JPH10326965A - Manufacture of multilayered wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayered wiring board, wherein an electronic component such as a semiconductor element and a capacitance element can be rigidly connected with a bonding pad without changing the characteristics. SOLUTION: Organic resin insulating layers and thin film wiring conductor layers 3 are alternately laminated on a board, and the thin film wiring conductor layers 3 positioned in the upper part and the lower part are electrically connected via a through hole conductor formed on the organic resin insulating layers. A bonding pad 11 which is electrically connected with the thin film wiring conductor layer 3, and with which an electrode of an external electronic component is connected is formed in a hole 10 formed on an organic resin insulating layer 2a of the uppermost layer. A copper layer 13 is stuck on the bonding pad 11. Nonelectrolytic solder plating wherein solder is substituted for copper is performed to the copper layer 13, and the copper layer 13 is changed to a first solder layer 15. Finally, a second solder layer 16 is stuck on the first solder layer 15 by using an electrolytic plating method, and a solder bump is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board, and more particularly to a multilayer wiring board used for a hybrid integrated circuit device, a semiconductor element housing package for housing a semiconductor element, and the like.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board used for a hybrid integrated circuit device, a package for accommodating a semiconductor element, or the like, has its wiring conductor formed by a thick film forming technique such as the Mo-Mn method.

[0003] This Mo-Mn method is generally used for tungsten,
Organic solvents for high melting point metal powders such as molybdenum and manganese,
A solvent is added and mixed, and a paste-like metal paste is applied by printing on the outer surface of the green ceramic body in a predetermined pattern by a screen printing method. This is a method of sintering and integrating a metal powder and a green ceramic body.

The ceramic body on which the wiring conductor is formed is usually an oxide ceramic such as an aluminum oxide sintered body or a mullite sintered body, or an aluminum nitride having an oxide film deposited on the surface. Non-oxide ceramics such as a porous sintered body and a silicon carbide sintered body are used.

However, when the wiring conductor is formed by using the Mo-Mn method, the wiring conductor is formed by screen-printing a metal paste. Had the drawback that it could not be done.

In order to solve the above-mentioned drawbacks, a multi-layer wiring board formed using a thin film forming technique capable of miniaturization instead of forming the wiring conductor by the conventional thick film forming technique is used. It has become.

A multilayer wiring board in which such wiring conductors are formed by a thin film forming technique is provided on a substrate made of a glass epoxy resin or the like formed by impregnating a cloth woven with a bismaleimide triazine resin or glass fiber with an epoxy resin. Adopt organic resin insulation layer made of epoxy resin formed by spin coating method and thermosetting treatment, and thin film forming technology such as electroless plating and vapor deposition of metal such as copper and aluminum, and photolithography technology. And the thin film wiring conductor layers formed by the above are alternately laminated, and the upper and lower thin film wiring conductor layers are electrically connected via the through-hole conductors attached to the inner walls of the through holes provided in the organic resin insulating layer. Having a connection structure, and a bonding pad electrically connected to the thin film wiring conductor layer on the upper surface of the uppermost organic resin insulating layer. Forming a Ingupaddo advance, so as to connect through the active component, a capacitor such as a semiconductor element, the passive components of the electrode of the resistor such as solder on the bonding pads.

The connection between the bonding pad of the multilayer wiring board and the electrode of the electronic component is performed by forming a bump made of solder in advance on the surface of the bonding pad and the electrode surface of the electronic component, and connecting the bonding pad of the multilayer wiring board to the bonding pad. This is performed by bringing the solder bumps of the electronic component into contact with the solder bumps that have been applied, and then subjecting the solder bumps to heat treatment to melt both solder bumps.

Also, the method of applying solder bumps to the bonding pad surface of the multilayer wiring board is disclosed in
No. 6196, specifically, first, a solder resist is applied onto the uppermost organic resin insulating layer on which the bonding pads are formed, leaving the bonding pads, and then the solder resist is applied. A copper layer is applied on the surface and the surface of the bonding pad by a chemical plating method, and the copper layer applied on the solder resist surface is covered with a plating resist, and then on the copper layer applied on the bonding pad. This is performed by depositing solder by electrolytic plating and finally removing the copper layer deposited on the surfaces of the plating resist and the solder resist.

[0010]

However, in the above-described multilayer wiring board, the solder bumps attached to the bonding pads are formed by applying a solder to the surface of a copper layer formed by a chemical plating method by an electrolytic plating method. When the solder bumps are heated and melted to connect the bonding pads of the multilayer wiring board to the electrodes of the electronic component, the underlying copper diffuses into the solder, increasing the melting point of the solder bumps and increasing the solder bumps. The mechanical strength of the bumps is weakened, and as a result, the heat of heating and melting the solder bumps changes the characteristics of the electronic components, causing the electronic components to malfunction and after connecting the electronic components to the bonding pad When an external force is applied to the electronic component, the external force may damage the solder connecting the bonding pad and the electronic component. Occurs, has the disadvantage that the reliability of connection to the bonding pads of the electronic components is significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to provide a multilayer wiring board capable of firmly connecting electronic components such as semiconductor elements and capacitance elements to bonding pads without causing a change in characteristics. It is to provide a manufacturing method of.

[0012]

According to the present invention, there is provided a through-hole in which an organic resin insulating layer and a thin film wiring conductor layer are alternately laminated on a substrate, and thin film wiring conductor layers positioned vertically above and below are provided in the organic resin insulating layer. Electrically connected through conductors,
And a multilayer wiring board in which a bonding pad electrically connected to the thin film wiring conductor layer and an electrode of an external electronic component is formed in a hole provided in the uppermost organic resin insulating layer. A solder bump is applied to the bonding pad by the following steps (a) to (f).

(A) The surface roughness of the upper surface of the uppermost organic resin insulating layer and the inner surface of the hole is defined as a center line average roughness (Ra) of 0.0
A step of performing a roughening treatment so that 5 μm ≦ Ra ≦ 5 μm; and (b) a bonding pad exposed in the upper surface and the inner surface of the hole of the roughened organic resin insulating layer and in the hole of the organic resin insulating layer. (C) coating a copper layer on the upper surface of the uppermost organic resin insulating layer with a plating resist film, and A) performing electroless solder plating by replacing copper with solder on the copper layer adhered to the inner surface of the hole provided in the uppermost organic resin insulating layer and the surface of the bonding pad exposed in the hole; Applying a first solder layer instead of a copper layer, and (e) electrolytically forming the first solder layer and the copper layer covered with a plating resist film on the surface of the first solder layer as electrode wires. A step of applying a second solder layer by a plating method; Removing the copper layer deposited on the upper surfaces of the plating resist film and the uppermost organic resin insulating layer.

According to the method of manufacturing a multilayer wiring board of the present invention, a copper layer is deposited on a bonding pad, and then the copper layer is subjected to electroless solder plating by replacing copper with solder. To a first solder layer, and finally, a second solder layer is applied on the first solder layer by electrolytic plating to form a solder bump on a bonding pad.
There is no copper that raises the melting point of the solder on the base of the second solder layer and weakens the mechanical strength, and only the same solder as the second solder layer exists, so that the solder bump is maintained at a low melting point, In addition, the mechanical strength is maintained to be tough. Therefore, in this multilayer wiring board, when the solder bump is heated and melted to connect the bonding pad to an electrode such as a semiconductor element or a capacitor element, the characteristics of the electronic component change due to the low heat melting temperature of the solder bump. Can be connected to the bonding pad without any damage. Also, after connecting the electronic component to the bonding pad at the same time, even if an external force is applied to the electronic component, the solder connecting the bonding pad and the electronic component has toughness, and thus is damaged. This is very rare, and the reliability of the connection of the electronic component to the bonding pad is extremely high.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a multilayer wiring board according to the present invention, wherein 1 is a substrate, 2 is an organic resin insulating layer, and 3 is a thin-film wiring conductor layer.

The substrate 1 has an organic resin insulating layer 2 on its upper surface.
And a thin-film wiring conductor layer 3, and a multilayer wiring portion 4 is provided, and functions as a support member for supporting the multilayer wiring portion 4.

The substrate 1 is made of an oxide ceramic such as an aluminum oxide sintered body or a mullite sintered body, or a non-conductive body such as an aluminum nitride sintered body or a silicon carbide sintered body having an oxide film on the surface. Oxide ceramics, and further made of an electrically insulating material such as glass epoxy resin impregnated with epoxy resin in a cloth woven with glass fiber, for example, when formed of aluminum oxide sintered body , Alumina, silica, calcia, magnesia, etc., an appropriate organic solvent and a solvent are added and mixed to form a slurry, and the ceramic green sheet is formed by employing a conventionally known doctor blade method or calendar roll method. Ceramic green sheet), and after that, the ceramic green sheet is subjected to an appropriate punching process to obtain a predetermined shape. Hot together form (about 1600
C) or by mixing a raw material powder such as alumina with an appropriate organic solvent and solvent to adjust the raw material powder and form the raw material powder into a predetermined shape by a press molding machine. If the body is made by firing the body at a temperature of about 1600 ° C. and is made of glass epoxy resin, for example, a cloth woven with glass fiber is impregnated with the epoxy resin precursor and the epoxy resin precursor is heated to a predetermined temperature. It is manufactured by heat curing.

The substrate 1 is formed with a through hole 5 having a diameter of, for example, 300 μm to 500 μm, which penetrates the upper and lower surfaces of the substrate 1. Layer 6 has been applied.

The through hole 5 electrically connects the thin-film wiring conductor layer 3 of the multilayer wiring portion 4 formed on the upper surface of the substrate 1 and an external electric circuit to be described later, or the multilayer wiring portion is formed on both upper and lower surfaces of the substrate 1. When the substrate 1 is formed, it acts as a forming hole for forming a conductive layer 6 for electrically connecting the thin film wiring conductor layers of the multilayer wiring portion 4 on both surfaces, and the substrate 1 is subjected to a drilling method. Thereby, a predetermined shape is formed at a predetermined position on the substrate 1.

The conductive layer 6 formed on the inner wall of the through-hole 5 and on the upper and lower surfaces of the substrate 1 is made of a metal material such as copper or nickel, and employs well-known plating and etching methods. As a result, it is formed on the inner wall of the through hole 5 with both ends being led out to the upper and lower surfaces of the substrate 1.

On the upper surface of the substrate 1, a multilayer wiring portion 4 formed by alternately arranging an organic resin insulating layer 2 and a thin film wiring conductor layer 3 in multiple layers is attached. 4
The organic resin insulating layer 2 has a function of electrically insulating the thin film wiring conductor layers 3 located above and below, and the thin film wiring conductor layer 3 functions as a transmission path for transmitting electric signals.

The organic resin insulating layer 2 of the multilayer wiring section 4
It is made of an organic resin such as an epoxy resin, a bismaleimide triazine resin, a polyphenylene ether resin, and a fluorine resin. And a curing agent such as an imidazole-based curing agent and an acid anhydride-based curing agent are added and mixed to obtain a paste-like epoxy resin precursor, and the epoxy resin precursor is applied to the upper portion of the substrate 1 by spin coating. After that, this is heated to 80-200 ° C.
Is formed by heat-treating with heat of 0.5 to 3 hours.

Further, the organic resin insulating layer 2 of the multilayer wiring section 4
Has a through hole 8 having a minimum diameter of about 1.5 times the thickness of the organic resin insulating layer 2 at each predetermined position.
And serves as a forming hole for forming a through-hole conductor 9 for electrically connecting each of the thin-film wiring conductor groups 3 located above and below via.

The through hole 8 provided in the organic resin insulating layer 2 is formed in the organic resin insulating layer 2 to have a predetermined diameter by employing a conventionally known photolithography technique.

A thin-film wiring conductor layer 3 having a predetermined pattern is provided on the upper surface of each organic resin insulating layer 2, and a through-hole conductor 9 is provided on the inner wall of a through hole 8 provided in each organic resin insulating layer 2. Each of the thin-film wiring conductor layers 3 located above and below the organic resin insulating layer 2 with the through-hole conductor 9 therebetween is electrically connected.

The thin-film wiring conductor layer 3 and the through-hole conductor 9 disposed on the upper surface of each of the organic resin insulating layers 2 and the inner wall of the through-hole 8 are made of a metal material such as copper, nickel, gold, or aluminum by electroless plating. For example, in the case of being formed of copper, the upper surface of the organic resin insulating layer 2 and the inner surface of the through hole 8 are formed by employing a thin film forming technique such as a vapor deposition method or a sputtering method and a photolithographic technique. 0.06 mol / l copper sulfate, 0.3 mol / l formalin, 0.35 sodium hydroxide
Mol / liter, and an electroless copper plating bath consisting of 0.35 mol / liter of ethylenediaminetetraacetic acid.
A copper layer having a thickness of m to 40 μm is applied, and then the copper layer is processed into a predetermined pattern by photolithography technology to be disposed between the organic resin insulating layers 2 and on the inner wall of the through hole 8. In this case, the thin film wiring conductor layer 3
In addition, since the through-hole conductor 9 is formed by a thin-film forming technique, it is possible to miniaturize the wiring, whereby the thin-film wiring conductor layer 3 can be formed at an extremely high density.

The multilayer wiring portion 4 formed by alternately arranging the organic resin insulating layers 2 and the thin film wiring conductor layers 3 in a multilayer structure has a center line average roughness (upper surface) of each organic resin insulating layer 2. R
If a rough surface of 0.05 μm ≦ Ra ≦ 5 μm is set in a), the bonding between the organic resin insulating layer 2 and the thin film wiring conductor layer 3 and the bonding between the organic resin insulating layers 2 located above and below can be made strong. . Accordingly, the upper surface of each organic resin insulating layer 2 of the multilayer wiring portion 4 is roughened by an etching technique or the like, and the center line average roughness (Ra) is 0.05 μm ≦ Ra ≦ 5.
It is preferable that the surface be roughened to a thickness of μm.

The count value of the height (Pc) of the unevenness at a length of 2.5 mm on the surface of the organic resin insulating layer 2 is 500 or more for 1 μm ≦ Pc ≦ 10 μm.
2500 μm of 1 μm ≦ Pc ≦ 1 μm, 0.01 μm
If ≦ Pc ≦ 0.1 μm is set to 12,500 or more, the bonding between the organic resin insulating layer 2 and the thin-film wiring conductor layer 3 and the bonding between the organic resin insulating layers 2 located above and below become stronger. Therefore, the organic resin insulating layer 2 has a thickness of 2.5
The count value of the height (Pc) of the unevenness in the length of mm is 1 μm ≦ Pc ≦ 10 μm.
2500 or more m ≦ Pc ≦ 1 μm, 0.01 μm ≦ P
It is preferable that c ≦ 0.1 μm is set to 12,500 or more.

The count value of the center line average roughness (Ra) of the upper surface of the organic resin insulating layer 2 and the height of the unevenness (Pc) at a length of 2.5 mm are obtained by measuring the surface of the organic resin insulating layer 2 with an atomic force. Microscope (Dimensio manufactured by Digital Instruments Inc.
n 300-Nano Scope III)
m), the surface condition was inspected and measured, and each numerical value was obtained from the measurement result.

The center line average roughness (Ra) is 0.0
5 μm ≦ Ra ≦ 5 μm, the count value of the height of unevenness (Pc) at a length of 2.5 mm is 1 μm ≦ Pc ≦ 10 μm
m is 500 or more, and 0.1 μm ≦ Pc ≦ 1 μm is 250
0 or more, 0.01 μm ≦ Pc ≦ 0.1 μm is 1250
Zero or more organic resin insulating layers 2 are subjected to a reactive ion etching process by blowing a gas such as CHF ₃ , CF ₄ , Ar, etc. onto the upper surface of the organic resin insulating layers 2, whereby the surface is roughened to a predetermined roughness. Is done.

Further, when the thickness of each of the organic resin insulating layers 2 exceeds 100 μm, the etching processing time becomes long when the through holes 8 are formed by adopting the photolithography technology for the organic resin insulating layers 2. It is difficult to form the through hole 8 into a desired clear shape, and if the thickness is less than 5 μm, rough surface processing for increasing the bonding strength of the organic resin insulating layer 2 located above and below the organic resin insulating layer 2 is performed. When applying, there is a risk that an unnecessary hole is formed in the organic resin insulating layer 2 and an unnecessary electrical short circuit is caused in the thin film wiring conductor layer 3 which is vertically shifted. Accordingly, the organic resin insulating layer 2 has a thickness of 5 μm to 100 μm.
It is preferable to set the range of m.

Further, when the thickness of each thin-film wiring conductor layer 3 of the multilayer wiring portion 4 is less than 1 μm, the electric resistance of each thin-film wiring conductor layer 3 becomes large and a predetermined value is applied to each thin-film wiring conductor layer 3. It is difficult to transmit the electric signal of
If the thickness exceeds 40 μm, a large stress is present inside the thin-film wiring conductor layer 3 when the thin-film wiring conductor layer 3 is applied to the organic resin insulating layer 2, and the large intrinsic stress causes the thin-film wiring conductor layer 3 to break down the organic resin insulating layer. It becomes easy to peel off from the layer 2.
Therefore, it is preferable that the thickness of each thin-film wiring conductor layer 3 of the multilayer wiring portion 4 be in the range of 1 μm to 40 μm.

The organic resin insulating layer 2 and the thin film wiring conductor layer 3
The multilayer wiring portion 4 formed by alternately laminating a plurality of layers further has a hole 10 formed in the uppermost organic resin insulating layer 2a, and the thin film wiring conductor layer 3 is formed on the inner surface of the hole 10. A bonding pad 11 is formed which is electrically connected to the bonding pad 11.

The hole 10 formed in the uppermost organic resin insulating layer 2a acts as a forming hole for forming a bonding pad 11 having an electrical connection to the thin film wiring conductor layer 3, and the uppermost organic resin insulating layer 2a serves as a forming hole. The resin insulating layer 2a is formed at a predetermined position with a predetermined opening diameter by employing a conventionally known photolithography technique.

The bonding pad 1 formed on the inner surface of the hole 10 provided in the uppermost organic resin insulating layer 2a
Reference numeral 1 denotes a function of electrically connecting electrodes of the electronic component A such as a semiconductor element and a capacitor to the thin-film wiring conductor layer 3. Each electrode of the electronic component A is connected to the bonding pad 11 via solder.

The bonding pad 11 is made of, for example, the same metal material as the thin film wiring conductor layer 3, specifically, a metal material such as copper, nickel, gold or the like. Thus, the thin film wiring conductor layer 3 is formed in the hole 10 provided in the uppermost organic resin insulating layer 2a with electrical connection.

Further, the bonding pad 11 has a solder bump 12 attached to the surface thereof. The solder bump 12 electrically connects the electrode of the electronic component A to the bonding pad 11 with the solder bump a of the electronic component A. Acts to connect.

The solder bump 12 is attached to the surface of the bonding pad 11 by a method described later.

Thus, according to the above-described multilayer wiring board, the electrodes of the electronic component A such as a semiconductor element and a capacitance element are connected to the bonding pad 11 provided on the uppermost organic resin insulating layer 2a via the solder. If the electrode A is electrically connected to the thin film wiring conductor layer 3 through the bonding pad 11, a semiconductor device or a hybrid integrated circuit device is obtained. By connecting a part of the thin film wiring conductor layer 3 to an external electric circuit, A is connected to an external electric circuit.

Next, a method of forming the solder bumps 12 on the bonding pads 11 in the above-described multilayer wiring board will be described with reference to FIG. First, as shown in FIG. 2A, the upper surface of the uppermost organic resin insulating layer 2a of the multilayer wiring portion 4 and the inner surface of the hole portion 10 are roughened, and the upper surface and the hole portion of the uppermost organic resin insulating layer 2a are roughened. The inner surface of No. 10 has a center line average roughness (Ra) of 0.05 μm ≦ Ra ≦ 5 μm, preferably 0.1 μm.
05 μm ≦ Ra ≦ 3 μm. The roughening treatment includes a chemical polishing treatment and a physical polishing treatment. The upper surface of the uppermost organic resin insulating layer 2a and the inner surface of the hole 10 are subjected to a chemical polishing treatment such as etching or a physical polishing treatment such as buff polishing. Is formed to a predetermined roughness.

When the center line average roughness (Ra) of the upper surface of the roughened uppermost organic resin insulating layer 2a and the inner surface of the hole 10 is less than 0.05 μm, the copper is formed by electroless plating described later. If the layer exceeds 5 μm, the mechanical strength of the uppermost organic resin insulating layer 2a is greatly deteriorated, and if an external force is applied, the layer may be damaged. There is a risk. Therefore, when the upper surface of the uppermost organic resin insulating layer 2a and the inner surface of the hole 10 are roughened, the surface roughness is in the range of 0.05 μm ≦ Ra ≦ 5 μm in center line average roughness (Ra). Specified.

Next, as shown in FIG. 2B, the upper surface of the roughened uppermost organic resin insulating layer 2a and the inner surface of the hole 10 and the bonding pad 11 exposed inside the hole 10 are formed.
A copper layer 13 is applied to the surface of the substrate by electroless plating.

The copper layer 13 is the uppermost organic resin insulating layer 2
Since the upper surface of a and the inner surface of the hole 10 are roughened, they are firmly adhered to the upper surface of the organic resin insulating layer 2a, the inner surface of the hole 10 and the surface of the bonding pad 11 exposed inside the hole 10.

The copper layer 13 was formed by the electroless plating method at a rate of 0.06 mol / l of copper sulfate, 0.3 mol / l of formalin, 0.35 mol / l of sodium hydroxide, 0.35 mol / l of ethylenediaminetetraacetic acid. This is performed by preparing an electroless plating solution of 1 liter and disposing it in the upper surface of the uppermost organic resin insulating layer 2a and in the hole 10.

The copper layer 13 has a thickness of 0.1 μm.
If it is less than 1, the electric resistance of the copper layer 13 increases, and the second solder layer 16 is formed by electrolytic plating on the first solder layer 15 that is adhered to the surface of a bonding pad 11 described later using the copper layer 13 as an electrode wire. When there is a risk that the thickness of the second solder layer 16 may vary greatly,
If the thickness exceeds 20 μm, the inner surface of the hole 10 provided in the uppermost organic resin insulating layer 2 a and the copper layer 13 covering the bonding pad 11 exposed in the hole 10 are replaced with copper and solder. When the first solder layer 15 is changed to the first solder layer 15 by electroless plating, a part of the copper layer 13 remains, and this enters the solder to increase the melting point of the solder and weaken the mechanical strength of the solder. Therefore, it is preferable that the thickness of the copper layer 13 be in the range of 0.1 μm to 20 μm.

Next, as shown in FIG. 2C, the copper layer 13 deposited on the upper surface of the uppermost organic resin insulating layer 2a is covered with a plating resist film.

The plating resist film 14 is made of, for example, an acrylic photosensitive film. The plating resist film 14 is applied on the uppermost organic resin insulating layer 2a on which the copper layer 13 is applied by thermocompression bonding, and is exposed to light. The copper layer 1 deposited on the uppermost organic resin insulating layer 2a by performing development
Three surfaces are applied in a predetermined pattern. The plating resist film 14 is for preventing the solder for forming the solder bump from being attached to an unnecessary area.

Next, as shown in FIG. 2 (d), it is adhered to the inner surface of the hole 10 provided in the uppermost organic resin insulating layer 2a and the surface of the bonding pad 11 exposed in the hole 10. The copper layer 13 is subjected to electroless solder plating by replacement of copper and solder, and the copper layer 13 is changed to the first solder layer 15.

The electroless solder plating is performed using lead borofluoride.
An electroless solder plating solution consisting of 03 mol / l, tin borofluoride 0.1 mol / l, and thiourea 75 g / l was prepared, and this was applied to the uppermost organic resin insulating layer 2a.
This is performed by arranging in the hole 10 provided in the above. The first solder layer 15 functions as a base metal layer when a second solder layer 16 described later is applied to the bonding pad 11.

Next, as shown in FIG. 2E, the first solder layer 1
The second solder layer 16 is deposited on the fifth solder layer 5. This second solder layer 1
No. 6 was formed by an electrolytic plating method, and a lead aliphatic sulphate compound 0.08 mol / l and an aliphatic tin sulphate compound 0.1.
A predetermined electric field is applied to the first solder layer 15 via the copper layer 13 covered with the plating resist film 14 while being immersed in an electrolytic solder plating bath of 4 mol / liter. It is formed by depositing solder. In this case, even if the underlying first solder layer 15 diffuses into the second solder layer 16, the first and second solder layers 15, 16
Are made of the same solder, so that the melting point of the second solder layer 16 does not increase or the mechanical strength does not become weak, and the low melting point and the toughness are maintained. Can be.

Finally, as shown in FIG. 2F, the plating resist film 14 and the uppermost organic resin insulating layer 2a are formed.
The copper layer 13 deposited on the upper surface of the
If this is heat-treated to melt and integrate the first and second solder layers 15 and 16, a predetermined solder bump is formed on the bonding pad 11. In this case, the second solder layer 16
There is no copper which raises the melting point of the solder and weakens the mechanical strength on the base, and only the first solder layer 15 similar to the second solder layer 16 exists, so that the solder bump formed has a low melting point. , And the mechanical strength is also maintained tough. Therefore, in this multilayer wiring board, when the solder bump is heated and melted to connect the bonding pad 11 to the electrode of the electronic component A such as a semiconductor element or a capacitor, the electronic component A is characterized by a low heat melting temperature of the solder bump. Can be connected to the bonding pad 11 without any change in the electronic component A. Also, after the electronic component A is connected to the bonding pad 11 at the same time, even when an external force is applied to the electronic component A, the bonding pad 11 and the electronic component A can be connected. Since the solder to be connected has toughness, it hardly breaks,
The reliability of the connection of the electronic component A to the bonding pad 11 becomes extremely high.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. A multilayer wiring portion 4 formed by alternately laminating a plurality of organic resin insulating layers 2 and a plurality of thin film wiring conductor layers 3 is applied only on the side of the substrate 1. It may be provided only on the upper and lower surfaces.

[0053]

According to the method of manufacturing a multilayer wiring board of the present invention, a copper layer is deposited on a bonding pad, and then the copper layer is subjected to electroless solder plating by replacing copper with solder. A copper bump is formed on a bonding pad by changing the copper layer to a first solder layer and finally depositing a second solder layer on the first solder layer by electrolytic plating.
There is no copper that raises the melting point of the solder and weakens the mechanical strength on the base of the second solder layer formed by the electrolytic plating method.
Since only the same solder as the second solder layer is present, the solder bumps are maintained at a low melting point, and the mechanical strength is maintained at a tough one. Therefore, in this multilayer wiring board, when the solder bump is heated and melted to connect the bonding pad to an electrode such as a semiconductor element or a capacitor element, the characteristics of the electronic component change due to the low heat melting temperature of the solder bump. Can be connected to the bonding pad without any damage. Also, after connecting the electronic component to the bonding pad at the same time, even if an external force is applied to the electronic component, the solder connecting the bonding pad and the electronic component has toughness, and thus is damaged. This is very rare, and the reliability of the connection of the electronic component to the bonding pad is extremely high.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a multilayer wiring board manufactured by a manufacturing method of the present invention.

2 (a) to 2 (f) are enlarged cross-sectional views of main parts in each step for explaining formation of solder bumps of the multilayer wiring board shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Organic resin insulation layer 2a ... The topmost organic resin insulation layer 3 ... Thin film wiring conductor layer 4 ... Multilayer wiring part 8 ... Through-hole 9 ... Through-hole Conductor 10: Hole provided in uppermost organic resin insulating layer 11: Bonding pad 12, Solder bump 13, Copper layer 14, Plating resist film 15, First solder layer 16, Second solder Layer A: Electronic components

Claims (1)

[Claims] An organic resin insulating layer and a thin-film wiring conductor layer are alternately laminated on a substrate, and electrically connected via a through-hole conductor provided on the upper and lower thin-film wiring conductor layers in the organic resin insulating layer. A multi-layer wiring board formed with a bonding pad electrically connected to the thin-film wiring conductor layer and connected to an electrode of an external electronic component in a hole provided in the uppermost organic resin insulating layer and connected to the hole; Wherein a solder bump is applied to the bonding pad in the following steps (a) to (f). (A) The surface roughness of the upper surface of the uppermost organic resin insulating layer and the inner surface of the hole is 0.05 μm as a center line average roughness (Ra).
Performing a roughening treatment so as to satisfy ≦ Ra ≦ 5 μm;
(B) depositing a copper layer by electroless plating on the upper surface and the inner surface of the hole of the roughened organic resin insulating layer and the surface of the bonding pad exposed in the hole of the organic resin insulating layer; (C) a step of coating a copper layer deposited on the upper surface of the uppermost organic resin insulating layer with a plating resist film; and (d) a hole inner surface and a hole provided in the uppermost organic resin insulating layer. (C) subjecting the copper layer applied to the surface of the bonding pad exposed in the portion to electroless solder plating by replacing copper with solder, and applying a first solder layer instead of the copper layer; e) applying a second solder layer to the surface of the first solder layer by electrolytic plating using the first solder layer and the copper layer covered with the plating resist film as electrode wires; and (f) On the upper surface of the plating resist film and the uppermost organic resin insulating layer Removing the copper layer being deposited