JP3495627B2 - Build-up multilayer printed wiring board and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention proposes a printed wiring board in which characters such as a serial number are printed on a solder resist layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, an IC is provided on the surface of a printed wiring board.
In order to mount a chip or the like, solder bumps or the like are formed, and a solder resist layer is provided so that these solder bumps do not fuse with each other. Various characters and symbols such as display characters and recognition characters for identifying the product are formed on the solder resist layer.

[0003]

However, there is a problem that the surface of the solder resist layer has a low wetting property and the ink for character printing is easily repelled. Therefore, the characters formed on the surface are faint. If the viscosity of the character printing ink is reduced as a countermeasure against this, the formed characters will bleed and stain the solder resist layer or the solder bumps provided on the solder resist layer.
The connection with the C chip may be lost.

By the way, the characters provided on such a printed wiring board include a process recognition target mark which serves as a mark when the printed wiring board is mounted. Since this target mark is mainly optically recognized by the image recognition device, if a mark is formed on the solder resist layer with such printed characters, accurate image recognition may not be possible due to the above-mentioned bleeding or blurring, and it may take time for recognition. There was a problem that it took. Further, when the color of the solder resist layer is semi-transparent, especially in a built-up wiring board in which conductor circuits are laminated in multiple layers, the conductor circuits under the solder resist layer can be seen through and the printed characters cannot be discriminated. Sometimes.

According to the present invention, there is no blurring or blurring of characters,
It is possible to correctly perform image recognition in process recognition regardless of the color of the solder resist layer and the position of the conductor circuit.
Moreover, it is to provide a printed wiring board having excellent connectivity and reliability, and a method for manufacturing the same.

[0006]

As a result of intensive studies, the present inventors have found the following facts regarding character printing.
That is, when characters are printed on the solder resist layer with the ink for printing characters, if the characters for printing characters are formed by two ink layers, bleeding and blurring do not occur, and image recognition of the characters for process recognition is accurate. I knew I could do it.

The character printing ink used may be a known thermosetting resin such as a polyimide resin, a phenol resin, or an epoxy resin for both the lower ink layer and the upper ink layer. In particular, it has been found that when the lower ink layer and the upper ink layer have substantially the same material and composition, the ink thickness of characters formed on the upper layer has a desired uniform thickness. The thermosetting resin preferably has a glass transition temperature in the range of 100 to 180 ° C. This is because it is close to the glass transition temperature of the solder resist layer, so that peeling and chipping due to thermal history can be prevented.

The characters formed by the character printing of the present invention are at least one or more selected from product recognition characters, manufacturing recognition characters, and process recognition characters.

Here, the product recognition characters are hiragana, katakana, kanji, numbers, alphabets, trademarks, etc. to determine the company name, product name, product characteristics, etc.
A character that can be distinguished.

The manufacturing recognition character means a manufacturing date, a control number, a lot number, data related to manufacturing based on an inspection result (process before printing characters), and a character capable of determining and distinguishing the result.

The process recognition character is a character such as a target mark, a bar code, etc., which is related to a process such as product recognition in the mounting and inspection processes and a target for alignment.

At least two ink layers for forming characters are (a) a lower ink layer forming step, (b) a lower ink layer drying step, and (c) an upper ink layer forming step (using a mask). It is formed by a character printing process including a character printing process) and (d) a drying process of the upper ink layer. Hereinafter, each ink layer will be described together with steps.

The lower ink layer serves as a base of the upper ink layer, and also serves to clarify the character printing formed by the upper ink layer and prevent the occurrence of bleeding and blurring. (A) Lower ink layer forming step Is formed on the solder resist layer. Its thickness is 10 to 50 μm. Particularly, it is preferably 15 to 40 μm. The reason is that it is easy to maintain the thickness uniformity of the upper ink layer formed later. The color of the lower ink layer is not particularly limited, but the accuracy of image recognition is improved when the color is not close to the color of the upper ink layer. In particular, when the print character is a process recognition character such as a target mark, as described above,
In order to be optically read by the image recognition device, it is desirable to use a combination having a high color contrast with the upper ink layer, that is, a high contrast. The formation range of the lower ink layer is not particularly limited as long as it is the surface of the solder resist layer excluding the area where the solder bumps are formed, and may be a part or the entire surface of the solder resist layer.

This lower ink layer is dried in the step (b) lower ink layer drying step. The drying temperature is not particularly limited as long as it is a temperature at which the thermosetting resin used in the ink can be cured, and is preferably 50 to 250 ° C. further,
Step curing in which the temperature is gradually raised from a low temperature is also preferable. Further, the degree of drying is such that even if the thermosetting resin used for the lower ink layer is completely cured, the two layers are completely cured after the upper ink layer is provided while remaining in a semi-cured state. Good. When the underfill is placed on the character print with air bubbles in the lower ink layer, cracks may be generated from the air bubbles to reduce reliability. It is desirable to perform defoaming to remove bubbles.

On the other hand, the upper ink layer is for forming characters by being laminated on the lower ink layer in the printed wiring board, and is formed by the step (c) of forming the upper ink layer. In this step, a masking material on which a character symbol or the like is formed is arranged and brought into close contact with the lower ink layer, and character printing is performed by forming an upper ink layer on the surface of the lower ink layer.
Character printing is effectively performed by so-called screen printing. The thickness of the upper ink layer is preferably 10 to 50 μm, and the total thickness of the lower ink layer is preferably not more than 100 μm. Especially 15-40
μm is preferred. The reason for this is that it is easy to obtain an ink layer having a uniform thickness, and it is possible to obtain clear printed characters with excellent printability and workability when printing characters.
In particular, by forming process recognition characters such as a target mark to have the above-mentioned thickness, the image can be accurately read by the image detecting device for recognition.

If the thickness of the upper ink layer is less than 10 μm, the characters may be too thin to be recognized by the image recognition device. On the other hand, if the thickness of the upper ink layer and the thickness of the lower ink layer are more than 100 μm, the height is higher than the height of the solder bumps, which may interfere with the mounting of external electronic components such as IC chips. is there.

As described above, the color of the ink in the upper ink layer is the same as or similar to the color of the ink in the lower ink layer (eg, when the lower ink layer is green, the upper ink layer is yellow-green, etc.). It is desirable not to do so, for example, when the lower ink layer is black, the upper ink layer is a reference color such as white. That is, by making the contrasts different from each other, the image can be read with high accuracy by the image detection device.

Further, after forming the upper ink layer so as to have substantially the same size (area) as the lower ink layer, the upper ink layer is removed in a character shape, and the color of the lower ink layer is formed on the surface of the upper ink layer. Characters can also be effectively printed by revealing them. In that case, it is preferable to carry out after (d) the upper ink layer drying step described below. It is effective to remove the upper ink layer by plasma, laser irradiation, and liquid spraying.

The plasma used may be known plasma such as ozone, oxygen, UV, carbon tetrachloride and the like.
The irradiation time of these plasmas is preferably about 5 to 20 minutes. This plasma irradiation is also expected to have an effect of removing the oxide film of the solder resist layer, improving the contact angle, and improving the applicability of the underfill when the IC chip is mounted.

As the laser used, a commonly used laser such as a carbon dioxide gas laser or a YAG laser can be used without any problem. By using such a laser, fine printing can be performed even on a small wiring board.

Further, as the liquid to be sprayed,
Liquids containing suitable abrasives in water, solvents and mixtures thereof are used. When a liquid is used, a masking material on which predetermined characters are formed is placed on the upper ink layer surface,
By ejecting the liquid at once from the pen-like nozzle, the upper ink layer can be formed in the shape of a character by removing the upper ink layer. The injection pressure is about 0.1 to 10 atm.
Depending on the composition of the character printing ink used and the like, the upper ink layer may be in a semi-cured state and may be completely cured after the characters are formed.

Next, (d) the step of drying the upper ink layer,
The same process as the drying process of the lower ink layer described above is performed at a temperature of 5
It is preferable to carry out at 0 to 250 ° C. Further, it is desirable to carry out step hardening in which the temperature is gradually increased from a low temperature. In this drying step, the upper ink layer is cured by drying. However, when the lower ink layer is left in a semi-cured state in the lower ink layer drying step, the upper ink layer drying step is performed. It is sufficient to completely cure both layers. Furthermore, in order to remove air bubbles in the upper ink layer, depressurization and vacuum defoaming may be performed.

The upper ink layer and the lower ink layer can be preferably formed by any of commonly used methods such as printing using a squeegee and coating by potting.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a printed wiring board of the present invention will be described below. The following method is based on the semi-additive method, but the full-additive method may be adopted.

First, a wiring board having a conductor circuit formed on the surface of the board is prepared. As the substrate, a glass epoxy substrate, a polyimide substrate, a resin insulating substrate such as a bismaleimide-triazine resin substrate, a copper-clad laminate, a ceramic substrate, a metal substrate, or the like can be used. An adhesive layer for electroless plating is formed on this substrate, the surface of the adhesive layer is roughened to form a roughened surface, and thin electroless plating is applied to the entire roughened surface. Subsequently, after forming the plating resist, and after performing the electrolytic plating of thickening the non-plating resist forming portion,
The plating resist is removed, etching is performed, and a conductor circuit including an electrolytic plating film and an electroless plating film is formed. The conductor circuit is preferably a copper pattern.

On the substrate on which the conductor circuit is formed, a recess is formed by the conductor circuit or the through hole. In order to fill and smooth the concave portions, a resin filler is applied and dried, and then unnecessary resin filler is ground by polishing to expose the conductor circuit, and then the resin filler is fully cured.

Next, a roughening layer is provided on the exposed conductor circuit. The roughened layer formed is an etching treatment, a polishing treatment,
A roughened surface of copper formed by oxidation treatment or redox treatment or a roughened surface formed by a plating film is desirable.

In the adhesive for electroless plating used in the present invention, the heat-resistant resin particles soluble in the acid or the oxidant which have been subjected to the curing treatment are contained in the uncured heat-resistant resin which is hardly soluble in the acid or the oxidant. What is dispersed is optimal. By treating with an acid or an oxidizing agent, the heat-resistant resin particles are dissolved and removed, and a roughened surface composed of octopus-like anchors can be formed on the surface.

In the above adhesive for electroless plating, the heat-resistant resin particles that have been particularly hardened include heat-resistant resin powder having an average particle size of 10 μm or less, and an average particle size of 2 μm.
Aggregated particles obtained by aggregating heat-resistant resin powder of m or less, a mixture of heat-resistant powder resin powder having an average particle diameter of 2 to 10 μm and heat-resistant resin powder having an average particle diameter of 2 μm or less, and an average particle diameter of 2 to 10 μm. The average particle size is 2μ on the surface of the heat-resistant resin powder
pseudo particles formed by adhering at least one of heat-resistant resin powder of m or less or inorganic powder, heat-resistant powder resin powder having an average particle diameter of 0.1 to 0.8 μm, and average particle diameter of 0.8 μm. It is desirable to use a mixture with a heat-resistant resin powder having an average particle size of more than 2 μm and less than 2 μm, or a heat-resistant powder resin powder having an average particle size of 0.1 to 1.0 μm. This is because they can form more complex anchors.

As the heat resistant resin which is hardly soluble in the acid or the oxidizing agent, there are used "resin composites composed of thermosetting resin and thermoplastic resin" or "resin composites composed of photosensitive resin and thermoplastic resin". Is desirable. This is because the former has high heat resistance, and the latter allows openings for via holes to be formed by photolithography.

As the thermosetting resin, epoxy resin, phenol resin, polyimide resin or the like can be used. In addition, in the case of photosensitization, methacrylic acid, acrylic acid or the like is subjected to an acrylate reaction with a thermosetting group. Particularly, acrylate of epoxy resin is most suitable.

As the epoxy resin, a novolac type epoxy resin such as phenol novolac type or cresol novolac type, a dicyclopentadiene-modified alicyclic epoxy resin, or the like can be used. As the thermoplastic resin, polyether sulfone (PES), polysulfone (PSF), polyphenylene sulfone (PP)
S), polyphenylene sulfide (PPES), polyphenyl ether (PPE), polyetherimide (P
I) or the like can be used.

The mixing ratio of the thermosetting resin (photosensitive resin) and the thermoplastic resin is preferably thermosetting resin (photosensitive resin) / thermoplastic resin = 95/5 to 50/50. A high toughness value can be secured without impairing heat resistance. The mixing ratio of the heat resistant resin particles is 5 to 50% by weight, preferably 10 to 40% by weight based on the solid content of the heat resistant resin matrix. The heat-resistant particles are preferably amino resin (melamine resin, urea resin, guanamine resin), epoxy resin, or the like. The adhesive may be composed of two layers having different compositions.

Next, while curing the interlayer insulating resin layer,
The interlayer resin is provided with an opening for forming a via hole in the resin layer.

When the resin matrix of the adhesive for electroless plating is a thermosetting resin, the interlayer insulating resin layer is subjected to perforation by using laser light, oxygen plasma or the like to form a photosensitive resin. In some cases, the holes are formed by exposure and development. In addition,
In the exposure and development process, a photomask (a glass substrate is preferable) on which a circular pattern for forming a via hole is drawn is placed with the circular pattern side being in close contact with the photosensitive interlayer resin insulation layer. After that, it is exposed and developed.

Next, the surface of the interlayer resin insulation layer (adhesive layer for electroless plating) provided with openings for forming via holes is roughened. In particular, in the present invention, the surface of the adhesive layer is roughened by dissolving and removing the heat-resistant resin particles existing on the surface of the adhesive layer for electroless plating with an acid or an oxidizing agent. At this time, a roughening layer is formed on the interlayer insulating resin layer.

As the acid treatment, phosphoric acid, hydrochloric acid, sulfuric acid, or an organic acid such as formic acid or acetic acid can be used.
It is particularly desirable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is unlikely to corrode. For the oxidation treatment, it is desirable to use chromic acid or permanganate (potassium permanganate or the like).

The roughening layer has a maximum roughness Rmax of 0.1 to 0.1.
20 μm is preferable. This is because if it is too thick, the roughening layer itself is likely to be damaged or peeled off, and if it is too thin, the adhesiveness is reduced. Particularly in the semi-additive method, 0.1 to 5 μm is preferable. This is because the electroless plating film can be removed while ensuring the adhesiveness.

Next, a thin electroless plating film is formed on the entire surface of the interlayer insulating resin which has been roughened and provided with catalyst nuclei. This electroless plated film is preferably electroless copper plated and has a thickness of 1 to 5 μm, more preferably 2 to 3 μm. As the electroless copper plating solution, one having a liquid composition adopted in a conventional method can be used, and for example, copper sulfate: 29 g / l, sodium carbonate: 25 g / l, EDTA: 140 g / l,
A liquid composition of sodium hydroxide: 40 g / l, 37% holmaldehyde: 150 ml, (PH = 11.5) is preferable.

Next, a photosensitive resin film (dry film) is laminated on the electroless plated film thus formed.
And a photomask in which a plating resist pattern is drawn on this photosensitive resin film (a glass substrate is preferable)
Are closely contacted with each other, exposed, and developed to form a non-conductor portion having a plating resist pattern.

Next, an electrolytic plating film is formed on the electroless copper plating film other than the non-conductor portion to provide a conductor circuit and a conductor portion to be a via hole. It is desirable to use electrolytic copper plating as the electrolytic plating, and the thickness thereof is 10 to 20 μm.
m is good.

Next, after removing the plating resist on the non-conductor circuit portion, it is further treated with a mixed solution of sulfuric acid and hydrogen peroxide or an etching solution such as sodium persulfate, ammonium persulfate, ferric chloride or cupric chloride. To remove the electroless plating film,
An independent conductor circuit consisting of two layers, an electroless plated film and an electrolytic plated film, and a via hole are obtained. The palladium catalyst nucleus on the roughened surface exposed in the non-conductor portion is dissolved and removed with chromic acid, sulfuric acid / hydrogen peroxide and the like.

Next, a roughening layer is formed on the surface conductor circuit. The roughened layer formed is an etching treatment, a polishing treatment,
A roughened surface of copper formed by oxidation treatment or redox treatment or a roughened surface formed by a plating film is desirable.

Next, a solder resist layer is formed on the conductor circuit. The thickness of the solder resist layer in the present invention is preferably 5 to 40 μm. This is because if it is too thin, it does not function as a solder dam, and if it is too thick, it becomes difficult to open, and it also causes contact with the solder body and causes cracks in the solder body.

As the solder resist layer, various resins can be used. For example, bisphenol A type epoxy resin, acrylate of bisphenol A type epoxy resin,
A novolac type epoxy resin or a resin obtained by curing an acrylate of a novolac type epoxy resin with an amine-based curing agent or an imidazole curing agent can be used. In particular, in the case of forming a solder bump by forming an opening in the solder resist layer, it is preferable to use "novolac type epoxy resin or acrylate of novolac type epoxy resin" and include "imidazole curing agent" as a curing agent.

The solder resist layer having such a structure is
It has the advantage that lead migration (a phenomenon in which lead ions diffuse in the solder resist layer) is small. Moreover, this solder resist layer is a resin layer obtained by curing an acrylate of a novolac type epoxy resin with an imidazole curing agent, has excellent heat resistance and alkali resistance, and does not deteriorate even at the temperature at which the solder melts (around 200 ° C.). It does not decompose with a strongly basic plating solution such as plating or gold plating.

However, since such a solder resist layer is made of a resin having a rigid skeleton, peeling easily occurs. The roughened layer according to the present invention is advantageous because it can prevent such peeling.

Here, as the acrylate of the novolac type epoxy resin, an epoxy resin obtained by reacting glycidyl ether of phenol novolac or cresol novolac with acrylic acid or methacrylic acid can be used. The imidazole curing agent is preferably liquid at 25 ° C. This is because if it is liquid, it can be uniformly mixed.

As such a liquid imidazole curing agent, 1-benzyl-2-methylimidazole (product name: 1
B2MZ), 1-cyanoethyl-2-ethyl-4-methylimidazole (product name: 2E4MZ-CN), 4-methyl-2-ethylimidazole (product name: 2E4MZ) can be used.

The amount of the imidazole curing agent added is 1 to 10 relative to the total solid content of the solder resist layer composition.
It is desirable to set it as the weight%. The reason for this is that if the addition amount is within this range, uniform mixing is easy. The pre-curing composition for the solder resist layer preferably uses a glycol ether solvent as a solvent. The solder resist layer using such a composition does not generate free oxygen and does not oxidize the copper pad surface. It is also less harmful to the human body.

As such a glycol ether solvent, at least one selected from the following structural formulas, particularly preferably diethylene glycol dimethyl ether (DMDG) and triethylene glycol dimethyl ether (DMTG) is used. This is because these solvents can completely dissolve benzophenone and Michler's ketone which are reaction initiators by heating at about 30 to 50 ° C. _{CH 3 O- (CH 2 CH 2} O) n
—CH ₃ (n = 1 to 5) The glycol ether-based solvent is 10 to 10 with respect to the total weight of the solder resist composition.
40 wt% is preferable.

In addition to the above-mentioned solder resist layer composition, various antifoaming agents, leveling agents, thermosetting resins for improving heat resistance and base resistance and flexibility, and resolution improving. For this purpose, a photosensitive monomer or the like can be added.

For example, the leveling agent is preferably made of a polymer of acrylic acid ester. Further, as an initiator, Irgacure I907 manufactured by Ciba-Geigy, and as a photosensitizer, DETX-S manufactured by Nippon Kayaku is preferable. Further, a dye or pigment may be added to the solder resist layer composition. This is because the wiring pattern can be hidden. It is desirable to use phthalocyanine green as this dye.

A bisphenol type epoxy resin can be used as the thermosetting resin as an additive component. There are bisphenol A type epoxy resin and bisphenol F type epoxy resin in this bisphenol type epoxy resin. When the basic resistance is important, the former is required to have a low viscosity (when the coating property is important). The latter is better for.

As the photosensitive monomer as an additive component, a polyvalent acrylic monomer can be used.
This is because the polyvalent acrylic monomer can improve the resolution. For example, a polyvalent acrylic monomer having a structure such as DPE-6A manufactured by Nippon Kayaku or R-604 manufactured by Kyoeisha Chemical Co., Ltd. is desirable.

The composition of these solder resist layers is 0.5 to 10 Pa · s at 25 ° C., more preferably 1
10 Pa · s is preferable. This is because the viscosity is easy to apply with a roll coater. After forming the solder-resist layer, an opening is formed. The opening is formed by exposure and development processing.

Then, after forming the solder resist layer, a nickel plating layer is formed in the opening by electroless plating.
As an example of the composition of the nickel plating solution, nickel sulfate 4.5
g / l, sodium hypophosphite 25 g / l, sodium citrate 40 g / l, boric acid 12 g / l, thiourea 0.
There is 1 g / l (PH = 11). The solder-resist layer opening and surface are washed with a degreasing solution, a catalyst such as palladium is applied to the conductor portion exposed in the opening, and after activation, it is immersed in a plating solution to form a nickel plating layer. It was

The thickness of the nickel plating layer is 0.5 to 20.
A thickness of 3 μm to 10 μm is particularly desirable. here,
If it is less than 0.5 μm, it is difficult to connect the solder bump and the nickel plating layer. On the other hand, when the thickness exceeds 20 μm, the solder bumps formed in the openings cannot be completely accommodated and are peeled off.

After forming the nickel plating layer, the gold plating layer is formed by gold plating. The thickness is 0.03 μm.

After applying the metal layer to the opening, solder bumps are formed in the opening by printing. Then temperature 2
The solder bump is fixed in the opening through nitrogen reflow at 50 ° C.

Then, characters are printed on the solder resist layer. This character printing is performed by a character printing process including at least a lower ink layer forming process, a lower ink layer drying process, an upper ink layer forming process, and an upper ink layer drying process. Form. In the character printing step, characters or barcodes are printed by laminating the upper ink layer on the lower ink layer by a method such as screen printing or potting.

The viscosity of the character printing ink used is 3
Those in the range of 10,000 to 70,000 cps are less likely to cause bleeding and blurring, and moreover, it is easy to maintain the thickness uniformity of the ink layer. Particularly, the viscosity is 40,000 to 60,000.
It is desirable to adjust to the range of 0 cps. Within this range, a character having a desired thickness can be formed on the solder resist layer without contaminating the solder bumps and without causing blurring or blurring.

The viscosity of the character printing ink is 30,000 c
When it is less than ps, a character having a desired thickness can be formed on the solder resist layer, but the character may be blurred. In addition, when the characters are printed, they are dried, cured, or defoamed to remove air bubbles in the printed characters. Ink may scatter or flow to contaminate the solder resist, substrate, or solder bumps. . In particular, when the solder bumps are contaminated, it becomes impossible to make electrical connection with external electronic components such as IC chips.

On the other hand, the viscosity of the character printing ink is 70,0.
When it exceeds 00 cps, a character having a desired thickness cannot be formed or the character is faint. If the characters formed by character printing are for process recognition such as target marks and barcodes, position recognition in the mounting process and inspection process,
Cannot judge products. In addition, bubbles may remain in the printed characters. The bubbles have an ink viscosity of 70,
When it is 000 cps or less, it is removed and reduced during defoaming, drying and curing. Here, when the printed characters are covered with a sealing resin such as underfill, the reliability test may be deteriorated due to the bubbles in the characters as described above.

The position of the character formed on the solder resist layer is preferably formed at a position 3 mm or more away from the position where the solder bump is formed. In particular, it is desirable to form them at a distance of 5 mm or more. This is because the solder bumps are easily contaminated if they are formed in the vicinity of less than 3 mm. In addition, when printing characters, the solder bumps may be broken or scratched.

In this character printing step, it is also preferable that the upper ink layer is removed into a character shape by plasma irradiation, laser irradiation or liquid spraying, and the lower ink layer is exposed from the upper ink layer to perform character printing. .

After that, the individual dividing step, the plasma treatment,
A desired printed wiring board is obtained through a checker process for confirming short circuit and disconnection of wiring.

[0068]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a multilayer printed wiring board in which conductor circuits are laminated will be described as the printed wiring board. [First Embodiment] First, the structure of a multilayer printed wiring board 10 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a sectional view of the multilayer printed wiring board 10, and FIG. 9A is a sectional view of the multilayer printed wiring board 1 shown in FIG.
10 is a plan view of FIG. 0, FIG. 10 is a plan view of the multilayer printed wiring board 10 shown in FIG.
It shows a state of being placed on. Here, the AA cross section in FIG. 9A corresponds to the cross-sectional view of FIG. 8. As shown in FIG. 8, in the multilayer printed wiring board 10, conductor circuits 34, 34 are formed on the front surface and the back surface of the core substrate 30, and the build-up wiring layer 80A is further formed on the conductor circuits 34, 34.
80B is formed. The built-up layers 80A, 8
OB comprises an interlayer resin insulation layer 50 having a via hole 60 and a conductor circuit 58 formed therein, and an interlayer resin insulation layer 150 having a via hole 160 and a conductor circuit 158 formed therein. A solder resist layer 70 is formed on the via hole 160 and the conductor circuit 158, and bumps 76U and 76D are formed on the via hole 160 and the conductor circuit 158 through the opening 71 of the solder resist layer 70. ing.

As shown in FIG. 10, the solder bumps 76U on the upper surface side of the multilayer printed wiring board 10 are mounted on the IC chip 9
0 land 92. On the other hand, the lower solder bump 76D is connected to the land 96 of the daughter board 94.

As shown in FIG. 9A, which is a plan view of the multilayer printed wiring board 10, the solder bump 76U is arranged in the central portion of the printed wiring board. On the outer periphery of the solder bump 76U, a cross-shaped target mark 96A indicating a reference position when the IC chip 90 is mounted on the solder bump 76U is formed by printing. Similarly, on the solder resist layer 70, a circular target mark 96 indicating a reference position at the time of attachment to the daughter board 94.
B, a triangular target mark 96C is printed.
Further, on the solder resist layer 70, a bar code 98a for automatically recognizing a product by a mounting device for mounting an IC chip on the multilayer printed wiring board 10, a product name (product recognition character: 218AHM), and a lot number (manufacturing). Character information 98b composed of recognized characters: 3156) is printed.

As shown in FIGS. 8 and 9, the character information is formed by the two ink layers 110, which are the lower ink layer 100 and the upper ink layer 105, and therefore is clear without bleeding or smearing. is there. As shown,
In this embodiment, the lower ink layer 1 is formed by screen printing.
Predetermined characters were formed on the ink layer 00 with the upper ink layer 110.
The character information 98b is formed to have a line width of 0.3 mm as shown in an enlarged view in FIG. 9 (B).

The cross-shaped target mark 96A described above
Is printed 5 mm away from the solder bump 76U. The character information 98b is printed 8 mm away from the solder bump 76U. That is, the solder bump 76
By printing away from U, ink is prevented from splashing to the solder bump 76U side during printing. On the other hand, as shown in FIG. 7, the thickness of the character information 98b (t2)
Is formed to have a thickness of 30 μm. This is because the height (t1) of the solder bump 76U is 100 μm.
This is because when the thickness exceeds μm, the character information 98b and the IC chip 90 do not interfere with each other when the IC chip 90 is mounted.

In this embodiment, the viscosity of the character printing ink used in the two ink layers forming the above-mentioned target marks 96A, 96B, 96C, the bar code 98a and the character information 98b is adjusted to 50000 cps. Thus, the solder bump 76U is prevented from being contaminated with ink, and printing is performed without causing blurring or bleeding.

Subsequently, a method of manufacturing the multilayer printed wiring board 10 will be described. Here, first, the A.I. used in the method for manufacturing a multilayer printed wiring board according to the first embodiment is used. Adhesive for electroless plating, B.I. Interlayer resin insulating agent, C.I. Resin filler,
D. The composition of the raw material composition of the solder resist layer will be described.

A. Raw material composition for preparation of adhesive for electroless plating (adhesive for upper layer) [Resin composition] 25% acrylate of cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 2500) was added to DMDG at a concentration of 80 wt%. Dissolve the resin liquid in 3
5 parts by weight, photosensitive monomer (Toagosei, Aronix M315) 3.15 parts by weight, defoaming agent (San Nopco, S
-65) 0.5 part by weight and 3.6 parts by weight of NMP were obtained by stirring and mixing. [Resin Composition] Polyether Sulfone (PES) 1
After mixing 2 parts by weight, 7.2 parts by weight of epoxy resin particles (polymer pole manufactured by Sanyo Kasei) having an average particle size of 1.0 μm, and 3.09 parts by weight of particles having an average particle size of 0.5 μm are mixed. Further, 30 parts by weight of NMP was added, and the mixture was obtained by stirring and mixing with a bead mill. [Curing agent composition] Imidazole curing agent (manufactured by Shikoku Kasei,
2E4MZ-CN) 2 parts by weight, photoinitiator (manufactured by Ciba-Geigy, Irgacure I-907) 2 parts by weight, photosensitizer (manufactured by Nippon Kayaku, DETX-S) 0.2 parts by weight, NMP
1.5 parts by weight were obtained by stirring and mixing.

B. Raw Material Composition for Preparing Interlayer Resin Insulating Agent (Adhesive for Lower Layer) [Resin Composition] A 25% acrylate of cresol novolac type epoxy resin (Nippon Kayaku, molecular weight 2500) is dissolved in DMDG at a concentration of 80 wt%. 3 resin solution
5 parts by weight, photosensitive monomer (manufactured by Toagosei, Aronix M315) 4 parts by weight, antifoaming agent (manufactured by San Nopco, S-6)
5) 0.5 parts by weight and 3.6 parts by weight of NMP were obtained by stirring and mixing. [Resin composition] After mixing 12 parts by weight of polyether sulfone (PES) and 14.49 parts by weight of epoxy resin particles (polymer pole manufactured by Sanyo Kasei Co., Ltd.) having an average particle size of 0.5 μm,
Further, 30 parts by weight of NMP was added, and the mixture was obtained by stirring and mixing with a bead mill. [Curing agent composition] Imidazole curing agent (manufactured by Shikoku Kasei,
2E4MZ-CN) 2 parts by weight, photoinitiator (manufactured by Ciba-Geigy, Irgacure I-907) 2 parts by weight, photosensitizer (manufactured by Nippon Kayaku, DETX-S) 0.2 parts by weight, NMP
1.5 parts by weight were obtained by stirring and mixing.

C. Raw material composition for preparing resin filler [resin composition] Bisphenol F type epoxy monomer (Made by Yuka Shell, molecular weight 310, YL983U) 100
Parts by weight, spherical particles of SiO ₂ having an average particle size of 1.6 μm, coated with a silane coupling agent on the surface (manufactured by Admatech, CRS 1101-CE, here,
The maximum particle size is the thickness (1
5 parts by weight) and 170 parts by weight and 1.5 parts by weight of a leveling agent (manufactured by San Nopco, Perenol S4) are mixed by stirring to make the viscosity of the mixture 4 at 23 ± 1 ° C.
It was obtained by adjusting to 5,000 to 49,000 cps. [Curing agent composition] Imidazole curing agent (manufactured by Shikoku Kasei,
2E4MZ-CN) 6.5 parts by weight.

D. 60% by weight of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in DMDG, which is a raw material composition for the solder resist layer, is acrylated with 50% of epoxy groups (a molecular weight of 400).
0) 46.67 g, 80% by weight of a bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001) of 80 wt% dissolved in methyl ethyl ketone, 15.0 g of an imidazole curing agent (manufactured by Shikoku Kasei, 2E4MZ-CN) 1.6.
g, a polyvalent acrylic monomer (R604, manufactured by Nippon Kayaku), which is a photosensitive monomer, 1.5 g of the same polyvalent acrylic monomer (DPE6A, manufactured by Kyoeisha Chemical Co., Ltd.), a dispersion type defoaming agent (S-65, manufactured by San Nopco). ) 0.71 g was mixed, and further 2 g of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.2 g of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were added to the mixture to give a viscosity of 2 0.0P
A solder resist composition adjusted to a · s (25 ° C.) was obtained. The viscosity is measured using a B-type viscometer (Tokyo Keiki, D
In the case of 60 rpm with VL-B type), the rotor No. 4,
In the case of 6 rpm, the rotor No. According to 3.

F. Manufacturing of printed wiring board (1) Glass epoxy resin or BT with 1mm thickness
A copper clad laminate 30A having 18 μm copper foil 32 laminated on both sides of a substrate 30 made of (bismaleimide triazine) resin was used as a starting material (step (A) in FIG. 1).
First, this copper clad laminate was drilled, electroless plated, and patterned to form inner layer copper patterns 34 and through holes 36 on both sides of the substrate (step (B)).

(2) The substrate 30 on which the inner layer copper pattern 34 and the through holes 36 are formed is washed with water and dried, and then NaOH (10 g / g) is used as an oxidation bath (blackening bath).
l), NaClO ₂ (40 g / l), Na ₃ PO ₄ (6
g / l), as a reducing bath, NaOH (10 g / l), N
By the oxidation-reduction treatment with aBH ₄ (6 g / l),
A roughened layer 38 was provided on the surfaces of the inner layer copper pattern 34 and the through holes 36 (step (C)).

(3) The raw material composition for preparing the C resin filler was mixed and kneaded to obtain a resin filler.

(4) The resin filler obtained in (3) above is
Within 24 hours after the preparation, it was applied and filled between the conductor circuits or in the through holes 36. As a coating method, a printing method using a squeegee was used. For the first printing application, the through hole 36 is mainly filled, and the temperature in the drying oven is 100 ° C.
Allowed to dry for 20 minutes. In the second printing application, the resin filler 40 is filled mainly between the conductor circuits 34 and between the conductor circuits 34 and in the through holes 36 by filling the recesses formed mainly by the formation of the conductor circuits (inner layer copper pattern) 34. After filling with
It was dried under the above-mentioned drying conditions (step (D)).

(5) Substrate 3 which has undergone the processing of (4) above
One side of 0, # 600 belt sanding paper (Sankyo Rikagaku)
Inner layer copper pattern 3 by belt sander polishing using
The surface of No. 4 and the surface of the land 36a of the through hole 36 were polished so that the resin filler did not remain, and then buffed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate (step (E) in FIG. 2). Then 100
The resin filler 40 was cured by heat treatment at 1 ° C. for 1 hour and at 150 ° C. for 1 hour.

In this way, the surface layer portion and the inner layer conductor circuit 3 of the resin filler 40 filled in the through holes 36 and the like.
4. The roughening layer 38 on the upper surface is removed to smooth both surfaces of the substrate, and the resin filler 40 and the side surface of the inner-layer conductor circuit 34 form the roughening layer 38.
A wiring board was obtained in which the inner wall surface of the through hole 36 and the resin filler 40 are firmly adhered to each other via the roughening layer 38. That is, by this step, the surface of the resin filler 40 and the surface of the inner layer copper pattern 34 are flush with each other.

(6) Substrate 30 on which the conductor circuit 34 is formed
Alkali degreasing and soft etching, then treating with a catalyst solution consisting of palladium palladium and organic acid,
After applying a Pd catalyst and activating the catalyst, copper sulfate 3.9 × 10 ⁻² mol / l, nickel sulfate 3.8 × 1
0 ⁻³ mol / l, sodium citrate 7.8 × 10
^-3 mol / l, sodium hypophosphite 2.3 × 10
^-1 mol / l, surfactant (manufactured by Nisshin Chemical Industry, Surfeel 465) 1.1 x 10 ^-4 mol / l, PH = 9
The electroless plating solution consisting of 1 minute, and after 1 minute of immersion, vibrate longitudinally and laterally at a rate of once every 4 seconds to form Cu-Ni-P on the surface of the land of the conductor circuit and through hole.
A needle-like alloy coating layer and a roughening layer 42 were provided (step (F)). Furthermore, tin borofluoride 0.1 mol /
1, thiourea 1.0 mol / l, temperature 35 ° C., PH =
A Cu—Sn substitution reaction was performed under the conditions of 1.2, and a 0.3 μm thick Sn layer (not shown) was provided on the surface of the roughened layer.

(7) The raw material composition for preparing the interlayer resin insulating agent B was mixed with stirring to adjust the viscosity to 1.5 Pa · s to obtain an interlayer resin insulating agent (for lower layer). Next, the raw material composition for preparing the adhesive for electroless plating of A was mixed by stirring to adjust the viscosity to 7 Pa · s to obtain an adhesive solution for electroless plating (for the upper layer).

(8) On both sides of the substrate 30 of (6) above,
The interlayer resin insulation agent (for lower layer) 44 having a viscosity of 1.5 Pa · s obtained in (7) above is applied by a roll coater within 24 hours after preparation, and left in a horizontal state for 20 minutes, and then at 60 ° C.
For 30 minutes (pre-baking), then apply the photosensitive adhesive solution (for upper layer) 46 having a viscosity of 7 Pa · s obtained in (7) within 24 hours after preparation, and in a horizontal state. After standing for 20 minutes, drying (prebaking) was performed at 60 ° C. for 30 minutes to form an adhesive layer 50α having a thickness of 35 μm (step (G)).

(9) A photomask film 51 on which a black circle 51a of 85 μmφ is printed is adhered to both surfaces of the substrate 30 on which the adhesive layer is formed in (8) above, and exposed at 500 mJ / cm ² by an ultrahigh pressure mercury lamp. (Step (H)).
This was spray-developed with a DMTG solution, and the substrate was exposed with an ultra-high pressure mercury lamp at 3000 mJ / cm ² for 1 hour at 100 ° C., 1 hour at 120 ° C., and then 15
By performing a heat treatment (post-baking) at 0 ° C. for 3 hours, an interlayer resin insulating layer having a thickness of 35 μm having an opening (opening for forming a via hole) 48 of 85 μm φ excellent in dimensional accuracy equivalent to a photomask film ( 2 layer structure) 50
Was formed (step (I) in FIG. 3). In addition, a tin plating layer (not shown) was partially exposed in the opening 48 serving as a via hole.

(10) Substrate 30 in which opening 48 is formed
Is immersed in chromic acid for 19 minutes to dissolve and remove the epoxy resin particles existing on the surface of the interlayer resin insulation layer to roughen the surface of the interlayer resin insulation layer 2, and then to
It was immersed in a neutralizing solution (made by Shipley) and then washed with water (step (J)). Furthermore, roughening treatment (roughening depth 6μ
m) By applying a palladium catalyst (manufactured by Atotech) to the surface of the substrate, catalyst nuclei were attached to the surface of the interlayer resin insulating layer 50 and the inner wall surface of the via hole opening 48.

(11) The substrate is immersed in an electroless copper plating solution having the composition shown below to form a rough surface having a thickness of 0.6.
An electroless copper plating film 52 having a thickness of 1.2 μm was formed (step (K)). [Electroless plating aqueous solution] EDTA 0.08 mol / l Copper sulfate 0.03 mol / l HCHO 0.05 mol / l NaOH 0.05 mol / l α, α′-bipyridyl 80 mg / l PEG 0.10 g / L [electroless plating conditions] 20 minutes at a liquid temperature of 65 ° C

(12) A commercially available photosensitive dry film is attached on the electroless copper-plated film 52 formed in (11), a mask is placed, and exposure is performed at 100 mJ / cm ² .
Development processing was performed with 0.8% sodium carbonate to provide a plating resist 54 having a thickness of 15 μm (step (L)).

(13) Next, electrolytic copper plating was applied to the non-resist portion under the following conditions to form an electrolytic copper plating film 56 having a thickness of 15 μm (step (M) in FIG. 4). [Electrolytic plating aqueous solution] Sulfuric acid 2.24 mol / l Copper sulfate 0.26 mol / l Additive (manufactured by Atotech Japan, Kaparaside HL) 19.5 ml / l [Electrolytic plating conditions] Current density 1 A / dm ² hours 65 Min temperature 22 ± 2 ℃

(14) The plating resist 54 is replaced with 5% KO
After peeling and removing with H 2, etching is performed with a mixed solution of sulfuric acid and hydrogen peroxide to dissolve and remove the electroless plating film 52 under the plating resist, and the thickness of the electroless plating 52 and the electrolytic copper plating film 56 is 18 μm (10 to 10 μm). 30 μm) conductor circuit 58
And the via hole 60 was obtained (process (N)).

Further, at 70 ° C., 80 g / L of chromic acid was added to 3
The surface of the adhesive layer 50 for electroless plating between the conductor circuits 58 was etched for 1 μm by immersion for 1 minute to remove the palladium catalyst on the surface.

(15) The same process as in (6) is performed, and Cu-Ni- is formed on the surfaces of the conductor circuit 58 and the via hole 60.
A roughened surface 62 made of P is formed, and S is further formed on the surface.
N-substitution was performed (step (O)).

(16) By repeating steps (7) to (14), the upper interlayer resin insulation layer 160, the via hole 160 and the conductor circuit 158 are formed. Further, a roughening layer 162 is formed on the surfaces of the via hole 160 and the conductor circuit 158 to complete the multilayer printed wiring board (step (P)). In the step of forming the upper conductor circuit, Sn substitution was not performed.

(17) Then, solder bumps are formed on the above-mentioned multilayer printed wiring board. On both surfaces of the substrate 30 obtained in (16) above, D. The solder resist composition 70α described in Section 1 above was applied to a thickness of 20 μm (FIG. 5).
Process (Q)). Then, after performing a drying treatment at 70 ° C. for 20 minutes and at 70 ° C. for 30 minutes, a 5 mm-thick photomask film (not shown) on which a circular pattern (mask pattern) is drawn is closely attached and placed. , 1000 mJ / c
It was exposed to m ² of ultraviolet light and subjected to DMTG development processing. And then, at 80 ℃ for 1 hour, 100 ℃ for 1 hour, 120 ℃
Heat treatment for 1 hour at 150 ° C for 3 hours, and solder pad portion (including via hole and land portion)
The solder resist layer (thickness 20 μm) 70 having the openings 71 (opening diameter 200 μm) was formed (step (R)).

(18) Then, nickel chloride 2.3
× 10 ⁻¹ mol / l, sodium hypophosphite 2.8 ×
10 ⁻¹ mol / l, sodium citrate 1.6 × 10
^-1 mol / l for 20 minutes in an electroless nickel plating solution having a pH of 4.5, and the opening 71 has a thickness of 5
A μm nickel plating layer 72 was formed. Further, the substrate was treated with potassium gold cyanide 7.6 × 10 ⁻³ mol /
1, ammonium chloride 1.9 × 10 ⁻¹ mol / l, sodium citrate 1.2 × 10 ⁻¹ mol / l, sodium hypophosphite 1.7 × 10 ⁻¹ mol / l, electroless gold plating Immerse the liquid in the liquid at 80 ° C for 7.5 minutes,
A gold plating layer 74 having a thickness of 0.03 μm was formed on the nickel plating layer 72 (step (S) in FIG. 6).

(19) Then, the solder resist layer 7
Print the solder paste in the opening 71 of 0
The solder bumps (solder bodies) 76U and 76D were formed by reflowing at ℃ (step (T)).

(20) Characters were printed on the solder resist layer 70. A thermosetting resin was used as the character printing ink for forming the lower ink layer 100 and the upper ink layer 105, and character printing was performed by screen printing. The character printing ink had a viscosity of 50,000 cps.

First, using a white character printing ink, the lower ink layer 100 is placed 1 cm from the solder bumps 76a.
It was formed in a quadrangle having a length of 10 mm and a width of 20 mm at distant positions. The thickness was 20 μm. This lower ink layer 10
0 was heated and dried at 80 ° C./5 minutes + 120 ° C./10 minutes to be cured. (FIG. 7 (U)) FIG.
It is a U'-U 'sectional view of (U).

Next, a masking material on which a product number, a target mark, etc. are formed is placed on the lower ink layer 100 (not shown), and black character ink is further applied through this masking material, The upper ink layer 105 was laminated on the surface of the lower ink layer 100. As shown in FIGS. 8 and 9, on the surface of the solder resist layer 70, character information such as a product name, a lot number, a mounting target mark, and a bar code, which is composed of two ink layers 110, was printed. Thereafter, the upper ink layer 105 was cured by heating at 80 ° C./5 minutes + 120 ° C./10 minutes.

Subsequently, the surface of the solder resist layer including the two ink layers was subjected to plasma treatment to remove stains on the surface. In this embodiment, oxygen plasma is used. For the oxygen plasma treatment, a plasma cleaning device manufactured by Kyushu Matsushita was used, and the plasma irradiation amount was 800 W and the oxygen supply amount was 300 sec. / M, oxygen supply pressure 0.15 MPa, treatment time 10 minutes. The characters formed on the surface of the solder resist layer in the character printing process did not peel or chip. Further, this treatment makes the contact angle of the surface of the solder resist layer 20.
The maximum roughness (Rj) was 30 nm, and the underfill coatability was good.

A device having a router was used to divide and cut the substrate into appropriate sizes, and a checker process of inspecting the printed wiring board for short circuit and disconnection was performed to obtain a desired corresponding printed wiring board.

Thereafter, the target mark 96A of the multilayer printed wiring board 10 is optically read by an image detection camera, the solder bump 76U on the multilayer printed wiring board side and the land 92 of the IC chip 90 are aligned and reflowed. Thus, the solder bump 76U and the land 92 are joined (see FIG. 10). Here, the mounting of the IC chip 90 on the multilayer printed wiring board 10 is automatically performed by the mounting device, and the mounting device mounts the IC chips of the corresponding types on the multilayer printed wiring boards of various types. . At this time, the type of the multilayer printed wiring board 10 is automatically identified by the bar code 98a shown in FIG. 9A, and the corresponding IC chip is attached. Then, the IC chip 90
88 between the wiring and the multilayer printed wiring board 10
To fill.

Subsequently, the position, alignment, etc. are adjusted by the target marks 96B and 96C of the multilayer printed wiring board 10 by the daughter board mounting device, and the solder bumps 76D of the printed wiring board are connected to the pads 96 on the daughter board 94 side. . Then, an underfill 88 is filled between the multilayer printed wiring board 10 and the daughter board 94 (see FIG. 10).

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 11 (V)
Is a plan view showing the surface of the solder resist layer of the printed wiring board on which the lower ink layer is formed, and FIG.
It is a V'-V 'cross section of 1 (V). Also, FIG. 12 (W)
FIG. 12 is a plan view showing a printed wiring board in which an upper ink layer is formed on the surface of the lower ink layer, and FIG.
The W'-W 'cross section of (W) is shown. Furthermore, FIG. 13 (X)
Is a plan view of the printed wiring board showing a state in which the upper ink layer is removed in a character shape, and FIG. 13 (X ′) is a cross-sectional view taken along line X′-X ′ of FIG. 13 (X).

Basically, it is similar to the first embodiment, but in the character printing step, as shown in FIG. 11 (V) and its sectional view, FIG. 11 (V ′), the lower ink layer 1 is first formed.
00 is formed at a predetermined position on the surface of the solder resist layer 70. The color of the character printing ink used was black. After the lower layer ink layer 100 is dried, the upper layer ink layer 105 is formed on the lower layer ink layer 100 so as to be overlapped in substantially the same size. The color of the character printing ink used for the upper ink layer 105 was white (see FIG. 12 (W) and FIG. 12 (W ′)).

After the upper ink layer 105 is dried, a masking material (not shown) having characters formed thereon is placed on the upper ink layer 105, and a plasma irradiation amount of 1000 is applied by oxygen plasma.
W, oxygen supply rate 700 sec / M, oxygen supply pressure 0.30
Then, the upper ink layer 105 was removed at a portion corresponding to the opening of the masking material by treating with MPa for 5 minutes. The subsequent plasma treatment was not performed. FIG. 13 (X) and FIG.
3 (X ′), the solder resist layer 70
On the surface of the ink layer 110, two layers of ink layer 110 are formed by removing the upper ink layer 105 in a character shape and expressing the color of the lower ink layer 100.
The character was printed by.

[Third Embodiment] The third embodiment is basically the same as the second embodiment, but after forming the upper ink layer in the same region as the lower ink layer, the upper ink is applied by a carbon dioxide laser on which a masking material is placed. The layers were removed to form the letters. Although the masking material is used here, it is also possible to remove a predetermined portion of the upper ink layer without using the masking material, for example, by using a laser for trimming.

Next, a multilayer printed wiring board according to a comparative example constructed for performance comparison with the multilayer printed wiring board of this embodiment will be described. (Comparative Example) Basically the same as in Example 1, but a masking material having characters formed on the surface of the solder resist layer was arranged, and characters were formed by one layer of ink by screen printing.

As described above, regarding the printed wiring boards manufactured in the first embodiment, the second embodiment, the third embodiment and the comparative example, the thickness of the character print, the state of the printed character (whether there is bleeding or blurring), and image recognition are 3 The items were compared and evaluated. The result is shown in FIG. In each of the examples, the thickness of the upper ink layer on which characters are formed can be made uniform, and the character printing formed on the obtained printed wiring board is extremely clear and does not cause defects such as bleeding and haze. It was Therefore, even in process recognition, it is possible to accurately read in time, and various problems do not occur in subsequent processes.

[0113]

As described above, according to the multilayer printed wiring board and the method of manufacturing the same of the present invention, since characters for character printing are formed by the two ink layers, bleeding and blurring of character printing are prevented. Instead, it is possible to clearly print characters such as target marks. Therefore, it is possible to reliably perform image recognition in a post process such as mounting of a product.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a multilayer printed wiring board according to a first embodiment of the present invention.

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

FIG. 3 is a manufacturing process diagram of the multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of the multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 5 is a manufacturing process diagram for a multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 6 is a manufacturing process diagram of a multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 7 is a manufacturing process diagram of the multilayer printed wiring board according to the first embodiment of the present invention, FIG. 7 (U) is a plan view of the multilayer printed wiring board showing a printing process, and FIG. Figure 7 (U)
FIG. 7 is a U′-U ′ cross-sectional view of FIG.

FIG. 8 is a cross-sectional view of the multilayer printed wiring board according to the first embodiment of the present invention.

FIG. 9 (A) is a plan view of the multilayer printed wiring board 10 shown in FIG. 8, and FIG. 9 (B) is an explanatory view showing enlarged character information in FIG. 9 (A). is there.

10 is a cross-sectional view showing a state in which an IC chip is attached to the multilayer printed wiring board shown in FIG. 8 and placed on a daughter board.

FIG. 11 is a manufacturing process diagram according to the second embodiment of the present invention, FIG. 11 (V) is a plan view of a multilayer printed wiring board showing a character printing process, and FIG. 11 (V ′) is FIG. ) V'-
It is a V'sectional view.

FIG. 12 is a manufacturing process diagram according to the second embodiment of the present invention, in which FIG. 12 (W) is a plan view of the printed wiring board;
(W ') is a W'-W' sectional view of FIG.

13 (X) is a plan view of the printed wiring board obtained in the second embodiment, and FIG. 13 (X ′) is FIG.
It is an X'-X 'sectional view of (X).

FIG. 14 is a chart showing the results of testing the multilayer printed wiring boards according to the first example, the second example, the third example and the comparative example.

[Explanation of symbols]

30 core substrate 34 Conductor track 36 through hole 50 interlayer resin insulation layer 58 Conductor circuit 60 via holes 70 Solder resist 71 opening 80A, 80B Build-up wiring layer 96A, 96B, 96D target mark 98a barcode 98b Character information 100 Lower ink layer 105 upper ink layer 110 ink layer 150 interlayer resin insulation layer 158 Conductor circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H05K 3/46 H05K 3/46 Z (56) Reference JP-A-10-163588 (JP, A) JP-A-4-282884 ( JP, A) Actual development Sho 63-174475 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 1/02 H05K 3/00 H05K 3/28

Claims (6)

(57) [Claims] 1. A build-up multilayer printed wiring board in which a semitransparent solder resist layer having an opening is formed on a substrate provided with a conductor circuit, and characters are printed on the solder resist layer with a character printing ink. In the manufacturing method, the characters of the character printing are divided into an upper ink layer and a lower ink layer.
Layers, the two layers are formed of ink layers having different contrasts, and in the upper ink layer forming step, the upper ink layer is formed on the surface of the lower ink layer to have substantially the same size as the lower ink layer. Of a build-up multi-layer printed wiring board characterized by performing character printing by removing the upper ink layer into a character shape to expose the lower ink layer by plasma, laser irradiation or liquid spraying. Method. 2. The method for manufacturing a build-up multilayer printed wiring board according to claim 1, wherein the character printing ink is a thermosetting resin having a glass transition temperature in the range of 100 to 180 ° C. . 3. The character of the character print is a product recognition character,
The method for manufacturing a build-up multilayer printed wiring board according to claim 1, wherein the method is at least one selected from manufacturing recognition characters and process recognition characters. 4. The build-up multilayer printed wiring board according to claim 1, wherein each of the two ink layers has a thickness of 10 to 50 μm. Method. 5. The character printing wherein the two ink layers include at least a lower ink layer forming step, a lower ink layer drying step, an upper ink layer forming step, and an upper ink layer drying step. The build-up multilayer printed wiring board manufacturing method according to claim 1, wherein the build-up multilayer printed wiring board is formed by steps. 6. A build-up multilayer printed wiring board in which a semi-transparent solder resist layer having openings is formed on a substrate provided with a conductor circuit, and characters are printed on the solder resist layer with a character printing ink. In the above, the character printed is formed of two layers of an upper ink layer and a lower ink layer having different contrasts, and the upper ink layer is formed in substantially the same size as the lower ink layer, and the character printed is A build-up multilayer printed wiring board comprising an upper ink layer and a lower ink layer which is formed by removing the upper ink layer in a letter shape.