JP2015076598A - Package substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package substrate.SOLUTION: A package substrate comprises: metal pads 110 formed atop an insulator substrate 100; a diffusion prevention layer 200 formed atop the metal pads 110; and a plating layer 300 formed atop the diffusion prevention layer 200.

Description

  The present invention relates to a package substrate, and more particularly, to a package substrate capable of improving the reliability between an electronic component bonded to the package substrate and a pad of the package substrate.

  In recent years, electronic products have been required to have various functions, and not only various functions but also miniaturization to facilitate carrying are required.

  Along with such a trend, ultra-small size, high integration, multiple functions, and high performance are also demanded for electronic components used in electronic products. One of the important technologies that make it possible to achieve such product development goals is the System In Package (SIP) technology.

  Such SIP technology is a technology for mounting electronic components such as a semiconductor die (Die) and a main board (Main board) on a package substrate in a vertical direction or a horizontal direction. In order to meet the demands of technological development, a technique of directly bonding a semiconductor chip to an insulating substrate by a flip chip method using a solder bump is used.

  At this time, the package substrate includes an insulating substrate and a pad formed on the insulating substrate, and can be electrically connected by bonding the pad and the semiconductor chip.

  When manufacturing such a package, a highly reliable fine pitch bonding technique is required, and in order to prevent a defect that the electronic component is dropped from the insulating substrate, a solder for connecting the electronic component and the insulating substrate is used. ) Interface is required to have high reliability.

  In particular, since the bump pitch (Pitch) decreases with the trend toward miniaturization, it is necessary to ensure the reliability between the electronic component and the insulating substrate.

  However, conventionally, the insulating substrate pad used a method of forming only a copper (Cu) or tin (Sn) plated metal pad without solder, but in the case of a copper pad, the copper pad disappears due to copper diffusion. A problem arises, and in the case of a tin plating pad, there arises a problem that whiskers are generated on the interface, and the reliability between the electronic component and the insulating substrate is lowered.

Korean open patent 2012-0050755

  An object of the present invention, which has been derived in order to solve the above-described problems, is to provide a package substrate that can ensure high reliability between an insulating substrate having a fine-pitch pad and an electronic component bonded to the insulating substrate. To do.

  In order to achieve the above object, a package substrate according to an embodiment of the present invention includes a metal pad formed on an insulating substrate, a diffusion prevention layer formed on the metal pad, and the diffusion prevention layer. And a plating layer formed on the upper part.

  Here, the diffusion preventing layer may be made of nickel (Ni) or an alloy material containing nickel (Ni).

  At this time, the diffusion prevention layer may be formed to a thickness of 0.01 to 5 μm.

  In addition, the diffusion prevention layer may be formed only on the upper surface of the metal pad.

  Meanwhile, the plating layer may be made of copper (Cu) or an alloy material containing copper (Cu).

  Here, the plating layer may be formed to a thickness of 0.01 to 5 μm.

  At this time, the plating layer may be formed only on the upper surface of the diffusion preventing layer.

  Furthermore, electronic components can be electrically connected to the upper portion of the plating layer by solder bumps.

  As described above, the package substrate according to the embodiment of the present invention prevents the disappearance of the metal pad by forming the diffusion prevention layer on the metal pad of the insulating substrate, and prevents the whisker from being generated. Accordingly, the reliability of the bonding between the insulating substrate and the electronic component can be improved.

It is sectional drawing which shows the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention. It is sectional drawing for showing the manufacturing process of the package board | substrate by embodiment of this invention.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, this is only an example, and the present invention is not limited to this.

  In describing the present invention, when it is determined that a specific description of a known technique related to the present invention may obscure the gist of the present invention, a detailed description thereof will be omitted. Further, the terms described later are terms defined in consideration of the function in the present invention, and this can be changed depending on the intention or custom of the user or the operator. Therefore, the definition should be based on the contents throughout this specification.

  The technical idea of the present invention is determined by the scope of the claims, and the following embodiments are merely one means for efficiently explaining the technical idea of the present invention to those who have ordinary knowledge in the technical field to which the present invention belongs. Absent.

  FIG. 1 is a cross-sectional view showing a package substrate according to an embodiment of the present invention, and FIGS.

  1 to 7, the package substrate according to the embodiment of the present invention includes a metal pad 110 formed on an insulating substrate 100 and a diffusion barrier formed on the metal pad 110. A layer 200 and a plating layer 300 formed on the diffusion barrier layer 200.

  The insulating substrate 100 serves as a support for forming the metal pad 110, the diffusion prevention layer 200, and the plating layer 300, and may be made of an insulating material. Here, as the insulating substrate 100, a fine circuit can be easily realized using ABF (Ajinomoto Build Up Film), or a package substrate can be thinly formed using a prepreg. However, the present invention is not limited to this, and it is made of a resin material such as an epoxy resin or a modified epoxy resin, a bisphenol A resin, an epoxy-novolak resin, an aramid reinforced glass fiber reinforced or paper reinforced epoxy resin. May be.

  A metal pad 110 may be formed on at least one surface of the insulating substrate 100. Here, the metal pad 110 may be made of copper (Cu), which is a metal having electrical conductivity. At this time, the metal pad 110 may be formed by electrolytic plating on a portion selected from a seed layer (not shown) formed on the insulating substrate 100 by electroless plating, and a diffusion prevention layer 200 described later. In addition, it is preferable to form a thicker layer than the plating layer 300.

  In addition, a solder resist 120 for protecting the insulating substrate 100 may be formed on both surfaces of the insulating substrate 100 other than the region where the metal pad 110 is formed.

  A diffusion barrier layer 200 may be formed on the metal pad 110 to prevent a copper diffusion phenomenon of the metal pad 110. Here, the diffusion preventing layer 200 can be formed by a nickel (Ni) electrolytic plating method. At this time, the diffusion prevention layer 200 may be made of only nickel (Ni) or an alloy of nickel (Ni) and P (phosphorus), B (boron), W (tungsten), or Co (cobalt). .

  Further, the diffusion prevention layer 200 may be formed to a thickness of 0.01 to 5 μm. This is because if the diffusion prevention layer 200 is formed to be thinner than 0.01 μm, the copper diffusion phenomenon of the metal pad 110 cannot be prevented, and if it is formed to be thicker than 5 μm, the package substrate This is because there is a problem that the overall thickness of the film becomes thick.

  In addition, the diffusion prevention layer 200 is formed only on the upper surface of the metal pad 110, thereby maintaining a fine pitch of the metal pad 110 and preventing a defect in which adjacent metal pads 110 are in contact with each other. can do.

  A plating layer 300 may be formed on the diffusion barrier layer 200. Here, the plating layer 300 can be made of copper (Cu), which is a metal having electrical conductivity, and can be formed on the diffusion prevention layer 200 by electrolytic plating. At this time, the plating layer 300 can be prevented from oxidizing the diffusion prevention layer 200 by being formed on the diffusion prevention layer 200. In addition, since the plating layer 300 is made of copper (Cu), the production cost of the package substrate can be reduced compared to the conventional method of plating gold (Au). Without adding a construction method, the electroplating method for forming the metal pad 110 can be performed again, thereby reducing the manufacturing cost and the lead time.

  In particular, the plating layer 300 is formed only on the upper surface of the diffusion prevention layer 200, thereby maintaining a fine pitch of the metal pads 110 and preventing defects between adjacent metal pads 110 contacting each other. can do.

  At this time, the plating layer 300 may be formed to a thickness of 0.01 to 5 μm. This is because, when the thickness of the plating layer 300 is less than 0.01 μm, as will be described later, when the electronic component 400 is joined to the upper portion of the plating layer 300 by the solder bump 500, the plating layer 300 is used. This is because the bonding strength between the solder bumps 500 and the solder bumps 500 is reduced, and when the thickness is larger than 5 μm, the entire thickness of the package substrate is increased.

  In particular, the thickness of the plating layer 300 and the diffusion prevention layer 200 may be formed so that the thickness of the plating layer 300 and the diffusion prevention layer 200 may be the same in order to improve the bonding strength between the solder bumps 500 or plating. The layer 300 is preferably formed to have a thickness greater than that of the diffusion preventing layer 200.

  An electronic component 400 may be bonded to the top of the plating layer 300. An electrode 410 made of a copper (Cu) material can be formed below the electronic component 400 for bonding to the plating layer 300, and a solder bump 500 is formed between the electrode 410 and the plating layer 300. Thus, the electronic component 400 can be electrically joined to the upper part of the plating layer 300.

  Here, the plating layer 300 is absorbed by the solder bumps 500 and combined with tin (Sn) which is the main component of the solder bumps 500 to form tin (Sn) -copper (Cu) or tin (Sn) -copper ( A Cu) -nickel (Ni) intermetallic compound (Intermetallic Compound, IMC) can be formed. At this time, by forming the diffusion prevention layer 200 below the plating layer 300, an intermetallic compound can be formed only in the plating layer 300.

  Further, when the electronic component 400 is joined to the upper part of the plating layer 300, the solder bump 500 is formed so as to cover the side surface of the plating layer 300 by the diffusion prevention layer 200 formed at the lower part of the plating layer 300. be able to.

  Accordingly, in the package substrate according to the embodiment of the present invention, the nickel (Ni) material diffusion prevention layer 200 and the copper (Cu) material plating layer 300 are sequentially formed on the copper (Cu) material metal pad 110. Thus, when the electronic component 400 is bonded by the solder bump 500, the diffusion prevention layer 200 prevents the metal pad 110 from diffusing and prevents the metal pad 110 from disappearing, and the whisker grows longer. This can be prevented, and the reliability of the solder bump 500 for joining the electronic component 400 can be improved.

  The manufacturing process of the package substrate according to the embodiment of the present invention configured as described above will be described as follows.

  First, as shown in FIG. 2, dry films 150 are formed on both surfaces of an insulating substrate 100 made of an insulating material. Here, the opening 151 can be formed by removing the region where the metal pad 110 is formed from the dry film 150. At this time, the dry film 150 is a means for preventing a portion other than a region where the metal pad 110 is formed when performing a plating process as a subsequent process, and sequentially performs exposure, development, and etching. The dry film 150 in which the opening 151 is formed can be formed by a photolithography method.

  Next, as shown in FIG. 3, a metal pad 110 may be formed. Here, the metal pad 110 may be made of a copper (Cu) material. At this time, the metal pad 110 can be formed by an electrolytic plating method, and can be formed by a fill plating method that fills the opening 151 of the dry film 150.

  Next, as illustrated in FIG. 4, the diffusion prevention layer 200 may be formed on the metal pad 110. Here, the diffusion preventing layer 200 can be made of nickel (Ni) or an alloy material containing nickel (Ni). At this time, the diffusion preventing layer 200 can be formed only on the upper surface of the metal pad 110 by performing an electroplating method in a state where the dry film 150 is not removed.

  Next, as shown in FIG. 5, a plating layer 300 can be formed on the diffusion prevention layer 200. Here, the plating layer 300 may be made of a copper (Cu) material. At this time, the plating layer 300 can be formed only on the upper surface of the diffusion prevention layer 200 by performing an electrolytic plating method in a state where the dry film 150 is not removed.

  Next, as shown in FIG. 6, the dry film 150 is removed.

  Further, as shown in FIG. 7, the electronic component 400 can be joined to the upper part of the plating layer 300 by the solder bump 500.

  At this time, the nickel (Ni) material diffusion prevention layer 200 is formed between the copper (Cu) material metal pad 110 and the plating layer 300 to prevent the metal pad 110 from diffusing and disappearing. The whisker can be prevented from growing, and the reliability of the electronic component 400 can be improved by the solder bump 500.

  As described above, the present invention has been described in detail with reference to the representative embodiments. However, those who have ordinary knowledge in the technical field belonging to the present invention can apply the scope of the present invention to the above-described embodiments. It will be understood that various modifications are possible without departing from the above.

  Therefore, the scope of rights of the present invention should not be limited to the above-described embodiments, but should be determined not only by the claims described later but also by the equivalents to the claims.

100 Insulating substrate 110 Metal pad 200 Diffusion prevention layer 300 Plating layer 400 Electronic component 500 Solder bump

Claims (8)

Metal pads formed on top of the insulating substrate;
A diffusion preventing layer formed on the metal pad;
And a plating layer formed on the diffusion prevention layer.   The package substrate according to claim 1, wherein the diffusion prevention layer is made of nickel (Ni) or an alloy material containing nickel (Ni).   The package substrate according to claim 2, wherein the diffusion prevention layer is formed to a thickness of 0.01 to 5 μm.   The package substrate according to claim 2, wherein the diffusion prevention layer is formed only on an upper surface of the metal pad.   The package substrate according to claim 2, wherein the plating layer is made of copper (Cu) or an alloy material containing copper (Cu).   The package substrate according to claim 5, wherein the plating layer is formed to a thickness of 0.01 to 5 μm.   The package substrate according to claim 5, wherein the plating layer is formed only on an upper surface of the diffusion prevention layer.   The package substrate according to claim 1, wherein an electronic component is electrically connected to the upper part of the plating layer by a solder bump.

Images