JP3447029B2 - Printed wiring board manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board manufacturing method, and more particularly to a manufacturing method for manufacturing a large number of printed wiring boards from a worksheet.

[0002]

2. Description of the Related Art In manufacturing a printed wiring board, a work sheet is used for multiple cutting. This worksheet is generally 340mm x 510mm, or 510
After forming a large number of conductive patterns for a printed wiring board on this worksheet with a shape of mm × 510 mm, the printed wiring board is divided into individual printed wiring boards by dicing or the like.

In recent years, along with the progress of electronics, there has been a demand for higher density in printed wiring boards, and multilayer printed wiring boards having multiple wiring circuits have come to be used. This multilayer printed wiring board is manufactured by alternately building up conductor circuits and resin insulating layers on a worksheet.

When a multilayer wiring layer is built up on this worksheet, unnecessary portions of the copper-clad substrate are removed by etching from the lowermost wiring layer, that is, by the subtrackive method. A plurality of wiring patterns 23 as shown in FIG. 7A are formed. Then, a method of stacking a plurality of wiring layers by the additive method on the wiring pattern 23 formed by the sub-trackive method is generally adopted. Here, the lowermost wiring layer is formed by the sub-tracktive method because the sub-trackive method can form a highly reliable wiring layer at a low cost.

[0005]

However, since the wiring layer is laminated on the wiring pattern 23, the roll coater 50 shown in FIG. 4 has the work sheet 20 shown in FIG. 7A.
When applying the intercalation agent through the direction of the arrow C in the figure, the thickness of the intercalation agent was different between the wiring 23a at the end of the entrance side to the roll coater 50 and the wiring 23b inside. This will be described with reference to FIG. FIG. 8A shows a vertical cross section of the worksheet passed through the roll coater 50 in the arrow C direction. A relatively high printing pressure is applied to the wiring 23a at the end of the entrance side that first passes through the roll coater 50,
After this, the inner wiring 23 passing through the roll coater 50
After b, a substantially uniform printing pressure is applied. Therefore, the film thickness α1 on the wiring 23a at the entrance side is equal to that of the wiring 23b on the inside.
It becomes thinner than the upper film thickness β1.

Here, as shown in FIG. 8 (B), when forming an opening for a via hole in the applied interlayer agent 24 by photolithography, the film thickness β on the inner wiring 23b
When the condition is set to 1, the via hole opening 16b on the wiring 23b can be properly opened. On the other hand, the via hole opening 16a on the wiring 23a at the end of the entry side becomes defective in shape and causes insulation failure, or the wiring 23a itself may be damaged by an etching solution when the via hole opening 16a is formed. Deterioration, and further, the wiring 2
The adhesive (not shown) that fixes 3a to the work sheet 20 is melted, causing a problem such as floating of the wiring 23.

On the contrary, if the condition is adjusted to the film thickness α1 on the wiring 23a at the entry side end, the via hole opening 16a on the wiring 23a can be properly opened, but the via hole on the inner wiring 23b can be formed. The opening 16b is left unopened, and the connection with the upper wiring pattern cannot be performed properly.

Further, the roll coater 50 is covered with a flexible member such as rubber, and grooves 50a are formed on the surface at a pitch of about 1 mm. An enlarged view of the surface of the roll coater 50 is shown in FIG. The above-mentioned interlayer agent is carried in the groove 50a of the roll coater 50 and is pressed against the worksheet 20 with a predetermined pressure, whereby the worksheet 2
It is transferred to the 0 side. Here, as shown in FIG. 4 (A), when the work sheet 20 on which the wiring pattern 23 is formed is passed through the roll coater 50 to apply the intercalation agent, the end portion of the work sheet 20 has relatively large irregularities or scratches. Therefore, there is a portion where the intercalating agent cannot be transferred to the surface of the worksheet 20. Here, as shown in FIG. 7B, if the intercalation agent is not transferred at the end 20a of the worksheet 20, a so-called coating streak 46 in which the intercalation agent is not transferred in a streak form from the end 20a is generated. As a result, the printed wiring board becomes defective.

Further, when the interlayer agent was cured by heating or exposure, stress was applied and the work sheet 20 was warped.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a printed wiring board that allows proper formation of via holes.

Another object of the present invention is to provide a method for manufacturing a printed wiring board which does not cause coating stripes and does not cause warp in the substrate.

[0012]

In order to achieve the above object, in the method for manufacturing a printed wiring board according to the first aspect of the present invention, a conductive foil attached to a substantially rectangular worksheet is provided with a plurality of conductive patterns and the plurality of conductive patterns. And removing the frame-shaped pattern surrounding the conductive pattern, and applying an intercalation agent to the worksheet using a roll coater to open the via hole.
A technical feature is that it has a step of forming a mouth and a step of curing the intercalation agent applied in the above step.

In order to achieve the above object, in the method of manufacturing a printed wiring board according to a second aspect of the present invention, a conductive foil attached to a substantially rectangular worksheet is provided with a plurality of conductive patterns and the peripheral edge of the worksheet is plated. A step of removing the lead portion and leaving, a step of applying an interlayer agent to the worksheet using a roll coater , forming a via hole opening, and a step of curing the interlayer agent applied in the above step, The technical feature is that the plating lead portion at the peripheral portion of the worksheet has a thickness that does not warp the worksheet when the interlayer agent is cured.

[0014] In any of the manufacturing method according to claim 1, to form a conductive pattern on an interlayer agent.

[0015]

According to the invention of claim 1, a plurality of conductive patterns and a frame-shaped pattern surrounding the plurality of conductive patterns are formed on the worksheet. Thereby, when applying the intercalation agent using a roll coater, a high printing pressure is applied to the frame-shaped pattern, and the high printing pressure is not applied to the conductive pattern. The agent can be applied. In addition, even if the intercoating agent cannot be attached from the roll coater at the outer edge of the worksheet and coating streaks occur, high printing pressure is applied when the roll coater comes into contact with the frame-shaped pattern, and Since it adheres to the frame-shaped pattern, no coating streaks remain on the conductive pattern. Furthermore, by leaving the conductor foil in the shape of a frame, a uniform force is applied when the interlayer agent is cured, and the work sheet is not warped.

According to the second aspect of the invention, the plating lead surrounding the plurality of conductive patterns is formed thick. As a result, a uniform force is applied when the intercalating agent is cured, and the work sheet is not warped. In addition, even if the intercoating agent cannot be attached from the roll coater at the outer edge of the worksheet and coating streaks occur, a high printing pressure is applied when it comes into contact with the thick plating lead, and the intercalating agent attaches to the plating lead. Therefore, coating streaks do not remain on the conductive pattern.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments embodying the present invention will be described below with reference to the drawings. 1 and 2 show a manufacturing process of a multilayer printed wiring board according to an embodiment of the present invention. As shown in FIG. 1 (A), a 520 mm × 520 mm worksheet 20 is formed by laminating a copper foil 22 of 18 μm on both sides of a base material 20 a made of glass epoxy or BT (bismaleide triazine) having a thickness of 1 mm. A plurality of wiring patterns 23 are formed by etching the copper foil 22 as a material into a pattern according to a conventional method. At this time, 10 is attached to the peripheral portion of the worksheet 20.
A frame-shaped pattern 40 having a width of mm is left as shown in FIG. The frame-shaped pattern 40 is not connected to the wiring pattern 23 side. A cross section of the worksheet 20 illustrated in FIG. 3A is illustrated in FIG.

Here, 25 of cresol novolac type epoxy resin (manufactured by Nippon Kayaku: molecular weight 2500) dissolved in DMTG (trimethylene glycol dimethyl ether) is used.
% Acrylate, 70 parts by weight of polyether sulfone (PES), 4 parts by weight of imidazole curing agent (manufactured by Shikoku Kasei: product name 2E4MZ-CN), caprolactone modified tris (acryloxyethyl) isocyanate as a photosensitive monomer. Nurate (manufactured by Toagosei: trade name Aronix M325) 10 parts by weight, benzophenone as a photoinitiator (manufactured by Kanto Kagaku) 5 parts by weight, Michler's ketone as a photosensitizer (manufactured by Kanto Kagaku) 0.5 parts by weight, and further The average particle size of the epoxy resin particles was 5.5 μm for the mixture.
After mixing 5 parts by weight of 5 parts by weight and an average particle size of 0.5 μm with 5 parts by weight of NMP, the mixture was further mixed by adding NMP, and the viscosity was adjusted to 2000 cps with a homodisper stirrer. A solvent-based adhesive solvent.

The photosensitive adhesive material (interlayer agent) is applied to both sides of the work sheet 20 shown in FIG. 1 (B) after the etching process by using the roll coater 50 shown in FIG. That is, the worksheet 20 is applied to the roll coater 50.
Through in the direction of arrow C in FIG. At this time, FIG.
Wiring 23 at the end on the entry side to the roll coater shown in (A)
The thickness of the intercalation agent 26 is uniform between a and the inner wiring 23b. This will be described with reference to FIG. FIG. 8C shows
The longitudinal section of the worksheet 20 which passed the roll coater 50 in the arrow C direction is shown. A relatively high printing pressure is applied at the frame-shaped pattern 40 that first passes through the roll coater 50, and thereafter, the wiring 23a at the entrance side and the wiring 23b at the inner side that pass through the roll coater 50 have a substantially uniform printing pressure. Join. Therefore, the film thickness γ on the frame-shaped pattern 40
Is thinner than the film thickness α2 on the wiring 23a at the entry side end and the film thickness β2 on the wiring 23b on the inner side, the wiring 23a
The upper film thickness α2 is equal to the inner film thickness β2 on the wiring 23b. That is, the film thickness is uniform on the entire wiring pattern 23 shown in FIG.

Here, as described above with reference to FIG. 7B, since the end portion of the work sheet 20 has relatively large unevenness, the work sheet 20 is rolled by the roll coater 50 as shown in FIG. 4A. When the intercalation agent is applied through the sheet, there are portions where the intercalation agent cannot be transferred to the surface of the worksheet 20. Here, as shown in FIG. 3B, the worksheet 2
If the intercalation agent is not transferred at the end portion 20a of 0, a so-called coating stripe 46 in which the intercalation agent is not transferred in a stripe shape from the end portion 20a is generated. However, the roll coater 50
When comes into contact with the frame-shaped pattern 40, the surface of the roll coater 50 is pressed against the frame-shaped pattern 40, and the interlayer agent is transferred to the roll coater 50 again. That is, since the coating stripe 46 generated at the end portion of the worksheet 20 does not extend beyond the frame-shaped pattern 40 to the wiring pattern 23 side, the printed stripe does not cause a trouble on the printed wiring board.

After applying the interlayer agent 24, the work sheet 20 is left in a horizontal state for 20 minutes and then dried at 60 ° C. for 30 minutes to obtain a thickness of 60 as shown in FIG. 1 (C).
An adhesive layer 26 of μm is formed.

As shown in FIG. 1C, in order to form a via hole on the work sheet 20 on which the adhesive layer 26 is formed, a photomask film on which a black circle of 100 μmφ is printed is brought into close contact with the work sheet 20, and an ultrahigh pressure mercury lamp is used. Exposure at 500 mj / cm ² . This is spray-developed with a DMTG solution to form an opening 28a which becomes a via hole of 100 μmφ in the adhesive layer 26 (FIG. 1D). In addition, the worksheet 20 is 3000 mj / cm with an ultra-high pressure mercury lamp.
² exposure, heat treatment at 100 ° C. for 1 hour, and then at 150 ° C. for 5 hours to obtain a 50 μm-thick film having openings (via-hole forming openings) with excellent dimensional accuracy equivalent to a photomask film. The resin interlayer insulating layer 27 is formed. In addition, a tin plating layer (not shown) is partially exposed in the opening 28a serving as a via hole.

In the method for manufacturing a multilayer printed wiring board according to the prior art described above with reference to FIG. 8A, the film thickness is different between the wiring 23a at the end of the entrance side and the wiring 23b at the inner side. In the first embodiment, the film thicknesses on the wiring 23a at the entrance side and the wiring 23b on the inside are equal.
Therefore, as shown in FIG. 8D, the openings 28a and 28b, which are via holes, can be formed on the wiring pattern 23 with high dimensional accuracy. Therefore, the work sheet 20 can be properly connected to a conductor circuit in an upper layer, which will be described later, and the work sheet 20 is formed by over-etching the wiring 23a at the entrance side.
Does not occur, and insulation failure due to over-etching does not occur.

As shown in FIG. 1 (D), the work sheet 20 having the openings 28a formed therein was treated with CrO ₃ (80 ° C.) at 70 ° C.
0 g / l) It is immersed in an aqueous solution for 10 to 30 minutes to dissolve the epoxy resin particles in the resin interlayer insulating layer 27 to roughen the surface of the resin interlayer insulating layer 27 (see FIG. 2E), and then It is immersed in a neutralizing solution (made by Shipley) and then washed with water.

A palladium catalyst (manufactured by Atotech) is applied to the worksheet 20 shown in FIG. 2 (E) which has been subjected to this roughening treatment, so that a catalyst nucleus is attached to the resin interlayer insulating layer 27 and the via hole opening 28a. .

On the other hand, a cresol novolak type epoxy resin (manufactured by Nippon Kayaku: trade name EOCN) dissolved in DMTG.
-103S) 25% epoxidized acrylate-sensitized oligomer (molecular weight 4000), imidazole curing agent (manufactured by Shikoku Kasei: trade name 2 PMHZ-PW), photosensitive monomer acrylic isocyanate (manufactured by Toagosei: Brand name Aronix M215), benzophenone (manufactured by Kanto Kagaku) as a photoinitiator, and Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer are mixed with NMP with the following composition, and the viscosity is 3000 cps with a homodisper agitator.
And then kneading with a three-roll mill to obtain a liquid resist. Resin composition; Photosensitive epoxy / M215 / BP / MK /
Imidazole = 70/10/5 / 0.5 / 5

The liquid resist is coated on both sides of the work sheet 20 which has been subjected to the above-mentioned catalyst nucleation treatment by using a roll coater, and dried at 60 ° C. for 30 minutes to have a thickness of 3
A 0 μm resist layer is formed. Next, a mask film on which a conductor circuit pattern of L / S (line to space ratio) = 50/50 is drawn is brought into close contact, exposed with an ultrahigh pressure mercury lamp at 1000 mj / cm ² , and spray-developed with DMTG. As a result, a plating resist with a missing conductor circuit pattern portion is formed on the work sheet 20, and further exposed at 6000 mj / cm ² with an ultra-high pressure mercury lamp to 100 ° C.
1 hour, and thereafter, heat treatment is performed at 150 ° C. for 3 hours to form a permanent resist 30 on the interlayer insulating layer 27 as shown in FIG.

The worksheet 20 on which the permanent resist 30 is formed is preliminarily subjected to plating pretreatment (specifically, sulfuric acid treatment and activation of catalyst nuclei), and then electroless copper plating having the composition shown in FIG. Electroless copper plating with a thickness of approximately 15 μm on the non-resist area by electroless plating with a bath 3
4 is deposited and the outer layer copper pattern and the via hole 32 are formed to form a conductor layer by the additive method (FIG. 2G).

Then, by repeating the process shown in FIG. 1C to the process shown in FIG. 2G, one more conductor layer is formed by the additive method (FIG. 2H). In this way, the wiring layers are built up to form six wiring layers.

Finally, the work sheet 20 is cut by dicing to obtain a product-sized printed wiring board.

Next, the second embodiment of the present invention will be described with reference to FIG. In the first embodiment described above with reference to FIG. 3, the frame-shaped pattern 40 was formed on the periphery of the worksheet 20, but in the second embodiment, the plating lead 44 for performing electrolytic plating has the worksheet. It is arranged at the periphery of 20. Here, the worksheet 20 is 340 mm × 340 mm in the second embodiment.
The size of the copper foil is 18 μm. The width of the plating lead 44 is 10 mm. The plating lead 44 and the wiring pattern 2
3 is electrically connected, but it should be noted that the pattern for connection is omitted because the drawing is complicated.

FIG. 6B shows a worksheet 20 according to the prior art in which the plating leads 144 are arranged.
The conventional plating lead 144 is formed with a width of about 1 mm so that a necessary current can be passed therethrough. Therefore, when applying the intercalation agent by the roll coater 50, if the intercalation agent cannot be transferred at the end 20a of the worksheet 20, a so-called coating stripe in which the intercalation agent is not transferred in a streak shape from the end 20a. 46 extended beyond the plated leads 144. On the other hand, since the work sheet 20 of the second embodiment is formed with the plating leads 44 having a width of 10 mm, the coating stripes are formed over the plating leads 44 and the wiring is formed in the same manner as in the first embodiment described above. It does not extend to the pattern 23.

Further, in the second embodiment, the work sheet 20 is provided with the plating lead 44 having a width of 10 mm, and the residual copper rate on the work sheet 20 is made to be nearly uniform, whereby the applied intercalation agent is cured. When this happens, the worksheet 20 does not warp. Incidentally, in this second embodiment, 340
Worksheet 20 of mm x 340 mm was used, but 520 mm
Even with a x520 mm worksheet, by disposing the plating lead 44 having a width of 10 mm, it is predicted that the worksheet 20 will not warp when the interlayer agent is cured as in the first embodiment. It should be noted that the plating lead 144 and the wiring pattern 23 in FIG. 6B are electrically connected, but the pattern for connection is omitted because the drawing is complicated.

In the first and second embodiments described above,
Although an example in which glass epoxy or BT is used as the base material 20a of the worksheet 20 has been given, the present invention shows that when various materials having flexibility such as glass polyimide and a polyimide film are used as the worksheet 20, warpage is prevented. It can prevent the occurrence. Furthermore, low flexibility, alumina substrate, low temperature firing ceramic substrate, aluminum nitride substrate,
When using an aluminum substrate, iron substrate, copper substrate, etc.,
According to the present invention, it is possible to properly form a via hole and prevent the occurrence of coating stripes by making the thickness of the interlayer agent uniform.

[0035]

As described above, according to the manufacturing method of the invention of claim 1, by forming the frame-shaped pattern on the worksheet, the interlayer agent is applied to the conductive pattern with a uniform thickness. It is possible to properly form the via hole. Moreover, since no coating stripes are formed on the wiring pattern, a defective printed wiring board is not generated. Further, the frame-shaped pattern applies uniform force when curing the intercalating agent, so that the work sheet is not warped.

According to the second aspect of the present invention, by forming the plating lead to be thick, it becomes possible to apply the intercalation agent on the conductive pattern with a uniform thickness, and the via hole can be appropriately formed. Moreover, since no coating stripes are formed on the wiring pattern, a defective printed wiring board is not generated. Further, the thick plated lead exerts a uniform force when curing the intercalating agent, so that the work sheet is not warped.

[Brief description of drawings]

FIG. 1 is a plan view of a worksheet according to a first embodiment of the present invention.

FIG. 2 is a process drawing showing a manufacturing process of a multilayer printed wiring board according to an embodiment of the present invention.

FIG. 3 is a process chart showing a manufacturing process of a multilayer printed wiring board according to an embodiment of the present invention.

FIG. 4 is a perspective view of a roll coater.

FIG. 5 is a table showing compositions of electrolytic plating baths.

FIG. 6 (A) is a plan view of a worksheet according to a second embodiment of the present invention, and FIG. 6 (B) is a plan view of a worksheet according to a conventional technique.

FIG. 7 is an explanatory diagram showing an interlayer agent transferred by a roll coater and a via hole provided in the interlayer agent.

FIG. 8 is a plan view of a worksheet according to the related art.

[Explanation of symbols]

20 worksheets 20a base material 23 Wiring pattern 26 Adhesive layer 27 Resin interlayer insulation layer 32 via hole

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-254189 (JP, A) JP-A-59-151498 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 3/46

Claims (2)

(57) [Claims] 1. A step of removing a conductive foil attached to a substantially rectangular worksheet, leaving a plurality of conductive patterns and a frame-shaped pattern surrounding the plurality of conductive patterns, and a roll coater on the worksheet. A build-up print comprising: a step of applying an intercalation agent using the above to form an opening for a via hole; and a step of curing the intercalation agent applied in the above step. Wiring board manufacturing method. 2. A step of removing a conductive foil attached to a substantially rectangular worksheet, leaving a plurality of conductive patterns and a plating lead portion at a peripheral portion of the worksheet, and a roll coater on the worksheet. And applying an intercalation agent to form an opening for a via hole, and curing the intercalation agent applied in the above step. A build-up method for manufacturing a printed wiring board, characterized in that the work sheet has a thickness that does not warp when the interlayer agent is cured.