.

Description

Technical Field

[0001] The invention relates to the technical field of IC packaging, in particular to a POP welding method. Background Art

[0002] POP (Packaging on Packaging) packaging welding is also called stacked packaging welding. It is a welding method developed for IC packaging of mobile devices and can be used for system integration. It is composed of two layers of packaging stacked on top of each other. The bottom package and the upper package, as well as the bottom package and the motherboard are interconnected through solder ball arrays.

[0003] There are two existing POP welding process methods. Method 1: attach an interposer (transfer board) on top of the multi-layer chip (such as Figure 1 , 101 interposer, 103 plastic package, 104 substrate, 105 chip), there is a PAD welding point on the interposer surface, then the whole is plastic-sealed, and then the TMV process is used to open a hole in the plastic package to expose the PAD point on the interposer surface, so as to realize POP welding of another BGA device on top. However, this method will cause the PAD on the interposer surface to be affected by the laser operation when the TMV hole is opened, and the PAD will be damaged, affecting the welding effect of the BGA device. Method 2, see Figure 2 , solder 301 solder balls on the PAD on the interposer surface in advance, then plastic seal the whole, then grind the surface of the plastic seal to expose the solder balls, and then perform Flux pretreatment on the surface to make the originally flat solder balls return to spherical shape, which is convenient for POP soldering of another BGA device. However, this method has more process flows and the cost is correspondingly increased. Summary of the invention

[0004] In view of the above problems, the present invention provides a POP welding method, which can ensure that the pad surface of the adapter board is intact and reliable, and simplifies the process flow and production cost.

[0005] A POP welding method, characterized in that it comprises the following steps:

[0006] S1, attaching the adapter plate above the multi-layer chip, and then sealing the adapter plate and the multi-layer chip together in a plastic package;

[0007] S2. Use the TMV process to open a hole in the plastic package above the PAD on the surface of the adapter board to expose the PAD;

[0008] S3, plating a copper layer on the side wall of the opening and the surface of the PAD by EMI sputtering;

[0009] S4, removing the oxide on the surface of the copper layer, and then performing POP welding of another BGA device.

[0010] It is further characterized by:

[0011] In step S3, a film is applied to the surface of the package except the opening area, and then EMI sputtering is performed, so that the remaining surface of the package is plated with a copper layer;

[0012] In step S3, the thickness of the copper layer is 5 μm to 15 μm;

[0013] In step S4, the film is removed in advance, and then the oxide on the surface of the copper layer is pretreated by Flux.

[0014] After adopting the method of the present invention, it is only necessary to form a copper layer by EMI sputtering on the PAD surface of the adapter board with an opening formed by the TMV process. The copper layer can reliably repair the damage on the PAD surface caused by the laser. The entire method only needs to add one process, which can ensure that the pad surface of the adapter board is intact and reliable, and simplify the process flow and production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the operation flow of method 1 of the prior art;

[0016] Figure 2 It is a schematic diagram of the operation flow of method 2 of the prior art;

[0017] Figure 3 It is a schematic diagram of the operation flow of the present invention;

[0018] The names corresponding to the serial numbers in the figure are as follows:

[0019] Adapter board 101 , PAD 102 , plastic package 103 , multi-layer chip 105 , opening 201 , solder ball 301 , film 601 , copper layer 701 , BGA device 901 . DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] A POP welding method, see Figure 3 : When implemented specifically, it includes a multi-layer chip 105, a transfer board 101, a BGA device 901, and a plastic package 103, and includes the following steps:

[0025] S1, attaching the adapter board 101 above the multi-layer chip 105, and then plastic-sealing the adapter board 101 and the multi-layer chip 105 together in the plastic packaging body 103;

[0026] S2, using the TMV process to open a hole 201 in the plastic package 103 above the PAD 102 on the surface of the adapter board 101, so as to expose the PAD 102, the opening 201 is a hole expanded from bottom to top, and the bottom area of ​​the opening 201 is not larger than the upper surface area of ​​the corresponding PAD 102;

[0027] S3, a film is applied to the surface of the package body 103 except the opening 201 area. The film 601 is pre-processed or removed to form a notch at the position corresponding to the opening 201, and then a copper layer 701 is plated on the side wall of the opening 201 and the upper surface of the PAD 102 by EMI sputtering;

[0028] S4, tear off the film. Before tearing off, pre-cut the copper layer at the position corresponding to each opening 201, so that the film 601 can be quickly torn off without affecting the side wall of the opening 201 and the copper layer on the upper surface of PAD102. Then, the oxide on the surface of the copper layer 701 is pre-treated by Flux, and then the solder ball on the lower surface of another BGA device 901 is embedded in the corresponding opening 201 and soldered to the bottom PAD102.

[0029] In a specific implementation, the thickness of the copper layer sputtered by EMI is 10 μm, ensuring reliable repair of the surface of PAD1023.

[0030] It only needs to form a copper layer by EMI sputtering on the PAD surface of the adapter board with an opening formed by the TMV process. The copper layer can reliably repair the damage on the PAD surface caused by the laser. Since the side wall of the opening also has a copper layer, and the copper layer of the opening is connected to the copper layer used for repair on the upper surface of the PAD, the effective welding area of ​​the BGA device 901 during POP welding is increased, making POP welding easier. The whole method only needs to add one process, which can ensure that the pad surface of the adapter board is intact and reliable, and simplify the process flow and production cost.

[0031] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0032] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A POP welding method, characterized in that: It includes the following steps: S1, attaching the adapter plate above the multi-layer chip, and then sealing the adapter plate and the multi-layer chip together in a plastic package; S2. Use the TMV process to open a hole in the plastic package above the PAD on the surface of the adapter board to expose the PAD; S3, plating a copper layer on the side wall of the opening and the surface of the PAD by EMI sputtering; S4, removing the oxide on the surface of the copper layer, and then performing POP welding of another BGA device.

2. A POP welding method according to claim 1, characterized in that: In step S3, a film-laminating operation is performed on the remaining surface of the package except the opening area, and then EMI sputtering is performed, so that the remaining surface of the package is plated with a copper layer.

3. A POP welding method according to claim 1, characterized in that: In step S3, the thickness of the copper layer is 5 μm to 15 μm.

4. A POP welding method according to claim 1, characterized in that: In step S4, the film is removed in advance, and then the oxide on the surface of the copper layer is pretreated by Flux.

Images