JP2002353627A - Multilayer printed wiring board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a build-up type printed wiring board which enables a pat-on-via structure by which a drilling process by laser can be skipped and via holes of a small diameter can be filled in. SOLUTION: A first metal foil 2 and a group of conductor bumps 3, 3,... are printed, and then an insulation substrate precursor 4 and a second metal foil 5 are laid on top of the first metal foil and the group of conductor bumps 3, 3,..., and these are heat-pressed to form a laminate 10. A group of conductor bumps 6, 6,... is formed on a wiring pattern 2a obtained by patterning the laminate 10, and then an insulation substrate precursor 16 and another two-layer board 20a are laid and aligned on top of the group of conductor bumps 6, 6,..., and all these are heat-pressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a multilayer printed wiring having a plurality of wiring patterns interposed between a plurality of insulating layers and connected to one another. The present invention relates to a method for manufacturing a plate.

[0002]

2. Description of the Related Art In response to the arrival of the multimedia age, electronic devices such as mobile phones, Internet mobile terminals, and mobile personal computers have been put into practical use.
Light weight, light weight, high density, and low cost are required. As a technique for manufacturing a printed wiring board that satisfies this requirement, attention has been paid to a build-up type multilayer printed wiring board. As a method for manufacturing a build-up type multilayer printed wiring board, two types of methods are known: drilling by laser and drilling by selective exposure and development of a photosensitive resin.

In the former method of manufacturing a build-up type multilayer printed wiring board by laser drilling, a wiring circuit pattern is formed on the front and back surfaces of an insulating substrate, and resin sheets with copper foil are arranged on both upper and lower surfaces. It is laminated integrally by mounting it on a tool and applying heat and pressure. The outermost copper foil at the via hole formation position is removed by selective etching. Next, a laser beam is applied to the position where the etching has been removed to perform drilling. By forming a metal plating layer on the inner wall surface of the hole, electrical connection between wiring layers is performed, and a multilayer printed wiring board is manufactured.

In the latter method of manufacturing a build-up type multilayer printed wiring board, a wiring circuit pattern is formed on the front and back surfaces of a wiring board, and a photosensitive resin layer is applied thereon.

[0005] A desired portion of the photosensitive resin layer, which has an interlayer connection with the inner layer circuit wiring pattern, is selectively exposed and developed to remove the photosensitive resin layer and form a non-through via hole for interlayer connection. A chemical plating process is applied to the entire inner wall surface of the via hole, and a conductor, for example, a copper film is applied by an electroplating process to perform interlayer connection. That is, a multilayer printed wiring board is produced by a build-up method in which an interlayer connection via hole is formed.

[0006]

In recent years, CSP mounting with a narrow pitch has become widespread as the electronic devices have become lighter and smaller. The CSP mounting means that the number of electrode pins per unit area increases as the degree of integration increases. This increase in the number of electrode pins means an increase in the number of solder bumps.
There has been a demand for a miniaturization technique for forming the land pattern portion and development of a flat land capable of mounting components on via lands, that is, a method of manufacturing a pad-on-via structure at low cost.

However, in the former method, an increase in the number of laser drilling steps becomes a problem as the number of holes increases, and the latter method has a limit in miniaturization. Further, in any of the methods, a complicated process is required to realize the pad-on-via structure, which causes a cost increase.

[0008] The present invention has been made in view of the above points. That is, an object of the present invention is to provide a manufacturing method of a build-up type printed wiring board which can omit a laser drilling step and fill a small diameter via, that is, a pad-on-via structure.

[0009]

According to a method of manufacturing a printed wiring board of the present invention, a step of forming a conductor bump at a predetermined position on one surface of a first metal foil, and a step of forming a conductor bump on the conductor bump of the first metal foil is performed. Stacking an insulating substrate precursor and a second metal foil, and pressing the first metal foil, the insulating substrate precursor, and the second metal foil to allow the conductor bumps to penetrate the insulating substrate. Electrically connecting the first metal foil and the second metal foil, and patterning the first metal foil and the second metal foil to form a first wiring pattern; And / or a step of forming a two-layer board provided with a second wiring pattern, and a step of forming a conductor bump on the first wiring pattern or the second wiring pattern to form a two-layer board with bumps; An insulating substrate precursor on the conductor bump tip of the bumped two-layer board; Positioning another superimposed two-layer board by superposing, and pressing the two-layer board with bumps, the insulating substrate precursor, and the other two-layer board under heating to insulate the conductive bumps. Inserted into the substrate precursor,
Electrically connecting the wiring pattern on the layer board to the wiring pattern on the another two-layer board.

In the method of manufacturing a printed wiring board, as an example of the step of forming the two-layer board with bumps, a step of forming the conductive bumps on the bottom side of the conductive bumps disposed in the insulating substrate is given. As an example of the step of positioning the two-layer board with bumps and the core material, a step of positioning the conductor bumps disposed in the two-layer board with bumps so that the front ends thereof face outward. Can be mentioned.

In the method for manufacturing a printed wiring board according to the present invention,
After forming the two-layer plate, the conductor bumps are formed on the two-layer plate, and the two-layer plate is further laminated thereon, so that the laser drilling process can be omitted, and the pad-on-via structure can be easily and reliably formed. Can be formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a printed wiring board according to an embodiment of the present invention will be described.

FIG. 1 is a flowchart of a method for manufacturing a printed wiring board according to the present embodiment, and FIGS. 2 and 3 are vertical sectional views of the printed wiring board according to the present embodiment during manufacturing. In order to manufacture the printed wiring board according to the present embodiment, first, a predetermined position on one surface of a metal foil 2 such as a copper foil as shown in FIG. Then, a conductive paste such as a silver paste is printed using a printing technique to form a plurality of conductive bumps 3, 3,... As shown in FIG. 2B (step 1).

At this time, silver powder or copper powder is used as the metal powder used for the conductive paste used to form the conductive bumps 3. The shape may be spherical, scale-like or the like, and a mixture thereof may be used.

These metal powders are mixed with a binder component such as a polycarbonate resin, a polysulfone resin, a polyester resin, a phenoxy resin, a phenol resin, and a polyimide resin to prepare. The conductive paste is printed on the copper foil surface or the circuit surface of the inner layer plate using a metal mask plate or the like, and when the formation of the conductive bumps 3, 3,... As shown in c), the insulating substrate precursor, that is, the prepreg 4 and another metal foil 5 are overlapped and aligned (step 2).
At this time, examples of the resin forming the insulating substrate precursor (prepreg) include an epoxy resin, a polyimide resin, and a modified resin thereof, and these can be used alone or in combination. Further, the resin may contain an insulating inorganic or organic filler. The insulating layer is formed using these resins, but the method is not particularly limited, and the insulating layer can be formed by a known method such as a prepreg state impregnated in glass cloth or a coating method using the resin alone.

Next, in this state, a stack of the metal foil 2, the insulating substrate precursor 4, and the other metal foil 5 is pressed under heating by, for example, being passed between heated rollers (step 3). . By the heating press, the conductor bumps 3, 3,... On the metal foil 2 are penetrated in the thickness direction of the insulating substrate precursor 4 as shown in FIG. The head penetrates through the insulating substrate precursor 4 and abuts on the other metal foil 5, so that the metal foil 2 and the other metal foil 5 are electrically connected. Further, the insulating substrate precursor 4 is cured by heating. Thus, FIG. 2 (d)
The metal foil 2 and the other metal foil 5 as shown in FIG.
Are provided with two metal layers 2, 5 electrically connected to each other via conductor bumps 3, 3,....
Next, the metal layers 2 and 5 on both surfaces of the two-layer laminate 10 are patterned by, for example, etching (step 4) to form wiring patterns 2a and 5a as shown in FIG. I do. Thus 2
A two-layer board 10a having the layered wiring patterns 2a and 5a is formed.

Next, conductor bumps 6, 6,... Are formed on the wiring pattern 2a on one side of the two-layer board 10a by the same method as in the step 1 (step 5), as shown in FIG. The bumped two-layer board 10b is formed.

Next, in the steps 1 to 4, another two-layer plate 2 similar to the two-layer plate 10a is formed.
0a is formed in advance. Thereafter, the two-layer plate with bumps 10b, another insulating substrate precursor 16 similar to the insulating substrate precursor 4, and the other two-layer plate 20a
Are aligned and superimposed as shown in FIG. 3A (step 6).

In this state, a laminate of the two-layer plate with bumps 10b, the insulating substrate precursor 16, and the another two-layer plate 20a, which are superposed, is passed through, for example, between heating rollers, thereby obtaining Press under heating (step 7). By this heating press, the two-layer plate with bumps 10b
The upper conductive bumps 6, 6,... Are inserted through the other insulating substrate precursor 16 in the thickness direction, and the conductive bumps 6, 6,.
.. Penetrate the other insulating substrate precursor 16 and form the wiring pattern 1 of the other two-layer plate 20b.
5a contacts and is abutted. These conductor bumps 6,
The wiring patterns 2a and 15a are electrically connected by the heads of 6,... Further, the other insulating substrate precursor 16 is cured by heat at the time of hot pressing. Thus, the wiring patterns 5a and 5a as shown in FIG.
A multilayer printed wiring board 1 having a four-layer wiring pattern in which a, 15a, and 12a are interconnected is formed.

As described above, in the method of manufacturing a printed wiring board according to the present embodiment, a two-layer board is prepared first, and conductor bumps are printed thereon to form a two-layer board with bumps. Another insulating substrate precursor and another two-layer plate are stacked on the attached two-layer plate and heated and pressed to be stacked. Therefore, a step of irradiating a laser beam or mechanically drilling with a drill or the like can be omitted, and the number of steps can be reduced. Also,
Since no equipment for irradiating a laser beam or mechanical equipment such as a drill is required, manufacturing equipment can be manufactured at low cost. In addition, maintenance of the manufacturing equipment is easy, and the cost of the maintenance can be reduced.

Furthermore, in the method of manufacturing a printed wiring board according to the present embodiment, since the two-layer board for stacking outside the core material is formed first and then stacked, it is possible to select the orientation of the two-layer board. it can. Therefore, by stacking the conductor bumps inserted into the two-layer plate toward the core material that is stacked on the bottom surface side, the front ends of the conductor bumps can be directed to the outside of the multilayer plate. Since lines are formed at a fine pitch on the tip side, a fine pattern with a fine pitch can be formed on the surface of the multilayer board, and a multilayer board type printed wiring board for a semiconductor package with a high degree of integration can be manufactured. .

(Example) Next, an example of the printed wiring board of the present invention will be described. In the present example, an attempt was made to form a four-layer plate according to the same process as in the above embodiment. As a conductive paste for forming conductive bumps, silver paste (CT
-217K, manufactured by Toshiba Chemical Co., Ltd.), the silver paste was printed and applied five times on a copper foil 2 through a metal screen having a thickness of 100 microns, and dried.
3, ... were formed. A 100 micron thick glass epoxy prepreg (TLP-551HN, Toshiba Chemical Corporation)
(Product name) 4 and another copper foil 5 are superimposed and pressurized under heating, and the protrusions (conductor bumps) 3 of the copper foil 2
The laminate 10 having two layers of copper foils 2 and 5 disposed on both sides thereof by penetrating through 3,... Was formed, and further the same laminate 20 was formed.

Next, after masking these multi-layered bodies 10 and 20, they are immersed in an etching solution, and the wiring circuit patterns 2a, 5a, 12a and 15
was formed to obtain two-layer plates 10a and 20a. Two-layer board 10
are formed on the wiring pattern 2a on which the bottom surfaces of the conductor bumps 3, 3,... are formed in the same manner as described above, to obtain a bumped two-layer plate 10b. The other glass epoxy prepreg 16 is placed on the conductor bumps 6, 6,... Of the bumped two-layer board 10b, and the other two-layer board 20a is further stacked thereon. While performing the alignment, and temporarily fixed with an adhesive. The temporarily assembled laminate thus obtained was passed between heated rollers and hot-pressed. After heating for a predetermined time and further cooling sufficiently, a four-layered multilayer board 1 was obtained. When the characteristics of the multilayer plate 1 were examined, it was confirmed that the multilayer plate 1 had the following favorable characteristics.

1. In a cooling / heating cycle test in which one cycle is -65 ° C for 30 minutes and 125 ° C for 30 minutes, 1000
It has connection reliability of more than cycles. 2.85 ° C,
12 V. in an environment of 85% RH. As a result of conducting a DC conduction test, it has good migration resistance. 3.
A liquid-phase cooling / heating cycle test in which one cycle is performed at 20 ° C. for 20 seconds and 260 ° C. for 10 seconds shows connection reliability of 100 cycles or more.

[0025]

According to the method of manufacturing a printed wiring board of the present invention, a two-layer plate is formed, then conductor bumps are formed on the two-layer plate, and the two-layer plate is further laminated thereon. So
Drilling by laser can be omitted, and a put-on via structure can be formed easily and reliably.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for manufacturing a printed wiring board according to the present invention.

FIG. 2 is a vertical cross-sectional view of the printed wiring board of the present invention during manufacture.

FIG. 3 is a vertical cross-sectional view of the printed wiring board of the present invention in the process of being manufactured.

[Explanation of symbols]

2 ... metal foil (first metal foil), 3 ... conductor bump, 4 ... prepreg (insulating substrate precursor), 5 ... metal foil (second metal foil), 2a ... wiring pattern (second wiring pattern) , 6
... bumps, 5a ... wiring patterns (second wiring patterns), 10a ... two-layer boards, 10b ... two-layer boards with bumps.

Continuation of the front page (72) Inventor Nobuyuki Sato 5-14-25 Ryoke, Kawaguchi-shi, Saitama F-term (reference) in Toshiba Chemical Corporation Kawaguchi Plant 5E346 AA35 AA43 CC04 CC09 CC10 CC32 CC58 DD02 DD12 DD32 EE02 EE09 EE13 FF35 GG19 GG22 GG28 HH32

Claims (2)

[Claims] A step of forming a conductor bump at a predetermined position on one side of a first metal foil; and a step of superposing an insulating substrate precursor and a second metal foil on the conductor bump of the first metal foil; The first metal foil, the insulating substrate precursor, and the second
Pressurizing the metal foil to allow the conductor bumps to penetrate through the insulating substrate to electrically connect the first metal foil and the second metal foil; and Patterning the second metal foil to form a two-layer board provided with a first wiring pattern and / or a second wiring pattern; and on the first wiring pattern or the second wiring pattern. Forming a two-layer board with bumps by forming conductive bumps on the two-layer board; and positioning an insulating substrate precursor and another two-layer board on top of the conductive bumps of the two-layer board with bumps. Pressurizing the two-layer board with bumps, the insulating substrate precursor, and the other two-layer board under heating to penetrate the conductor bumps into the insulating substrate precursor, and form wiring on the two-layer board. Electrically connect the pattern and the wiring pattern of the other two-layer board A method for manufacturing a printed wiring board, comprising: 2. The method of manufacturing a printed wiring board according to claim 1, wherein the step of forming the two-layer board with bumps includes the step of forming the conductor on a bottom surface side of a conductor bump provided in the insulating substrate. A step of forming a bump, wherein the step of positioning the two-layer board with bumps and the core material comprises positioning the conductor bumps disposed in the two-layer board with bumps so that the tip ends face outward. A method for manufacturing a printed wiring board, the method comprising: