KR20030010521A - Wiring board for mounting electronic parts and method for producing the wiring board - Google Patents

Abstract

PURPOSE: To provide a substrate for packaging electronic components and a method for manufacturing the same, capable of securing full wire bonding strength, even if gold plated layer made as thin possible. CONSTITUTION: The substrate for packaging the electronic component comprises an insulation substrate 11, a wiring pattern 12 formed on one side of the insulation substrate 11, a solder resist layer 16 for covering the surface except for a terminal section of the wiring pattern 12 with a nickel plated layer 22 and the gold plated layer 23 laminated on the surface of the terminal section. The nickel plated layer 22 is to be 3 μm or larger in thickness and larger than 350 in Vickers hardness.

Description

WIRING BOARD FOR MOUNTING ELECTRONIC PARTS AND METHOD FOR PRODUCING THE WIRING BOARD}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing an electronic component mounting substrate and an electronic component mounting substrate used for mounting an electronic component, in particular, a chip size package (CSP), a ball grid array (BGA), and a μ-BGA (μ). -An electronic component mounting substrate (hereinafter referred to simply as an electronic component mounting substrate) having a size almost the same as an electronic component to be mounted such as a ball grid array, FC (Flip® Chip), QFP (Quad Flatpack package), and the like. The manufacturing method of the board | substrate for electronic component mounting.

With the development of the electronics industry, the demand for printed wiring boards for mounting electronic components such as ICs (Integrated Circuits), LSIs (Large Integrated Circuits), etc. is rapidly increasing, and miniaturization, light weight, and high functionality of electronic devices are desired. As a method of mounting these electronic components, a mounting method using a TAB tape, a T-BGA tape, an ASIC tape, or the like has recently been adopted. In particular, in order to mount electronic components at higher densities and improve reliability of electronic components in accordance with lighter, shorter and shorter electronic devices, boards of a size substantially corresponding to the size of the electronic components to be mounted. The frequency of use of, for example, CSP, BGA, μ-BGA, etc., in which an external connection terminal is disposed almost in front of, is increasing.

The film carrier tape for electronic component mounting which becomes this board | substrate for electronic component mounting is manufactured as follows. That is, first, copper foil is affixed to insulating films, such as a polyimide film, for example, photoresist is apply | coated on the surface of this copper foil, and the parts other than the wiring pattern to form this photoresist are exposed, and the exposed Remove the photoresist. Subsequently, the copper foil of the part from which the photoresist was removed is removed by etching, and a wiring pattern is formed again by removing a photoresist.

In this way, the solder resist which becomes a protective layer of a circuit is apply | coated to the film carrier tape for electronic component mounting which formed the wiring pattern except terminal parts, such as an inner lead, an outer lead, and a solder ball terminal. Moreover, after apply | coating a soldering resist, a plating layer is formed in the terminal part which is an exposed part.

Here, a nickel plating layer and a gold plating layer are given to the terminal part connected to an electronic component etc. by wire bonding. Moreover, in order to ensure sufficient bonding strength, generally, a nickel plating layer is formed in thickness of 0.01-1 micrometer, and a gold plating layer has a thickness of 0.7-1. It is formed at 3 μm.

However, in such an electronic component mounting board, it is desired to make the gold plating layer thin for cost reduction, but there is a problem that sufficient wire bonding strength cannot be obtained if the gold plating layer has a thickness of 0.7 µm or less.

In view of such circumstances, an object of the present invention is to provide a method for manufacturing an electronic component mounting substrate and an electronic component mounting substrate that can secure sufficient wire bonding strength even if the gold plating layer is as thin as possible.

(Means to solve the task)

The 1st aspect of this invention which solves the said subject is provided with the insulating base material, the wiring pattern formed in one side of this insulating base material, and the soldering resist layer which coats the surface except the terminal part of this wiring pattern, The said terminal part In the electronic component mounting board | substrate with which the nickel plating layer and the gold plating layer are laminated | stacked on the surface of this, the said nickel plating layer is a board | substrate for electronic component mounting characterized by having a thickness of 3 micrometers or more and Vickers hardness of 350 or more.

In this first aspect, the wire bonding strength can be increased, and sufficient wire bonding strength can be obtained even if the gold plating layer is thinned, for example, to 0.5 µm or less.

In a second aspect of the present invention, in the first aspect, the surface roughness Rz of the nickel plating layer is in the range of 1 to 3 µm.

In this second aspect, the wire bonding strength can be increased, and sufficient wire bonding strength can be obtained even if the gold plating layer is thinned, for example, to 0.5 µm or less.

According to a third aspect of the present invention, in the first aspect, the thickness of the gold plating layer is 0.5 µm or less.

In such a third aspect, the gold plating layer can be made thinner than 0.5 µm, and the cost can be reduced.

According to a fourth aspect of the present invention, in the second aspect, there is provided a substrate for mounting electronic components, wherein the gold plating layer has a thickness of 0.5 µm or less.

In this fourth aspect, the gold plating layer can be made thinner to 0.5 µm or less, and the cost can be reduced.

A fifth aspect of the present invention is the substrate for mounting electronic components, wherein the thickness of the gold plating layer is 0.3 µm or less in any one of the first to fourth aspects.

In this fifth aspect, the gold plating layer can be thinned to 0.3 µm or less, and the cost can be reduced.

A sixth aspect of the present invention includes an insulating substrate, a wiring pattern formed on one side of the insulating substrate, and a solder resist layer covering a surface except the terminal portion of the wiring pattern, wherein the surface of the terminal portion is a nickel plated layer. And a method for producing a substrate for mounting electronic components in which a gold plating layer is laminated, the method comprising forming the nickel plating layer with a thickness of 3 µm or more and Vickers hardness of 350 or more, and forming the gold plating layer thereon. The manufacturing method of the board | substrate for electronic component mounting characterized by the above-mentioned.

In this sixth aspect, the wire bonding strength can be increased, and sufficient wire bonding strength can be obtained even if the gold plating layer is thinned, for example, to 0.5 µm or less.

According to a seventh aspect of the present invention, in the sixth aspect, after the nickel plating layer is formed, the surface is treated to provide a surface roughness Rz of 1 to 3 µm. It is a manufacturing method of the board | substrate.

In this seventh aspect, the wire bonding strength can be increased, and sufficient wire bonding strength can be obtained even if the gold plating layer is thinned, for example, to 0.5 µm or less.

In an eighth aspect of the present invention, in the sixth aspect, the gold plating layer is formed to a thickness of 0.5 µm or less, which is a method for manufacturing an electronic component mounting substrate.

In this eighth aspect, the gold plating layer can be made thinner to 0.5 µm or less, and the cost can be reduced.

In a ninth aspect of the present invention, in the seventh aspect, the gold plating layer is formed with a thickness of 0.5 µm or less, which is a method for manufacturing an electronic component mounting substrate.

In this ninth aspect, the gold plating layer can be made thinner to 0.5 µm or less, and the cost can be reduced.

10th aspect of this invention is a manufacturing method of the board | substrate for electronic component mounting in any one of Claims 6-9 which forms the thickness of the said gold plating layer to 0.3 micrometer or less. have.

In this tenth aspect, the gold plating layer can be thinned to 0.3 mu m or less, and the cost can be reduced.

1 is a schematic plan view showing an example of a board for mounting electronic components according to an embodiment of the present invention;

2 is a schematic cross-sectional view showing an example of a board for mounting electronic components according to one embodiment of the present invention;

3 is a schematic cross-sectional view showing an example of an embodiment in which an electronic component is mounted on an electronic component mounting substrate according to one embodiment of the present invention;

4 is an explanatory diagram showing a method for measuring wire bonding strength between an electronic component mounting board and an electronic component according to one embodiment of the present invention;

(Explanation of the sign)

10 Board for mounting electronic components

11 Insulation Materials

12 Wiring Pattern

13 Device side connection terminal

14 External connection terminal

15 slits

19 adhesive layer

21 conductor

22 Nickel Plating Layer

23 gold plated layer

30 IC (Electronic Components)

31 bonding wire

33 Sealing resin

EMBODIMENT OF THE INVENTION Hereinafter, the board | substrate for electronic component mounting which concerns on one Embodiment of this invention, and its manufacturing method are demonstrated. 1 and 2 show schematic planes and cross sections showing an example of the electronic component mounting substrate of the present invention and the electronic component mounting substrate manufactured by the method for manufacturing the same.

As shown in FIG. 1, the board | substrate 10 for mounting electronic components is formed in multiple numbers on the tape-shaped insulating film 1 continuously. The insulating film 1 has sprocket holes 2 for transfer at both sides in the width direction at regular intervals, and in general, electronic components are mounted while being transferred, and after mounting electronic components, the substrate 10 for mounting electronic components 10 Are cut every time. 1, two electronic component mounting substrates 10 are provided in the width direction of the insulating film 1.

Such an electronic component mounting board 10 has a wiring pattern 12, a device side connection terminal 13, and an external connection on almost the entire surface of an insulating base 11 of a size substantially corresponding to the size of the electronic component to be mounted. The terminal 14 is provided. In addition, a plurality of slits 15 for connecting the wiring pattern 12 and electronic components are provided. Such a slit 15 is for electrically connecting the mounted electronic component and the wiring pattern 12 by wire bonding, and the shape and arrangement pattern are not particularly limited.

The wiring pattern 12 except for the device side connection terminal 13 and the external connection terminal 14 is covered with the solder resist layer 16 and the solder resist layer 16 corresponding to the external connection terminal 14. The terminal hole 17 is formed in this. In other words, the external connection terminal 14 becomes a solder ball pad and is connected to the outside via the solder ball. Of course, the board for electronic component mounting of the type which does not have a terminal hole and is connected to the outside by means other than a solder ball may be sufficient.

In addition, on the device side connection terminal 13 and the external connection terminal 14 which are not covered by the solder resist layer 16, the nickel plating layer 22 on the conductor foil 21 which forms the whole wiring pattern 12. ) And a gold plating layer 23 are provided. The structure of the nickel plating layer 22 and the gold plating layer 23 is suitable for the terminal which joins by wire bonding, and in this embodiment, it is necessary to provide it in the device side connection terminal 13 at least. In addition, another plating layer may be provided in the terminal which does not perform wire bonding, for example, the external connection terminal 14.

As the insulating film 1 (insulating base material 11), a material having flexibility and chemical resistance and heat resistance can be used. Polyester, polyamide, polyimide, etc. are mentioned as a material of this insulating film 1, Especially, the wholly aromatic polyimide which has a biphenyl skeleton (for example, brand name: Eupyrex; Ubegyo Co., Ltd.) Is preferred. Moreover, the thickness of the insulating film 1 is generally 25-125 micrometers, Preferably it is 25-75 micrometers.

The wiring pattern 12, the device side connection terminal 13, and the external connection terminal 14 provided on the surface of the insulating film 1 are generally formed by patterning a conductor foil made of copper or aluminum. Such a conductor foil may be directly laminated on the insulating film 1 or may be formed by thermocompression bonding or the like through an adhesive layer. The thickness of the conductor foil is, for example, 6 to 70 µm, preferably 8 to 35 µm. As the conductor foil, in view of copper foil, in particular, etching characteristics, operability, and the like, electrolytic copper foil is preferable.

In addition, without providing a conductor foil on the insulating film 1, for example, a polyimide precursor may be applied to the conductor foil and fired to form the insulating film 1 made of a polyimide film.

Moreover, the conductor foil provided on the insulating film 1 is patterned as the wiring pattern 12, the device side connection terminal 13, and the external connection terminal 14 by the photolithography method. That is, the photoresist material coating layer formed by applying the photoresist material coating liquid is patterned by exposure and development through a photomask, and chemically dissolved (etched) with the etching solution using the patterned photoresist material coating layer as a mask. The conductor foil is patterned by removing and resolving the photoresist with an alkali solution or the like again.

The solder resist material coating liquid is apply | coated to the conductor foil patterned in this way, and the soldering resist layer 16 is formed by predetermined patterning.

As a material for forming the solder resist layer 16, for example, a photosolder resist material is used. The photosolder resist material may be a negative type or a positive type, and may be one having a property of a general photoresist and a conductor foil. For example, a photoinitiator etc. are added to photosensitive resin, such as an acrylate resin, especially epoxy acrylate resin. Examples of the epoxy acrylate resins include bisphenol A type epoxy acrylate resins, novolac type epoxy acrylate resins, bisphenol A type epoxy methacrylate resins, and novolac type epoxy methacrylate resins. As the solder resist layer 16, a general solder resist material coating liquid which is applied only to a region required by screen printing technology and is thermally cured can be used.

In this way, the electronic component to be mounted is mounted on the surface (rear surface) on the opposite side of the insulating film 1 on which the wiring pattern 12, the device side connection terminal 13, the external connection terminal 14, and the solder resist layer 16 are provided. The adhesive layer 19 and the protective film 20 for temporarily fixing are provided. As such an adhesive layer 19, it is preferable to form using an adhesive which is thermosetting and elastic, and may be formed by apply | coating directly to a back surface, and may be formed using an adhesive tape. Moreover, the adhesive bond layer 19 does not need to be provided in the whole area | region which mounts an electronic component, You may provide it in a some area | region.

Here, the nickel plating layer 22 and the gold plating layer 23 laminated on the device side connection terminal 13 and the external connection terminal 14 of the wiring pattern 12 of the electronic component mounting substrate 10 will be described. do.

In the present invention, the nickel plating layer 22 and the gold plating layer 23 are formed using the same plating solution as in the prior art, and the plating method, plating conditions and the like are not particularly limited. That is, it may be formed by an electroless plating method or an electrolytic plating method, and can be formed to a desired thickness by adjusting the plating solution composition, applied voltage, current density, plating temperature and the like.

In addition, the gold plating layer 23 may be comprised only with gold, and the gold alloy containing gold as a main metal may be sufficient. In addition, the nickel plating layer 22 may be comprised only with nickel, and the nickel alloy containing nickel as a main metal may be sufficient as it. Sn-Ni, Co-Ni, etc. are mentioned as an example of the metal which can form this layer with nickel. In any case, however, the main metal forming the layer is preferably contained in an amount of at least 50% by weight, preferably at least 90% by weight, in the total of the metals forming the layer.

As a nickel plating bath which can form the nickel plating layer 22, a sulfamic-acid nickel bath etc. are mentioned, for example. Moreover, as a gold plating bath which can form the gold plating layer 23, cyan gold bath etc. are mentioned, for example.

In the present invention, the thickness and hardness of the nickel plated layer 22 formed as a base are important. The thickness of the nickel plating layer 22 is 3 micrometers or more, and hardness is set to Vickers hardness 350 or more. This is to secure the wire bonding strength sufficiently. Here, hardness can be adjusted by changing the density | concentration of the brightening agent in a plating liquid, for example.

In addition, it is preferable that the underlying nickel plating layer 22 is subjected to surface treatment after the plating layer is formed so that the surface roughness Rz is in the range of 1 to 3 µm. If it is larger than this, it is because the ultrasonic wave is less likely to be transmitted to the nickel-plated layer 22 when the wire is bonded, or the bonding strength is lowered. If smaller than this, the bonding strength with the gold plating layer is lowered, and the bonding strength is reduced. Is lowered, which is not preferable. The surface treatment method is not particularly limited, but can be adjusted by acid treatment such as hydrochloric acid.

In addition, the thickness of the gold plating layer 23 is not particularly limited, but by using the nickel plating layer 22 as described above, sufficient bonding strength can be obtained even if the thickness is 0.5 µm or less, or even 0.3 µm or less. have. Here, the bonding strength is said to be preferably 8 g or more, which is the cutting strength of the bonding wire generally used. Even if the gold plating layer 23 is thin as 0.2 µm by using the nickel plating layer described above, even more bonding strength is required. You can get In addition, when the gold plating layer 23 is thickened, stronger bonding strength can be obtained.

3 shows an example of a state in which an electronic component is mounted on such an electronic component mounting substrate 10. As shown in FIG. 3, the device-side connection terminal 13 formed on the surface of the IC 30 and the insulating film 1 as an electronic component mounted on the back surface of the insulating film 1 is connected via a bonding wire 31. The slit 15 including the bonding wire 31 and the device side connection terminal 13 are molded by the sealing resin 33. As a result, a conductive circuit between the IC 30 and the device side connection terminal 13 is ensured.

(Example)

Next, the present invention will be described in more detail based on Examples and Comparative Examples.

On the conductor foil 21 provided on the insulating base 11, a nickel plating layer 22 having different hardness, thickness, and surface roughness was provided, and a gold plating layer 23 having a thickness of 0.2 µm was provided thereon. . The hardness of the nickel plating layer was set to 400 and 350 in Examples, and 300 in the comparative example. Moreover, thickness was 4 micrometers and 3 micrometers in the Example, and was 2 micrometers in the comparative example. In addition, surface roughness Rz was 0.5 micrometer, 1 micrometer, 2 micrometers, 3 micrometers, and 4 micrometers.

The hardness of the nickel plating layer 22 was adjusted with the density | concentration of a brightening agent. In addition, surface roughness Rz was adjusted with the processing time by 30% hydrochloric acid.

In addition, the thickness of the plating layer was measured based on the fluorescent X-ray plating thickness measuring method (JIS H 8501).

On the gold plating layer 23 thus formed, a 25 µm gold wire 41 was joined by wire bonding. The wire bonding was made under the conditions of an ultrasonic output 1.26 W, application time 22 msec, weight 80 g, and stage temperature 160 degreeC using the apparatus made from Micro-Swiss.

In addition, as shown in FIG. 4, the bonding strength fixes the other end of the gold wire 41 bonded to the gold plating layer 23 to the fixed substrate 42 and pulls the hook 43 hooked on the gold wire 41. The weight was measured when the bonding portion with the gold plating layer 23 was peeled off or the gold wire 41 was cut off.

The results are shown in Table 1. In addition, in 8g or more of intensity | strength, the cutting | disconnection of the gold wire 41 is shown, and below, the peeling of the junction part with the gold plating 23 is shown.

As a result, when the nickel plating layer was Vickers hardness 350 or more and thickness was 3 micrometers or more, it turned out that sufficient bonding strength is obtained even if a gold plating layer is thin as 0.2 micrometer. Moreover, it turned out that 1-3 is suitable for the surface roughness Rz of a nickel plating layer, and bonding strength falls in 0.5 or 4 micrometers. Moreover, also in such a surface roughness, when the gold plating layer was thickened, it turned out that bonding strength improves and sufficient practical strength can be ensured.

As described above, the wire bonding strength can be improved by adjusting the thickness, hardness, and surface roughness of the nickel plated layer formed on the terminal portion of the wiring pattern, so that the thickness of the gold plated layer has been increased from 0.1 to 1. Even if it is thinner than 3 micrometers, the effect which can ensure sufficient wire bonding strength is achieved.

Claims (10)

An electronic substrate, comprising an insulating substrate, a wiring pattern formed on one side of the insulating substrate, and a solder resist layer covering the surface of the wiring pattern except for the terminal portion, wherein a nickel plating layer and a gold plating layer are laminated on the surface of the terminal portion. In the substrate for And the nickel plating layer has a thickness of 3 µm or more and Vickers hardness of 350 or more. The substrate for mounting electronic components according to claim 1, wherein the surface roughness Rz of the nickel plating layer is 1 to 3 µm. The board for mounting electronic components according to claim 1, wherein the gold plating layer has a thickness of 0.5 µm or less. The board for mounting electronic components according to claim 2, wherein the gold plating layer has a thickness of 0.5 µm or less. The board | substrate for mounting electronic components in any one of Claims 1-4 whose thickness of the said gold plating layer is 0.3 micrometer or less. An insulating base material, a wiring pattern formed on one side of the insulating base material, and a solder resist layer covering a surface except for the terminal part of the wiring pattern, wherein the nickel plated layer and the gold plating layer are laminated on the surface of the terminal part In the manufacturing method of the board for component mounting, And forming a nickel plating layer having a thickness of 3 µm or more and a Vickers hardness of 350 or more, and forming the gold plating layer thereon. The method for manufacturing an electronic component mounting substrate according to claim 6, further comprising a step of treating the surface thereof to form a surface roughness (Rz) of 1 to 3 µm after the nickel plating layer is formed. The method of manufacturing a substrate for mounting electronic components according to claim 6, wherein the gold plating layer is formed to a thickness of 0.5 탆 or less. The method of manufacturing an electronic component mounting board according to claim 7, wherein the gold plating layer is formed to a thickness of 0.5 탆 or less. The method for manufacturing an electronic component mounting board according to any one of claims 6 to 9, wherein the thickness of the gold plating layer is formed to be 0.3 µm or less.