JP2002198628A - Printed circuit board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize extremely simple process and reduction in cost, and furthermore attain fining by adopting a punching method, which enables positioning more precisely than a print method. SOLUTION: A unit substrate 19 is constituted so that conductive substance 17 charges a through hole 16 of a polyimide sheet 11 wherein a wiring pattern 13 is formed and conductive substance is subjected to slight projection 18 from a wiring pattern. When a plurality of unit substrates 19, 19a, 19b, 19c of a similar constitution are laminated and compressed via insulation adhesive layers 20, 20a, 20b, the projection part passes through an insulation adhesive layer and is electrically connected to a wiring pattern or conductive substance of an adjacent unit substrate, and a multilayer printed wiring substrate can be manufactured by a simple compression operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a printed circuit board and a method for manufacturing the same, and more particularly, to a multilayer printed wiring board that can be manufactured using a punching press and a method for collectively manufacturing the same.

[0002]

2. Description of the Related Art Various types of circuit boards having conductor layers on the front and back surfaces have been used. Specifically, TAB (Tape Automated) using flexible polyimide resin or the like for the substrate
ated Bonding) Tape, CSP (Chip Size Package)
, BGA (Ball Grid Array), FPC (Flexible Pr
In addition to an inted circuit, there is a multilayer wiring board using a rigid substrate such as glass epoxy. The mainstream of the conventional method for laminating a plurality of circuit boards having a wiring layer on both sides or one side is a build-up method disclosed in, for example, JP-A-8-125344. This method will be described with reference to FIGS.

First, a desired first wiring pattern 2 is formed on the surface of an insulating substrate 1 having one surface covered with a first copper-clad layer by masking and etching, and a conical shape is formed on the wiring pattern 2. The first conductive bump 3 is printed. A first insulating adhesive layer 4 having the same shape as that of the insulating substrate 1 and covered with a second copper clad layer 2a on the upper surface is positioned above the insulating substrate 1 (FIG. 3A). When it is moved downward and pressed against the insulating substrate 1, the conical tip of the first conductive bump 3 is crushed and flattened, and penetrates the insulating adhesive layer 4 to contact the second copper clad layer 2a. (Fig. 3
b), the first laminate 5 is configured.

Subsequently, the surface of the second copper-clad layer 2a of the first laminate 5 of FIG. 3b is masked and etched to form a desired second wiring pattern 2b on the surface, and the second wiring pattern 2b is formed on the wiring pattern 2b. A second conductive bump 3a having the same shape as the one conductive bump is printed. Next, the second insulating adhesive layer 4a having the third copper-clad layer 2c on the upper surface is located above the first laminate 5 (FIG. 3C). When the second insulating adhesive layer 4a is moved downward and pressed against the first insulating adhesive layer 4, the tip of the cone of the second conductive bump 3a is crushed and flattened, and the second insulating adhesive is bonded. The third copper-clad layer 2c contacts the third copper-clad layer 2c through the agent layer 4a, and is converted into a desired third wiring pattern 2d by masking and etching the third copper-clad layer 2c, thereby forming the second laminate 5a. (FIG. 3d).

[0005]

As described above, in the conventional build-up method shown in FIG. 3, a plurality of wiring patterns 2, 2 are formed on an insulating substrate 1 via insulating adhesive layers 4, 4a.
When forming b and 2d, printing of the conductive bumps and press-bonding of the insulating adhesive layer the same number of times as the number of layers of the wiring pattern are performed. That is, formation of the wiring pattern and printing of the conductive bumps are performed for each layer. Will be needed. Further, the wiring patterns to be formed are continually becoming finer in accordance with recent demands for miniaturization, and it is not easy to form bumps corresponding to such fine wiring patterns by a printing method. Performing the printing method as many times as the number of layers of the wiring pattern is a very heavy burden, and when many products must be manufactured, the time and economic loss cannot be ignored.

In order to meet the demand for such fine wiring pattern printing, a printing machine with an image recognizing device that not only has high printing performance but also has excellent image recognizing function and can ensure high positional accuracy is required. However, such devices are generally expensive and the capital investment is enormous. Further, in the prior art shown in FIG. 3, a wiring pattern layer can be similarly formed below the insulating substrate 1, but in this case, the upper wiring pattern and the lower wiring pattern of the insulating substrate 1 are electrically connected. In order to connect to the substrate, it is necessary to form a through-hole penetrating the insulating substrate 1, which requires not only the labor of forming the through-hole but also the plating of the through-hole, which greatly complicates the manufacturing process. become.

[0007]

SUMMARY OF THE INVENTION A printed circuit board according to the present invention has a polyimide sheet having a wiring pattern formed on both sides or one side, and a through hole penetrating the wiring pattern and the polyimide sheet. A printed circuit board comprising a conductor, wherein at least one end surface of the conductor protrudes from an alignment surface with the polyimide sheet and / or the wiring pattern. When a plurality of printed circuit boards having the protruding portion are laminated and pressed together via an insulating adhesive layer, the protruding portion penetrates the insulating adhesive layer and electrically connects to an adjacent printed circuit board, Multilayer printed wiring boards can be manufactured at once. Further, in the method of the present invention, at least one of both ends of the conductor protrudes from a surface of the wiring pattern and / or the insulating sheet through a through hole in which a conductor is filled in an insulating sheet having a wiring pattern formed on both surfaces or one surface. A printed circuit board is formed in such a manner that a plurality of the printed circuit boards are laminated via an insulating adhesive layer, and the plurality of the laminated printed circuit boards are press-bonded to each other so that the protrusions of the conductor are bonded to each other. A method for manufacturing a multilayer printed wiring board, characterized by forming a wiring pattern of an adjacent printed circuit board penetrating the agent layer and / or making contact with a conductive material to form an electrical connection between the adjacent wiring patterns. is there.

Hereinafter, the present invention will be described in detail. The present invention
Instead of the conventional method of printing conductive bumps in the build-up method, a polyimide sheet is used as the insulating sheet on which the conductive material corresponding to the conventional conductive bumps is formed. A through-hole is formed, the through-hole is filled with the conductive material, and at least one of both ends of the conductive material in the through-hole protrudes from a wiring pattern or a polyimide sheet surface ( (A unit substrate). At present, as wiring patterns are being miniaturized, it is easier and more accurate to form through holes by punching or the like than to form conductive bumps by printing.

When a plurality of unit substrates each having the protruding portion are laminated via an insulating adhesive layer and each unit substrate is pressed, the protruding portion penetrates the insulating adhesive layer between adjacent unit substrates. Electrically connect wiring patterns and conductive materials. Therefore, regardless of the number of unit substrates, a multilayer printed wiring board can be easily manufactured by electrically connecting the unit substrates collectively by a single operation of crimping each unit substrate. The conductive material filled in the through holes of the unit substrate not only connects the wiring patterns of the adjacent unit substrates but also electrically connects the upper and lower wiring patterns of the filled unit substrate. As the conductive substance, lead, tin, copper, nickel or an alloy containing these as a main component, for example, solder is suitable, and in addition, noble metals such as indium, gold, and silver can be used.

The material of the unit substrate used in the present invention is a polyimide resin. The material and the forming method of the wiring pattern are not particularly limited, and a desired wiring pattern may be formed by forming a copper-clad layer, masking by applying a photoresist, exposing, developing, and etching. If necessary, a wiring pattern may be formed on the other surface of the unit substrate in the same manner to form a unit substrate having a wiring pattern on both surfaces. The number of through holes to be generated depends on the number and positional relationship of wiring patterns that require electrical connection, and it is desirable that the diameter of the through hole be as small as possible within a range where sufficient electrical connection is ensured.

The formation of the through hole in the unit substrate and the filling of the conductive material into the through hole are performed by first forming the through hole using a mold or the like and then filling the conductive material into the through hole. Preferably, a through hole is opened using a mold or the like, and a conductive metal sheet (the same material as the conductive material) placed between the mold and the unit substrate is punched into the through hole by a punching press. You may make it enter and fill it. However, when the through hole formation and the filling of the conductive material are performed in a single operation, the tip of the formed protrusion tends to be rounded, and the conduction reliability is likely to be inferior. It is desirable to fill the through hole with a conductive material. Punching, which is preferably used for forming the through hole and filling the conductive material, may be performed in the same manner as in the related art, and the operation itself is simple, but the thickness (t1) of the conductive material excluding the thickness of the protruding portion and It is necessary to pay attention to the relationship between the thickness (t2) of the polyimide sheet of the unit substrate and the selection and setting of post-processing such as caulking.

The relationship between the thickness (t1) of the conductive material and the thickness (t2) of the polyimide sheet has an optimum region, preferably 1.4 × t2 ≧ t1 ≧ 0.7 × t2, more preferably 1.2 × t2 ≧ t1. ≧ 0.9 × t2. This is because if the polyimide sheet is too thick, irregularities may occur on the surface to cause problems in dimensional accuracy, and if the polyimide sheet is too thin, electrical connection with the wiring pattern may be insufficient. The crimping affects the reliability of conduction of the through-hole filled with the conductive material, and the conductive material is fixed in the through-hole according to the conventional method so as to prevent displacement or dropout. The protruding length of the protruding portion formed on at least one of the upper and lower sides of the conductive material depends on the thickness of the insulating adhesive layer to be used, but usually about 10 to 500 μm is appropriate. Depending on the electrical connection required, the protrusion may be provided above or below the conductive material, and when forming a plurality of conductive materials, the protrusion may be partially provided therein. It may not be formed.

The insulating adhesive layer is preferably made of a thermosetting resin which is not completely cured, that is, a so-called prepreg. In addition, a hot melt type, that is, a thermoplastic resin can also be used. Since the conductive material in the through hole and the wiring pattern are not always sufficiently electrically connected, a plating layer may be formed so as to extend between the conductive material and the wiring pattern, or both or one of the plating layers may be formed. May be reflowed to form an alloy at the contact interface between the two, so that electrical connection can be made more reliable. The multilayer printed wiring board manufactured according to the present invention includes TAB tape, CSP, BGA, F
The present invention can be applied to various printed circuit boards using a rigid circuit board such as a glass epoxy in addition to a PC.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a printed circuit board according to an embodiment of the present invention; 1a-e
FIG. 3 is a longitudinal sectional view illustrating a series of manufacturing steps of a single printed circuit board (unit substrate). Polyamide sheet 11
A laminate (CCL, Copper Crad Laminate) called a two-layer type in which a copper clad layer 12 is coated on both upper and lower surfaces is used (FIG. 1a). Instead of the two-layer type, a three-layer type in which an adhesive layer is positioned between the polyimide sheet 11 and the copper-clad layer 12 may be used. May decrease.

The copper clad layer 12 is masked and etched with an appropriate reagent to form a wiring pattern 13 (FIG. 1).
b). After this operation, two separate methods (FIG. 1c or FIG. 1)
A through hole is formed by any one of the methods d), and the through hole is filled with a conductor. In the method shown in FIG. 1C, a conductive metal sheet 14 made of a metal or the like of the same material as the conductor is positioned above the polyimide sheet 11 on which the wiring pattern 13 is formed, and an opening is further formed thereon. A punching die 15 having the same diameter as the through hole is positioned, and the conductive metal sheet 14, the wiring pattern 13 and the polyimide sheet 11 are punched by the die 15 using a press machine, and the wiring pattern 13 and the polyimide sheet 11 are punched.
The through hole 16 is opened at the
16 through the conductive metal sheet 14 and
16 is filled with a part of the conductive material 17 of the conductive metal sheet, and the leading end of the conductive material 17 has a lower wiring pattern.
A projecting portion 18 protruding from 13 is formed to constitute a unit substrate 19 (FIG. 1E).

On the other hand, in the method shown in FIG. 1D, a through hole 16 is opened in the polyimide sheet 11 having the wiring pattern 13 of FIG. 1B by using the same mold as that of FIG. The functional metal sheet 14 is located, the mold 15 used for forming the through hole 16 is located,
The conductive metal sheet 14 is punched by the mold 15 by a press machine to fill the through hole 16 with a part of the conductive metal sheet 14, and the tip of the conductive substance 17 has a lower wiring pattern. A projecting portion 18 protruding from 13 is formed to constitute a unit substrate 19 (FIG. 1E).

FIG. 2 is a longitudinal sectional view showing a procedure for manufacturing a multilayer laminated printed wiring board by laminating the unit substrates manufactured in FIG. 1 at a time. FIG. 2A shows a state before lamination, and FIG. 2B shows a state after lamination. The state of is shown. In FIG. 2a, a total of four unit substrates are located apart from each other, and the uppermost unit substrate 19 is the one shown in FIG.
e is the same as the unit substrate 19 of FIG. The other three unit boards 19a, 19b, and 19c are the same as the top unit board except for the wiring pattern and the opening position of the through hole. Unit boards 19a, 19b, 19c other than the highest-order unit boards
Of the members attached to the uppermost unit substrate 19 are given subscripts a, b, and c, respectively, and description thereof is omitted. Although the drawing shows an example in which the wiring pattern 13 has already been formed as the uppermost unit substrate 19, only the uppermost unit substrate 19 is collectively stacked without forming the wiring pattern 13, and then the uppermost unit substrate 19 is formed. The wiring pattern 13 may be formed on the unit substrate 19.

Three insulating adhesive layers 2 are interposed between the four unit substrates 19, 19a, 19b, and 19c which are sequentially stacked and separated from each other.
0, 20a, 20b are located and the top unit board 19
The left through hole 16a of the second unit board 19a is located at the same position as the left through hole 16a of the second unit board 19a, and the other through hole 16a of the second unit board 19a is located on the left side of the third unit board 19b. And another through hole in the same position as the third unit substrate 19b
16b is the through hole on the right side of the lowest unit board 19c
It is in the same position as 16c. The four unit substrates and the three insulating adhesive layers are set on a press having a heating, pressing, and cooling mechanism, and pressed and heated and pressed. Then, when removed from the press, a multilayer printed wiring board 21 is obtained as shown in FIG. 2b.

In the obtained multilayer printed wiring board 21, the following electrical connections are formed. That is, the lower end protruding portion 18 of the conductive material 17 in the through hole 16 on the left side of the uppermost unit substrate 19 in FIG. 2A penetrates the uppermost insulating adhesive layer 20 and the second unit substrate 19a Is integrated with the conductive material 17a in the through hole 16a on the left side of the above to form a new conductive material (17 + 17a), and the wiring pattern 13 of the uppermost unit substrate 19 is the second and third unit substrates 19a, It is electrically connected to the wiring patterns 13a and 13b of 19b. Similarly, the protrusion 18a of the conductive material 17a in the through hole 16a on the right side of the second unit substrate 19a in FIG. 2A is integrated with the conductive material 17b in the through hole 16b on the left side of the third unit substrate 19b. To form a new conductive material (17a + 17b), and the wiring pattern 13a of the second unit substrate 19a is electrically connected to the wiring patterns 13b, 13c of the third and lowermost unit substrates 19b, 19c. I have. Similarly, a new conductive material (17b +
17c) is formed between the third and lowest unit boards 13b and 13c.

Also, for example, the uppermost unit substrate 19 shown in FIG.
The wiring pattern of the second unit substrate 19a penetrates through the insulating adhesive layer 20 located thereunder even if the conductive material 17 is not integrated with another conductive material such as the conductive material 17 in the through hole 16 on the right side of FIG. 13a, an electrical connection is formed between the uppermost and second unit substrates 19, 19a. By adjusting the position of the through-hole formed through each unit substrate in this way, it is possible to electrically connect any part of the wiring pattern having various shapes of the plurality of unit substrates, and furthermore, the conventional build-up As in the method, it is not necessary to print a conductive bump for each layer (each unit substrate) or the like, and a plurality of unit substrates can be stacked at a time, so that operability is dramatically improved.

EXAMPLE An example of manufacturing a multilayer printed wiring board will be described in the manner shown in FIGS. 1 and 2, but this example does not limit the present invention. A copper-clad layer is patterned on both sides of a 25-μm-thick polyimide resin to form a wiring pattern on a two-layer type CCL.
Of a total of 400 through-holes. This CCL
A conductive metal sheet made of high-temperature solder is placed on the metal sheet, and the sheet is punched using the mold. The above copper is adjusted to about 100 μm on the lower side so that the upper side of the CCL is aligned with the CCL.
Only a unit substrate was embedded in the through hole so as to protrude from the CCL.

Four such unit substrates are laminated via a thermosetting adhesive layer (prepreg) not containing glass fibers having a thickness of about 40 μm and a press having a heating, pressing and cooling mechanism. And press and heat at 150 ° C. and 2 atm for 10 minutes to stack them all together.
Cooled to room temperature over minutes. The electrical resistance between the wiring patterns on the upper and lower surfaces of the unit substrate of the obtained multilayer printed wiring board and the electrical resistance between the wiring patterns between adjacent unit substrates via the adhesive layer were both low on average of 2 mΩ. Was. In order to test the reliability of the electrical connection, the obtained multilayer printed wiring board was immersed in oil at 260 ° C. for 10 seconds, and then immersed in oil at 20 ° C. for 20 seconds, and 100 cycles were repeated. No defects occurred in the multilayer printed wiring board even after the test, and the reliability was confirmed.

[0023]

The printed circuit board according to the present invention includes a polyimide sheet having a wiring pattern formed on both sides or one side, and a conductor filled in a through hole penetrating the wiring pattern and the polyimide sheet. A printed circuit board (Claim 1), wherein at least one end surface of the conductor projects from a matching surface with the polyimide sheet and / or the wiring pattern, and the projection length is 10 to 500. μm (claim 2) is desirable. This printed circuit board is particularly useful as an intermediate for producing a multilayer printed wiring board by laminating a plurality of printed circuit boards. A plurality of such printed circuit boards are laminated via an insulating adhesive layer, and these are pressed together to obtain a multilayer printed wiring board which is laminated at a time.

At this time, the protruding portion of the conductive material penetrates the insulating adhesive layer and electrically contacts the wiring pattern of the adjacent unit substrate or the conductive material. Are connected in a desired electrical relationship, and if necessary, connections between the upper and lower wiring patterns of each unit substrate can be simultaneously secured. By appropriately setting the number and the position of the conductive substance filled in the through holes of each unit substrate, a multilayer printed wiring board having a desired wiring pattern and electrical connection can be collectively laminated by a single crimping operation. .

According to the method of the present invention, an insulating sheet having a wiring pattern formed on both sides or one side is filled with a through-hole by forming at least one of both ends of the conductor from the surface of the wiring pattern and / or the insulating sheet. The printed circuit board is formed so as to protrude, a plurality of the printed circuit boards are laminated via an insulating adhesive layer, and the plurality of laminated printed circuit boards are press-bonded to form a protrusion of the conductor. Manufacturing a multilayer printed wiring board, wherein the electrical connection is formed between adjacent wiring patterns by contacting a wiring pattern and / or a conductive material of an adjacent printed circuit board through the adhesive layer. A method (claim 4).

According to the method of the present invention, as described above, a multilayer printed wiring board can be laminated at a time by a single press-fitting operation, so that the process is extremely simple and the cost can be reduced as compared with the conventional build-up method. Further, since it can be manufactured by a dry method, no waste liquid is generated, the used materials can be recycled, and this is an excellent method from the viewpoint of environmental conservation. In the method of the present invention, it is desirable to form the through hole and fill the conductive material by punching (claim 5). Since the punching method can perform positioning with higher precision than the printing method, miniaturization required in recent printed wiring boards is required. Suitable to achieve.

[Brief description of the drawings]

1A to 1E are longitudinal sectional views showing a series of manufacturing steps of a printed circuit board according to the present invention.

FIGS. 2A and 2B are longitudinal sectional views showing a procedure for manufacturing a multilayer laminated printed wiring board by collectively laminating the unit substrates shown in FIGS. 1A and 1B, and FIGS. 2A and 2B show states before lamination and after lamination, respectively. .

FIG. 3 is a longitudinal sectional view showing a series of steps for manufacturing a multilayer laminated printed wiring board by a conventional build-up method.

[Explanation of symbols]

 11 Polyimide sheet 12 Copper clad layer 13 Wiring pattern 14 Conductive metal sheet 15 Mold 16 Through hole 17 Conductive substance 18 Projection 19 Unit board 20 Insulating adhesive 21 Multi-layer printed circuit board

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Daisuke Arai 1333-2, Hara-shi, Ageo-shi, Saitama F-term (reference) in Mitsui Kinzoku Mining Co., Ltd. 5E317 AA24 BB03 BB12 CC08 CD32 GG14 GG17 5E346 AA22 AA43 CC10 CC32 DD02 DD12 DD32 EE04 EE09 FF33 GG15 GG22 GG24 GG28 HH26 HH32

Claims (5)

[Claims] 1. A polyimide sheet having a wiring pattern formed on both sides or one side thereof, and a conductor filled in a through hole penetrating the wiring pattern and the polyimide sheet, wherein at least one end face of the conductor is provided. A printed circuit board protruding from an alignment surface with the polyimide sheet and / or wiring pattern. 2. A projection according to claim 1, wherein the protrusion length is 10 to 500 μm.
A printed circuit board according to claim 1. 3. A polyimide sheet having a wiring pattern formed on both surfaces or one surface thereof, and a conductor filled in a through hole penetrating the wiring pattern and the polyimide sheet, and at least one end surface of the conductor. A plurality of printed circuit boards having a protruding portion from the alignment surface with the polyimide sheet and / or the wiring pattern are laminated via an insulating adhesive layer, and the plurality of printed circuit boards are pressed and laminated together. A multilayer printed wiring board, characterized in that: 4. A through hole in which an electric conductor is filled in an insulating sheet having a wiring pattern formed on both surfaces or one surface so that at least one of both ends of the electric conductor protrudes from the surface of the wiring pattern and / or the insulating sheet. Forming a printed circuit board, laminating a plurality of the printed circuit boards via an insulating adhesive layer, and pressing the laminated plurality of printed circuit boards by crimping so that the projecting portion of the conductor becomes the adhesive. A wiring pattern of an adjacent printed circuit board penetrating the layer and / or
Alternatively, a method for manufacturing a multilayer printed wiring board, comprising forming an electrical connection between wiring patterns adjacent to each other by contacting a conductive substance. 5. The method according to claim 4, wherein the formation of the through hole and the filling of the conductive material are performed by punching.