JP2008243899A - Circuit board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board having high precision and connection reliability even if a stress is released after a flexible film is applied to a reinforcing board and then peeled, and to provide a method of manufacturing the same. <P>SOLUTION: In the manufacturing method of the circuit board, a reinforcing board 12 is applied to at least one surface of the flexible film 6 by way of an organic layer 11, and then, a circuit pattern is formed on the surface opposite to the applied surface of the flexible film. The circuit pattern is then jointed to the electrodes of an electronic component. A×(T-T1)+B×(H-H1)<0 is satisfied, wherein the linear expansion coefficient, humidity expansion coefficient, and temperature of the flexible film at pasting to the reinforcing board are Appm/°C, Bppm/%RH, and T°C, respectively; storage humidity of the flexible film before pasting is H%RH; and the storage temperature and storage humidity of the flexible film with a circuit pattern after electronic component joint are T1°C and H1%RH. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a circuit board manufacturing method and a circuit board using a high-quality flexible film having a highly accurate circuit pattern and excellent in productivity.

  As electronic products become lighter, smaller, and more precise, there is a need for higher precision in patterning of printed circuit boards. Among them, the demand for flexible film substrates is increasing because three-dimensional wiring is possible due to its flexibility and it is suitable for downsizing of electronic products. However, the progress of miniaturization of circuit patterns is approaching the limit. For miniaturization, there are an index represented by a line width and a space width between lines, and an index represented by a position of a pattern on a substrate. The latter index, so-called positional accuracy, is obtained by indexing the alignment between the circuit board and an electronic component such as an IC, and the required accuracy is becoming stricter.

  On the other hand, in the circuit board processing process, there are a heat treatment process such as drying and curing, and a wet process such as etching and development, and the flexible film repeatedly expands and contracts. The hysteresis at this time causes displacement of the circuit pattern on the substrate. In addition, when there are a plurality of processes that need alignment, if there is expansion or contraction between these processes, positional deviation occurs between the formed patterns. Deformation due to expansion and contraction of the flexible film has an even greater effect in the case of an FPC (Flexible Printed Circuit) in which processing is performed with a relatively large substrate size. Further, the positional shift is caused by an external force such as pulling or twisting, and special attention is required when a thin substrate is used to increase flexibility.

  On the other hand, a reinforcing film such as inorganic glass or metal is bonded to a flexible film to form a circuit pattern through an organic material layer, and attempts to suppress deformation due to external force by increasing the overall strength. A technique has been proposed (see, for example, Patent Document 1). However, even if a highly accurate circuit pattern is formed in a state where the flexible film is bonded to the reinforcing plate, the stress of the flexible film may be released after peeling and the position accuracy of the circuit pattern may be lowered. It was.

As a method for solving this, a technique has been proposed in which humidity is controlled before the flexible film is bonded to the reinforcing plate, thereby controlling the moisture content of the flexible film to improve the positional accuracy. (For example, refer to Patent Document 2). However, due to thermal contraction of the flexible film when bonding electronic components such as ICs, there is a case where the disconnection of the wiring or the bonding portion between the wiring and the electronic component such as the IC peels off. In addition, when the temperature applied to the flexible film is increased when bonding electronic parts such as ICs, bonding failure may occur or the electronic part and the flexible film may stick to each other.
International Publication No. 03/009657 Pamphlet JP 2004-319869 A (pages 3 to 8)

  The object of the present invention is to disconnect the wiring or to connect the wiring and the electronic component such as the IC even when the electronic film such as the IC is bonded to the flexible film with the circuit pattern even if the flexible film is thermally contracted. An object of the present invention is to provide a circuit board manufacturing method and a circuit board capable of stably and easily manufacturing a highly reliable flexible film circuit board without peeling. Furthermore, a highly reliable flexible film circuit board can be stably and easily adapted to the temperature applied to the flexible film when an electronic component such as an IC is bonded to the flexible film with a circuit pattern peeled from the reinforcing plate. It is an object of the present invention to provide a circuit board method and a circuit board that can be manufactured.

In order to achieve the above object, the present invention adopts the following configuration. That is,
(1) The reinforcing plate is bonded to at least one surface of the flexible film via an organic layer, and then a circuit pattern is formed on the surface opposite to the bonding surface of the flexible film, and then the circuit pattern and the electronic A method of manufacturing a circuit board for bonding component electrodes, wherein the flexible film has a linear expansion coefficient of Appm / ° C. when the flexible film is bonded to the reinforcing plate, and the flexible film is attached to the reinforcing plate. The humidity expansion coefficient of the flexible film when bonding is set to Bppm /% RH, and the temperature of the flexible film when bonding the flexible film to the reinforcing plate is set to T ° C. Save humidity of the flexible film prior to bonding the flexible film and H% RH, a circuit pattern with a flexible film storage temperature after bonding the electronic component and T ₁ ° C., bonding the electronic component A circuit pattern with a flexible film storage humidity after the When H _1% RH,
A × (T−T ₁ ) + B × (H−H ₁ ) <0
A circuit board manufacturing method characterized by satisfying the relationship:

  (2) The method for producing a circuit board according to (1), wherein the flexible film is a polyimide film.

  (3) A circuit board obtained by the manufacturing method according to (1) or (2).

  According to the present invention, when an electronic component such as an IC is bonded to a flexible film with a circuit pattern bonded to a reinforcing plate or a flexible film with a circuit pattern peeled from the reinforcing plate, the flexible film is thermally shrunk. Even in this case, disconnection of the wiring and separation of the joint between the wiring and an electronic component such as an IC do not occur, and a highly reliable circuit board can be obtained stably and easily. Furthermore, a highly reliable flexible film circuit board according to the temperature applied to the flexible film when an electronic component such as an IC is bonded to the flexible film with a circuit pattern peeled from the reinforcing plate is stable and easy. Can get to.

In the present invention, at least one surface of a flexible film is bonded to a reinforcing plate via an organic layer, and then a circuit pattern is formed on the surface opposite to the bonding surface of the flexible film, A method of manufacturing a circuit board for bonding an electrode of an electronic component, wherein the flexible film has a linear expansion coefficient of Appm / ° C. and a humidity expansion of the flexible film when the flexible film is bonded to the reinforcing plate. The coefficient is Bppm /% RH, the temperature of the flexible film when the flexible film is bonded to the reinforcing plate is T ° C, and the storage humidity of the flexible film before the flexible film is bonded to the reinforcing plate is H % RH, a flexible film with a circuit pattern after joining electronic components storage temperature is T ₁ ° C, and the storage humidity is H ₁ % RH,
A × (T−T ₁ ) + B × (H−H ₁ ) <0
It is important that

Further, it is preferable that A × (T−T ₁ ) + B × (H−H ₁ ) ≧ −700. When electronic parts such as ICs are joined to a flexible film with a circuit pattern, the effect of preventing the peeling of the joint between the metal layer forming the circuit pattern and the electrode of the electronic part and the prevention of disconnection of wiring due to thermal stress effect is a trade-off relationship with respect to the value of _{a × (T-T 1)} + B × (H-H 1). If the value of A × (T−T ₁ ) + B × (H−H ₁ ) is smaller than −700, when the flexible film with a circuit pattern is peeled from the reinforcing plate, the wiring is disconnected due to a large tensile stress applied to the wiring. In addition, when an electronic component such as an IC is bonded to the flexible film with a circuit pattern, the bonding between the metal layer forming the circuit pattern and the electrode of the electronic component may be deteriorated. In addition, when an electronic component such as an IC is connected to the flexible film with a circuit pattern peeled from the reinforcing plate, the wiring position accuracy of the flexible film with respect to the electrode position of the electronic component may be significantly reduced. Therefore, it is more preferable that A × (T−T ₁ ) + B × (H−H ₁ ) ≧ −600, and A × (T−T ₁ ) + B × (H−H ₁ ) ≧ −500. More preferably.

The flexible film expands or contracts due to a temperature change of the flexible film. In addition, the flexible film expands or contracts due to changes in storage humidity. Since the expansion and contraction of the flexible film is the expansion and contraction due to the temperature change of the flexible film and the storage humidity change of the flexible film, A × (T−T ₁ ) + B × (H−H ₁ ) It is important to control the dimensional change and stress of the flexible film with the formula.

  The linear expansion coefficient A of the flexible film is a linear expansion coefficient per unit temperature. When the flexible film is in the same storage humidity environment and the temperature of the flexible film is in the range of 30 ° C. to 200 ° C., the linear expansion amount Is measured every 10 ° C., and the coefficient of linear expansion at each obtained temperature is averaged. If the linear expansion coefficient A is too large, the tensile stress and the compressive stress when the heat stress is applied to the flexible film with a circuit pattern peeled from the reinforcing plate increases, and the wiring is disconnected or bonded to an electronic component such as an IC. The part may peel off. From this, the linear expansion coefficient A is preferably 40 ppm / ° C. or less, more preferably 30 ppm / ° C. or less, and further preferably 0 ppm / ° C. or more and 20 ppm / ° C. or less. At 0 ppm / ° C., the tensile stress and the compressive stress when the thermal stress is applied to the flexible film with a circuit pattern peeled from the reinforcing plate are the smallest.

  The humidity expansion coefficient B of the flexible film is a coefficient of humidity expansion per unit humidity. When the flexible film is stored in the same temperature environment and the storage humidity of the flexible film is in the range of 10% RH to 90% RH, the humidity It is a value obtained by measuring the linear expansion amount every 10% RH and averaging the humidity expansion coefficient at each obtained humidity. If the humidity expansion coefficient B is too large, the tensile stress or compressive stress of the flexible film with a circuit pattern peeled off from the reinforcing plate is increased, and the wiring is disconnected or bonded to an electronic component such as an IC. The part may peel off. Accordingly, the humidity expansion coefficient B is preferably 40 ppm /% RH or less, more preferably 30 ppm /% RH or less, and further preferably 0 ppm /% RH or more and 20 ppm /% RH or less. At 0 ppm /% RH, the tensile stress and the compressive stress when the humidity stress is applied to the flexible film with a circuit pattern peeled from the reinforcing plate are the smallest.

  The storage humidity of the flexible film before the flexible film is bonded to the reinforcing plate is the environmental humidity in which the flexible film is stored, and may be any humidity condition of 0% RH to 100% RH. In order to prevent oxidation of the metal layer due to humidity stress, 75% RH or less is preferable, and preferable conditions are appropriately selected according to the type of film. Moreover, it is preferable to adjust humidity in a state where the flexible films do not overlap.

  The temperature of the flexible film when the flexible film is bonded to the reinforcing plate is the surface temperature of the flexible film. In order to prevent deformation of the flexible film surface, two different points are used in the non-contact type thermometer. It is a value obtained by averaging measured temperatures. The temperature condition of the flexible film may be more than 0 ° C. and less than 100 ° C., but when the flexible film has a metal layer, it is preferably 80 ° C. or less, more preferably 60 ° C. or less in order to prevent oxidation of the metal layer. 40 ° C. or lower is more preferable. If the storage humidity and the humidity at which the flexible film is bonded to the reinforcing plate are different, the flexible film at the time of bonding absorbs moisture or dries, so the humidity is preferably the same. In addition, when the flexible film is moved in a short time, for example, when the flexible film moves from the storage environment to the bonding environment, the moisture absorption state of the flexible film does not change suddenly. The humidity at which the flexible film is bonded may be different.

  The storage temperature of the flexible film with a circuit pattern after bonding electronic parts is the surface temperature of the flexible film during storage, and a non-contact type thermometer is used to prevent deformation of the flexible film surface. It is a value obtained by averaging temperatures measured at two different points. The storage temperature condition of the flexible film may be more than 0 ° C. and less than 100, but is preferably 80 ° C. or less, more preferably 60 ° C. or less, and most preferably 40 ° C. or less in order to prevent the wiring from being oxidized.

  The storage humidity of the flexible film with the circuit pattern after joining the electronic parts is the environmental humidity in which the flexible film is stored, and the storage humidity condition of the flexible film is 0% RH to 100% RH. However, 75% RH or less is preferable in order to prevent the wiring from being oxidized.

  In the present invention, the flexible film is a plastic film, and it is important that the film has a heat resistance sufficient to withstand a thermal process in a circuit pattern manufacturing process and electronic component mounting, such as polycarbonate, polyether sulfide, Films such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyimide, polyamide, and liquid crystal polymer can be employed. Among these, a polyimide film is suitably employed because it is excellent in heat resistance and chemical resistance. In addition, a liquid crystal polymer is preferably used because it has excellent electrical characteristics such as low dielectric loss. 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 epoxy, polyphenylene sulfide, polyphenylene ether, maleimide, polyamide, and polyimide.

  The thickness of the flexible film is preferably thinner in order to reduce the weight and size of electronic devices, or to form fine via holes. On the other hand, in order to ensure mechanical strength and maintain flatness. A thicker one is preferable, and a range of 4 μm to 125 μm is preferable.

  In the present invention, it is preferable that the flexible film is heat-treated particularly before conditioning. By performing the heat treatment, it is possible to suppress the heat shrinkage distortion from being accumulated in the flexible film due to the thermal history applied to the flexible film in the circuit board manufacturing process. In this invention, it is preferable that the heat processing temperature of a flexible film is 100 degreeC or more and 200 degrees C or less, and it is further more preferable that it is more than the highest temperature of a circuit board manufacturing process.

  In the present invention, the flexible film may have a sputtered film in which a metal layer is formed by a sputtering method. In addition, it is preferable that a sputtered film in which a metal layer is formed on the flexible film by a sputtering method before being bonded to the reinforcing plate is used from the viewpoint of improving the production efficiency of the semi-additive method. The sputtered film is preferably used as a power supply for electrolytic plating, and the metal layer in contact with the insulating layer is at least one of chromium, nickel, titanium, tungsten, molybdenum, and an alloy containing these metals for improving adhesion to the insulating layer. It is preferable that the metal layer is composed of a kind and a copper layer.

  In the present invention, the method of forming the metal film constituting the circuit pattern is not particularly limited. For example, the metal film such as copper foil can be formed by pasting with an adhesive layer, sputtering, plating, or the like. It can form with the combination of these. Moreover, the flexible film with a metal layer can also be obtained by apply | coating the raw material resin or its precursor of a flexible film on metal foil, such as copper, and drying and curing.

  In the present invention, the reinforcing plate is an inorganic glass such as soda lime glass, borosilicate glass or quartz glass, a metal such as Invar alloy, stainless steel or titanium, a ceramic such as alumina, zirconia or silicon nitride, or a glass fiber reinforced resin plate. Etc. can be adopted. Both are preferable in terms of a low coefficient of linear expansion and a coefficient of humidity expansion, but are excellent in heat resistance and chemical resistance in the circuit pattern manufacturing process, and are easy to obtain at a low cost because a large area and high surface smoothness are available. Inorganic glasses are preferred because they are difficult to plastically deform.

  An ultraviolet curable pressure-sensitive adhesive may be used as the organic material layer between the reinforcing plate and the flexible film. In this case, a reinforcing plate that transmits ultraviolet rays is desirable. In this respect, inorganic glass is preferable.

  When a metal or glass fiber reinforced resin is used for the reinforcing plate, it can be manufactured as a long continuous body, but the circuit board manufacturing method of the present invention is a single wafer type because it is easy to ensure positional accuracy. Is preferred. A sheet means a state where it is handled as an individual sheet, not a long continuous body.

  When inorganic glass is used for the reinforcing plate, if the Young's modulus is small or the thickness is small, warping and twisting will increase due to the expansion / contraction force of the flexible film, and the reinforcing plate will be when vacuum-adsorbed on a flat stage. It may break. Moreover, a flexible film will deform | transform by vacuum adsorption | suction and removal | desorption, and there exists a tendency for ensuring of position accuracy to become difficult. On the other hand, if the reinforcing plate is thick, the flatness may deteriorate due to uneven thickness, and the exposure accuracy tends to deteriorate. In addition, the load increases during handling by a robot or the like, which makes it difficult to handle quickly and causes a decrease in productivity, and also tends to increase the transportation cost. From these points, the thickness of the inorganic glass is preferably in the range of 0.3 mm to 1.1 mm.

  When metal is used for the reinforcing plate, if the metal has a low Young's modulus, or if the thickness is thin, the warp and twist of the metal will increase due to the expansion and contraction of the flexible film, making it impossible to vacuum-adsorb on a flat stage. In addition, since the flexible film is deformed by the amount of warping or twisting of the metal, it is difficult to maintain the positional accuracy. Further, if the metal is broken, it becomes a defective product at that time. On the other hand, if the metal is thick, the flatness may deteriorate due to uneven thickness, and the exposure accuracy will deteriorate. In addition, the load is increased during handling by a robot or the like, which makes it difficult to handle quickly and causes a decrease in productivity, and also increases the transportation cost. From these points, the thickness of the metal is preferably in the range of 0.1 mm to 0.7 mm.

  As the organic layer used in the present invention, an adhesive or a pressure-sensitive adhesive is used. Examples of the adhesive or pressure-sensitive adhesive include pressure-sensitive adhesives called acrylic or urethane re-peeling agents. In order to have a sufficient adhesive force during the processing of the flexible film, easily peel off at the time of peeling, and not cause distortion in the flexible film, a material having an adhesive strength in a region called a weak adhesive to a medium adhesive is preferable. A silicone resin having tackiness can also be used. It is also possible to use an epoxy resin having tackiness.

  As organic substances, those whose adhesive strength and adhesive strength are reduced in a low temperature region, those whose adhesive strength and adhesive strength are reduced by ultraviolet irradiation, and those whose adhesive strength and adhesive strength are reduced by heat treatment are suitably used. Among these, those caused by ultraviolet irradiation are preferable because of large changes in adhesive strength and adhesive strength. An example of a material whose adhesive strength and adhesive strength are reduced by ultraviolet irradiation is a two-component cross-linking acrylic pressure-sensitive adhesive. Examples of those in which adhesive strength and adhesive strength decrease in a low temperature region include acrylic pressure-sensitive adhesives that reversibly change between a crystalline state and an amorphous state, and are preferably used.

  The thickness of the organic layer in the present invention is preferably in the range of 0.1 μm to 20 μm, and more preferably in the range of 0.3 μm to 10 μm.

  In the present invention, the peel force when peeling the flexible film from the reinforcing plate is measured by the 180 ° peel strength when peeling the 1 cm wide flexible film bonded to the reinforcing plate via the organic layer. Is done. The peeling speed when measuring the peeling force is 300 mm / min. In the present invention, the peel force is preferably in the range of 0.098 N / m to 98 N / m. If the peeling force is too low, the flexible film may peel from the organic layer during circuit pattern formation. On the other hand, if the peeling force is too high, the flexible film may be deformed or curled.

  The peeling interface may be either the interface between the reinforcing plate and the organic material layer or the interface between the organic material layer and the flexible film, but the step of removing the organic material layer from the flexible film can be omitted. It is preferable to peel at the interface with the flexible film.

  In order to improve the adhesive force between the reinforcing plate and the organic layer, the reinforcing plate may be subjected to a primer treatment such as application of a silane coupling agent. In addition to the primer treatment, cleaning by ultraviolet treatment, ultraviolet ozone treatment, etc., surface roughening treatment such as chemical etching treatment, sand blast treatment or fine particle dispersion layer formation is also preferably used.

  As a method for connecting an electronic component such as an IC and a circuit board, for example, a metal layer such as tin, gold, or solder formed on the connection portion of the circuit board and a gold or solder formed on the connection portion of the electronic component is used. A method in which a metal layer is bonded by thermocompression bonding, a metal layer such as tin, gold, or solder at a connection portion of a circuit board and a metal layer such as gold or solder formed at a connection portion of an electronic component while being bonded. A method of curing and mechanically bonding an anisotropic conductive adhesive or non-conductive adhesive placed between the board and the electronic component, a metal layer such as tin, gold, solder, etc. of the connection part of the circuit board and the electronic component There is a method in which a metal layer such as gold or solder formed on a connection portion is surface-activated by plasma or the like and joined.

  In the flexible film used in the present invention, a circuit pattern may be formed on one surface which is a pasting surface prior to pasting with the reinforcing plate. In this case, it is preferable to form an alignment mark with the circuit pattern formed on the other surface simultaneously with the pattern formation. In order to make use of the high definition of the high definition pattern formed on the surface opposite to the bonding surface, it is very effective for the production of the high definition pattern to provide the alignment mark. The alignment mark reading method is not particularly limited, and for example, an optical method, an electrical method, a mechanical method, or the like can be used. The alignment mark can also be used for alignment when the flexible film is bonded 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 suitably used.

  After the flexible film is attached to the reinforcing plate, the circuit pattern formed on the opposite side of the flexible film attachment surface prevents deformation of the flexible film caused by the reinforcing plate and the metal layer. Therefore, a particularly high-precision pattern can be formed.

  According to the present invention, it is possible to easily provide a circuit board with double-sided wiring in which a particularly fine pattern is formed on one side. Advantages of using double-sided wiring include crossover through through-holes, increasing the degree of freedom in wiring design, and LSI that operates at high speed by propagating the ground potential to the vicinity of the required location with thick wiring In addition, the power supply potential can be propagated to the vicinity of the necessary location with thick wiring as well, so that the potential drop can be prevented even at high-speed switching, the operation of the LSI can be stabilized, and external noise can be blocked as an electromagnetic wave shield. This is advantageous as LSI speeds up and the number of pins increases due to the increase in functionality.

  Furthermore, in the present invention, it is possible to use a reinforcing plate when processing both sides of the flexible film, and to form a pattern with particularly high precision on both sides. For example, the first surface is formed after the first reinforcing plate and the second surface of the flexible film are bonded to each other through the organic layer to form a circuit pattern on the first surface of the flexible film. And the second reinforcing plate are bonded to each other through the organic layer, and then the flexible film is peeled off from the first reinforcing plate, and then a circuit pattern is formed on the second surface of the flexible film. The method of peeling a flexible film from a 2nd reinforcement board is mentioned, High-precision circuit pattern processing can be implement | achieved on both surfaces.

  An example of the method for producing a circuit board of the present invention will be described below, but the present invention is not limited to this.

  A silane coupling agent is applied to soda lime glass (hereinafter referred to as a glass reinforcing plate) having a thickness of 1.1 mm using a spin coater, a blade coater, a roll coater, a bar coater, a die coater, a screen printing machine or the like. In order to uniformly apply a thin film of a silane coupling agent having a relatively low viscosity to the sheet reinforcing plate sent intermittently, it is preferable to use a spin coater. After application of the silane coupling agent, drying is performed by heat drying or vacuum drying to obtain a silane coupling agent layer having a thickness of 20 nm.

  Next, an ultraviolet curable re-peeling adhesive is applied on the silane coupling agent layer with a spin coater, blade coater, roll coater, bar coater, die coater, screen printer or the like. In order to uniformly apply an adhesive having a relatively high viscosity to the sheet reinforcing plate sent intermittently, it is preferable to use a die coater. After applying the ultraviolet curable re-peeling adhesive, it is dried by heat drying or vacuum drying to obtain an ultraviolet curable organic layer having a thickness of 2 μm. An air-blocking film in which a silicone resin layer is provided on a polyester film is attached to the ultraviolet curable organic material layer and allowed to stand for about one week. Instead of laminating the air blocking film, it can be stored in a nitrogen atmosphere or in a vacuum. It is also possible to apply an ultraviolet curable organic material layer to a long film substrate, dry it, and then transfer it to a sheet reinforcing plate.

  In the present invention, the ultraviolet curable organic material layer may be initially formed on the flexible film side, may be formed on the reinforcing plate side, or may be formed on both. In order to control the ease of formation and the peeling interface to be a flexible film and an ultraviolet curable organic material layer, it is preferably formed on the reinforcing plate side.

Next, the air blocking film is peeled off, and a polyimide film having a sputtered film formed on both sides or one side is attached. The polyimide film is preliminarily heat-treated at 100 to 200 ° C. for 1 hour. Next, the polyimide film is conditioned at 20 ° C. or higher and 100 ° C. or lower, 0% RH or higher and 100% RH or lower for 1 minute to 24 hours, and 20 ° C. or higher and 100 ° C. or lower, 0% RH or higher and 100% RH or lower. A polyimide film is bonded to the substrate. At this time, the linear expansion coefficient A of the flexible film when bonded to the reinforcing plate is 14 ppm / ° C., the humidity expansion coefficient B of the flexible film is 15 ppm /% RH, and the flexible film is bonded to the reinforcing plate. The storage temperature before bonding the flexible film to the reinforcing plate is H, the storage temperature T ₁ of the flexible film with a circuit pattern after joining the electronic components is 25 ° C., the same storage humidity H ₁ was 45% RH. It is important to satisfy the relationship of A × (T−T ₁ ) + B × (H−H ₁ ) <0.

  As described above, a metal layer may be formed in advance on one side or both sides of the polyimide film. It is preferable to provide a metal layer on the side of the polyimide film on which the reinforcing plate is attached because it can be used as a ground layer for shielding electromagnetic waves. The polyimide film may be pasted in a cut sheet of a predetermined size, or may be pasted and cut while being unwound from a long roll. For such a pasting operation, a laminator shown in FIG. 2 is preferably used.

  FIG. 2 is a schematic front view of a laminating apparatus preferably used in the present invention.

  The flexible sheet 5 is charged by the electrostatic charging device 4 to adsorb the polyimide film 6. A flexible fabric or thin film can be used for the flexible planar body 5 and is fixed to the frame body 7. Further, the electrostatic charging device 4 is supported by a support column 9 on the base 8, and the support column 9 is electrostatically charged with the frame body 7 and the mounting table 10 which move to the left and right in FIG. The device 4 moves so as not to interfere. Next, the glass reinforcing plate 12 coated with the organic material layer 11 is held on the mounting table 10 by vacuum suction or the like. The mounting table 10 may have a heating / cooling function. The polyimide film 6 is pressed against the peelable organic layer 11 together with the flexible planar body 5 with a squeegee 13, and the polyimide film 6 is transferred to the glass reinforcing plate 12 side. The squeegee 13 is held by a squeegee holder 14 and can move and move up and down. The mounting table 10 can be moved to the left and right in the figure by a rail 15, a guide 16, a nut 17, a bracket 18, a ball screw 20, and a motor 21.

  A photoresist is applied onto a sputtered film provided in advance on the surface opposite to the bonding surface by sputtering using a spin coater, blade coater, roll coater, die coater, screen printer, or the like, and dried. The photoresist is exposed and developed through a photomask having a predetermined pattern to form a resist layer in a portion where the plating film is unnecessary. Next, electrolytic plating is performed using the base layer 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, the photoresist is peeled off, and then the underlying layer is removed by a light etching, and further, gold, nickel, tin, etc. are plated if necessary, and a circuit pattern Get.

  After peeling off the air-blocking film on the glass reinforcing plate and attaching the polyimide film to the glass reinforcing plate with the surface on which the circuit pattern is formed as the bonding surface, the above-mentioned semi-additive method, full-additive method, or A high-definition circuit pattern is formed on the surface opposite to the bonding surface by the subtractive method.

  The subtractive method is a method in which a circuit pattern is formed using a photoresist and an etching solution when a solid metal layer is formed on a polyimide film, and the manufacturing process is short and the cost is low. . In particular, in order to obtain a high-definition circuit pattern, it is preferable to employ a semi-additive method or a full additive method.

  Furthermore, connection holes can be provided in the polyimide film. That is, it is possible to provide a via hole for electrically connecting to a metal layer provided on the bonding surface side with the glass reinforcing plate, or to provide a ball mounting hole for the ball grid array. As a method for providing the connection hole, laser drilling such as a carbon dioxide laser, YAG laser, or excimer laser, or chemical etching can be employed. In the case of employing laser etching, it is preferable that a metal layer is present on the side of the polyimide film on which the glass reinforcing plate is attached as an etching stopper layer.

  As the chemical etching solution for the polyimide film, hydrazine, potassium hydroxide aqueous solution, or the like can be used. Further, a patterned photoresist or a metal layer can be employed as the chemical etching mask. In the case of electrical connection, it is preferable that after the connection hole is formed, the inner surface of the hole is made into a conductor by plating at the same time as the formation of the metal layer pattern. In this case, the connection hole preferably has a diameter of 15 μm to 200 μm. The hole for installing the ball preferably has a diameter of 80 μm to 800 μm.

  Although the timing which forms a connection hole is not limited, It is preferable to form a connection hole from the surface opposite to the bonding surface of a polyimide film, after bonding a polyimide film to a glass reinforcement board.

  If necessary, a solder resist film is formed on the circuit pattern. A photosensitive solder resist is applied onto the circuit pattern with a spin coater, blade coater, roll coater, bar coater, die coater, screen printing machine or the like and dried. Next, curing is performed at 100 ° C. to 200 ° C.

  Next, the polyimide film on which the circuit pattern is formed is peeled from the glass reinforcing plate. It is preferable to use a laser, a high-pressure water jet, a cutter, or the like to cut the polyimide film with a circuit pattern into individual pieces or an assembly of individual pieces before peeling because the handling becomes easy. Furthermore, in order to maintain the positional accuracy of the connection with the electronic component, it is more preferable to peel the polyimide film from the glass reinforcing plate after connecting the electronic component to the circuit pattern on the polyimide film. As a connection method with an electronic component, for example, solder connection, connection using an anisotropic conductive film, connection using a metal eutectic, connection using a non-conductive adhesive, wire bonding connection, or the like can be employed.

  When forming a high-definition circuit pattern on both surfaces of a flexible film, it is preferable that it is bonded to the glass reinforcing plate also in the processing of the surface on which the circuit pattern is first formed. In this case, the flexible film is bonded to the glass reinforcing plate, and a circuit pattern is formed on the surface opposite to the glass reinforcing plate bonding surface by the subtractive method, semi-additive method or full additive method, After bonding the circuit forming side of the flexible film to the glass reinforcing plate, peel off the first glass reinforcing plate, and use the subtractive method, semi-additive method or full additive method on the other side. A method of forming a glass reinforcing plate and then peeling the glass reinforcing plate is preferably used.

  The circuit board obtained by the manufacturing method of the present invention is subjected to an electronic component connection and a flexible film peeling process to be used as an electronic device wiring board, an IC package interposer, a wafer level prober, a wafer level burn-in socket board, and the like. Preferably used. It is preferable to use a resistor element or a capacitor element in the circuit pattern as appropriate.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. Moreover, the peeling force, the linear expansion coefficient, the humidity expansion coefficient, the thermal contraction rate, the warpage amount, and the resistance change rate were measured by the following methods.

<Peeling force measurement method>
The peeling force of the flexible film (polyimide film in the examples) peeled from the reinforcing plate was measured by the following method. After bonding a flexible film on the re-release agent layer formed on the reinforcing plate, the flexible film was cut to a width of 10 mm. The force when peeling a flexible film having a width of 10 mm in the 180 ° direction at a peeling speed of 300 mm / min using “Tensilon” manufactured by TMI was defined as the peeling force.

<Measuring method of linear expansion coefficient>
The distance between two diagonal points of a flexible film (polyimide film in the examples) cut to 50 mm square (hereinafter referred to as diagonal distance) was measured in a temperature and humidity environment of 23 ° C. and 55% RH. It was measured with a long machine SMIC-800 (manufactured by Sokkia Co., Ltd.). At this time, the temperature of the flexible film was also 23 ° C. By using the heat stage of the bonding machine FC2000 (manufactured by Toray Engineering Co., Ltd.) and the alignment displacement distance confirmation function by the CCD camera, the diagonal distance of the flexible film in a temperature and humidity environment of 23 ° C. and 55% RH The displacement of the diagonal distance of the flexible film was measured at a stage temperature of 30 ° C., 50 ° C., 70 ° C., 100 ° C., 120 ° C., 150 ° C., and 180 ° C. in a 55% RH humidity environment. An average value of the obtained linear expansion coefficients was obtained and used as a linear expansion coefficient. At this time, the stage temperature and the temperature of the flexible film are the same.

<Measurement method of humidity expansion coefficient>
The diagonal distance of a flexible film (polyimide film in the examples) cut to 200 mm square is 20% RH, 30% RH, 40% RH, 50% RH, 60% RH, 70% in a 23 ° C. temperature environment. Measurement was performed with a length measuring machine SMIC-800 (manufactured by Sokkia Co., Ltd.) under an RH and 80% RH humidity environment, and the average value of the linear expansion coefficient obtained at each humidity was determined, which was defined as the humidity expansion coefficient.

<Measurement method of thermal shrinkage>
The polyimide film on which the circuit pattern is formed is peeled off from the glass, and the total pitch of the wires separated by about 19 mm on the long side of the inner lead is measured under a temperature and humidity environment of 25 ° C. and 60% RH. Measured by Co., Ltd.). At this time, the temperature of the polyimide film was also 25 ° C.

  Next, the IC from which the bumps were removed was bonded to a polyimide film on which a circuit pattern was formed with a bonding machine FC2000 (manufactured by Toray Engineering Co., Ltd.) under the conditions of a tool temperature of 450 ° C. and a bonding time of 1 second. At this time, the wiring and the IC were not bonded, and the polyimide film and the IC were not bonded.

  The polyimide film with the bump-removed IC grounded is measured with a length measuring machine SMIC-800 (manufactured by SOKIA CORPORATION) under a temperature and humidity environment of 25 ° C. and 60% RH, with a total pitch of the wires about 19 mm away from the long side of the inner lead. ). At this time, the temperature of the polyimide film was also 25 ° C.

  The thermal contraction rate was obtained from the total pitch change amount of the wiring before and after the IC was grounded.

<Measurement method of warpage>
The distance between one corner of the polyimide film peeled off from the glass reinforcing plate and the stage of the laser microscope was measured with a laser microscope VK-9500 (Keyence Co., Ltd.), and the average value was taken as the amount of warpage of the polyimide film. A warp amount of ± 1 mm or less was considered good, assuming that the warp of polyimide on the surface side on which the circuit pattern was formed was positive, and the warp of polyimide on the side opposite to the surface on which the circuit pattern was formed was negative. .

<Measurement method of resistance change rate>
IC is bonded to the polyimide film on which the circuit pattern is formed, the circuit pattern and the polyimide film with the IC are peeled off from the glass reinforcing plate, and the film is put into a small thermal shock device TSE-11 (manufactured by Espec Corp.) at a temperature of −55 ° C. One cycle was 15 minutes under the environment and 15 minutes under the temperature environment of 125 ° C., and the resistance change rate before and after the thermal cycle test was determined. The rate of change in resistance was determined as follows.

  A chain circuit pattern 1 formed on the polyimide film shown in FIG. 1 and a chain circuit pattern 3 in the IC are joined by bumps 2 on the IC using a digital multimeter CDM-17D (Custom Co., Ltd.). The resistance value of the chain circuit before and after the thermal cycle was measured, and the resistance change rate before and after the thermal cycle was obtained. The rate of change in resistance was considered to be ± 10% or less.

Example 1
Sputtering was performed on one side of a long polyimide film ("Kapton 150EN" manufactured by Toray DuPont Co., Ltd., linear expansion coefficient A of 14 ppm / ° C, and humidity expansion coefficient B of 15 ppm /% RH) with a thickness of 38 µm and a width of 400 mm. A 10 nm Ni ₈₀ Cr ₂₀ layer and a 100 nm copper layer were laminated in this order to prepare 15 samples of a polyimide film with a sputtered film.

  To a soda-lime glass with a thickness of 1.1 mm and 400 mm square, with a die coater, as an organic material layer, an ultraviolet curing acrylic adhesive “SK Dyne” SW-22 (manufactured by Soken Chemical Co., Ltd.) and a curing agent L45 (Soken) A 50: 1 mixture of Chemical Co., Ltd. was applied to a glass reinforcing plate and dried at 80 ° C. for 2 minutes. The organic layer thickness after drying was set to 2 μm. Next, an air blocking film composed of a film in which a silicone resin layer that is easy to release is provided on a polyester film is attached to the organic layer (soda lime glass glass / organic substance layer / silicone resin layer / polyester film configuration) ) Leave at room temperature for 1 week.

Next, with the laminator shown in FIG. 2 on the side where the organic layer of the glass reinforcing plate is formed, the polyimide film with a sputtered film previously stored at 30 ° C. and 50% RH for 24 hours while peeling off the air blocking film. The temperature of the polyimide film was adjusted to 30 ° C., and the film was attached in a humidity environment of 50% RH. Thereafter, ultraviolet rays were irradiated from the glass substrate side at 5000 mJ / cm ² to cure the organic layer.

  Next, a positive photoresist was applied onto the copper layer with a spin coater and dried at 80 ° C. for 10 minutes. Next, after exposing the photoresist through a photomask, the photoresist was developed to form a resist layer having a thickness of 15 μm in a portion where a plating film was unnecessary. The test photomask pattern was a chain circuit pattern having an outer dimension of 30 mm × 40 mm with a line width of 10 μm and a pitch of 25 μm. After development, it was post-baked at 120 ° 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 with a thickness of 8 μm, the photoresist is stripped with a photoresist stripping solution, and then the copper layer and the nickel-chromium alloy film under the resist layer are removed by soft etching with an iron chloride aqueous solution. Thus, a chain circuit pattern as shown in FIG. 1 was obtained. The chain circuit pattern is formed by joining the chain circuit pattern 1 formed on the flexible film of FIG. 1 and the chain circuit pattern 3 in the IC such as an IC with bumps 2 on the IC.

  As a solder resist layer, SN9000 (manufactured by Hitachi Chemical Co., Ltd.) is used as a test pattern in a 30 mm × 20 mm area excluding the inner leads from the center of each pattern on the polyimide film on which the chain circuit pattern is formed. It was applied by screen printing and dried at 90 ° C. for 10 minutes. Next, it was cured by curing at 150 ° C. for 30 minutes.

  The polyimide used was measured when the total pitch of the long lead of the inner lead about 19 mm away was measured with a length measuring machine SMIC-800 (manufactured by Sokkia Co., Ltd.) in a temperature and humidity environment of 25 ° C. and 60% RH. The film 15 samples had ± 20 ppm relative to the photomask pattern.

When the peeling force of the polyimide film from the glass reinforcing plate was measured for 5 samples out of 15 polyimide films on which the chain circuit pattern was formed, a numerical value in the range of 1.96 to 2 N / m was obtained. . During the formation of the circuit pattern, the polyimide film did not peel from the organic layer. Next, the polyimide film was gradually peeled from the glass reinforcing plate from the end of 5 samples out of 15 samples of the polyimide film on which the chain circuit pattern was formed. The polyimide film was peeled off at the interface with the organic layer and visually confirmed, and curling to such an extent that the end of the polyimide film touched the other part of the same film was not expressed. Further, the amount of warpage of the polyimide film was −1 mm or less. The thermal shrinkage rate of the polyimide film on which the pattern for the chain circuit peeled from the glass reinforcing plate was formed was 200 ± 100 ppm.

  Among the 15 samples of polyimide film on which the pattern for the chain circuit is formed, 5 samples that are not peeled off from the glass reinforcing plate are attached to the bonding machine FC2000 (manufactured by Toray Engineering Co., Ltd.) while being attached to the glass reinforcing plate. Then, an IC having a bump size of 90 μm × 13 μm and 1298 bumps was bonded. The ambient temperature at which the IC was bonded was 25 ° C. and the ambient humidity was 60% RH. At this time, the surface temperature of the polyimide film was 25 ° C.

  Next, 5 samples of the polyimide film bonded with the IC were peeled off from the glass reinforcing plate, and the small thermal shock apparatus TSE-11 (manufactured by Espec Co., Ltd.) was used for 15 minutes in the -55 ° C temperature environment and in the 125 ° C temperature environment. A thermal cycle test with one cycle of 15 minutes was performed 300 cycles. The resistance change rate of the chain circuit was within ± 10%.

In Example 1, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, and the temperature T when the polyimide film is bonded to the glass substrate is 20 ° C. The storage humidity H before bonding the polyimide film is 30% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 27 ° C., the storage humidity H ₁ is 60% RH, and A × (T−T _{1) + B × (H-} H 1) is, 14 × (30-25) + 15 × (50-60) = - 80.

Example 2
A pattern for a chain circuit was obtained on the polyimide film in the same manner as in Example 1 except that the condition for attaching the polyimide film to the glass substrate was changed from 30 ° C. to 25 ° C. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was −1 mm or less.

  The thermal shrinkage rate of the polyimide film on which the chain circuit pattern peeled from the glass reinforcing plate was formed was 200 ± 100 ppm.

  The IC was bonded in the same manner as in Example 1 to 5 samples of polyimide film that was not peeled off the glass reinforcing plate among 10 samples of polyimide film on which the chain circuit pattern was formed. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. After peeling from the glass reinforcing plate, a thermal cycle test was conducted in the same manner as in Example 1. The resistance change rate of the chain circuit was within ± 10%.

In Example 2, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, the temperature T when the polyimide film is bonded to the glass substrate is 25 ° C., and the glass plate The storage humidity H before bonding the polyimide film is 50% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T−T ₁ ) + B × (H−H ₁ ) is 14 × (25−25) + 15 × (50−60) = − 150.

Example 3
The same conditions as in Example 1 except that the condition for preserving the polyimide film on the glass substrate was changed from 50% RH to 52% RH, and the condition for attaching the glass film to the glass substrate was changed from 30 ° C to 20 ° C. The pattern for chain circuits was obtained on the polyimide film by the method. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was −1 mm or less.

  The thermal shrinkage rate of the polyimide film on which the chain circuit pattern peeled from the glass reinforcing plate was formed was 200 ± 100 ppm.

  The IC was bonded in the same manner as in Example 1 to 5 samples of polyimide film that was not peeled off the glass reinforcing plate among 10 samples of polyimide film on which the chain circuit pattern was formed. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. The sample was peeled from the glass reinforcing plate and subjected to a thermal cycle test in the same manner as in Example 1. The resistance change rate of the chain circuit was within ± 10%.

In Example 3, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, and the temperature T when the polyimide film is bonded to the glass substrate is 20 ° C. The storage humidity H before bonding the polyimide film to the film is 52% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T− _{T 1) + B × (H} -H 1) is, 14 × (20-25) + 15 × (52-60) = - is 190.

Example 4
A pattern for a chain circuit was obtained on the polyimide film in the same manner as in Example 1 except that the condition for attaching the polyimide film to the glass reinforcing plate was changed from 30 ° C. to 35 ° C. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was −1 mm or less.

  The thermal shrinkage rate of the polyimide film on which the chain circuit pattern peeled from the glass reinforcing plate was formed was 200 ± 100 ppm.

  The IC was bonded in the same manner as in Example 1 to 5 samples of polyimide film that was not peeled off the glass reinforcing plate among 10 samples of polyimide film on which the chain circuit pattern was formed. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. The sample was peeled from the glass reinforcing plate and subjected to a thermal cycle test in the same manner as in Example 1. The resistance change rate of the chain circuit was within ± 10%.

In Example 4, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, and the temperature T when the polyimide film is bonded to the glass substrate is 35 ° C. The storage humidity H before bonding the polyimide film to the film is 50% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T− _{T 1) + B × (H} -H 1) is, 14 × (35-25) + 15 × (50-60) = - 10.

Example 5
Example 1 with the exception that the conditions for preserving the polyimide film before being bonded to the glass reinforcing plate were changed from 50% RH to 52% RH, and the conditions for applying the glass film to the glass reinforcing plate were changed from 30 ° C. to 20 ° C. A chain circuit pattern was obtained on the polyimide film in the same manner. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was −1 mm or less.

  The thermal shrinkage rate of the polyimide film on which the chain circuit pattern peeled from the glass reinforcing plate was formed was 200 ± 100 ppm.

  Of the 10 samples of polyimide film on which the pattern for the chain circuit was formed, 5 samples of polyimide film that had not been peeled off from the glass reinforcing plate were peeled off from the glass reinforcing plate, and an IC was bonded in the same manner as in Example 1. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. At this time, the stage temperature of the bonding machine was 80 ° C., and all the wirings were bonded to the IC bumps. Of the 5 polyimide film samples with IC, 2 samples were filled with underfill material “Chip Coat” 8462-21 (manufactured by NAMICS Co., Ltd.), temporarily cured at 150 ° C. for 20 minutes, and observed with an optical microscope. The gap between the polyimide films was filled with an underfill material. Of the 5 samples of polyimide film with IC, 3 samples in which the underfill material was not encapsulated were peeled from the glass reinforcing plate and subjected to a thermal cycle test in the same manner as in Example 1. The resistance change rate of the chain circuit was within ± 10%.

In Example 4, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, and the temperature T when the polyimide film is bonded to the glass substrate is 20 ° C. The storage humidity H before bonding the polyimide film to the film is 52% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T− _{T 1) + B × (H} -H 1) is, 14 × (20-25) + 15 × (52-60) = - is 190.

Comparative Example 1
Same as Example 1 except that the condition for preserving the polyimide film on the glass reinforcing plate is changed from 50% RH to 65% RH, and the condition for attaching the glass film to the glass substrate is changed from 30 ° C. to 60 ° C. Thus, a chain circuit pattern was obtained on a polyimide film. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was 1 mm or less.

  The IC was bonded in the same manner as in Example 1 to 5 samples of polyimide film that was not peeled off the glass reinforcing plate among 10 samples of polyimide film on which the chain circuit pattern was formed. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. After peeling from the glass reinforcing plate, a thermal cycle test was conducted in the same manner as in Example 1. The resistance change rate of the chain circuit of 3 out of 5 samples was as large as 20% to 60% due to the crack of the wiring or the deterioration of the connection between the wiring and the IC.

In Comparative Example 1, the linear expansion coefficient A of the polyimide film is 14 ppm / ° C., the same humidity expansion coefficient B is 15 ppm /% RH, and the temperature T when the polyimide film is bonded to the glass substrate is 60 ° C. The storage humidity H before bonding the polyimide film to the film is 65% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T− _{T 1) + B × (H} -H 1) is, 14 × (60-25) + 15 × (65-60) = 565 there.

Comparative Example 2
Same as Example 1 except that the condition for preserving the polyimide film on the glass reinforcing plate is changed from 50% RH to 65% RH, and the condition for attaching the glass film to the glass substrate is changed from 30 ° C. to 60 ° C. Thus, a chain circuit pattern was obtained on a polyimide film. A solder resist layer was formed by the same method as in Example 1, and then 5 samples out of 10 polyimide films on which the chain circuit pattern was formed were gradually peeled off from the glass reinforcing plate from the ends. The warp amount of the polyimide film was 1 mm or less.

  Of the 10 samples of polyimide film on which the pattern for the chain circuit was formed, 5 samples of polyimide film that had not been peeled off from the glass reinforcing plate were peeled off from the glass reinforcing plate, and an IC was bonded in the same manner as in Example 1. At this time, environmental temperature was 25 degreeC and environmental humidity was 60% RH, and the surface temperature of the polyimide film at this time was 25 degreeC. At this time, the stage temperature of the bonding machine was 130 ° C., and all the wirings were bonded to the IC bumps. Of the 5 polyimide film samples with IC, 2 samples were filled with underfill material “Chip Coat” 8462-21 (manufactured by NAMICS Co., Ltd.), temporarily cured at 150 ° C. for 20 minutes, and observed with an optical microscope. The polyimide film was stuck and the gap was not sufficiently filled with the underfill material. Of the 5 samples of polyimide film with IC, 3 samples in which the underfill material was not encapsulated were peeled from the glass reinforcing plate and subjected to a thermal cycle test in the same manner as in Example 1. The resistance change rate of the chain circuit of 3 out of 5 samples was as large as 20% to 60% due to the crack of the wiring or the deterioration of the connection between the wiring and the IC.

In Comparative Example 2, the linear expansion coefficient A of the polyimide film was 14 ppm / ° C., the same humidity expansion coefficient B was 15 ppm /% RH, the temperature T when the polyimide film was bonded to the glass substrate was 60 ° C., and the glass plate The storage humidity H before bonding the polyimide film to the film is 65% RH, the storage temperature T ₁ of the polyimide film after bonding the IC is 25 ° C., the storage humidity H ₁ is 60% RH, and A × (T− _{T 1) + B × (H} -H 1) is, 14 × (60-25) + 15 × (65-60) = a 565.

FIG. 2 is a schematic diagram of a chain circuit on a flexible film and in an IC. It is a schematic front view of the laminating apparatus preferably used for this invention.

Explanation of symbols

1: Pattern for chain circuit formed on flexible film 2: Bump on IC 3: Pattern for chain circuit in IC 4: Electrostatic charging device 5: Flexible surface state 6: Plastic film 7: Frame 8 : Base 9: Post 10: Mounting table 11: Organic layer 12: Reinforcement plate 13: Squeegee 14: Squeegee holder 15: Rail 16: Guide 17: Nut 18: Bracket 20: Ball screw 21: Motor

Claims (3)

Bonding to the reinforcing plate on at least one surface of the flexible film via the organic layer, and then forming a circuit pattern on the surface opposite to the bonding surface of the flexible film, the circuit pattern and the electrode of the electronic component A method for manufacturing a circuit board for bonding a flexible film, wherein the flexible film has a linear expansion coefficient of Appm / ° C. when the flexible film is bonded to the reinforcing plate, and the flexible film is bonded to the reinforcing plate. The humidity expansion coefficient of the flexible film is Bppm /% RH, the temperature of the flexible film when the flexible film is bonded to the reinforcing plate is T ° C., and the flexible plate is flexible. Save humidity of the flexible film before laminating the film to a H% RH, a circuit pattern with a flexible film storage temperature after bonding the electronic component and T ₁ ° C., and joining the electronic part Taha A circuit pattern with a flexible film Storage humidity When H _1% RH in,
_{A × (T-T 1)} + B × (H-H 1) <0
A circuit board manufacturing method characterized by satisfying the relationship: The method for manufacturing a circuit board according to claim 1, wherein the flexible film is a polyimide film. A circuit board obtained by the manufacturing method according to claim 1.

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