JPH08130376A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE: To provide a method of manufacturing a multilayer printed wiring board, wherein the multilayer printed wiring board is lessened in overall thickness and number of manufacturing processes and enhanced in circuit reliability and production efficiency. CONSTITUTION: A copper foil 8 is bonded to an uppermost insulating board 1u for the formation of a laminate 10 covered with a lid 9, a through-hole 3 is provided in the laminate 10 and plated, and then an outermost circuit is provided in the laminate 10. The lid 9 is electrically isolated, then an opening smaller than a prescribed opening is bored rough in it by machining, the residue 9a of the lid 9 is left unremoved, a conductor protecting layer 28 of metal smaller in etching rate than copper is formed on the exposed surface of a conductor circuit 4 by electroplating, and then the residue 9a is removed by etching, and a housing hole 2 is bored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a PG used in, for example, electronic equipment, electric equipment, computers and communication equipment.
The present invention relates to a method for manufacturing a multilayer printed wiring board used for mounting semiconductor chips and chip components such as A, BGA and chip carriers.

[0002]

2. Description of the Related Art In recent years, electronic parts such as semiconductor chips and chip parts have become lighter, thinner, shorter, and smaller, and accordingly, there has been an increasing demand for higher density mounting boards for electronic parts. In addition, since it is necessary to use a semiconductor package with good heat dissipation, a ceramic material has been used in the past, but since the ceramic material is expensive, it is possible to increase the density and reduce the cost. Multilayer printed wiring boards that can be used have come to be used. There are roughly two types of methods for manufacturing such a multilayer printed wiring board having an opening represented by PGA. That is, the first method is
The second method is a method for manufacturing a multilayer printed wiring board in which a through hole is formed in a laminated body having no opening in the uppermost layer, the through hole is subjected to chemical plating, and then the opening is formed. This is a method for manufacturing a multilayer printed wiring board in which a through hole is formed in a laminated body having a portion, the through hole is subjected to chemical plating, and then the unnecessary chemical plated portion attached to the insulating portion is removed.

The first method is, for example, Japanese Patent Publication No. 2-5.
It is disclosed in Japanese Patent Application No. 014, Japanese Patent Application Laid-Open No. 4-369252, and the like.

In Japanese Patent Publication No. 2-5014, a printed circuit board type PGA package in which semiconductor element accommodating holes, through holes and wiring patterns are formed in a plurality of laminated plates, and the through holes are plated. In the manufacturing method, the laminated plurality of plate bodies are not formed with openings for forming semiconductor element storage holes in the outer plate bodies, and the wiring except the outer surface of the outer plate bodies is provided. The patterns are laminated so as to be sealed by the plate bodies on both outer sides. Through holes are formed in the laminated plate bodies and the through holes are plated, and then at least the plate bodies on both outer sides are plated. A method for manufacturing a printed circuit board type PGA package is disclosed in which an opening for forming a semiconductor element accommodation hole is formed on one side. The above is the method of manufacturing a printed circuit board type PGA package disclosed in Japanese Patent Publication No. 2-5014. However, this manufacturing method has some drawbacks as described below. That is, since the lid that covers the opening is a plate, the thickness of the lid increases. Further, there is a problem that the scraps during the processing of the plate adhere to the opening of the outermost layer on the circuit pattern or inside the through hole.

On the other hand, in Japanese Unexamined Patent Publication (Kokai) No. 4-369252, a multilayer wiring board having a stepped portion is formed by stacking a plurality of organic substrates on which wiring is formed while forming a concave portion having a flat bottom surface in the central portion. In the method of forming a through hole at any place other than the recess and plating the through hole to manufacture a semiconductor element mounting device, after stacking organic substrates, copper foil is bonded to the outermost side Then, a through hole is formed, a plating film is formed on the surface and the through hole, and then the plating film and the copper foil in the portion corresponding to the recess are removed by etching to form an open state. A method of manufacturing a device is disclosed. The above is the method for manufacturing a multilayer printed wiring board disclosed in Japanese Patent Laid-Open No. 4-369252. However,
This manufacturing method also has the following drawbacks.
That is, even when the copper foil forming the lid of the recess is removed to form an open state, the circuit inside the opening is also attacked. In order to prevent this, as shown in the example, it is necessary to perform a process of solder plating and printing of the overcoat resin on each layer of the circuit layer, and curing, which is very time-consuming and requires a step of removing the solder plating part. It also takes time,
When the etching is insufficient and the solder remains in the pinholes or the like, there is a problem that the adhesion with the plating layer to be plated thereafter becomes insufficient.

The second method is, for example, Japanese Patent Application No. 6-1.
The present inventor proposed in 0123. That is, the first
Of the circuit pattern and the first printed wiring board having the opening and the second printed wiring board having the second circuit pattern as an object to be pressured through an adhesive sheet, and the object to be heated is heated and pressed. A step of molding to obtain a laminated body in which the second circuit pattern is exposed in the opening; through holes are formed in the laminated body, and then nucleation is performed to form the first and second circuit patterns and the insulating circuit pattern. And a step of subjecting the through hole to chemical plating; a step of closing the opening of the through hole with a cover and then performing soft etching to remove the chemical plating to remove the nucleus; and after removing the cover, A step of electroplating the first and second circuit patterns and the through holes; a resist is coated on the front surface of the first printed wiring board and the back surface of the second printed wiring board which are the outermost layers of the laminate. A step of coating; a method for manufacturing a multilayer printed wiring board having the opening portion comprising a step of resist plated with gold on the circuit pattern and the through holes are exposed from the laminate. However,
Since the multilayer plate having the opening is directly subjected to the chemical plating, the insulating portion other than the exposed conductor of the opening is also plated. Therefore, in the etching process, the unnecessary portion chemically plated on the insulating portion is removed. However, if radical etching is performed at this time, the circuit portion is also etched and finally completely removed. On the other hand, if the etching is performed under mild conditions, the palladium and the like, which are used as nuclei for chemical plating, cannot be sufficiently removed this time. As a result, by electroplating (nickel plating + gold plating) after etching,
The periphery of the palladium nucleus remaining in the insulating portion will also be plated, and plating will be performed as if the circuit portions were short-circuited. Therefore, etching requires strict process control conditions, and the finer the pattern, the more difficult the control becomes.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the total thickness of a multilayer printed wiring board to obtain a highly reliable circuit. An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board, which can improve the production efficiency and save the process.

[0008]

According to a first aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, comprising: a plurality of laminated insulating substrates 1 for accommodating electronic parts, a through hole 3, a through hole 3 and a conductor. In a method for manufacturing a multilayer printed wiring board in which a circuit 4 is formed and through holes 3 are plated, a lowermost insulating substrate 1d having an electronic component mounting portion 5 and a conductor circuit 4, and a lowermost insulating substrate 1d. An uppermost insulating substrate 1u having an opening 6 corresponding to the accommodation hole 2 arranged above the opening 6, and the opening 6 arranged between the uppermost insulating substrate 1u and the lowermost insulating substrate 1d. And a predetermined number of inner layer circuit boards 1n having conductor circuits 4 are pressure-bonded via an adhesive sheet 7 having openings 6 corresponding to the storage holes 2, respectively, and further, the uppermost insulating substrate 1u.
A copper foil 8 is adhered to the top of the container at the same time as or after the pressure bonding to form a laminated body 10 in which the opening 6 of the storage hole 2 is covered with a lid 9 of the copper foil 8. And through-holes 3 are plated, then the outermost layer circuit of the laminated body 10 is formed and the through holes 3 are formed.
With the opening 6 of the lid 6 covered with the lid 9 of the copper foil 8,
Are electrically isolated, and then the lid 9 in the portion corresponding to the opening 6 of the storage hole 2 is mechanically machined to be coarsely cut to a size smaller than a predetermined opening to open the remaining portion 9a of the lid 9. In the formed state, a metal coating having a smaller etching solubility than copper is formed on the exposed exposed surface of the conductor circuit 4 as a conductor protective layer 28 by electroplating, and then the remaining portion 9a is removed by etching. The storage hole 2
It is characterized by opening.

In the method for manufacturing a multilayer printed wiring board according to a second aspect of the present invention, the metal coating is a group consisting of solder plating, nickel plating, nickel phosphorus plating, nickel tin plating, chromium plating, palladium plating and alloy plating thereof. 2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the plating is at least one kind selected from the group consisting of:

A method for manufacturing a multilayer printed wiring board according to a third aspect of the present invention is characterized in that the copper foil 8 has a thickness of 9 to 70 μm.

[0011]

In the method for manufacturing a multilayer printed wiring board according to claims 1 to 3 of the present invention, the lid 9 of the opening 6 of the storage hole 2 is covered.
Since it is made of the copper foil 8 and does not include the substrate, the thickness can be reduced and the rough cutting removal by mechanical processing is easy. Moreover, since the remaining portion 9a of the lid 9 is made of only the copper foil 8 and is electrically isolated, the exposed exposed surface of the conductor circuit 4 of each layer is coated with a metal film having a smaller etching solubility than copper. When the conductor protection layer 28 is collectively formed by electroplating, no metal coating is formed on the remaining portion 9a. Therefore, the remaining portion 9a can be easily and accurately removed by etching to open the storage hole 2.

[0012]

EXAMPLES The present invention will be described below with reference to examples.

As shown in FIG. 1A, on the lowermost insulating substrate 1d having the electronic component mounting portion 5 and the conductor circuit 4,
A predetermined number of inner layer circuit boards 1n each having an opening 6 corresponding to a housing hole 2 for mounting an electronic component and a conductor circuit 4, for example,
Each of the two sheets is placed via an adhesive sheet 7 such as a prepreg. On this inner layer circuit board 1n, an uppermost insulating substrate 1u having an opening 6 is attached to an adhesive sheet 7 such as a prepreg.
Then, the pressure-sensitive body 14 is mounted via After pressure-bonding the pressed body 14, as shown in FIG. 1B, the copper foil 8 is provided on the uppermost insulating substrate 1u via the prepreg 11 having the opening 6 corresponding to the storage hole 2. Is bonded at the same time as or after the pressure bonding to form the laminated body 10 in which the opening 6 of the storage hole 2 is covered with the lid 9. The lid 9 is made of only the copper foil 8. The copper foil 8 has a thickness of 9 to 70 μm.
m is preferred. That is, when the thickness of the copper foil 8 is less than 9 μm, the copper foil 8 is easily damaged during the through-hole plating process or the etching process for forming the outer layer circuit, and there is a risk that the conductor circuit 4 inside the housing hole 2 is damaged. If the thickness of the copper foil 8 exceeds 70 μm, it is difficult to form a circuit for the copper foil 8 and the accuracy deteriorates.

As shown in FIG. 1C, this laminated body 10
The through holes 3 communicating with the upper and lower sides of the through hole 3 are formed and nucleated, and plating such as chemical plating and electroplating is applied to the inner surface and the outermost layer of the through holes 3.

As shown in FIG. 1D, a copper foil 8 covering the upper and lower surfaces of the through hole 3 and the storage hole 2 and a laminated body 10 are provided.
The necessary portion of the outermost layer on the lower surface of the laminate 10 is covered with an etching resist, and exposure and development etching are performed to form a laminate 10.
The outermost conductor circuit 4 is formed, and at the same time, a continuous insulating portion (the portion from which the copper foil is removed) is provided on the outer periphery of the opening 6, and the opening 6 of the storage hole 2 covers the copper foil 8. In the state of being covered with 9, the lid 9 is electrically isolated. That is, the electrical isolation prevents the lid 9 from being coated with the metal coating when the conductor coating layer 28 is formed by electroplating in the next step. Then, as shown in FIG. 1 (e), the lid 9 at a portion corresponding to the opening 6 of the storage hole 2 is mechanically machined to be roughly cut into smaller portions than a predetermined opening, and the lid 9 is opened. The remaining portion 9a consisting of the copper foil 8 is formed. This lid 9
Rough cutting removal method, slitting cutter,
It is carried out by mechanical cutting such as router cutting, blade cutting, pressure cutting, high pressure water stream cutting and the like. Needless to say, simple manual work or peeling off by peeling may be used.
The thickness of the copper foil 8 is preferably 9 to 70 μm. That is, when the thickness of the copper foil 8 is less than 9 μm, the copper foil 8 is easily damaged during the through-hole plating process or the etching process for forming the outer layer circuit, and there is a risk that the conductor circuit 4 inside the housing hole 2 is damaged.

Next, as shown in FIG. 1 (f), with the remaining portion 9a of the lid 9 made of only the copper foil 8 being formed,
On the exposed surface of the exposed conductor circuit 4, a metal coating having a smaller etching solubility than copper is formed as a conductor protection layer 28 by electroplating, for example, by electrosolder plating. As the metal coating, other than solder plating,
At least one kind of plating selected from the group consisting of nickel plating, nickel phosphorus plating, nickel tin plating, chromium plating, palladium plating and alloy platings thereof can be exemplified. When the metal coating is formed as the conductor protection layer 28 by electroplating, the remaining portion 9a is electrically isolated, so that no metal coating is formed on the remaining portion 9a.

Therefore, as shown in FIG. 1 (g), the remaining portion 9a can be removed by etching to accurately open the storage hole 2.

Next, as shown in FIG. 1H, the solder plating is removed by etching. However, nickel plating, nickel phosphorus plating, nickel tin plating,
When at least one kind of plating selected from the group consisting of chrome plating, palladium plating and alloy platings thereof is formed as the conductor protective layer 28, the conductor protective layer 28 is not removed and the conductor protective layer 28 is not removed. It is possible to proceed to the next step with the state of being formed.

As shown in FIG. 1 (i), both outer surfaces of the laminated body 10 and the inside of the housing hole 2 are covered with a solder resist 17 if necessary, and then nickel plating (not shown) and gold plating 18 are applied. Thereby, the wiring pattern is formed.

As described above, in the method of manufacturing a multilayer printed wiring board according to the present invention such as a printed circuit board type PGA package, the copper foil 8 is bonded onto the uppermost insulating substrate 1u at the same time as the pressure bonding or after that. Since the opening 6 of the accommodation hole 2 is the laminated body 10 covered with the lid 9 including the copper foil 8, when the through hole 3 is plated, the conductor circuit 4 in the accommodation hole 2 is plated. It is possible to prevent
It is not necessary to insert a counterbore in the router processing part of the uppermost insulating substrate 1u. That is, conventionally, it was necessary to increase the thickness of the uppermost insulating substrate 1u in advance due to the need for counterboring. However, in the method for manufacturing a multilayer printed wiring board according to the present invention, such a need is eliminated, and the multilayer printing is not necessary. It is possible to reduce the total thickness of the wiring board.

In the method of forming the opening of the copper foil only by etching as in the conventional example, the solder plating and the overcoat resin are printed and cured separately for each circuit layer, and then the molding is performed. There are many steps. On the other hand, in the method for manufacturing a multilayer printed wiring board according to the present invention,
After forming the through hole 3 in the laminated body 10, plating the through hole 3 to form the outermost layer circuit of the laminated body 10, and electrically isolating the lid 9, the housing hole 2 The lid 9 at the portion corresponding to the opening 6 is mechanically machined to be coarsely cut into smaller pieces than a predetermined opening to open the lid 9.
In the state where the remaining portion 9a consisting only of the copper foil 8 is formed, a metal coating film having a smaller etching solubility than copper is formed as the conductor protective layer 28 on the exposed exposed surface of the conductor circuit 4 by electroplating. After that, the remaining portion 9a is removed by etching to open the storage hole 2,
Since it is possible to perform solder plating on each layer in a lump, it becomes possible to simplify the process and reduce the cost. That is, it is a method for manufacturing a multilayer printed wiring board, in which the total thickness of the multilayer printed wiring board is reduced, a highly reliable circuit is obtained, production efficiency is improved, and the number of steps is reduced.

[0022]

According to the method for manufacturing a multilayer printed wiring board according to the first to third aspects of the present invention, the total thickness of the multilayer printed wiring board can be reduced, a highly reliable circuit can be obtained, and the production efficiency can be improved. Can be improved and the number of steps can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a method for manufacturing a multilayer printed wiring board according to an embodiment of the present invention, in which (a) is a cross-sectional view of a body to be pressed,
(B) is a cross-sectional view in which a copper foil is arranged on the uppermost insulating substrate,
(C) is a cross-sectional view of a laminated body in which through holes are formed,
(D) is a cross-sectional view of a circuit formed on the outer layer portion of the laminate,
(E) is a cross-sectional view showing a state in which a storage hole is opened by roughly removing the outermost layer lid, (f) is a cross-sectional view in which a conductor protective layer is formed on the exposed surface of the exposed conductor circuit, (g) Is a cross-sectional view in which the remaining portion of the lid is removed by etching to open the storage hole,
(H) is a cross-sectional view with the conductor protection layer removed, and (i) is a cross-sectional view of a multilayer printed wiring board on which a wiring pattern is formed by performing nickel plating and gold plating.

[Explanation of symbols]

 1 Insulating Substrate 1d Lowermost Insulating Substrate 1n Inner Layer Circuit Substrate 1u Uppermost Insulating Substrate 2 Storage Hole 3 Through Hole 4 Conductor Circuit 5 Electronic Component Mounting Part 6 Opening 7 Adhesive Sheet 8 Copper Foil 9 Lid 9a Remaining Part 10 Laminate 28 Conductor Protective layer

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H05K 3/06 K 3/24 A 7511-4E 3/42 A 7511-4E (72) Inventor Toru Higuchi Osaka Prefecture 1048, Kadoma, Kadoma-shi, Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] 1. A storage hole (2) for mounting an electronic component, a through hole (3) and a conductor circuit (4) are formed in a plurality of laminated insulating substrates (1), and the through hole (3) is formed in the through hole (3). In a method of manufacturing a plated multilayer printed wiring board, a lowermost insulating substrate (1d) having an electronic component mounting portion (5) and a conductor circuit (4), and a lowermost insulating substrate (1).
d), an uppermost insulating substrate (1u) having an opening (6) corresponding to the accommodation hole (2), the uppermost insulating substrate (1u) and the lowermost insulating substrate (1d) A predetermined number of inner layer circuit boards (1n) having the opening (6) and the conductor circuit (4), which are arranged between
Each of them is pressure-bonded through an adhesive sheet (7) having an opening (6) corresponding to the storage hole (2), and further, a copper foil (8) is added on the uppermost insulating substrate (1u). A laminate (1) in which the opening portion (6) of the storage hole (2) is covered with a lid (9) of a copper foil (8) by pressure-bonding simultaneously or afterwards.
0), a through hole (3) is formed in the laminated body (10), the through hole (3) is plated, and then the outermost layer circuit of the laminated body (10) is formed.
After the opening (6) of the storage hole (2) is covered with the lid (9) of the copper foil (8), the lid (9) is electrically isolated, and then the storage hole (2). Of the lid (9) corresponding to the opening (6) of the lid (9) is mechanically machined to be coarsely cut to a size smaller than a predetermined opening to open the lid (9), and the remaining portion (9)
In the state where a) is formed, a metal coating having a smaller etching solubility than copper is formed as a conductor protective layer (28) on the exposed exposed surface of the conductor circuit (4) by electroplating, and then the remaining. A method for manufacturing a multilayer printed wiring board, characterized in that the portion (9a) is removed by etching to open the storage hole (2). 2. The metal coating is at least one type of plating selected from the group consisting of solder plating, nickel plating, nickel phosphorus plating, nickel tin plating, chromium plating, palladium plating and alloy platings thereof. The method for manufacturing a multilayer printed wiring board according to claim 1. 3. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the copper foil (8) has a thickness of 9 to 70 μm.