WO2020134722A1

WO2020134722A1 - Flip-chip assembly, flip-chip packaging structure, and manufacturing method

Info

Publication number: WO2020134722A1
Application number: PCT/CN2019/119478
Authority: WO
Inventors: 梅嬿
Original assignee: 颀中科技（苏州）有限公司
Priority date: 2018-12-29
Filing date: 2019-11-19
Publication date: 2020-07-02
Also published as: CN111384017B; CN111384017A

Abstract

Provided are a flip-chip assembly, a flip-chip packaging structure, and a manufacturing method. The flip-chip assembly comprises a chip, and a first conductive post and a second conductive post formed at a side surface of the chip along a first direction, wherein the second conductive post is larger than the first conductive post, a first solder bump is provided at one end of the first conductive post away from the chip, multiple mutually spaced-apart second solder bumps are provided at one end of the second conductive post away from the chip, and conductive bases are further provided between the second solder bumps and the second conductive post. The manufacturing method for the flip-chip assembly comprises: fabricating the multiple mutually spaced-apart conductive bases on the second conductive post, fabricating the corresponding second solder bumps on the conductive bases, and converting the first solder bump and the second solder bumps from an initial state to a finished state by means of a thermal treatment. The present invention adjusts solder structures on the second conductive post having a strip or elliptical shape and a large size, thereby improving product quality.

Description

Flip chip assembly, flip chip packaging structure and preparation method

Technical field

The invention relates to the technical field of electronic packaging, in particular to a flip chip assembly, a flip chip packaging structure and a preparation method.

Background technique

In recent years, due to the advantages of compact structure, high performance, short leads, etc., flip chip has received more and more attention and attention in the industry, which can better meet the needs of miniaturization of chip packaging structure, improve chip integration, and benefit chip data Improvement of processing power. Flip chips now mostly use copper pillar bumps (Cupillar) and a layer of solder placed on top of the copper pillar bumps to achieve the connection between the chip and the substrate. The structure of the aforementioned copper pillar bumps remains basically unchanged during the soldering process Compared with traditional solder bumps, it has superior electrical conductivity, thermal conductivity and structural reliability.

The common copper pillar bumps are mostly arranged in a round shape, but with the increase in electrical conductivity, thermal conductivity, structural strength and stress requirements, it has been disclosed to prepare strip copper pillar bumps with different aspect ratios on the surface of the chip 10' 20' (as shown in Figure 1). The aforementioned strip copper pillar bumps are consistent with the traditional round copper pillar bump production and soldering process. When reflow soldering is used to melt the solder bump on the top of the copper pillar bump to form a solder cap, the solder on the top of the strip copper pillar bump The height of the solder cap on the top of the cap and the round copper pillar bump will be different, and the height of the solder cap correspondingly generated on the top of the strip copper pillar bump of different shapes also has a large difference. This will result in poor coplanarity of the different copper pillar bumps on the flip chip surface, affecting the flip chip packaging.

The applicant has disclosed a new flip chip assembly in CN108364920A. The strip-shaped second conductive post is provided with two or more solder bumps spaced from each other at the top so that the solder bump on the second conductive post can form a solder cap The height of the solder cap on the first conductive post tends to be consistent, which improves the height coplanarity of the conductive posts of different specifications on the chip surface during soldering and packaging. However, according to on-site verification, the solder bumps on the second conductive post are more likely to spread along the end surface of the second conductive post until they stick together, causing local height changes on the second conductive post; and if the spacing between the solder bumps If the setting is too large, it is difficult to meet the performance requirements of chip bonding strength and electrical conduction.

In view of this, it is necessary to provide a new flip chip assembly, flip chip packaging structure and preparation method.

Summary of the invention

The purpose of the present invention is to provide a flip chip assembly, a flip chip packaging structure and a preparation method, which can effectively improve the highly coplanarity of the solder structures on different conductive posts on the chip surface and improve the product quality.

In order to achieve the above object of the invention, the present invention provides a flip chip assembly, including a chip, a first conductive pillar and a second conductive pillar formed on a surface of the chip along a first direction, the second conductive pillar The projection on the plane perpendicular to the first direction is greater than the projection of the first conductive pillar on the plane perpendicular to the first direction, and the end of the first conductive pillar facing away from the chip is provided with a first solder bump. The end of the second conductive column facing away from the chip is provided with a plurality of second solder blocks spaced apart from each other, and a conductive base is also provided between each second solder block and the second conductive column.

As a further improvement of the present invention, the specifications of both the first solder bump and the second solder bump are the same.

As a further improvement of the present invention, an end of the conductive base adjacent to the second solder block is flush with an end of the first conductive pillar facing away from the chip and the end surface structure of the two is consistent.

As a further improvement of the present invention, the distance between adjacent conductive bases on the same second conductive post is consistent, and the second solder bumps on the same second conductive post are also arranged at equal intervals.

As a further improvement of the present invention, the flip chip assembly further includes a pedestal disposed between the first conductive pillar and the first solder bump, and the end structure and the side of the pedestal facing away from the first conductive pillar The structure of the end surface of the side of the conductive base facing away from the second conductive column is consistent.

As a further improvement of the present invention, the first conductive pillar is arranged in a cylindrical shape; an end of the second conductive pillar facing away from the chip is formed with a strip-shaped second end surface.

As a further improvement of the present invention, several conductive bases on the same second conductive post are arranged at linear intervals along the length direction of the second end surface.

As a further improvement of the present invention, the first conductive pillar and the second conductive pillar are both configured as copper pillars; the conductive base is composed of copper, nickel or a copper-nickel alloy; the first solder block and the second solder block are both Both are made of metal tin or tin alloy.

The invention also provides a flip chip packaging structure, including a substrate, the flip chip assembly as described above and an insulating layer.

The invention also provides a method for preparing a flip chip assembly, which mainly includes:

A chip is provided, and a first conductive post and a second conductive post are prepared on one side surface of the chip, the projection of the second conductive post on a plane parallel to the chip is greater than that of the first conductive post parallel to the chip Projection on the plane of

A first solder block is prepared on the surface of the end of the first conductive post facing away from the chip, a plurality of conductive bases distributed at intervals are prepared on the end of the second conductive post facing away from the chip, and a second solder block is prepared on the conductive base;

The first solder block and the second solder block are heat-treated so that the first solder block and the second solder block are changed from the initial state to the finished state.

The beneficial effect of the present invention is that the flip chip assembly of the present invention is adopted by providing a plurality of mutually spaced conductive bases on the end of the second conductive column facing away from the chip, and then a corresponding second solder block is provided on the conductive base, the second solder During the heat treatment of the block to change from the initial state to the finished state, its morphological change tends to be consistent with that of the first solder block, to avoid adhesion of different second solder blocks to each other in the molten state, resulting in the height of the second solder block in the finished state difference. The flip chip assembly of the present invention can truly improve the high coplanarity of the solder on different conductive posts on the surface of the chip and improve the product yield.

BRIEF DESCRIPTION

1 is a schematic structural diagram of a conventional flip chip assembly;

2 is a schematic structural view of the first solder bump and the second solder bump in the flip chip assembly of the present invention;

3 is a schematic structural diagram of the first solder bump and the second solder bump in the flip chip assembly in FIG. 2 in a finished state;

4 is a schematic structural view of another embodiment of the flip chip assembly of the present invention;

5 is a schematic structural view of the flip-chip packaging structure of the present invention;

6 is a schematic diagram of the main flow of the method for manufacturing a flip chip assembly of the present invention.

detailed description

The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, this embodiment does not limit the present invention, and structural, method, or functional transformations made by a person of ordinary skill in the art according to this embodiment are all included in the protection scope of the present invention.

2 and 3, the flip chip assembly 100 provided by the present invention includes a chip 10, a first conductive post 21 and a second conductive post 22 disposed on a surface of the chip 10 along a first direction. The projection of the second conductive pillar 22 on the plane perpendicular to the first direction is greater than the projection of the first conductive pillar 21 on the plane perpendicular to the first direction. The end of the first conductive post 21 facing away from the chip 10 is provided with a first solder block 31; the end of the second conductive post 22 facing away from the chip 10 is provided with a plurality of second solder blocks 32 arranged at intervals from each other, and each A corresponding conductive base 40 is also provided between the second solder block 32 and the second conductive pillar 22.

Preferably, the distance between adjacent conductive bases 40 on the second conductive posts 22 is the same, and the second solder bumps 32 on the same second conductive posts 22 are also arranged at equal intervals. In this embodiment, an end of the second conductive pillar 22 facing away from the chip 10 is formed with a strip-shaped second end surface 221, and a plurality of conductive bases 40 on the same second conductive pillar 22 are along the second end surface 221 They are arranged at equal intervals in the length direction of.

The first conductive pillar 21 is substantially cylindrical, and an end of the first conductive pillar 21 facing away from the chip 10 is formed with a circular first end surface 211. Here, the height of the first end surface 211 relative to the surface of the chip 10 exceeds the height of the second end surface 221 relative to the surface of the chip 10. An end of the conductive base 40 adjacent to the second solder block 32 is flush with the first end surface 211 of the first conductive pillar 21, and the end surface of the conductive base 40 facing the second solder block 32 is parallel to the first The structure of the end surface 211 is consistent. Further, the conductive base 40 is also arranged in a cylindrical shape and its diameter is equivalent to the diameter of the first conductive pillar 21.

The specifications of both the first solder block 31 and the second solder block 32 are the same, and they have an initial state and a finished state. The specifications of the aforementioned two are the same, which means that the first solder block 31 and the second solder block 32 are The materials used and the initial state are the same. The initial state corresponds to the form where the first solder block 31 is formed on the first end surface 211, or the second solder block 32 is formed on the corresponding conductive base 40; the finished state is the first solder block 31, the second The solder bump 32 is changed to the state when it is "solder cap" by heat treatment. Here, the heights of the first solder bump 31 and the second solder bump 32 in the initial state are the same. In the initial state, the first solder block 31 and the second solder block 32 are arranged in a column shape, and the first solder block 31 does not exceed the first end surface 211 of the first conductive pillar 21 in the radial direction; the first The second solder block 32 does not exceed the end surface of the corresponding conductive base 40 facing the second solder block 32 along its radial direction.

The first solder block 31 and the second solder block 32 are also preferably arranged in a cylindrical shape and respectively correspond to the first conductive pillar 21 and the conductive base 40. When the first solder bump 31 and the second solder bump 32 transition to the finished state, the morphological transformation will occur under the action of gravity, interface stress, and surface tension after melting. Here, the arrangement of the aforementioned conductive base 40 enables the second solder bump 32 and the first solder bump 31 to better maintain the same shape transformation tendency. In addition, the distance W between the adjacent second solder blocks 32 in the initial state needs to be determined during the forming process of the second solder blocks 32. The distance W cannot be designed to be too small, which needs to ensure that the adjacent second solder blocks 32 When transitioning to the finished state, there will be no sticking to each other; the distance W cannot be designed too large, which affects the electrical connection performance and structural strength of the second conductive pillar 22.

In the present invention, not only are two or more second solder blocks 32 spaced apart from each other on the larger second conductive pillar 22, but also through the design of the conductive base 40, the second solder block 32 can be used in the heat treatment process Among them, the morphological change trend is truly in agreement with the change trend of the first solder block 31, effectively eliminating the height difference between the first solder block 31 and the second solder block 32 after melt deformation.

Generally, both the first conductive pillar 21 and the second conductive pillar 22 are configured as copper pillars; both the first solder block 31 and the second solder block 32 are made of metal tin or tin alloy. The conductive base 40 is made of copper, nickel, or copper-nickel alloy, not only to ensure the bonding performance of the conductive base 40 with the second conductive pillar 22 and the second solder block 32, but also to ensure that the conductive base 40 has good conductivity Performance and structural strength, and under the above conditions, the conductive base 40 can also be made of other conductive materials.

In actual production, the conductive base 40 can be formed in synchronization with the first conductive post 21 and the second conductive post 22, in other words, after the second conductive post 22 is formed, the second conductive post 22 The foregoing conductive bases 40 are etched at intervals on the end surface facing away from the chip 10. This method can also effectively ensure that the end surface of the conductive base 40 facing the second solder block 32 is flush with the first end surface 211 of the first conductive pillar 21, and the surface structure of the two is kept the same.

4 shows another embodiment of the present invention, which is different from the foregoing embodiment in that the flip chip assembly 100 further includes a first conductive post 21 and a first solder block 31 disposed between The base 50 has an end surface structure on the side facing away from the first conductive pillar 21 and the end surface structure on the side facing away from the second conductive pillar 22 of the conductive base 40.

Preferably, the base 50 is also composed of copper, nickel or a copper-nickel alloy to ensure the bonding performance of the base 50 with the first conductive pillar 21 and the first solder bump 31, and it is also necessary to ensure that the base 50 has Good conductivity and structural strength. When the above conditions are satisfied, the base 50 may also be made of other conductive materials.

In the above embodiment, the specifications of the first solder block 31 and the second solder block 32 and the spacing between the adjacent second solder blocks 32 are all set to be the same, which is to ensure the first solder block 31 to the greatest extent After melting and deforming with the second solder block 32, an optimal highly coplanar effect can be achieved. This point should not be construed as a limitation of the application of the present invention. In other embodiments of the invention, the design of the spacing between the second solder bump 32 on the second conductive pillar 22 and the conductive base 40 can be arranged reasonably according to actual needs , So that the height change of the second solder block 32 when it is converted into the finished state remains uniform, and is as consistent as possible with the height change of the first solder block 31.

As shown in FIG. 5, the present invention also provides a flip chip package structure 200, which includes a substrate 201, an insulating layer 202, and the flip chip assembly 100 as described above. The first conductive pillar 21, the second conductive pillar 22 and the first solder block 31 and the second solder block 32 are used to realize the electrical connection between the substrate 201 and the chip 100, and the insulating layer 202 plays a role It solidifies and supports, and is used to isolate outside air and moisture from erosion.

As shown in FIG. 6, the present invention also provides a method for manufacturing the flip chip assembly 100 as described above, which mainly includes:

S1. A chip 10 is provided, and a first conductive pillar 21 and a second conductive pillar 22 are prepared along a first direction on one side surface of the chip 10, and both the first conductive pillar 21 and the second conductive pillar 22 are in phase with the chip 10 Vertical, the projection of the second conductive pillar 22 on the plane perpendicular to the first direction is greater than the projection of the first conductive pillar 21 on the plane perpendicular to the first direction;

S2. Prepare the first solder bump 31 on the surface of the end of the first conductive pillar 21 facing away from the chip 10, and prepare a plurality of mutually spaced conductive bases 40 on the end of the second conductive pillar 22 facing away from the chip 10, and then prepare corresponding corresponding bases on the conductive base 40 The second solder block 32;

S3. Perform heat treatment on the first solder block 31 and the second solder block 32, so that the first solder block 31 and the second solder block 32 change from the initial state to the finished state.

In other embodiments of the present invention, step S2 further includes preparing a base 50 on the first end surface 211 of the first conductive pillar 21, and then preparing a first on the side of the base 50 facing away from the first conductive pillar 21 Solder block 31.

Specifically, a metallization layer is formed by sputtering on a predetermined area on one side surface of the chip 10, and then a first conductive pillar 21 and a second conductive pillar 22 are formed on the metallization layer through exposure and plating processes. The first conductive The pillar 21 and the second conductive pillar 22 are configured as copper pillars; again, positioning and growing on the second end surface 221 of the second conductive pillar 22 through exposure and electroplating processes to obtain a plurality of conductive bases 40 spaced apart from each other. The conductive base 40 is prepared simultaneously; then, the first solder block 31 and the second solder block 32 are prepared by electroplating or the like. Finally, the above heat treatment process specifically uses reflow soldering to melt and deform the first solder block 31 and the second solder block 32 into a hat shape, and at the same time, strengthen the fusion of the first solder block 31 and the second solder block 32 with the first The bonding strength of a conductive pillar 21 and a second conductive pillar 22.

In summary, the flip-chip assembly 100 and the flip-chip packaging structure 200 of the present invention are provided with a conductive base 40 and a corresponding second solder block 32 at the end of the second conductive pillar 22 facing away from the chip 10, so that the When the first solder block 31 and the second solder block 32 are heated and melted, the height change can better converge, and the difference in height change of different second solder blocks 32 on the second conductive pillar 22 is avoided, and the height of the different conductive pillars of the product is increased. Coplanarity, thereby improving product yield and enhancing product competitiveness. At the same time, the flip chip assembly 100 obtained by the preparation method of the present invention can also effectively guarantee the bonding strength of the fusion of the first solder block 31 and the second solder block 32 to the first conductive pillar 21 and the second conductive pillar 22, to avoid Accidentally peeled off.

It should be understood that although this specification is described according to embodiments, not every embodiment includes only an independent technical solution. This description of the specification is for clarity only, and those skilled in the art should treat the specification as a whole, each The technical solutions in the embodiments may also be combined appropriately to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention, they are not intended to limit the scope of protection of the present invention, and equivalent embodiments or technical equivalents made without departing from the technical spirit of the present invention Changes should be included in the protection scope of the present invention.

Claims

A flip chip assembly includes a chip, a first conductive pillar and a second conductive pillar formed on one surface of the chip along a first direction, and a projection of the second conductive pillar on a plane perpendicular to the first direction Greater than the projection of the first conductive pillar on a plane perpendicular to the first direction, the first conductive pillar has a first solder bump at an end facing away from the chip, characterized in that the second conductive pillar faces away from A plurality of second solder blocks spaced apart from each other are provided at one end of the chip, and a conductive base is further provided between each second solder block and the second conductive post.
The flip chip assembly of claim 1, wherein the specifications of both the first solder bump and the second solder bump are the same.
The flip chip assembly according to claim 1, wherein an end of the conductive base adjacent to the second solder block is flush with an end of the first conductive post facing away from the chip and the end surface structure of the two is consistent .
The flip chip assembly according to claim 1, wherein the distance between adjacent conductive bases on the same second conductive post is the same, and the second solder bumps on the same second conductive post They are also arranged at equal intervals.
The flip chip assembly of claim 1, wherein the flip chip assembly further comprises a base disposed between the first conductive pillar and the first solder bump, the base facing away from the first The end surface structure on the side of the conductive column is consistent with the end surface structure on the side of the conductive base facing away from the second conductive column.
The flip chip assembly according to claim 1, wherein the first conductive pillar is provided in a cylindrical shape; and the second conductive pillar has a strip-shaped second end surface at an end facing away from the chip.
The flip chip assembly according to claim 6, wherein a plurality of conductive bases on the same second conductive post are arranged at linear intervals along the length of the second end surface.
The flip chip assembly of claim 1, wherein the first conductive pillar and the second conductive pillar are both copper pillars; the conductive base is made of copper, nickel, or copper-nickel alloy; and the first Both the first solder block and the second solder block are made of metal tin or tin alloy.
A flip chip packaging structure, characterized in that the packaging structure includes a substrate, the flip chip assembly according to any one of claims 1-8 and an insulating layer.
A preparation method of flip chip assembly is characterized by:

A chip is provided, and a first conductive post and a second conductive post are prepared on one side surface of the chip, the projection of the second conductive post on a plane parallel to the chip is greater than that of the first conductive post parallel to the chip Projection on the plane of

A first solder block is prepared on the surface of the end of the first conductive post facing away from the chip, a plurality of conductive bases distributed at intervals are prepared on the end of the second conductive post facing away from the chip, and a second solder block is prepared on the conductive base;

The first solder block and the second solder block are heat-treated so that the first solder block and the second solder block are changed from the initial state to the finished state.