JP2003101193A - Production method for circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a circuit pattern of high accuracy even on a flexible film which is liable to cause a change in dimension by the influence of heat, humidity or external force. SOLUTION: In this production method for circuit board, the flexible film is stuck with a reinforcing plate through a releasable organic layer. After the circuit pattern is formed on the flexible film, the flexible film is released from the reinforcing plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a circuit board using a flexible film having a highly accurate circuit pattern and excellent in productivity.

[0002]

2. Description of the Related Art As the weight and size of electronic products are reduced, the patterning of printed circuit boards is required to be highly accurate. Since the flexible film substrate can be bent, three-dimensional wiring can be performed, and the flexible film substrate is suitable for downsizing of electronic products, and thus the demand is expanding. TAB used for IC connection to liquid crystal display panel
The (Tape Automated Bonding) technique can obtain the finest pattern as a resin substrate by processing a relatively narrow long polyimide film substrate, but is approaching the limit with respect to the progress of miniaturization. For miniaturization, there are an index represented by a line width and a space width between lines and an index represented by a pattern position on a substrate. Regarding the line width and the space width, there is a measure for further miniaturization, but the latter index and position accuracy depend on the alignment between the electrode pad and the circuit board pattern when connecting the circuit board and electronic parts such as IC. Therefore, it is becoming more and more difficult to meet the required accuracy as the number of pins of ICs increases.

[0003]

In view of the above positional accuracy, it is becoming difficult to improve the processing of flexible film substrates, in particular. The circuit board processing process includes a heat treatment process such as drying and curing, and a wet process such as etching and development, and the flexible film repeats expansion and contraction. The hysteresis at this time causes the displacement of the circuit pattern on the substrate. Further, when there are a plurality of processes that require alignment, if there is expansion or contraction between these processes, misalignment occurs between the formed patterns. Deformation due to expansion and contraction of the flexible film
FPC (Flexibl
In the case of e Printing Circuit), it has a greater effect. Further, the positional displacement is also caused by an external force such as pulling or twisting, and special attention is required when using a thin substrate to increase flexibility.

An object of the present invention is to solve the above problems and provide a high-definition flexible film circuit board.

[0005]

That is, the present invention is achieved by the following constitutions and manufacturing methods. (1) The flexible film is attached to a reinforcing plate via an organic layer that can be peeled off, and then a circuit pattern is formed on the flexible film, and then the flexible film is peeled off from the reinforcing plate. Circuit board manufacturing method. (2) The method of manufacturing a circuit board as described in (1) above, wherein the connection hole is formed from a surface of the flexible film opposite to a surface of the reinforcing film which is attached to the reinforcing plate. (3) The method for manufacturing a circuit board as described in (1) above, wherein the reinforcing plate is a sheet, and the long flexible film is cut along with the sheet reinforcing plate to be laminated. (4) Young's modulus (kg / mm ² ) and thickness (m of the reinforcing plate
m) cubed product is 2kg · mm or more 860000kg
-The method for manufacturing a circuit board according to (1) above, wherein the method is within a range of mm or less. (5) The reinforcing plate is glass, and the Young's modulus (kg / m
The product of the cube of m ² ) and thickness (mm) is 850 kg · mm
The method for producing a circuit board as described in (4) above, wherein the range is 860000 kg · mm or less. (6) The reinforcing plate is made of metal and Young's modulus (kg / mm ² )
And the product of the cube of the thickness (mm) are 2kg ・ mm or more 162
The method for producing a circuit board as described in (4) above, wherein the range is 560 kg · mm or less. (7) The method for producing a circuit board as described in (1) above, wherein the reinforcing plate is a single sheet, and a peelable organic material layer and / or a photoresist is applied to the reinforcing plate with a die coater.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION It is important that the flexible film of the present invention is a plastic film and has heat resistance sufficient to withstand a thermal process in a circuit pattern manufacturing process and electronic component mounting. Films of polycarbonate, polyether sulfide, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyimide, polyamide and the like can be used. Among them, the polyimide film is
It is suitable for use because it has excellent heat resistance and chemical resistance. It is also possible to employ a flexible glass fiber reinforced resin plate. Examples of the resin for the glass fiber reinforced resin plate include polyphenylene sulfide, polyphenylene ether, maleimide, polyamide, and polyimide. The thickness of the flexible film is preferably thin in order to reduce the weight and size of the electronic device, or to form a fine via hole. On the other hand, in order to secure mechanical strength and maintain flatness. 1 is preferable because it is thicker
The range from 2.5 μm to 125 μm is preferred.

A metal layer may be formed on one side or both sides of these flexible films prior to attachment to the reinforcing plate. The metal layer can be formed by adhering a metal foil such as a copper foil with an adhesive layer, or can be formed by sputtering, plating, or a combination thereof. A flexible film with a metal layer can also be obtained by applying a raw material resin for a flexible film or a precursor thereof onto a metal foil such as copper, followed by drying and curing.

Substrates used for the reinforcing plate of the present invention include inorganic glasses such as soda lime glass, borosilicate glass, aluminoborosilicate glass, and quartz glass, metals such as stainless steel, Invar alloy, titanium, alumina, and nitride. Ceramics such as silicon and zirconia and glass fiber reinforced resin plates can be used. Both are preferable in that the linear expansion coefficient and the hygroscopic expansion coefficient are small, but the heat resistance in the circuit pattern manufacturing process, the excellent chemical resistance, and the large surface area and high surface smoothness of the substrate are easily available at low cost. Inorganic glasses are preferable because they are less likely to be plastically deformed or particles are less likely to be generated by contact. Among them, borosilicate glass represented by aluminoborosilicate glass is particularly preferable because it has a high elastic modulus and a small thermal expansion coefficient.

When a metal or glass fiber reinforced resin is used for the reinforcing plate, it can be manufactured in a long continuous body, but the manufacturing method of the present invention is performed by a single-wafer type because it is easy to secure the positional accuracy. Is preferred. The sheet is not a long continuous body but a state of being handled as individual sheets.

Young's modulus (kg / m) of the reinforcing plate of the present invention
The product of m ³ ) and the cube of the thickness (mm) is preferably in the range of 2 kg · mm or more and 860000 kg · mm or less. When it is smaller than this range, the reinforcing plate cannot withstand the stress caused by the flexible film and is deformed, and it becomes difficult to maintain the position accuracy in the flexible film processing which is the point of the present invention. On the other hand, if it is larger than this range, it becomes difficult to prepare a reinforcing plate with low cost and small thickness unevenness, and the accuracy in photolithography processing decreases. In addition, the load on the transfer device increases, which is an obstacle to improving productivity.

When a glass substrate is used as the reinforcing plate, if the Young's modulus of the glass substrate is small or the thickness is small, the expansion and contraction force of the flexible film increases warping and twisting,
The glass substrate may be broken when vacuum-adsorbed on a flat stage. Further, the vacuum adsorption / desorption deforms the flexible film, which makes it difficult to secure positional accuracy.
On the other hand, if the glass substrate is thick, the flatness may be deteriorated due to the uneven thickness, and the exposure accuracy may be deteriorated. In addition, the load of handling by a robot or the like becomes large, which makes it difficult to swiftly handle the robot, which lowers productivity, and also increases transportation costs. Therefore, the product of the Young's modulus (kg / mm ² ) and the cube of the thickness (mm) of the glass substrate which is the single-wafer reinforcing plate is 850 kg · mm or more and 860000 kg ·
The range is preferably less than or equal to mm, 1500 kg
mm or more and 190000 kg · mm or less is more preferable,
The range of 2400 kg · mm or more and 110000 kg · mm or less is most preferable.

When a metal substrate is used as the reinforcing plate, if the Young's modulus of the metal substrate is small or the metal substrate is thin, warping or twisting becomes large due to the expansion / contraction force of the flexible film, and vacuum adsorption on a flat stage occurs. If the flexible film is deformed due to the warp or twist of the metal substrate, it becomes difficult to secure the positional accuracy. Also, if there is a break, it becomes a defective product at that time. On the other hand, if the metal substrate is thick, the flatness may be deteriorated due to the uneven thickness, and the exposure accuracy may be deteriorated. In addition, the load of handling by a robot or the like becomes large, which makes it difficult to swiftly handle the robot, which lowers productivity, and also increases transportation costs. Therefore, the Young's modulus (kg / mm
² ) The product of the cube of thickness (mm) is 2kg · mm or more 1
It is preferably in the range of 62560 kg · mm or less. Young's modulus (kg / mm ² ) and thickness (m
m) cubed product is 10 kg ・ mm or more and 30,000 kg
・ It is more preferable that it is less than or equal to mm, 15 kg · mm
The most preferable range is 20500 kg · mm or less.

The peelable organic material layer used in the present invention is an adhesive or a pressure-sensitive adhesive, and is easy to peel the flexible film after the flexible film is attached and processed. Examples of such adhesives or pressure-sensitive adhesives include pressure-sensitive adhesives called acrylic or urethane-based removable agents. Adhesive strength in the region called weak to medium adhesion is preferable because it has sufficient adhesive strength during flexible film processing, can be easily peeled off at the time of peeling, and does not cause distortion in the flexible film substrate. . The silicone resin film may be used as a release agent in the present invention, but a silicone resin having tackiness can also be used as a removable adhesive. It is also possible to use an epoxy resin film having tackiness as a re-peeling pressure-sensitive adhesive.

In the present invention, when the adhesive strength is expressed numerically, a 180 ° peel strength at the time of sticking and peeling an adhesive tape having a polyester film as a base material and a 25 μm-thick adhesive layer laminated on a stainless steel plate is 1 g. / 25 mm to 500 g / 25 mm. 2g / 25mm to 200g / 25m called weak adhesion
A range of m is preferred. Those having reduced adhesive strength and adhesive strength in a low temperature region, those having reduced adhesive strength and adhesive strength by ultraviolet irradiation, and those having reduced adhesive strength and adhesive strength by heat treatment are also preferably used. Among these, ultraviolet irradiation is preferable because of large changes in adhesive strength and adhesive strength. As an example of the adhesive whose adhesive strength and adhesive strength are reduced by irradiation with ultraviolet rays, a two-liquid cross-linking acrylic adhesive can be mentioned. Further, as an example of the adhesive whose adhesive strength and adhesive strength are reduced in a low temperature region, there is an acrylic adhesive which reversibly changes between a crystalline state and an amorphous state.

A wet coating method is used to apply a peelable organic material layer or a photoresist. As the wet coating device, various ones such as a spin coater, a roll coater, a bar coater, a blade coater, a die coater, screen printing, a dip coater, and a spray coater can be adopted. A die coater is preferably used in the case of directly applying a photoresist or directly applying a photoresist for forming a circuit board on a single-piece flexible film substrate. In other words, a spin coater is generally used as a wet coating method for a single-wafer substrate, but since the thickness is controlled by the balance between the centrifugal force due to the high speed rotation of the substrate and the adsorption force to the substrate, the use efficiency of the coating liquid is improved. Is less than 10%, which is inefficient. Further, since a centrifugal force is not applied to the center of rotation, the thixotropic coating liquid cannot be uniformly applied. In addition, if the viscosity of the coating liquid is high, the wetting and spreading may be poor and the coating may not be uniformly applied. Various types of roll coaters, bar coaters, and blade coaters have been proposed. However, in order to obtain a stable coating thickness, in general, coating of several cm to several m or more after the start of discharging the coating liquid is performed. It requires a length and is not suitable for coating single-wafer substrates. Screen printing, dip coater, and spray coater are difficult to apply because the coating thickness accuracy is difficult to obtain and the tolerance of coating liquid flow characteristics is narrow, and the dip coater and spray coater are difficult to apply thick film. On the other hand, the die coater, unlike other methods, combines an intermittently operating metering pump, a mechanism for relatively moving the substrate and the coating head and a metering pump, a system for comprehensively controlling the substrate and the coating head. As a result, the film thickness unevenness between the coating start portion and the coating end portion is several meters.
It can be applied to a single-wafer substrate while suppressing it from m to less than several cm. A gear pump, a piston pump, etc. are mentioned as an example of the metering pump which can operate intermittently.

Since the peelable organic material layer generally has a higher viscosity than photoresist, it is difficult to apply a spin coater, and a die coater is particularly preferable.

The peelable organic material layer may be directly applied to the reinforcing plate, or may be applied to another substrate such as a long film and then transferred to the reinforcing plate. When the transfer is used, there is an advantage that only a portion having a uniform coating film thickness can be adopted, but there are disadvantages that the number of steps is increased and another substrate for transfer is required.

It is also possible to apply a peelable organic material layer to the side of the flexible film serving as the circuit board and then bond it to the reinforcing plate. In this case, when peeling the flexible film, a step for increasing the adhesive force between the organic layer and the reinforcing plate surface so that the organic layer remains on the reinforcing plate side, or the organic substance remaining on the flexible film side after peeling The step of removing the layer is added to reduce the productivity.

The flexible film used in the present invention may have a circuit pattern and a positioning mark formed on one surface, which is the bonding surface, prior to bonding with the reinforcing plate. When the alignment mark is a transparent reinforcing plate, it may be read through the reinforcing plate or through the flexible film, but a metal layer is formed on the side opposite to the bonding surface of the flexible film. In this case, reading from the side of the reinforcing plate is preferable because reading can be performed regardless of the pattern of the metal layer. This alignment mark can also be used for alignment when the flexible film is attached to the reinforcing plate. The shape of the alignment mark is not particularly limited, and a shape generally used in an exposure machine or the like can be preferably adopted.

The circuit pattern formed on the surface opposite to the sticking surface after sticking to the reinforcing plate can form a particularly highly accurate pattern having a pitch of 60 μm or less. The pattern to be formed mainly serves as the input / output terminals for the printed wiring board and the wiring around it and the power supply and ground potential wiring, and is formed on the surface opposite to the surface attached to the reinforcing plate. In some cases, it is not required to have a high definition as high as the pattern. One example of the present invention provides a double-sided wiring in which a highly precise pattern is formed on one side. The advantage of being double-sided wiring is that LSI can be operated at high speed by allowing wiring to intersect through through holes, increasing the degree of freedom in wiring design, and by propagating the ground potential to the vicinity of the required location with thick wiring. Noise can be reduced. Similarly, by propagating the power supply potential to the vicinity of the required place with a thick wiring, the potential drop is prevented even at high speed switching, the operation of the LSI is stabilized, and external noise is shielded as an electromagnetic wave shield. This is very important as the speed of the LSI increases and the number of pins increases due to multi-functionalization.

An example of the manufacturing method of the present invention will be described below, but the invention is not limited thereto. A weakly adhesive re-release agent is applied to a 0.7 mm thick aluminoborosilicate glass with a die coater. After the re-release agent is applied, it is dried by heating or vacuum drying to obtain a re-release agent layer having a thickness of 20 μm. An air barrier film consisting of a release film having a silicone resin layer on a polyester film was attached to the applied re-release agent layer, and left at room temperature for 1 week.
During this period, which is called aging, crosslinking of the re-release agent layer proceeds, and the adhesive force gradually decreases. The storage period and storage temperature are
It is selected so as to obtain the desired adhesive strength. Instead of sticking an air barrier film, it can be stored in a nitrogen atmosphere or in a vacuum. It is also possible to apply the weakly adhesive re-release agent to a long film substrate, dry it, and then transfer it to the reinforcing plate.

Next, a polyimide film having a thickness of 25 μm is prepared. The air blocking film on the glass substrate is peeled off, and the polyimide film is attached to the glass substrate. As described above, a metal layer may be previously formed on one side or both sides of the polyimide film. When a metal layer is provided on the side where the polyimide film is attached, it is preferable because it can be used as a ground layer for shielding electromagnetic waves. The polyimide film may be preliminarily formed as a cut sheet having a predetermined size and attached, or may be attached and cut while being unwound from a long roll. For such pasting work,
A roll laminator or a vacuum laminator can be used.

When the metal layer is not provided on the surface opposite to the bonding surface of the polyimide film, the metal layer is formed by the full additive method or the semi-additive method.

The full additive method is the following process. The surface on which the metal layer is formed is treated with a catalyst such as palladium, nickel or chromium, and dried. The catalyst here does not act as a nucleus for plating growth as it is, but becomes a nucleus for plating growth by performing activation treatment. The catalyst application treatment may be performed after the flexible film is attached to the reinforcing plate, or may be performed on the long flexible film before the attachment.
Next, a photoresist is applied with a die coater and dried. The photoresist is exposed through a photomask having a predetermined pattern and developed to form a resist layer on a portion where the plating film is unnecessary. After this, after activating the catalyst,
The polyimide film is dipped in an electroless plating solution composed of a combination of copper sulfate and formaldehyde to form a copper plating film having a thickness of 2 μm to 20 μm to obtain a circuit pattern.

The semi-additive method is the following process. On the surface on which the metal layer is formed, chromium, nickel, copper or an alloy thereof is sputtered to form a base layer. The thickness of the underlayer is in the range of 1 nm to 1000 nm. A copper sputtered film having a thickness of 50 nm is further formed on the underlayer.
To 3000 nm is effective for ensuring electrical continuity for subsequent electrolytic plating, improving adhesion of the metal layer and preventing pinhole defects. Prior to forming the underlayer,
Plasma treatment, reverse sputtering treatment, primer layer coating, and adhesive layer coating are appropriately permitted on the surface of the polyimide film to improve the adhesive strength. Above all, epoxy type, acrylic type, polyamide type, polyimide type, NBR
The application of an adhesive layer such as a system is preferable because it has a large effect of improving the adhesive strength. These treatments and coatings may be performed before the single-wafer substrate is attached or after the single-wafer substrate is attached. It is preferable that a long polyimide film is continuously processed by roll-to-roll processing before being attached to a single-wafer substrate because productivity can be improved. The base layer may be formed after the flexible film is attached to the reinforcing plate, or may be formed, for example, on a long flexible film before the attachment. A photoresist is applied to the underlayer thus formed by a spin coater, a blade coater, a roll coater, a die coater, screen printing or the like and dried. It is preferable to use a die coater in order to apply the material uniformly to the single-wafer substrate that is intermittently sent with high material usage efficiency. The photoresist is exposed through a photomask having a predetermined pattern and developed to form a resist layer on a portion where the plating film is unnecessary. Next, electrolytic plating is performed using the underlayer as an electrode. As the electrolytic plating solution, a copper sulfate plating solution, a copper cyanide plating solution, a copper pyrophosphate plating solution, or the like is used. After forming a copper plating film with a thickness of 2 μm to 20 μm, further plating with gold, nickel, tin, etc. is performed if necessary, the photoresist is peeled off, and then the underlying layer is removed by slight etching to remove the circuit pattern. To get

In forming these metal wiring circuits,
Connection holes can be provided in the polyimide film. That is, it is possible to provide a via hole for electrical connection with the metal layer provided on the bonding surface side of the single-wafer substrate, or to provide a ball installation hole for the ball grid array. As a method of providing the connection hole, a carbon dioxide laser, Y
Laser drilling such as AG laser and excimer laser and chemical etching can be adopted. When laser etching is adopted, it is preferable that the etching stopper layer has a metal layer on the side where the polyimide film is attached. As the chemical etching liquid for the polyimide film, hydrazine, potassium hydroxide aqueous solution or the like can be adopted. A patterned photoresist or a metal layer can be used as the chemical etching mask. When making an electrical connection,
After forming the connection hole, it is preferable to make the inner surface of the hole a conductor by a plating method at the same time when the metal layer pattern is formed. The connection hole for electrical connection has a diameter of 15 μm to 200 μm
Is preferred. The diameter of the holes for placing the balls is preferably 50 μm to 800 μm, more preferably 80 μm to 800 μm.

Next, the polyimide film having the circuit pattern formed thereon is peeled off from the single substrate. The polyimide film with the circuit pattern is cut into individual pieces or an assembly of individual pieces before peeling by using a laser, a high-pressure water jet, a cutter, or the like so that the electronic component mounting device for the circuit pattern can be easily handled. It is preferable. Further, it is preferable that the polyimide film is less likely to have stress when it is made small like an individual piece or an assembly of individual pieces not only at the time of peeling but also at the time of circuit pattern production. In order to maintain the positional accuracy of the connection with the electronic component, it is more preferable to peel the film from the sheet substrate after connecting the electronic component to the circuit pattern on the polyimide film. As a method for connecting to an electronic component, solder connection, anisotropic conductive adhesive / film connection, metal eutectic connection, non-conductive adhesive / film connection, wire bonding connection, or the like can be adopted.

The circuit board of the present invention is a wiring board for electronic equipment,
Used in IC package interposers.
It is appropriately permitted to insert a resistance element or a capacitance element in the circuit pattern. It is also possible to stack an insulating layer and a wiring layer on at least one surface of the flexible film substrate to form a multilayer structure.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the present invention, the Young's modulus of glass is JIS
The value obtained by R1602. In addition, the Young's modulus of the metal is a value obtained by ASTM E1876-00.

Example 1 A 300 mm square aluminoborosilicate glass having a thickness of 0.7 mm was fixed on a moving platen by vacuum adsorption. Piston type pump for weak adhesive removability agent "SKDyne" 1491 (manufactured by Soken Chemical Industry Co., Ltd.) and curing agent L-45 (Soken Chemical Industry Co., Ltd.)
While supplying a mixture of the product manufactured by M.M. Co., Ltd.) in a ratio of 75: 1 to the die coater head, the platen on which the glass was fixed was moved in the direction perpendicular to the width direction of the die coater head to apply the re-release agent. At the start of coating, the glass and the die coater head were moved to the coating start position, then stopped once, and the re-release agent was supplied to the die coater head to form beads (coating solution pool) on the die coater head. After forming the beads, the thickness of the re-peeling agent at the coating start portion was controlled by starting relative movement of the glass and the die coater head.
Further, at the end of coating, the supply of the re-release agent is stopped before the coating end position, coating is performed while consuming the bead, and the die coater head is separated from the glass at the coating end position to remove the coating end portion. The thickness of the removable agent was controlled.
After coating, transfer the glass from the surface plate to the oven, 90 ℃
And dried for 2 minutes. The thickness of the removable agent after drying was set to 15 μm. Next, an air barrier film made of a film having a silicone resin layer on the polyester film, which is easy to release, is attached to the removable agent layer (aluminoborosilicate glass / removable agent layer / silicone resin layer / polyester film). It's been a week. The Young's modulus of the glass substrate was 7140 kg / mm ² , and the Young's modulus (kg /
The product of the cube of mm ² ) and the thickness (mm) is 2449 kg.
It was mm.

An adhesive for improving the adhesive strength of the metal layer was prepared as follows. The inside of the flask was replaced with a nitrogen atmosphere, 228 parts of N, N-dimethylacetamide was added,
19.88 parts of 1,1,3,3-tetramethyl-1,3-bis (3-aminopropyl) disiloxane was dissolved.
Next, 25.76 parts of 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride was added, and the mixture was stirred under a nitrogen atmosphere at 10 ° C. for 1 hour. Subsequently, the mixture was reacted at 50 ° C. for 3 hours while stirring to obtain an adhesive composed of a polyimide precursor varnish.

Using a comma coater, which is a type of roll coater, a long polyimide film having a thickness of 25 μm and a width of 300 mm (“UPILEX” manufactured by Ube Industries, Ltd.)
Manufactured) was continuously coated with the adhesive. Then, it was dried at 80 ° C. for 10 minutes, 130 ° C. for 10 minutes, 150 ° C. for 15 minutes, and cured at 250 ° C. for 5 minutes. The film thickness of the adhesive layer after curing was 1 μm. Five polyimide films with different lots were prepared.

While peeling off the air barrier film consisting of the polyester film and the silicone resin layer, the glass on which the re-release agent layer is formed is coated with an adhesive using a roll laminator. I pasted it to become. The polyimide film laminated on the glass was cut according to the glass end.

Then, a chromium-nickel alloy film having a thickness of 50 nm and a copper film having a thickness of 100 nm were laminated in this order on the adhesive layer by sputtering. A positive photoresist was applied on the copper film with a spin coater and dried at 80 ° C. for 10 minutes. The photoresist was exposed through a photomask and developed to form a resist layer having a thickness of 10 μm on a portion where the plating film was unnecessary. The test photomask pattern was a pattern in which a grid pattern having a line width of 10 μm and a pitch of 500 μm was positive-negative inverted. That is, a grid-shaped plating pattern is obtained. After development, it was post-baked at 120 ° C. for 10 minutes. Next, electrolytic plating was performed using the metal layer as an electrode. The electrolytic plating solution was a copper sulfate plating solution. After forming a copper plating film having a thickness of 5 μm, the photoresist is removed with a photoresist removing solution, and then the copper film and the chromium-nickel alloy film under the resist layer are removed by soft etching with an aqueous iron chloride solution. As a result, a grid-shaped metal pattern was obtained.

Vacuum suction was performed from the metal pattern surface side of the polyimide film, and the polyimide film was gradually peeled from the single-sided substrate from the end.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 2 2mm thick, 300mm square soda glass was used
A metal film pattern was obtained in the same manner as in Example 1 except for the above. The
Young's modulus of the glass substrate is 6832 kg / mm ²And
, Young's modulus (kg / mm²) And the cube of the thickness (mm)
The product was 54656 kg · mm.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 3 A metal film pattern was obtained in the same manner as in Example 1 except that 300 mm square soda glass having a thickness of 0.5 mm was used. Young's modulus of the glass substrate is 6832 kg / mm ²
And Young's modulus (kg / mm ² ) and thickness (mm) are 3
The product of powers was 854 kg · mm.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, it was found that all 5 polyimide films of different lots were within ± 10 μm with respect to the photomask pattern, which was good, but compared with Examples 1 and 2. The variability has increased.

Example 4 A metal film pattern was obtained in the same manner as in Example 1 except that 300 mm square soda glass having a thickness of 0.4 mm was used. Young's modulus of the glass substrate is 6832 kg / mm ²
And Young's modulus (kg / mm ² ) and thickness (mm) are 3
The product of powers was 437 kg · mm.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, some of the photomask patterns were distorted by 20 μm toward the outside of the substrate. Although it was better than the comparative example, it was at a level that would be a problem in comparatively fine processing with a pitch of 120 μm or less.

Example 5 Adhesive "SKDyne" S whose adhesive strength is reduced by UV irradiation
A mixture of W-11A (manufactured by Soken Chemical Industry Co., Ltd.) and a curing agent L-45 (manufactured by Soken Chemical Industry Co., Ltd.) at a ratio of 50: 1 was applied,
It was dried at 80 ° C. for 2 minutes. Thickness of adhesive after drying is 20 μm
And Before changing the adhesive and peeling from the single-wafer substrate, ultraviolet rays of 1000 mJ / cm ² were applied from the glass substrate side.
A metal film pattern was obtained in the same manner as in Example 1 except that the irradiation was performed.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 6 A polyimide film was prepared by adhering a copper foil having a thickness of 18 μm on one surface with an epoxy adhesive. An adhesive was applied to the surface of the polyimide film opposite to the copper foil bonding surface in the same manner as in Example 1, and the polyimide film was bonded to a glass substrate.

Using a carbon dioxide laser, the diameter is 100 μm.
m holes were formed in a grid pattern at a pitch of 10 mm. The connection hole penetrates through the polyimide film and reaches the back side of the copper foil.

A chromium-nickel alloy film having a thickness of 50 nm and a copper film having a thickness of 100 nm were laminated in this order on the adhesive layer by sputtering. A positive photoresist was applied on the copper film with a spin coater and dried at 80 ° C. for 10 minutes. The photoresist was exposed to light through a photomask and developed to form a resist layer on a portion where the plating film was unnecessary. The test photomask pattern was a pattern in which a grid pattern having a line width of 10 μm and a pitch of 500 μm and a circle having a diameter of 300 μm repeatedly arranged in a portion punched by a laser having a pitch of 1 mm were positive-negative inverted. After development, it was post-baked at 130 ° C. for 10 minutes. Next, electrolytic plating was performed using the copper film as an electrode. The electrolytic plating solution was a copper sulfate plating solution. After forming a copper plating film having a thickness of 5 μm, the photoresist is removed with a photoresist removing solution, and then the copper film and the chromium-nickel alloy film under the resist layer are removed by soft etching with an aqueous iron chloride solution. A metal film pattern was obtained. A metal film was also attached to the inside of the connection hole, and conduction between the front and back sides was achieved.

Vacuum suction was performed from the metal pattern surface side of the polyimide film, and the polyimide film was gradually peeled from the single substrate from the end.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 7 A metal film pattern was obtained in the same manner as in Example 1 except that a 300 mm square stainless steel plate having a thickness of 0.5 mm was used as the reinforcing plate. The Young's modulus of the stainless steel plate is 20320 kg / mm ² , and the Young's modulus (kg /
The product of the cube of mm ² ) and thickness (mm) is 2540 kg.
It was mm.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 8 A metal film pattern was obtained in the same manner as in Example 1 except that a 300 mm square stainless steel plate having a thickness of 0.2 mm was used as the reinforcing plate. The Young's modulus of the stainless steel plate is 20320 kg / mm ² , and the Young's modulus (kg /
The product of the cube of mm ² ) and thickness (mm) is 163 kg · m
It was m.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, all 5 polyimide films of different lots were within ± 5 μm with respect to the photomask pattern, which was very good.

Example 9 A metal film pattern was obtained in the same manner as in Example 1 except that a 300 mm square stainless steel plate having a thickness of 0.05 mm was used as the reinforcing plate. The Young's modulus of the stainless steel plate is 20320 kg / mm ² , and the Young's modulus (kg
/ Mm ² ) and the thickness (mm) cubed are 2.5 kg
It was mm.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions) was measured, some of the photomask patterns were distorted by 17 μm toward the outside of the substrate. Although it was better than the comparative example, it was at a level that would be a problem in comparatively fine processing with a pitch of 120 μm or less.

Comparative Example 1 In the same manner as in Example 1, an adhesive was applied to a polyimide film having a thickness of 25 μm and a width of 300 mm, dried and cured.
Without attaching the polyimide film to the single-wafer substrate, 300
Same as in Example 1 for a single mm square polyimide film, formation of sputtered film, formation of photoresist pattern,
Plated film formation, photoresist stripping, and soft etching were performed.

Length measuring machine SMIC-800 (Sokia Corporation)
Manufactured), the position of the intersection of the grid-shaped metal patterns was measured as the intersection of the center lines of the intersecting metal film lines. Two points that were originally about 283 mm apart in the diagonal direction (200 m in the x direction)
When a distance of 200 mm in the m and y directions was measured, it was found that some photomask patterns were distorted by 45 μm toward the outside of the substrate. Even a relatively rough processing with a pitch of 200 μm or more was at a level to be a problem.

Comparative Example 2 Aluminoborosilicate glass having a thickness of 0.7 mm and a size of 300 mm was set on a spin coater, and the same weak-adhesive re-release agent "SKDyne" 1491 used in Example 1 was used.
A mixture of H (manufactured by Soken Chemical Industry Co., Ltd.) and curing agent L-45 (manufactured by Soken Chemical Industry Co., Ltd.) at a ratio of 75: 1 was dropped on glass. Optimum coating conditions were sought by changing the number of revolutions, but wetting and spreading were poor, and uniform coating could not be performed.

Comparative Example 3 A 0.7 mm thick, 300 mm square aluminoborosilicate glass was vacuum-adsorbed on a moving platen, and the same weak-adhesive removing agent "SKDyne" 1491 used in Example 1 was used.
A mixture of H (manufactured by Soken Chemical Industry Co., Ltd.) and curing agent L-45 (manufactured by Soken Chemical Industry Co., Ltd.) at a ratio of 75: 1 was dropped at the coating start position. Then, the distance between the glass and the tip of the doctor blade was maintained at 50 μm, the glass and the doctor blade were moved relatively to each other, and the removable agent was applied. A desired thickness of 15 μm was obtained in the central portion of the glass, but there was a large thickness unevenness in the width direction at the coating start portion and the coating end portion. The end portion was defective because the film thickness could be three times or more.

[0060]

According to the present invention, since the flexible film substrate is bonded to the sheet reinforcing plate, the circuit pattern is processed, and then the flexible film is peeled off and used, the heat treatment process in the processing step is performed. The expansion and contraction due to the wet process or the deformation due to the external force such as pulling and twisting is suppressed, and the fine processing closer to the design value is enabled. In particular, the effect is great in improving the positional accuracy related to the positioning accuracy between the electrode pad and the circuit board pattern when connecting an electronic component such as an IC.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Oguni             1-1 1-1 Sonoyama, Otsu City, Shiga Prefecture Toray Co., Ltd.             Ceremony company Shiga business site F term (reference) 5E343 AA02 AA18 AA33 BB24 CC01                       CC62 DD25 DD43 ER12 ER18                       ER21 ER26 FF30 GG08

Claims (7)

[Claims] 1. A flexible film is attached to a reinforcing plate via a peelable organic layer, a circuit pattern is formed on the flexible film, and then the flexible film is peeled from the reinforcing plate. And a method for manufacturing a circuit board. 2. The method of manufacturing a circuit board according to claim 1, wherein the connection hole is formed from a surface opposite to a surface of the flexible film bonded to the reinforcing plate. 3. The method for manufacturing a circuit board according to claim 1, wherein the reinforcing plate is a sheet, and the long flexible film is cut and stuck together with the sheet reinforcing plate. 4. The product of the cube of Young's modulus (kg / mm ² ) and thickness (mm) of the reinforcing plate is 2 kg · mm or more and 860000.
2. The range of kg · mm or less.
A method for manufacturing the circuit board described. 5. The Young's modulus (kg /
The product of the cube of mm ² ) and the thickness (mm) is 850 kg · m
The method for manufacturing a circuit board according to claim 4, wherein the range is m or more and 860000 kg · mm or less. 6. The reinforcing plate is made of metal and Young's modulus (kg / m)
The method for manufacturing a circuit board according to claim 4, wherein the product of m ³ ) and the cube of thickness (mm) is in the range of 2 kg · mm or more and 162560 kg · mm or less. 7. The method for manufacturing a circuit board according to claim 1, wherein the reinforcing plate is a single sheet, and the peelable organic material layer and / or photoresist is applied to the reinforcing plate by a die coater.