CN101217134A - Substrate structure of ball grid array package and ball mounting method thereof - Google Patents

Abstract

The invention relates to a substrate structure applied to ball grid array packaging and a ball mounting method thereof; a ball grid array package substrate structure, comprising: a substrate; a wiring provided inside the substrate; and a plurality of solder ball pads arranged on one surface of the substrate and electrically connected with the wiring, wherein the solder ball pads are composed of a layer of tin and a layer of organic solderability protection pad. A ball planting method for ball grid array package includes: providing a ball grid array package substrate, wherein the solder ball pad is composed of a layer of tin and an organic solderability protection pad; coating a soldering flux on the surface of the solder ball pad; arranging a plurality of solder balls on the soldering flux; and reflowing to electrically connect the solder balls and the wires. Therefore, the invention can solve the problems of copper oxidation, solder ball migration, solder ball cracking and the like in the prior art, so the ball grid array packaging substrate and the ball mounting method thereof have the advantages of high quality, low cost and the like.

Description

Substrate Structure of Ball Grid Array Package and Its Ball Planting Method

technical field

The invention relates to a substrate structure and a ball planting method thereof, in particular to a substrate structure applied to ball grid array packaging and a ball planting method thereof.

Background technique

In recent years, with the development trend of terminal consumer electronic products towards "light, thin, short, small" and multi-functionality, the chip (chip) packaging technology of integrated circuits (Integrated Circuit, IC) is also moving towards high density, The direction of miniaturization and high pin count is advancing. In order to achieve miniaturization and narrow pitch packaging and improve heat dissipation, the current ball grid array packaging structure (BallGrid Array, BGA), flip chip (Flip Chip), chip size Advanced packaging technologies such as Chip Scale Package (CSP) have become the mainstream. Compared with wire bonding packaging, ball grid array packaging has the advantages of small signal transmission delay, high application frequency, strong heat dissipation capability and small packaging volume. Therefore, it is widely used in various types of packaging structures, including: window ball grid array packaging structure, fine pitch BGA (FBGA) packaging structure, ultra-fine pitch ball grid array (Very Fine pitch BGA, VFBGA) ) packaging structure, micro BGA (micro BGA, μBGA) packaging structure and stacked-type Multi-Chip Package BGA (Stacked-type Multi-Chip Package BGA, St-MCP BGA) packaging structure, etc.

Therefore, high-density chip assembly requires a high-density, high-quality, and low-cost chip packaging substrate to cooperate.

FIG. 1 is a schematic cross-sectional view of a conventional ball grid array package substrate. A substrate 2 has a first surface 6 and a second surface 10, and a wiring (trace) 4 is provided inside the substrate 2, and its material is copper (Cu). , wherein the first surface 6 has a plurality of first grooves exposing part of the wiring 4; a plurality of solder ball pads (solder ball pads) 8 are arranged in the first grooves and expose the first surface 6, wherein the solder balls The pad 8 is electrically connected to the wiring 4, and any solder ball pad 8 is an organic solderability protection pad (Organic Solderability Preservative, OSP), which is used to electrically connect multiple solder balls (solder ball) (not shown in the figure) ), the solder balls are used as input/output (Input/Output, I/O) terminals, so that the substrate 2 can be electrically connected to an external device (not shown in the figure), for example, it is completed by surface mount technology (Surface Mount Technology, SMT) The assembly and electrical connection between the BGA packaging structure and a Printed Circuit Board (PCB) (not shown in the figure).

Continuing the above description, the second surface 10 has a plurality of second grooves exposing part of the wiring 4, and a plurality of welding pads 12 are arranged in the second grooves and expose the second surface 10, wherein the welding pads 12 are electrically connected to the wiring 4 Any pad 12 is composed of a layer of nickel (Ni) 14 and a layer of gold (Au) 16, wherein the nickel 14 is located on the surface of the wiring 4, and the gold 16 is located on the nickel 14; the pad 12 is used To electrically connect a plurality of bonding wires (not shown in the figure), the function of the bonding wire is to electrically connect a chip (not shown in the figure) mounted in the package structure with the wiring 4, so that the chip can be electrically It is electrically connected to the substrate 2, and thus can be electrically connected to an external device (not shown in the figure), such as a printed circuit board (not shown in the figure).

2A to 2B are schematic diagrams of the steps of a conventional ball grid array package ball mount method, the steps include: providing a ball grid array package substrate 2, the substrate 2 has a first surface 6, and the first The surface 6 has a plurality of grooves, the inside of the substrate 2 has wiring 4, and the grooves expose part of the wiring 4, and a plurality of solder ball pads 8 are arranged in the grooves and expose the first surface 6, wherein the solder ball pads 8 and the wiring 4. Electrical connection, and the solder ball pad 8 is an organic solderability protection pad; coating a flux (flux) 18 on the surface of the solder ball pad 8; planting (mount) a plurality of solder balls 20 on the flux (flux) 18 ; and reflow (reflow), so that a plurality of solder balls 20 are electrically connected to the wiring 4 .

However, the ball grid array package substrate using organic solderability protection pads as solder ball pads has several disadvantages, including Cu oxidation and ball shifting of copper under the solder ball pads. )Phenomenon.

3 is a schematic cross-sectional view of another conventional ball grid array package substrate. The substrate 22 has a first surface 26 and a second surface 34, and a wiring (trace) 24 is provided inside the substrate 22, and its material is copper (Cu), wherein , the first surface 26 has a plurality of first grooves exposing part of the wiring 24; a plurality of solder ball pads 28 are located in the first grooves and expose the first surface 26, wherein the solder ball pads 28 are electrically connected to the wiring 24 connection, any solder ball pad 28 is composed of a layer of nickel 30 and a layer of gold 32, wherein the nickel 30 is arranged on the surface of the wiring 24, and the gold 32 is arranged on the nickel 30, and the nickel 30/gold 32 is usually formed by electroplating ( plating) or electroless nickel immersion gold (Electroless Nickel ImmersionGold, ENIG) and other methods; the solder ball pad 28 is used to electrically connect a plurality of solder balls (solderball) (not shown in the figure), and the solder balls are used as input/output ( Input/Output (I/O) terminal enables the substrate 22 to be electrically connected to an external device (not shown in the figure).

Continuing the above description, the second surface 34 has a plurality of second grooves exposing part of the wiring 24, and a plurality of welding pads 36 are arranged in the second grooves and expose the second surface 34, wherein the welding pads 36 are electrically connected to the wiring 24. Any solder pad 36 is composed of a layer of nickel 38 and a layer of gold 40, wherein the nickel 38 is arranged on the surface of the wiring 24, and the gold 40 is arranged on the nickel 38; the solder pad 36 is used to electrically connect multiple Bonding wire (not shown in the figure), the function of the bonding wire is to electrically connect a chip (not shown in the figure) mounted in the package structure with the wiring 24, so that the chip can be electrically connected to the substrate 22, and Therefore, an external device (not shown in the figure), such as a printed circuit board (not shown in the figure), can be electrically connected.

However, the disadvantage of this ball grid array package substrate using a layer of nickel and a layer of gold as solder ball pads is that the material cost is high, and the solder balls on the intermetallic compound (Inter-Metallic Compound, IMC) are prone to cracking (crack). )Phenomenon.

Contents of the invention

In order to solve the problems such as copper oxidation and solder ball migration produced by using organic solderability protection pads as solder ball pads in the prior art, one of the purposes of the present invention is to propose a method that uses tin/organic solderability protection pads as solder ball pads. substrate structure and its ball planting method.

In order to solve problems such as solder ball ruptures produced by gold/nickel solder ball pads in the prior art, one of the objectives of the present invention is to propose a substrate structure and its ball planting using tin/organic solderability protection pads as solder ball pads method.

In order to achieve the above object, the present invention provides a ball grid array package substrate structure, comprising: a substrate having a surface with a plurality of grooves; a wiring, which is arranged inside the substrate, wherein the grooves are exposed Part of the wiring; and a plurality of solder ball pads, which are arranged in the groove and exposed on the surface, wherein the solder ball pads are electrically connected to the wiring, and any solder ball pad includes: a layer of tin, which is arranged on the surface of the wiring; and a A layer of organic solderability protection pad is provided on the tin.

In order to achieve the above object, the present invention also provides a ball-planting method for a ball grid array package, including: providing a ball grid array package substrate, wherein the substrate has a surface with a plurality of grooves, and the inside of the substrate has a wiring , a plurality of solder ball pads are arranged in the groove and expose the surface, wherein the solder ball pads are electrically connected to the wiring, and any solder ball pad is composed of a layer of tin and a layer of organic solderability protection pad, wherein the tin Provided on the surface of the wiring, and the organic solderability protection pad is provided on the tin; coating a flux on the surface of the solder ball pad; planting a plurality of solder balls on the flux; and reflowing, so that the solder ball and the wiring are electrically connected .

Therefore, the ball grid array packaging substrate using the tin/organic solderability protection pad as the solder ball pad and the ball planting method of the present invention have the advantages of high quality and low cost.

In the following, detailed descriptions will be given through specific embodiments in conjunction with the accompanying drawings, so that it will be easier to understand the purpose, technical content, features and effects of the present invention.

Description of drawings

1 is a schematic cross-sectional view of a conventional ball grid array package substrate;

2A to 2C are schematic diagrams of the steps of a ball planting method for a conventional ball grid array package;

3 is a schematic cross-sectional view of a conventional ball grid array package substrate;

4 is a schematic cross-sectional view of a ball grid array package substrate according to an embodiment of the present invention;

FIG. 5A to FIG. 5C are schematic diagrams of steps of a ball planting method for a ball grid array package according to an embodiment of the present invention.

Explanation of symbols in the figure

2, 22, 42 Substrate

4, 24, 44 Wiring

6, 26, 46 The first surface

8, 28, 48 solder ball pads

10, 34, 54 Second surface

12, 36, 56 solder pads

14, 30, 38, 58 nickel

16, 32, 40, 60 Gold

18, 48, 62 flux

20, 64 solder balls

50 tin

52 Organic Solderability Protection Pad

Detailed ways

The specific implementation of the present invention is as follows in detail, and the preferred embodiments are only for illustration and not intended to limit the present invention.

4 is a schematic cross-sectional view of a ball grid array package substrate according to an embodiment of the present invention. A substrate 42 has a first surface 46 and a second surface 54, and there is a wiring (trace) 44 inside the substrate 42, wherein the first The surface 46 has a plurality of first grooves exposing part of the wiring 44; a plurality of solder ball pads 48 are disposed in the first grooves and expose the first surface 46, wherein the solder ball pads 48 are electrically connected to the wiring 44, any A solder ball pad 48 is composed of a layer of tin (Sn) 50 and a layer of organic solderability protection pad 52, wherein the tin 50 is arranged on the surface of the wiring 44, and the organic solderability protection pad 52 is arranged on the tin 50; The solder ball pad 48 is used to electrically connect a plurality of solder balls (solder ball) (not shown in the figure), and the solder ball is used as an input/output (Input/Output, I/O) terminal, so that the substrate 42 can be electrically connected to an external environment. device (not shown in the figure).

In one embodiment, the substrate 42 can be FR4 (Fire retardant grade of G10) substrate, FR5 (Fire retardant grade of G11) substrate or BT (thin core) substrate, and its material can be organic glass fiber, epoxy resin or The combination of the above; the material of the wire 44 can be copper (Cu); the thickness of the tin 50 can be equal to or less than 30 microns (μm), and the thickness of the organic solderability protection pad 52 can be equal to or less than 20 microns.

Continuing the above description, the second surface 34 has a plurality of second grooves exposing part of the wiring 44. In one embodiment, a plurality of solder pads 56 are disposed in the second grooves and expose the second surface 34, wherein the solder pads 56 Pad 56 is electrically connected with wiring 44, and any pad 56 is made up of one layer of nickel 58 and one layer of gold 60, wherein, nickel 58 is arranged on the surface of wiring 44, and gold 60 is arranged on nickel 58; To electrically connect a plurality of bonding wires (not shown in the figure), the function of the bonding wire is to electrically connect a chip (not shown in the figure) mounted in the package structure with the wiring 44, so that the chip can be electrically It is electrically connected to the substrate 42, and thus electrically connected to an external device (not shown in the figure), such as a printed circuit board (not shown in the figure).

Therefore, one of the characteristics of the ball grid array package substrate of the present invention is to use tin/organic solderability protection pads as solder ball pads, so it can avoid the copper oxidation phenomenon in the prior art that uses organic solderability protection pads as solder ball pads The solder ball migration phenomenon can also solve the solder ball cracking problem of the gold/nickel solder ball pad in the prior art, and the cost is lower than that of the gold/nickel solder ball pad.

5A to FIG. 5B are schematic diagrams of the steps of the ball planting method of the ball grid array package according to an embodiment of the present invention, and the steps include: providing a ball grid array package substrate 42, the substrate 42 has a first surface 46, and the first surface 46 has A plurality of grooves, the substrate 42 has wiring 44 inside, and the groove exposes part of the wiring 44, and a plurality of solder ball pads 48 are arranged in the groove and expose the first surface 46, wherein the solder ball pad 48 is electrically connected to the wiring 44 connection, and the solder ball pad 48 is composed of a layer of tin 50 and a layer of organic solderability protection pad 52, wherein the tin 50 is arranged on the surface of the wiring 44, and the organic solderability protection pad 52 is arranged on the tin 50; distributing a solder flux 62 on the surface of the solder ball pad 48 ; planting a plurality of solder balls 64 on the solder flux 48 ; and reflowing to electrically connect the solder balls 64 to the wiring 44 .

In one embodiment, the material of the solder ball 64 may include tin.

In summary, the ball grid array packaging substrate using tin/organic solderability protection pads as solder ball pads and the ball planting method of the present invention have the advantages of high quality and low cost.

The above-described embodiments are only to illustrate the technical ideas and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. When it cannot limit the protection scope of the present invention, that is, generally The equivalent changes or modifications made by the spirit disclosed in the present invention should still be covered within the patent scope of the present invention.

Claims (15)

1. structure of base plate for packaging ball grid array comprises:

One substrate, it has a first surface, and wherein, this first surface has a plurality of first grooves;

One wiring, it is located at this substrate inside, and wherein, those first grooves expose this wiring of part; And

A plurality of solder ball pads, it is located at those first grooves and exposes this first surface, and wherein, those solder ball pads and this wiring electrically connect, and it is characterized in that arbitrary this solder ball pad comprises:

One deck tin, it is located at this wiring surface; And

One deck Organic Solderability neonychium, it is located on this layer tin.

2. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, this substrate is FR4 substrate, FR5 substrate or BT substrate.

3. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, the material of this substrate is polymethyl methacrylate fiber, epoxy resin or above-mentioned combination.

4. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, the material of this wiring is a copper.

5. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, the thickness of this layer tin is for being equal to or less than 30 microns.

6. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, the thickness of this layer Organic Solderability neonychium is for being equal to or less than 20 microns.

7. structure of base plate for packaging ball grid array as claimed in claim 1, wherein, this substrate has a second surface, and this second surface has a plurality of second grooves, and wherein, those second grooves expose this wiring of part.

8. structure of base plate for packaging ball grid array as claimed in claim 7 comprises a plurality of weld pads, and it is located at those second grooves and exposes this second surface, and wherein, those weld pads and this wiring electrically connect, and arbitrary this weld pad comprises:

One deck nickel, it is located at this wiring surface; And

One deck gold, it is located on this layer nickel.

9. the ball-establishing method of a BGA Package comprises:

One base plate for packaging ball grid array is provided, and wherein, this substrate has a surface, and this surface has a plurality of grooves, this substrate inside has a wiring, and those grooves expose the part this wiring, a plurality of solder ball pads are located at those grooves and are exposed this surface, it is characterized in that, those solder ball pads and this wiring electrically connects, and arbitrary this solder ball pad is made up of one deck tin and one deck Organic Solderability neonychium, wherein, this layer tin is located at this wiring surface, and this Organic Solderability neonychium is located on this layer tin;

Be coated with a scaling powder in this solder ball pad surface;

Cloth is planted a plurality of soldered balls on this scaling powder; And

Reflow electrically connects those soldered balls and this wiring.

10. the ball-establishing method of BGA Package as claimed in claim 9, wherein, this substrate is FR4 substrate, FR5 substrate or BT substrate.

11. the ball-establishing method of BGA Package as claimed in claim 9, wherein, the material of this substrate is polymethyl methacrylate fiber, epoxy resin or above-mentioned combination.

12. the ball-establishing method of BGA Package as claimed in claim 9, wherein, the material of this wiring is a copper.

13. the ball-establishing method of BGA Package as claimed in claim 9, wherein, the thickness of this layer tin is for being equal to or less than 30 microns.

14. the ball-establishing method of BGA Package as claimed in claim 9, wherein, the thickness of this layer Organic Solderability neonychium is for being equal to or less than 20 microns.

15. the ball-establishing method of BGA Package as claimed in claim 9, wherein, the material of those soldered balls comprises tin.

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