JP2001168147A - Method for manufacturing film carrier tape for mounting electronic components - Google Patents

Abstract

(57) Abstract: A method of manufacturing a film carrier tape for mounting electronic components according to the present invention is characterized in that at least a lead portion of a wiring pattern formed on a flexible insulating film is preferably Sn.
After performing press plating for a short time using an electroless tin plating bath having a ²⁺ concentration of 13 to 50 g / liter, at least a lead portion on which the pre-plating has been applied has an Sn ²⁺ concentration of 1%.
The tin plating is performed at least once using an electroless tin plating bath in the range of 3 to 50 g / liter. Further, a press plating layer may be formed before forming the solder resist layer. According to the present invention, by adjusting the concentration of Sn ²⁺ contained in the electroless tin plating bath, it is possible to suppress and prevent the occurrence of lead clogging caused by the infiltration of the plating solution below the solder resist layer. The depth of the formed lead can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film carrier tape for mounting electronic parts (for example, TAB (Tape Automat).
ed Bonding) tape, T-BGA (Tape Ball Grid Arra)
y) Tape, ASIC (Application Specific Integrate)
d Circuit) tape).

[0002]

2. Description of the Related Art With the development of the electronics industry,
The demand for printed wiring boards on which electronic components such as C (integrated circuits) and LSIs (large-scale integrated circuits) are mounted has been rapidly increasing, but there has been a demand for smaller, lighter, and more sophisticated electronic devices. As a method for mounting these electronic components, a mounting method using a film carrier tape for mounting electronic components has recently been adopted. In particular, high definition and thinness, such as a personal computer, and a reduction in a frame area of a liquid crystal screen have been adopted. Is increasingly important in the electronics industry using liquid crystal display elements (LCDs).

Conventionally, such a film carrier tape for mounting electronic parts has been manufactured through the following steps, for example. That is, first, after a flexible insulating film serving as a base material such as a polyimide film is punched by a press machine, a conductor foil such as a copper foil is laminated on the flexible insulating film. Then, a photoresist is applied to the upper surface of the conductive foil, and the photoresist is exposed to ultraviolet rays in a desired pattern using the photoresist, and the exposed photoresist portions are dissolved and removed by a developer. The conductive foil portion not covered with the photoresist is removed by chemically dissolving (etching) with an acid or the like, and then the photoresist is dissolved and removed with an alkali solution to remove the conductive material remaining on the insulating film. A desired wiring pattern is formed from the foil.

[0004] In order to prevent short-circuiting due to adhesion of dust, whiskers and migration during mounting, and to protect and insulate between wirings, one of the wiring patterns I
Except for lead parts such as inner leads and outer leads connected to devices (electronic parts) such as C and output outer leads connected to liquid crystal display elements, etc.
A solder resist, which is an insulating resin, is applied using a screen printing method, and then cured to form a solder resist layer.

Thereafter, in order to prevent oxidation and discoloration of the exposed lead portion and to secure bonding strength (bondability) with a connection portion such as a bump electrode of a device connected to the lead portion, the lead portion is formed. , Plating. Various metals are used in this plating process.Because the bump electrodes of the device are made of gold, electroless tin plating is relatively easy to connect by forming a gold-tin eutectic. Widely used.

[0006] Such electroless tin plating is performed by forming a solder resist layer and then immersing it in a tin plating bath to form a tin plating layer on the surface of the wiring pattern not covered by the solder resist layer. I have. In a normal case, the solder resist layer becomes a masking material for tin plating, and the wiring pattern at the portion where the solder resist layer is applied should not come into contact with the plating solution.

However, in reality, the solder resist layer has a portion at its edge where the adhesion with the wiring pattern or the flexible insulating film is incomplete,
From such a portion, the plating solution may enter the lower part of the solder resist. Then, in the portion where the plating solution has penetrated into the lower portion of the solder resist, a local battery is formed between the metal copper of the wiring pattern and the already deposited metal tin, and abnormal elution of the metal copper of the wiring pattern occurs. Such abnormal elution of the wiring pattern under the solder resist is usually called “egure”.

Conventionally, since the thickness of the conductive foil forming the wiring pattern is as large as several tens of μm, even if such scuffing occurs, there is little occurrence of a serious problem such as a decrease in lead strength or disconnection. However, under the recent demand for fine pitch in which the width of the lead is 25 μm or less and the thickness of the conductor foil is 18 μm or less in order to form such a fine wire lead, the depth is more than The scorched portion, which may be as large as μm, not only greatly affects the strength of the lead, but also may lead to disconnection of the lead due to the formation of such a scoured portion.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a film carrier tape for mounting electronic parts, in which a curled portion is hardly formed in a wiring pattern below a solder resist as described above. Further, the present invention provides a method for manufacturing a film carrier tape for mounting electronic components, in which a curving portion is not easily formed in a wiring pattern below a solder resist as described above, and a blister or peeling of a formed plating layer is hard to occur. It is intended to be.

[0010]

SUMMARY OF THE INVENTION According to a method of manufacturing a film carrier tape for mounting electronic parts of the present invention, at least a lead portion of a wiring pattern formed on a flexible insulating film has a Sn ²⁺ concentration of 13 to 50 g / liter. After a short press plating using an electrolytic tin plating bath, the Sn ²⁺ concentration is 13 to 5 at least in the pre-plated lead portion.
The present tin plating is performed at least once using an electroless tin plating bath within a range of 0 g / liter.

Further, according to the method of manufacturing a film carrier tape for mounting electronic parts of the present invention, the lead portion of the wiring pattern formed on the flexible insulating film has a Sn ²⁺ concentration of 13 ^%.
It is characterized in that the present tin plating is performed at least once using an electroless tin plating bath in the range of ５０50 g / liter. In the method of the present invention, it is preferable that a surface to be tin-plated is soft-etched before the press plating or the tin plating is performed.

Further, in the method of the present invention, the step of forming the electroless tin plating layer can be performed separately by press plating and tin plating. In this case, the thickness of the press plating layer is determined by the thickness of the tin plating. It is preferable that the thickness be smaller than the thickness. The film carrier tape for mounting electronic components production method of the present invention has been tinned by controlling the Sn ²⁺ concentration in a predetermined range in the plating bath to conduct electroless tin plating, the thus Sn ²⁺ concentration By controlling, generation of the screeching can be suppressed. Further, by forming the press plating layer before the formation of the tin plating layer, even in the case where an undercut portion is formed, the depth can be suppressed to the minimum.

[0013]

Next, a method for manufacturing a film carrier tape for mounting electronic parts according to the present invention will be described in detail. In the method for manufacturing a film carrier tape for mounting electronic components of the present invention, a conductive foil is laminated on a flexible insulating film, a photoresist is applied to the upper surface of the conductive foil, and the photoresist is coated with a desired photoresist. Exposure is performed so that a wiring pattern is formed, the excess photoresist is removed, and the conductive foil is etched using the remaining photoresist as a masking material to form a desired wiring pattern. Next, a solder resist, which is an insulating resin, is applied and hardened after leaving a lead portion for bonding a device or the like. Then, a wiring pattern portion on which the solder resist is not applied (that is, a lead portion) is tin-plated. Have been.

The flexible insulating film used in the method of the present invention is a flexible insulating resin film. In addition, this flexible insulating film has chemical resistance not to be attacked by such a chemical because it comes into contact with an acid or the like at the time of etching, and heat resistance that does not deteriorate even by heating when bonding the device. I have.
Examples of such a flexible insulating film as a material include:
Examples include polyester, polyamide, and polyimide. Particularly, in the present invention, it is preferable to use a film made of polyimide.

Examples of the polyimide film constituting the flexible insulating film include wholly aromatic polyimide synthesized from pyromellitic dianhydride and aromatic diamine, biphenyltetracarboxylic dianhydride and aromatic diamine. And a wholly aromatic polyimide having a biphenyl skeleton. Particularly, in the present invention, a wholly aromatic polyimide having a biphenyl skeleton (eg, trade name: Upilex, manufactured by Ube Industries, Ltd.) is preferably used.
The thickness of such a flexible insulating film is usually 25
１２５125 μm, preferably 50-75 μm.

When the flexible insulating film used in the present invention has a device hole, a sprocket hole, an outer lead hole, and a bent portion, a flex slit or the like is formed at the bent position by punching. The wiring pattern is formed by etching a metal foil laminated on at least one surface of the flexible insulating film having the predetermined holes as described above.
The metal foil is laminated on at least one surface of the flexible insulating film with or without an adhesive.
Here, when attaching a metal foil using an adhesive, an adhesive layer is formed using an insulating adhesive.

When an adhesive is used, the adhesive used must have properties such as heat resistance, chemical resistance, adhesive strength, and flexibility. Examples of the adhesive having such properties include an epoxy-based adhesive, a polyimide-based adhesive, and a phenol-based adhesive. Such an adhesive may be modified with a urethane resin, a melamine resin, a polyvinyl acetal resin, or the like, or the epoxy resin itself may be modified with a rubber. Such adhesives are usually heat-curable. The thickness of the adhesive layer is usually in the range of 8 to 23 μm, preferably 10 to 21 μm.

In the method of manufacturing a film carrier tape for mounting electronic components according to the present invention, when laminating a metal foil on a flexible insulating film as described above, the metal foil can be laminated without using an adhesive. . Further, apart from the method using a metal foil as described above, a metal layer can be formed by, for example, a vapor deposition method or a plating method, and in such a case, a metal thin layer is formed using a thin metal foil. And a metal layer having a predetermined thickness may be formed by depositing a metal on the thin metal layer by the vapor deposition method or the plating method.

When an adhesive is used, the adhesive layer may be provided by applying an adhesive to the surface of the flexible insulating film, or may be provided by applying an adhesive to the surface of the metal foil. Is also good. The metal foil used in the present invention has conductivity,
Examples of such a metal foil include a copper foil and an aluminum foil. In particular, in the present invention, it is preferable to use a copper foil as the metal foil. Copper foil used as a metal foil in the present invention, there are electrolytic copper foil and rolled copper foil, in the present invention, it is possible to use any copper foil,
When producing a fine pitch film carrier tape for mounting electronic components, it is preferable to use an electrolytic copper foil as the metal foil.

As the electrolytic copper foil used here, an electrolytic copper foil having a thickness usually used in the production of a film carrier tape for mounting electronic components can be used. For producing carrier tape, the average thickness is usually 3 to 150 μm,
Preferably within the range of 6 to 70 μm, particularly preferably 8 to 3 μm.
An electrolytic copper foil having a size of 5 μm, more preferably 8 to 18 μm is used. By using the electrolytic copper foil having such an average thickness, inner leads having a narrow pitch can be easily formed. The surface of such an electrolytic copper foil may be surface-regulated by mechanical polishing, chemical polishing, electrolytic polishing, or a combination thereof.

The above-described flexible insulating film and a metal foil are laminated, and a layer made of a metal (a metal foil layer, and a layer made of the metal is formed on at least one surface of the flexible insulating film). A base film on which a thin metal foil layer is plated or metal-deposited to a predetermined thickness, which may be a metal plating layer, a metal deposition layer, or a composite metal layer thereof may be used. To manufacture.

Then, a photoresist is applied to the surface of the metal layer of the base film, and a predetermined wiring pattern is baked on the photoresist to remove unnecessary portions of the photoresist. Is formed, and the metal layer is etched using this pattern as a masking material. That is, a phytoresist is applied to the surface of the metal layer of the base film, and a predetermined wiring pattern is exposed and baked to form a soluble portion and an insoluble portion in the aqueous medium. By removing the masking material, a masking material made of an insoluble photoresist can be formed on the surface of the metal layer. Here, the masking material made of an insoluble photoresist may be formed of a photoresist that cures by exposure, or, conversely, can be dissolved in a specific solvent such as an aqueous medium by exposure. After exposure using a photoresist, the photoresist may be formed by removing a portion of the photoresist solubilized by a specific solvent.

By contacting the base film masked by the photoresist with the etching solution, the metal of the unmasked portion elutes, and the metal of the masked portion remains on the flexible insulating film. Then, a wiring pattern composed of the metal foil (or metal layer) that has not been eluted is formed on the flexible insulating film. As the etchant used here, a commonly used acidic etchant can be used.

In the wiring pattern thus formed, the pitch width of the inner leads is usually 20 to 50.
0 μm, preferably 25-100 μm.
In particular, it is highly useful for a film carrier tape for mounting electronic components having a fine pitch of 30 to 80 μm. In the present invention, usually, after a predetermined wiring pattern is formed as described above, a solder resist layer is formed except for a tip portion of an inner lead and a tip portion of an outer lead to be plated in the next step.

In the present invention, such a solder resist layer is formed by applying a solder resist coating solution to a predetermined position using a screen printing technique.
In the method of the present invention, the coating average thickness of the solder resist is usually in the range of 1 to 80 μm, preferably 5 to 50 μm in terms of the thickness after curing. The curable resin contained in such a solder resist coating liquid is an epoxy resin, an elastomer-modified epoxy resin, a urethane resin, an elastomer-modified urethane resin, a polyimide resin, an elastomer-modified polyimide resin, and an acrylic resin. It is preferable that the resin contains at least one resin component selected from the group consisting of resins. In particular, it is preferable to use a modified elastomer.

In the present invention, in addition to the resin components described above, the solder resist coating solution usually contains a curing accelerator, a filler, an additive, a thixotropic agent, a solvent and the like. Can be added. Further, in order to improve the properties such as flexibility of the solder resist layer, fine particles having elasticity such as rubber fine particles can be blended.

When the solder resist is applied and hardened in this manner, the solder resist coating solution may flow outward from the application position at the edge of the applied solder resist, and the edge of the applied solder resist layer may In some cases, the adhesion to the wiring pattern is not good. Then, as shown in FIG. 1, the plating solution may penetrate into the lower portion of the solder resist from the edge of the solder resist. A local battery is formed between the already deposited metallic tins, and abnormal elution of metallic copper in the wiring pattern occurs, so-called “screebling portions” are formed. When the depth of such an undercut generally exceeds 5.5 μm, the presence of the undercut is specifically expressed as a decrease in lead strength in a recent fine pitch electronic component mounting film carrier tape. May not endure normal use.

The inventors of the present invention have studied a method for suppressing the formation of such a scoring portion, and have found that the depth of the scouring portion varies significantly depending on the concentration of Sn ^{2+ in} the plating solution. In the present invention, the tin plating includes press plating and the present tin plating. In the present invention, after performing the press plating, the present tin plating is performed.
Any method of directly performing tin plating without performing press plating can be employed.

In the present invention, when tin plating is performed, the Sn ²⁺ concentration in the plating bath is 13 g / liter to 50 g / l.
The tin is plated using an electroless tin plating bath in the range of g / l, preferably 15-30 g / l. In the method for producing a film carrier tape for mounting electronic components of the present invention, the tin plating layer can be formed by various methods.

For example, as a tin plating bath that can be used in the present invention, a plating bath containing the following components can be used. (1) Thiourea (NH ₂ ) ₂ CS tin borofluoride Sn (BF ₄ ) _secondary phosphorous acid H ₃ PO ₄ cationic surfactant (2) Thiourea (NH ₂ ) ₂ CS tin organic sulfonate phosphoric acid H ₃ PO ₄ surfactant and, in such a tin plating bath, Sn ²⁺ concentration is in the range of 13～50G / liter, preferably 1
It is necessary to adjust within the range of 5 to 30 g / liter. Sn ²⁺ in the tin plating bath used in the present invention
By performing the electroless tin plating by adjusting the concentration within the above range, even if the scorched portion is formed, the scorched portion is not so deep as to affect the lead strength, etc. No cause.

In the method of the present invention, the tin plating layer may be a single layer or may be formed from a plurality of layers. That is, before performing the tin plating as described above, the lead portion or the wiring pattern may be press-plated, and then the tin plating may be performed using a tin plating bath having a Sn ²⁺ concentration within the above range. That is, as shown in FIG. 3, after the lead portion is press-plated, the present tin plating can be performed on the press-plated layer, and two or more tin-plated layers may be formed. In such a case, it is preferable that the thickness of the press plating layer be smaller than the thickness of the tin plating layer. After performing the press plating in this manner, by performing the present tin plating, a thin press plating layer is formed on the surface of the wiring pattern below the solder resist, for example, even if there is a peeled portion at the edge of the solder resist. Therefore, even if a plating solution remains in the stripped portion during the tin plating, the conductive foil (electrolytic copper foil) forming the wiring pattern does not elute, and thus the generation of a scoured portion can be suppressed. When two tin plating layers are formed as described above, the ratio of the thickness of the press plating layer to the thickness of the tin plating layer is usually 0.5: 10 to 2: 1.
0, preferably 0.5: 10 to 1: 8, particularly preferably 0.5: 10 to 1:10. By reducing the thickness of the press plating layer in this manner, the effect of suppressing the generation of the scuffed portion is improved.

FIG. 2 shows an example of the relationship between the depth of the recess and the Sn ²⁺ concentration in the plating bath used for press plating when the press plating is combined with the present tin plating. In FIG. 2, “A” indicates that after applying and curing a solder resist coating solution, the Sn ²⁺ concentration in the tin plating bath was changed to form a press plating layer, and then the tin plating conditions were changed to Sn ²⁺ concentration: 20 g. / Liter, temperature 70 ° C., time; 210 seconds, this is a graph showing the relationship between the depth of the scoured portion and the Sn ²⁺ concentration generated when performing the tin plating, where “B” is the same as above. After the solder resist layer is formed as described above, the portion to be plated is soft-etched, and then S
It is a graph which shows the relationship between Sn2 ⁺ density ^| concentration and the depth of the scorched part which generate | occur | produced at the time of carrying out press plating with changing n2 ⁺ density ^| concentration and this tin plating similarly to the above.

As is apparent from FIG. 2, when the Sn ²⁺ concentration in the press plating solution is 7 g / liter or less, a very deep undercut occurs. Then, Sn ²⁺ concentration depth gradually curtailed portion becomes shallow accordance higher, 13 g / l or more, preferably 15 g / l or more of Sn ²⁺
The use of a press plating solution having a high concentration substantially stabilizes the depth of the undercut portion generated at 5.5 μm or less.

As shown in FIG. 5, the amount of scouring is also reduced depending on the press plating time. FIG.
The press plating conditions were changed to Sn in the press plating bath.
²⁺ concentration: 15 g / l, temperature: normal temperature (25 ° C), and press plating time was changed within the range of 10 to 210 seconds, and the tin plating conditions were changed to Sn ²⁺ concentration: 15 g / l, temperature: normal temperature (25 ° C). ), Time: 210 sec, and a graph showing the depth of a scoured portion generated when tin plating is performed. The lead to be plated is not soft-etched.

As is apparent from FIG. 5, if the press plating is not performed, a scoured portion having a depth exceeding 7.25 μm is formed. However, as the press plating time is increased to 10 seconds and 30 seconds, the depth of the scoured portion is increased. The depth gradually becomes shallow, and the pre-plating time is 6.5 μm when the pre-plating time is 30 seconds, which is about 0.75 μm lower than the depth when the pre-plating is not performed.

The press plating time is 40 to 50.
It is estimated that there is a critical point of the press plating time with respect to the scouring depth in the vicinity of second, and particularly when the pre-plating time is 50 seconds or more, preferably 55 seconds or more, the depth of the scouring part is 5 to 5.
It is almost constant between 5.5 μm. Therefore, in the method of the present invention, the pre-plating time is usually set to 20 seconds or more, preferably 40 seconds or more, particularly preferably 50 seconds or more, and more preferably 55 seconds or more. In addition, since the press plating does not significantly affect the scouring depth even when the press plating is performed for a long time, the upper limit of the press plating time is usually 2 times.
It is about 10 seconds.

Although the above shows that the depth of the undercut portion can be reduced by performing the press plating and the tin plating, it is necessary to change the Sn ²⁺ concentration even when only the tin plating is performed without the press plating. Thereby, the depth of the undercut portion can be reduced. For example, Sn ²⁺ is applied to a lead portion which has been soft-etched and not subjected to press plating to a plating temperature of 70 ° C. and a plating time of 210 seconds.
Concentration of 15 g / l, 20 g / l, 27 g / l
This tin plating was performed in place of liter, and the depth of the generated scorched portion was measured. The results are shown in Table 1 below.

[0038]

[Table 1]

As described above, by setting the Sn ²⁺ concentration in the present tin plating within the range of 13 to 50 g / liter, preferably within the range of 15 to 30 g / liter, the depth of the undercut portion is reduced. You. In order to reduce the depth of the undercut, it is effective to soft-etch the surface to be plated before plating.

In particular, in FIG. 2, the depth of the recessed portion is 3.5 μm by performing the press plating after performing the soft etching indicated by “B” and further performing the tin plating.
m or less, and if the depth of the scoring portion is 3.5 μm or less, the reduction in lead strength or deformation of the lead due to the occurrence of the scouring portion is less likely to occur, and furthermore, the disconnection of the lead due to the formation of the scouring portion does not occur. . That is, as shown by "B" in FIG. 2, in the method for manufacturing a film carrier tape for mounting electronic components of the present invention, it is preferable to soft-etch a portion to be plated before tin plating.

This soft etching is different from the etching for forming a wiring pattern, in order to prepare the surface of the formed wiring pattern and perform plating more uniformly in the next step (a copper foil surface). Etc.), which is a step of chemically polishing the lead portion, which is 1/3 to 1/20 of the etching rate for forming the wiring pattern.
The surface of the wiring pattern is etched at a moderate speed.

That is, the soft etching is a treatment for chemically polishing the surface to be plated with acid or the like very slightly using acid or the like. Metal oxide film,
Organic substances and the like are removed, and a uniform tin plating layer is easily formed on the soft-treated surface. Further, by performing the soft etching process, a uniform tin plating layer is formed, so that even if a scorched portion is formed, the depth thereof is reduced.

Such a soft etching liquid is essentially an acidic liquid capable of chemically polishing the surface of a wiring pattern. As such a soft etching solution,
For example, the following can be mentioned. (1) Sulfuric acid: 2 parts by volume Nitric acid: 1 part by volume Hydrochloric acid: 0.8 ml / liter (2) Sulfuric acid: 7 to 150 ml / liter Hydrogen peroxide: 50 ~ 150ml / l Stabilizer ・ ・ ・ about 50ml / l (3) Chromic acid ・ ・ ・ about 270g / l (4) Phosphoric acid ・ ・ ・ about 55% Nitric acid ・ ・ ・ about 29% Acetic acid ・ ・ ・ 25 % (5) Sulfuric acid: 50 to 100 ml / liter Hydrochloric acid: 100 to 200 ml / liter Borofluoric acid: 50 to 100 ml / liter (7) Ammonium sulfate: 120 g / liter (8) _{K 2 S 2 O 8, H} 2 and SO ₄ as a main component, further, a soft etching solution is an acidic aqueous solution containing metal ions such as copper (9) persulfate, hydrogen peroxide, acids containing sulfuric acid Soft etching solution is an aqueous solution (10) nitrate, soft etching solution is an acidic aqueous solution containing sulfuric acid.

In the present invention, in addition to the soft etching liquid described above, the soft etching liquid exemplified above can be used as long as it is an acidic liquid that can slightly etch a wiring pattern formed from a conductive foil on a film carrier tape for mounting electronic components. Anything other than a liquid can be used. Particularly in the present invention, it is preferable to use a soft etching solution containing ammonium persulfate.

The above-described treatment with the soft etching solution is carried out by bringing the surface to be soft-etched into contact with the soft etching solution at a temperature of usually 20 to 50 ° C. for 3 to 60 seconds. By subjecting the portion to be plated to soft etching using such a soft etching solution, an oxide film, an organic film, and the like on the surface of the surface to be plated are removed (usually etched to a depth of 2 μm or less and removed). ), And it is possible to form a very uniform tin plating layer. Further, as shown in FIG. 2, after performing such a soft etching treatment, tin plating is performed, so that when the same plating solution is used, there is an effect that the depth of the undercut portion is reduced by about 2 μm.

As described above, in the method of manufacturing a film carrier tape for mounting electronic parts according to the present invention, when forming an electroless tin plating layer on a lead or the like after forming a solder resist layer, the Sn ²⁺ concentration in a tin plating bath is reduced. Is within a predetermined range, it is possible to suppress the formation of the scorched portion. Further, in the present invention, by forming a press-plated layer on the surface of the wiring pattern formed before applying the solder resist layer, it is possible to suppress the occurrence of the scoured portion, and to form the press-plated layer and the tin-plated layer. Thus, blistering or peeling of the plating layer can be prevented.

That is, as shown in FIG. 3, in the method for manufacturing a film carrier tape for mounting electronic components of the present invention, a tin plating layer can be formed after applying a solder resist as described above. As shown in 4,
It is also possible to form a thin press-plated layer before applying the solder resist, then apply and cure the solder resist, and then tin-plate again to form the tin-plated layer. The thickness of the press-plated layer formed before the formation of the solder resist layer as described above is usually 0.1 mm.
The thickness is in the range of 005 to 0.3 μm, preferably 0.01 to 0.1 μm, and this press plating layer is formed thinner than the present tin plating layer which is plated after forming the solder resist layer. By forming a thin press-plated layer before applying the solder resist, then forming the solder resist layer, and then forming the tin plated layer, generation of a scorched portion can be prevented.

When forming a thin press-plated layer before forming a solder resist layer as described above,
Similarly to the above, the surface of the wiring pattern can be soft-etched. As described above, in the method for manufacturing a film carrier tape for mounting electronic components of the present invention, the thickness of the tin plating layer thus formed (the total thickness of the press plating layer and the tin plating layer) is usually , 0.2-
It is 0.7 μm, preferably 0.3 to 0.5 μm. By providing a tin plating layer having such a thickness, a bump electrode of a device can be satisfactorily bonded to the tin-plated lead and the like, and the corrosion resistance of the lead portion and the like can be improved. The thickness of the tin plating layer is the total thickness when a plurality of tin plating layers are formed.

After a tin plating layer is formed by using a plating solution having a predetermined Sn ²⁺ concentration in this way, it is usually subjected to a heat treatment to form a tin for forming the formed tin plating layer and a metal for forming a wiring pattern. Are mutually diffused. Here, the heat treatment is performed by heating the tin plating layer to usually 90 to 150 ° C, preferably 110 to 140 ° C, usually for 30 to 180 minutes, preferably for 40 to 120 minutes.

By forming the electroless tin plating layer using a tin plating bath having a specific Sn ²⁺ concentration in this way, the depth of the undercut is reduced by the erosion effect of the plating solution. The detailed reason why the depth of the undercut is reduced by using the tin plating bath having such a Sn ²⁺ concentration is unknown, but the tin plating layer is formed using the tin plating bath having the specific Sn ²⁺ concentration as described above. It is thought that this is because the formation of the slag maintains the immersion potential of the plating solution in a noble direction and inhibits the formation of a local battery.

The film carrier tape for mounting electronic parts thus manufactured by the method of the present invention can be used in the same manner as that manufactured by the usual method.

[0052]

The film carrier for mounting electronic parts according to the present invention.
In the method of manufacturing the tape, the specific Sn ²⁺With concentration
Forming a tin plating layer using a tin plating bath
Of the undercut of the solder resist
Can be suppressed. Also electroless tin plating
The wiring pattern on the underside of the solder resist layer
Depth of the undercut, even if it is formed
To reduce the lead strength and prevent lead disconnection.
Can be stopped.

In particular, the method for producing a film carrier tape for mounting electronic parts according to the present invention is highly useful in producing a film carrier tape having a fine pitch. Also in a film carrier tape having a portion, it is possible to suppress the occurrence of a curled portion which may be a serious defect of the film carrier tape such as a substantial decrease in lead strength and disconnection of a lead.

Also, by forming a press plating layer before forming a solder resist layer, and then forming a solder resist layer and then forming an electroless plating layer on a lead portion as described above, the generation of a scoured portion Can be suppressed. Further, by forming the tin plating separately into the press plating and the tin plating, plating defects such as peeling of the plating layer and blistering hardly occur.

Therefore, the device can be mounted more reliably by using the electronic component mounting film carrier tape prepared by the method of manufacturing the electronic component mounting film carrier tape of the present invention. Of the strength over time and failure due to disconnection and the like hardly occur.

[0056]

EXAMPLES Next, the method for producing a film carrier tape for mounting electronic parts of the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

[0057]

Examples 1 to 3 and Comparative Examples 1 to 3 Width 70 mm, thickness 5
Device holes, sprocket holes, and cutting slits for outer leads were formed in a 0 μm polyimide film by punching. Next, an epoxy-based adhesive was applied to the surface of the polyimide film, and the thickness was 18 μm.
Was adhered.

Further, a photoresist was applied on the electrolytic copper foil, and the photoresist was exposed to light and etched to form a wiring pattern on the copper foil. The lead pitch width in the formed wiring pattern is 50 μm.
m. A urethane-based solder resist coating solution is applied leaving the lead portions of the wiring pattern formed in this manner,
Heat cured. The average thickness of the solder resist layer thus formed is 30 μm.

After forming the solder resist layer as described above, the lead surface was soft-etched using a soft etching solution having the following composition. K ₂ S ₂ O ₈ ··· 100 g / L H ₂ SO ₄ ··· 10 g / L Copper ion concentration (copper sulfate equivalent) ··· 0.3 g / L Water is added to the above components to make a total volume of 1 L. And

The contact time between the soft etching solution and the lead surface was set to 10 seconds, and the temperature of the soft etching solution was set to 30 ° C. After washing with water, this tape was immersed in an electroless tin plating solution having the following composition at room temperature (25 ° C.) for 10 seconds to form a press plating layer on the lead portion. Thiourea (NH ₂ ) ₂ CS ··· 15% by weight Tin borofluoride Sn (BF ₄ ) ₂ ··· Predetermined amount Hypophosphorous acid H ₃ PO ₄ ··· 6% by weight Cationic surfactant ··· 1% by weight or less Water was added to the above components to make a total volume of 1 liter.

The tin borofluoride in the electroless tin plating bath had a Sn ²⁺ concentration of 2 g / liter (Comparative Example 1), 3 g / liter (Comparative Example 2), and 8 g / liter (Comparative Example) in the tin plating bath. 3), 14 g / liter (Example 1), 18 g / liter (Example 2), 27
g / liter (Example 3).

The conditions for the above press plating are as follows: temperature;
° C (room temperature) and a plating time of 10 seconds. After pre-plating in this way, the present tin plating was performed. The conditions of the electroless tin plating are as follows: temperature of plating bath; 70 ° C., contact time;
An Sn ²⁺ concentration of 20 g / liter was set for 210 seconds, and a tin plating layer having an average thickness of 0.45 μm was formed on the lead portion. The ratio of the thickness of the first electroless tin plating layer to the thickness of the second electroless plating layer is 1:10, and the first electroless plating layer is the second electroless plating layer. It is formed thinner than the electrolytic plating layer.

After performing the electroless tin plating in this manner, the substrate was washed with water and heated at 130 ° C. to produce a film carrier tape for mounting electronic components. By observing the leads of the obtained film carrier tape for mounting electronic components, a lead having a chipped lead was selected, and a photograph of a cross section of this part was taken. The depth of the lead was measured from this cross-sectional photograph. The results are shown in FIG.

[0064]

Examples 4 to 6 and Comparative Examples 4 to 7 Form carrier tapes for mounting electronic components were manufactured in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 3, except that the soft etching treatment was not performed. By observing the leads of the obtained film carrier tape for mounting electronic components, a lead having a chipped lead was selected, and a photograph of a cross section of this part was taken.

From the photograph of the cross section, the depth of the lead burrow was measured. The results are shown in FIG.

[0066]

Example 7 A film carrier tape for mounting electronic components was produced in the same manner as in Example 2, except that the electroless tin plating of the lead portion was performed in one stage. The total thickness of the thus formed electroless tin plating was 0.45 μm. By observing the leads of the obtained film carrier tape for mounting electronic components, a lead having a chipped lead was selected, and a photograph of a cross section of this part was taken.

When the depth of the lead digging was measured from this cross-sectional photograph, the depth of the generated lead digging was 4 μm, which was deeper than that of Example 2.

[0068]

Embodiment 8 In Embodiment 2, before applying a solder resist, the wiring pattern is soft-etched, and then a 0.03 μm-thick press-plated layer is formed by electroless tin plating. A solder resist layer was formed in the same manner as in Example 2, and an electroless tin plating layer was formed in the lead portion extending from the solder resist layer in the same manner as in Example 2. The total thickness of the tin plating layer thus formed was 0.45 μm.
m.

The lead portion of the obtained film carrier tape for mounting electronic components was observed to find a lead in which the chipping occurred, but no chipping occurred.

[0070]

Example 9 In Example 2, the Sn ²⁺ concentration in the press plating bath was changed to 15 g / liter, and press plating was performed at room temperature for 10 seconds, 30 seconds, 60 seconds, 120 seconds and 210 seconds, respectively. The present tin plating was carried out under the conditions of a plating temperature of 70 ° C., a time of 210 seconds, and a Sn ²⁺ concentration of 20 g / liter. The surface to be plated is not soft-etched.

Press plating was carried out for various times as described above, and the lead portion after the tin plating was observed. By observing the leads of the obtained film carrier tape for mounting electronic components, a lead having a chipped lead was selected, and a photograph of a cross section of this part was taken. When the depth of the lead digging was measured from this cross-sectional photograph, the depth of the digging gradually became shallower as the press plating time became longer, and the depth of the digging became stable at about 5 μm between 30 seconds and 60 seconds.

FIG. 5 shows the result.

[0073]

Embodiment 10 The tin plating was carried out in the same manner as in Embodiment 1 except that the Sn ²⁺ concentration was changed to 15 g / L, 20 g / L and 27 g / L without performing press plating on the soft-etched lead surface. By observing the leads of the obtained film carrier tape for mounting electronic components, a lead having a chipped lead was selected, and a photograph of a cross section of this part was taken.

The depth of the lead burrow was measured from the photograph of the cross section, and the results are shown in Table 2 below.

[0075]

[Table 2]

The tin plating conditions are as follows: plating temperature: 70 ° C., plating time: 210 seconds. From the above results, by setting the Sn ²⁺ concentration in the present tin plating within the range specified in the present invention, the depth of the undercut can be reduced without performing press plating.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a scoured portion of a lead generated by electroless tin plating.

FIG. 2 is a graph showing the relationship between the Sn ²⁺ concentration in a press plating bath and the scouring depth (screw amount) of a lead.

FIG. 3 is a diagram showing an embodiment in which a press plating layer and a main plating layer are provided.

FIG. 4 is a diagram showing an embodiment in which a press plating layer is provided below a solder resist.

FIG. 5 is a graph showing a relationship between a press plating time and a scouring depth.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hirofumi Kawamura 1-1-1 Hikoshima Nishiyamacho, Shimonoseki-shi, Yamaguchi FMC Term FMC (Reference) 5F044 MM03 MM23 MM48

Claims (12)

[Claims] 1. The method according to claim 1, wherein at least the lead portion of the wiring pattern formed on the flexible insulating film has a Sn ²⁺ concentration of 13 to 13.
After performing short-time press plating using a 50 g / liter electroless tin plating bath, at least the pre-plated lead portion has an Sn2 ⁺ concentration of 13 to 50 g / liter in an electroless tin plating bath. A method for producing a film carrier tape for mounting electronic components, wherein the present tin plating is performed at least once using the method. 2. The method for producing a film carrier tape for mounting electronic parts according to claim 1, wherein a surface to be tin-plated is subjected to soft etching before the press plating. 3. After forming a solder resist layer on the wiring pattern, a lead portion not covered with the solder resist layer is press-plated, and the lead portion is further subjected to at least one tin plating. 3. The method for producing a film carrier tape for mounting electronic components according to claim 1, wherein 4. After forming a solder resist layer on the entire wiring pattern before press-forming the solder resist layer on the wiring pattern, leaving a lead portion, a solder resist layer is formed, and then covered with the solder resist layer. 3. The method for producing a film carrier tape for mounting electronic components according to claim 1, wherein the tin plating is performed at least once on a lead portion that is not provided. 5. The press plating time is 10 to 210.
3. The method for manufacturing a film carrier tape for mounting electronic parts according to claim 1, wherein the time is within a range of seconds. 6. The method for manufacturing a film carrier tape for mounting electronic parts according to claim 1, wherein said tin plating layer is formed thicker than a press plating layer. 7. The method according to claim 1, wherein the total thickness of the press-plated layer and the tin-plated layer in the lead portion on which the tin-plated layer is formed is in the range of 0.2 to 0.7 μm. 3. The method for producing a film carrier tape for mounting electronic components according to claim 1 or 2. 8. The wiring pattern having an average thickness of 7 to 35 μm.
2. The method for manufacturing a film carrier tape for mounting electronic components according to claim 1, wherein the film carrier tape is formed by etching an electrolytic copper foil having a thickness of m. 9. The present tin plating is performed at least once on a lead portion of a wiring pattern formed on a flexible insulating film using an electroless tin plating bath having a Sn ²⁺ concentration in a range of 13 to 50 g / liter. A method for producing a film carrier tape for mounting electronic components, which is performed. 10. The electronic component mounting film according to claim 9, wherein a tin-plated surface is soft-etched before tin-plating the wiring pattern formed on the flexible insulating film. Manufacturing method of carrier tape. 11. The electronic component mounting according to claim 9, wherein an average thickness of the lead portion of the tin plating layer is in a range of 0.2 to 0.7 μm. A method for manufacturing a film carrier tape. 12. A wiring pattern according to claim 9, wherein said tin plating layer is formed using an electrolytic copper foil having an average thickness of 7 to 35 μm. The method for producing a film carrier tape for mounting electronic components according to the above.