JPH1174311A - Semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite ball having an electrically and thermally matching coating layer, by forming a solder layer on an outermost surface of a copper core ball with a fluctuation in diameter of a specific range within a specific range to make the entire coating layer have a thickness equal to or more than specific value. SOLUTION: After a substrate is formed by plating a copper core ball having a diameter of 40 to 100 μm (a fluctuation of the diameter of ±5%) with Ni, electroless Sn plating of a predetermined thickness is applied thereon, and further PbSn, AgSn, ZnSn or the like is solder-plated, thereby forming an FC ball with a thickness of an entire coating layer of 6 μm or more. A resin plating basket is provided at a lower end of a plating jig 13, and its bottom is made to be a cathode 14. In addition, a three-dimensional vibrating motor 17 is provided at an upper end of the plating jig 13 to apply three-dimensional vibration to the plating basket 15, thereby suppressing the copper core ball being aspherical. Thus, a coating ball having an electrically and thermally matching coating layer can be obtained without largely modifying a conventional mounting device and a system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor package and a method of manufacturing the same, and more particularly, to an area array terminal type semiconductor package represented by a ball grid array (BGA) and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the trend toward higher performance and higher density of electronic information equipment, that is, portability, has become more rapid. As a key technology supporting this, the importance of surface mounting of electronic components and semiconductor chips is increasing more and more.

A conventional quad flat package (QF
The shift from P) to an area array terminal type package represented by BGA is abrupt. Moreover, in the same flow,
Practical use of the tip size package (CSP) has also made great progress.

[0004] Internal electrodes, that is, a chip and a substrate (for example,
At present, connection terminals of the interposer are formed as flip-chip (hereinafter referred to as FC) connections by welding and cutting wires of solder, gold, or a gold alloy. Furthermore, more conventionally, wire bonding (hereinafter referred to as WB)
), But the demand for higher packing density has been severely limited.

[0005] By the way, it is known that FC connection has advantages such as an increase in the number of I / Os and low inductance as compared with WB. However, on the other hand, various reliability issues have emerged, and practically speaking, the electrical performance of the connection terminals has been secured, and in addition, a semiconductor package that is reliable against heat cycles during mounting has been constructed. Is required.

In the BGA CSP, 200-37
Pin 0 covers almost the region where the external operating frequency is 60 to 155 MHz.

[0007]

[Problems to be Solved by the Invention] However, the above-mentioned problems are inherent, and as the size of the device itself is further reduced in the future, higher packing density is required and further measures for signal delay and noise are needed. I can't.

In connection with internal electrodes at 800 to 1000 pins or more and an external operation frequency of 250 to 300 MHz or more according to the conventional display method, the conventional FC connection is insufficient.

C4 with the most reliable ball bump
In connection (Controlled Collapse Chip Connection),
Since most of the connection is made by soldering, the connection length cannot be maintained with high accuracy, and it is said that the connection length substantially varies from 5 to 15 μm. In addition, solder cracking or peeling during a heat cycle cannot be said to be sufficient due to embrittlement due to an alloying reaction with a pad or a core ball on the element side.

On the other hand, in the method using gold or a gold alloy, the connection length cannot be maintained with high accuracy, and the plating performed to ensure the connection or welding of the pad and the periphery is rather brittle as described above. In many cases, an alloying reaction that causes

However, the properties required of the core ball are as follows:
High-precision core ball, connection with elements and substrate can use conventional mounting machines and systems, at least the outermost layer is a solder layer, and alloying reaction with core ball and pad It is required that the material be a material that is unlikely to occur, that it has rolling properties, and that there is little adhesion between balls. In addition, it is essential to develop a reliable coating method with excellent mass productivity.

Furthermore, the coating layer having a solder layer with respect to the core ball is made of a material constituting the coating layer, and has a thickness (equal to or less than 5 μm, which is stable in assembling into a package) that can maintain easy connection and mass production stability. Anxious about the connection itself,
Further, the amount of the coating layer material that is sufficiently stable is preferably 10 μm or more, and of course, if it is 25 μm or more, the connection pitch interval in high-density mounting cannot be stably obtained, and it is practically meaningless.) Accuracy is essential.

This method cannot be handled with the conventional method using the BGA ball with the external electrode at the ball size (300 to 800 μm), and the plating technique is extremely difficult. Sticking to a simple process does not help.

Therefore, a technical problem of the present invention is to provide a composite ball formed by applying a coating layer that is electrically and thermally compatible so that a conventional mounting machine and system can be used as a FC ball without major changes. You can get it,
An object of the present invention is to provide a semiconductor package and a method of manufacturing the semiconductor package which are reliable against heat cycles by using the semiconductor element and others as bonding terminals, particularly internal electrodes.

[0015]

According to the present invention, a semiconductor package having a semiconductor element mounted thereon has a diameter of 0.3 mm.
Composed of a composite ball having a solder layer on the outermost skin of a core ball made of copper having a diameter of 04 to 0.1 mm and having a diameter variation within ± 5% of the diameter, and having a total coating layer thickness of 6 μm or more. Thus, a semiconductor package characterized by the following is obtained.

Further, according to the present invention, in the semiconductor package, a thickness of the entire coating layer is at least 10 μm.

Further, according to the present invention, in the semiconductor package, the coating layer is formed on the first side of the core ball.
A composite ball having a base layer as a layer, tin or an alloy plating layer containing tin as a main component as a second layer on the base layer, and a solder layer as a third layer on the second layer. Thus, a semiconductor package characterized by the following characteristics is obtained.

Further, according to the present invention, in the semiconductor package, the ratio of the diameter of the composite ball having the coating layer to the core ball is 1.1 or more. Can be

According to the invention, in the semiconductor package, the solder constituting the solder layer is made of PbS
n, CuSn, AgSn, SnZn, SnBi, Sn,
And a semiconductor package comprising at least one of Bi and Bi.

Furthermore, according to the present invention, in a method of manufacturing a semiconductor package on which a semiconductor element is mounted, a diameter of 0.04 to 0.1 mm and a variation of a diameter of ± 5 mm
% Of a copper ball having an electrically and thermally compatible coating layer having a solder layer on the outermost surface of a core ball made of copper within the range of a heat cycle as a connection terminal for joining the semiconductor element and others. On the other hand, a semiconductor package manufacturing method characterized by assembling into a reliable semiconductor package is obtained.

Specifically, in the present invention, first, the structure of the coating layer of the core ball made of copper (hereinafter, referred to as copper core ball) is made of nickel as an underlayer to suppress the reactivity of the copper as the core ball. Is coated with 1-3 micron electroplating.

Next, the thickness of the desired coating layer is approximately 2 to 10 μm by electroless tin plating, which is secondly held in the prior art.
Thick plating. Electroless tin plating (Patent No. 16238)
No. 69) resolves the adhesion of copper core balls by electric solder plating and solves the consistency of the entire plating process, which is important for securing the thickness of the entire coating layer.

Third, a solder plating of 2 to 5 μm
The total thickness is 6 μm or more, more preferably 10 μm or more, which enables more stable and easy joining. The coating layer obtained in this way has good rolling properties because it can provide a composite ball with electrical and thermal compatibility and stable film formation that can be practically used.

Here, the solder of the present invention may be selected from substantially possible materials in consideration of the melting point, reactivity, and the like.
The main components are PbSn, CuSn, AgSn, SnZn, S
A solder made of at least one of nBi, Sn, and Bi is used, and plating is performed by using the solder.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a semiconductor package according to an embodiment of the present invention. Referring to FIG. 1, a semiconductor package 1 includes a semiconductor chip 5 mounted on a base 2 via a flip chip (FC) ball 2 made of a composite ball, and an FC between the base 2 and the semiconductor chip 5. The resin 4 to be filled including the ball 2 and the base 2 are, for example,
And a ball grid array (BGA) ball 6 for mounting on a printed wiring board.

In the embodiment of the present invention, the core ball used for the FC ball 2 or the like is basically made of copper from the viewpoint of good heat conduction, and can be mass-produced inexpensively even if the skin is plated. From the physical properties, tungsten (which is not preferable with a lower thermal conductivity) and the like can be sufficiently considered, but there are not many other options.

In order to manufacture a copper core ball (hereinafter, referred to as a copper core ball) according to the embodiment of the present invention, element balls obtained by a rotating plasma electrode method or an atomizing method by high pressure injection are subjected to precision sieving. And removing the defective ball by the image processing system.

In the above-described semiconductor package, the FC ball has a diameter of 40 due to the resin inflow during FC connection.
If it is less than μm, it is substantially difficult to assemble from the viewpoint of adhesion and various characteristics, and from the mounting level according to the embodiment of the present invention, it is required to be 100 μm or less.
Desirably, it is 60 μm or less. Further, if a solder layer is applied to the outermost skin of the core ball in a thickness of 2 to 5 μm, connection of the pad and the periphery or welding can be performed by a conventional apparatus or method.

The FC ball 2 shown in FIG.
An underlayer made of 1 μm Ni plating is formed on a μm copper core ball, and a 7 μm layer for securing a thickness is further formed thereon.
~ 20μm electroless Sn plating and PbS
n, AgSn, ZnSn, etc.

FIG. 2 is a diagram showing a schematic configuration of a solder plating apparatus for producing a solder coating layer of the FC ball 2 of FIG.
Referring to FIG. 2, about 80 l of a plating solution 19 is stored in a plating tank 11, and a pair of anodes 12 and a plating jig 13 are disposed between the pair of anodes 12. Plating jig 13
A plating basket 15 made of resin is provided at the lower end of the plating basket 15, and the bottom of the plating basket 15 is a cathode 14. A three-dimensional vibration motor 17 for applying three-dimensional vibration to the resin plating basket 15 is provided at the upper end of the plating jig 13. Plating basket 15
Inside, a copper core ball work is inserted. Cathode 14 and anode 12 are each electrically connected to a rectifier 18,
It is configured to allow current to flow.

In the embodiment of the present invention, the most important point is a technique of forming a solder coating layer on a copper core ball by plating, which is obtained as a result of trial and error of various tests and combinations of materials. It is. Needless to say, the coating layer obtained by the embodiment of the present invention is much thicker than the layer thickness obtained by ordinary plating or the like, so that it is difficult by a dry method or the like, and it is practically impossible in terms of cost.

In the solder plating, even if the plating thickness is 5 μm or less during the growth of the plating layer, not only the adhesion of the microspheres occurs, but also the unevenness of the growth rate leads to the formation of a warped layer. It becomes non-spherical enough not to roll. In general, the film is formed by the use of an impeller (agitating blades with blades) or a particle suspension using a diaphragm. In this method, the above-mentioned disadvantage of non-spherical shape was not avoided.

In the embodiment of the present invention, the problem of the non-spherical shape of the copper core ball is solved by using a plating apparatus using a plating jig 13 provided with a three-dimensional vibration motor that moves three-dimensionally during plating. did.

In addition, by setting the number (concentration) of copper core balls in a predetermined liquid volume to be extremely higher than that of the conventional one, a stable film could be obtained.

The composite ball made of the copper core ball provided with the solder coating layer on the surface according to the embodiment of the present invention obtained by the above-described method is used as the FC ball 2 shown in FIG. Can be used without major changes, and a coated ball with an electrically and thermally compatible coating layer can be obtained, and the composite ball can be used as a bonding terminal, especially as an internal electrode, with a semiconductor element and others. It can be assembled into a semiconductor package that is reliable for heat cycles. This package can be a CSP,
Compatibility as a package, ease of mounting, KGD (Kn
It has the characteristic of own good die, which can be used especially for equipment in the general consumer field, and has the advantage that practical application can be greatly expected.

Hereinafter, a specific example of manufacturing a semiconductor package according to the embodiment of the present invention will be described.

(First Embodiment) After pre-treating approximately 5 million balls of precisely classified copper core balls (49 to 53 μm),
Using a Watt bath, undercoat Ni plating was performed at 0.5 A for 120 minutes using the apparatus shown in FIG. Plating thickness is 0.5-1.5
μm. Next, electric solder plating was performed in a commercially available organic acid solder plating bath at 0.5 A for 400 minutes. The plating thickness was 9 to 13 μm. However, approximately 10% of the balls adhered to each other, and a desired composite ball was obtained by classification. It was recognized that almost the entire amount rolled steadily with a slight inclined plate.

(Second Embodiment) In the same processing as in the first embodiment, after the base Ni plating and immersion in an electroless tin plating bath, 0.1 A for 60 seconds using the apparatus of FIG. After electrolysis (forming tin nuclei), the current was turned off and the temperature was reduced to 70 ° C.
For 3 hours. Plating thickness is 4 ~
It was 6 μm. Next, with an electric solder plating solution, 0.5
A was used for plating for 150 minutes using the same apparatus. Total plating thickness of electroless tin plating and solder plating is 7
A plating of about 11 μm was obtained, and each composite ball had no adhesion and no irregular shape. In the second embodiment, the same rolling performance as in the first embodiment was obtained.

(Third Embodiment) A copper core ball having a diameter of 83 to 88 μm similar to that of the first embodiment is shown in FIG.
Was subjected to Ni plating at 0.5 A for 60 minutes. The plating thickness was 0.8 to 1.0 μm. Then, electrosolder plating (1.8A, 110A) was performed in a commercially available organic acid solder plating bath.
Min). The plating thickness was 3-4 microns.
Finally, Bi plating of about 1.2 to 1.8 μm for 1 A for 30 minutes was performed with an electric Bi plating solution, and the total plating thickness (thickness of all coating layers) was about 6 μm. No adhesion of composite balls was observed. In this case, a sealing resin having a higher melting point than that used in the above-described embodiment and the like is required. Further, in order to make the resin smaller for expansion, the Bi-skin is used and the solder at the tip is also tin-rich.

According to the third embodiment, the first embodiment
In addition, the same rolling performance as that of the second embodiment was obtained, and the assembling was successfully performed.

The material of the solder is not limited to the above embodiment, although embrittlement due to alloy formation is taken into consideration.
If the concentration of the liquid in the ball is low, the film formation is rather uneven and not good. The heat cycle was determined by repeating heating / cooling by energizing / driving ON / OFF in order to inspect the performance of the element after joining these composite balls by heating or the like and then sealing the resin.

[0043]

As described above, the composite ball of the present invention can be used as an FC ball without using a conventional mounting machine and system without major changes, and is provided with an electrically and thermally compatible coating layer. Can be obtained. Moreover, the composite ball can be assembled into a semiconductor package that is reliable against heat cycles by using it as a bonding terminal, particularly an internal electrode, with a semiconductor element or the like.

This semiconductor package can be formed as a CSP, and has compatibility as a package, ease of mounting, and KGD.
(Known Good Die), which has the advantage that it can be used especially for equipment in the general consumer field, and that practical application can be greatly expected.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor package according to an embodiment of the present invention.

FIG. 2 is a view showing a schematic configuration of a solder plating apparatus for manufacturing a composite ball of the semiconductor package of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor package 2 Base 3 FC ball 4 Resin 5 Semiconductor chip 6 BGA ball 10 Solder plating apparatus 11 Plating tank 12 Anode 13 Plating jig 14 Cathode 15 Plating basket 16 Work 17 Three-dimensional vibration motor 18 Rectifier 19 Plating solution

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiko Doi 5--24-8 Higashi-Ueno, Taito-ku, Tokyo Inside Tokyo Tungsten Co., Ltd. -7 TOTEC Corporation

Claims (6)

[Claims] A semiconductor package having a semiconductor element mounted thereon has a solder layer on the outermost skin of a core ball made of copper having a diameter of 0.04 to 0.1 mm and a diameter variation of within ± 5% of the diameter, A semiconductor package comprising a composite ball having a coating layer having a total coating layer thickness of 6 μm or more. 2. The semiconductor package according to claim 1, wherein the thickness of the entire coating layer is 10 μm or more. 3. The semiconductor package according to claim 1, wherein the coating layer is formed of a base layer on the first layer on the core ball side, and tin or an alloy plating containing tin as a main component on a second layer on the base layer. A semiconductor package comprising a composite ball having a layer and a solder layer in a third layer on the second layer. 4. The semiconductor package according to claim 1, wherein a diameter ratio between the composite ball having the coating layer and the core ball is 1.1 or more. 5. The semiconductor package according to claim 1, wherein the solder constituting the solder layer is PbSn, CuS
A semiconductor package comprising at least one of n, AgSn, SnZn, SnBi, Sn, and Bi. 6. A method for manufacturing a semiconductor package on which a semiconductor element is mounted, wherein the diameter is 0.04 to 0.1 mm.
A composite ball formed by applying an electrically and thermally compatible coating layer having a solder layer on the outermost surface to a core ball made of copper having a diameter variation within ± 5% of the diameter of the semiconductor element and the like. A method for manufacturing a semiconductor package, comprising: assembling into a semiconductor package which is reliable to a heat cycle as a connection terminal to be joined to the semiconductor package.