KR100374075B1 - Film carrier tape for mounting electronic parts and method for manufacturing the same - Google Patents

Abstract

The film carrier tape for mounting an electronic component of the present invention is an electronic component mounting film carrier tape having a copper foil attached to an insulating film, and etching the copper foil to form a desired wiring pattern. A diffused tin plated layer (a) is formed, and a protective layer made of a hardener of solder resist is formed at a predetermined position except for the terminal portion of the wiring pattern, and the surface of the tin plated layer (a) with copper diffused on the terminal portion. The tin plating layer (b) which does not contain substantially copper is formed in the copper foil, and copper-tin-containing area | region is formed between the tin plating layer (a) which copper spread | diffused and pure tin plating layer (b) more suitably. .

Description

Film carrier tape for electronic component mounting and manufacturing method {FILM CARRIER TAPE FOR MOUNTING ELECTRONIC PARTS AND METHOD FOR MANUFACTURING THE SAME}

The present invention is a film carrier tape (TAB (Tape Automated Bonding) tape, T-BGA (Tape Ball Grid Array) tape, ASIC (Application Specific Integrated Circuit) tape, etc.) for mounting electronic components such as IC or SI And a method for producing this tape. More specifically, in the present invention, copper foil is not eroded by the plating solution when tin plating is performed, and film carrier tape (TAB (Tape Automated Bonding) tape, T-BGA (Tape Ball Grid Array) tape, ASIC (Application) Specific Integrated Circuit (Tape) and the like and a method of manufacturing the tape.

In recent years, electronic devices such as notebook PCs have become smaller and lighter. In addition, the wiring of semiconductor ICs is further miniaturized.

With such miniaturization of electronic devices, film carrier tapes for mounting electronic components such as TAB tapes, T-BGA tapes, and ASIC tapes are used. The film carrier tape for mounting electronic components is manufactured as follows. For example, copper foil is affixed on base films, such as a polyimide film, a photoresist is apply | coated on this copper foil surface, the part of this photoresist except the wiring pattern to form is exposed, The exposed photoresist is removed. Next, the copper foil of the part from which the photoresist was removed is removed by etching, and a wiring pattern is formed by removing a photoresist again. In this manner, a solder-resist serving as a protective layer of the circuit is applied to the film carrier tape for mounting the electronic component on which the wiring pattern is formed, except for the connecting portions such as inner lead and solder ball terminals. In this way, a tin plating layer is formed in the connection part which is exposed after apply | coating a soldering resist.

However, when the solder resist is applied in this manner, and the tin plating is carried out after drying and hardening, plating liquid penetrates into the bottom surface of the solder resist along the wiring pattern at the end of the solder resist, forming a local battery to form a local battery. Copper elutes. That is, as shown in FIG. 2, after the copper foil 30 is stuck on the base material 10 via the adhesive bond layer 12, the wiring pattern 30 is formed in a usual manner, and then the solder resist 20 is formed. In the case of coating and dry curing and forming the tin plating layer 31 thereon, the plating liquid penetrates from the end portion 21 of the solder resist 20 to the bottom surface of the solder resist 20, whereby a local battery is formed. The copper foil of this part is formed in the recessed form in groove shape. In FIG. 2, this recessed part (cavity) is shown by (35). Thus, when bending stress is applied to the film carrier tape for electronic component mounting in which the cavity part 35 was formed, stress concentrates in the cavity part 35, and in the worst case, a lead breaks.

Japanese Patent Application Publication No. 94-342969 relates to preventing the intrusion of liquid from the end of the solder resist 30 as described above in "Flexible Circuit Board in which a conductive pattern is formed on a film based on resin. The present invention discloses a flexible circuit board and a method of manufacturing the same, wherein the solder resist applied for the purpose of circuit protection is coated on a pattern and then coated.

According to the invention described in the above publication, the solder resist is applied after plating and heat cured, so that the plating liquid does not invade the underside of the solder resist, and the tin plating layer is also heat treated by heating at the time of hardening the solder resist. It is described that there is no need to perform a new heating step to prevent the occurrence of whiskers.

In practice, however, it is difficult to continuously perform the plating step and the heat curing step of the solder resist. After a considerable time, the tape obtained through the plating step is coated with the solder resist and the solder resist is heat cured again. In order to suppress the growth of a whisker, it is necessary to heat-process this plating layer immediately after plating, and a whisker grows with time. Moreover, the temperature condition at the time of hardening of a soldering resist does not necessarily correspond with the temperature condition which suppresses the growth of a whisker, and when it heats according to one condition, there exists a problem that the other effect is not fully acquired. . In addition, the suppression of the growth of the whisker by such a heat treatment is useful for a short period of time, but the whisker prevention effect is reduced for a long period of time (for example, 2 to 3 months).

As a method of suppressing the growth of whiskers, a method of diffusing copper in the tin plating layer by heating (annealing) the tin plating layer after performing tin plating as described above is known. According to this method, whiskers can be prevented to some extent in a short time, but there is a problem that it is impossible to completely prevent the growth of whiskers over a long period of time (for example, 2 to 3 months).

As a method of suppressing the growth of the whisker, Japanese Patent Laid-Open Publication No. 93-33187 describes, "When tin plating is performed on a fine pattern of copper or copper alloy, first, tin plating of 0.15 탆 or thicker is first applied, and then heated. Process of suppressing tin plating whisker, characterized in that the pure tin layer is formed into a Cu-Sn diffusion layer with all copper bases, and the tin plating is applied thereon to make the pure tin plating thickness 0.15 to 0.8 µm. It is. In other words, the invention described in this publication forms a tin plated layer and heat-treats the tin plated layer to diffuse copper into the tin plated layer, and then plated (flash plated) again to form a pure tin plated layer on the surface of the tin plated layer where the copper is diffused. To prevent the formation of.

However, in this publication, after the solder resist is applied and cured on the wiring pattern, tin plating is carried out and heat treatment is performed to diffuse copper in the tin plating layer, and then the tin plating layer is again formed on the surface of the tin plating layer in which the copper is diffused. . Therefore, in the invention of this publication, whisker formation is suppressed, but the plating is performed after coating and curing the solder resist, so that the plating solution penetrates the bottom surface of the solder resist as in the conventional plating so that the cavity 35 is still formed. do.

An object of the present invention is to provide a film carrier tape for mounting electronic components and a method of manufacturing the same, which can suppress the growth of a whisker over a long period of time without forming a cavity in the wiring pattern even by electroless plating.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the example of the cross section of the lead part in the film carrier tape for electronic component mounting of this invention.

It is sectional drawing which shows the example of the cross section of the lead part in the conventional film carrier tape for electronic component mounting.

3 is a view for explaining the mechanism in which the cavity is formed.

<Explanation of symbols for main parts of drawing>

10... Insulating film, 12... Adhesive layer, 20.. Solder resist, 30... Wiring pattern (copper foil), 31... Tin-plated layer (a), 33... Tin plating layer (b) (pure tin plating layer (b)) substantially free of copper

The film carrier tape for mounting electronic components of the present invention (film carrier tape for mounting electronic components) is

A film carrier tape for mounting electronic components in which copper foil is adhered to an insulating film, and the copper foil is etched to form a desired wiring pattern, wherein tin is diffused by tin plating almost all of the wiring pattern. A plating layer (a) is formed, a protective layer made of a cured body of solder resist is formed at a predetermined position except for the terminal portion of the wiring pattern, and a tin plating layer having copper diffused in the terminal portion ( It is characterized in that the tin plating layer (b) which does not substantially contain copper is formed in the surface of a).

The film carrier tape for mounting an electronic component of the present invention (the film carrier tape for mounting an electronic component) adheres a copper foil to an insulating film, etches the copper foil to form a desired wiring pattern, and spreads copper throughout the wiring pattern. After the tin plating layer (a) is formed, a solder resist is applied to a predetermined portion except for the terminal portion of the wiring pattern, and then hardened. After the solder resist is cured, tin plating is applied to the terminal portion of the wiring pattern again. It can manufacture by forming the tin plating layer (b) which does not contain copper.

Moreover, the film carrier tape for electronic component mounting (film carrier tape for 2nd electronic component mounting) of this invention adhere | attaches copper foil to an insulating film, the copper foil is etched, and the film carrier for electronic component mounting in which the desired wiring pattern was formed. As a tape, a tin-plated layer (a) in which copper is diffused by tin plating almost all of the wiring pattern is formed, and a protective layer made of a cured body of solder resist is formed at a predetermined position except for the terminal portion of the wiring pattern. At the same time, the copper diffusion concentration gradually decreases from the surface of the tin-plated layer (a) with copper diffused and the tin-plated layer (a) with copper diffused toward the surface of the tin-plated layer (b) substantially free of copper. Has a copper-tin-containing region, and the region is formed so as to be continuous with the tin plating layer (b) which does not substantially contain copper. It is done.

The film carrier tape for mounting an electronic component (the second film carrier tape for mounting an electronic component) of the present invention adheres a copper foil to an insulating film, etches the copper foil to form a desired wiring pattern, and almost the wiring pattern formed. A tin plating layer is formed on the whole, and a solder resist is applied to a predetermined portion except for the terminal portion of the wiring pattern to cure. After the solder resist is cured, tin plating is further performed on the terminal portion of the wiring pattern. In the manufacturing method of the film carrier tape for mounting electronic components,

In the terminal portion, copper and tin in which the copper diffusion concentration gradually decreases from the surface of the tin-plated layer (a) in which copper is diffused and the tin-plated layer (b) substantially free of copper from the surface of the tin-plated layer (a) in which copper is diffused. A containing region is formed, and it can manufacture by forming such an area | region continuously with the tin plating layer (b) which does not contain copper substantially.

In the film carrier tape for mounting an electronic component of the present invention, a tin plating layer (a) is formed on the surface of a wiring pattern made of copper foil coated with solder resist, and the tin plating layer (a) diffuses copper from the wiring pattern by heating. And a tin-copper diffusion layer. After forming the tin plating layer a in this way, a solder resist is apply | coated to the surface of this tin plating layer a except a junction part of an electrode in a desired position, and this solder resist is hardened dry. In this way, after hardening a soldering resist, the tin plating layer (b) which does not contain copper substantially is formed on the surface of a tin plating layer (a) by tin plating again.

Since the carrier tape formed in this way has no solder resist during the first tin plating, no cavity is formed in the copper by the formation of a local battery, and during the second tin plating, a plating solution is formed on the underside of the solder resist. Even when invading, the surface of the copper is formed with a tin-copper diffusion layer, and since the copper foil does not come into contact with the plating liquid, a local battery using copper as an electrode is not formed, and therefore, the cavity 35 as shown in FIG. 2 is not formed. .

Furthermore, after the first tin plating, a protective layer made from the cured product of the solder resist is formed, and the second tin plating is then performed to suppress the growth of the whisker and to prevent short circuit caused by the whisker. have.

The mechanism in which the cavity 35 is formed as shown in FIG. 2 is not all explained. However, the present inventors form the cavity 35 by forming a local battery as described below. I think. 3 is a diagram schematically showing a mechanism in which the cavity 35 is generated by the formation of a local battery.

First, when the plating liquid starts to penetrate into the bottom of the solder resist from the solder resist end, the resist rises due to the contraction force (internal stress) remaining in the solder resist, and the liquid collecting portion of the plating liquid is formed.

Tin is contained in the plating solution in the form of saturated tin, and the like, and electrochemical substitution reaction between the tin and the copper metal starts to proceed, and the substituted copper ions remain in the liquid collection part. .

In order to electrically neutralize the retained positive copper ions, anions (for example, povided ions) in the plating layer move.

At the solder resist end, positive tin ions remain due to the movement of anions, and copper ions receive electrons from the elution portion, and metal tin precipitates.

The elution of copper ions, the movement of anions, the movement of electrons, and the precipitation of tin occur in series, forming a local battery having the copper eluate as an anode and the tin precipitate as a cathode.

It is considered that the wiring pattern made of copper foil partially elutes the bottom surface of the solder resist by the above mechanism to form a cavity.

In the terminal portion of the film carrier tape for mounting the first electronic component of the present invention, as described above, a tin-plated layer (a) having copper diffused therein and a tin-plated layer (b) substantially free of copper are formed. The film carrier tape for mounting the second electronic component of the film includes a tin plated layer (a) (copper diffused tin plated layer (a)) in which copper is diffused, and a tin plated layer (b) (pure tin plated layer (b) substantially free of copper). A copper-tin-containing region is formed in which the copper diffusion concentration gradually decreases from the surface of the tin-plated layer (a) in which the copper is diffused toward the surface of the tin-plated layer (b) substantially free of copper.

That is, the film carrier tape for mounting the second electronic component of the present invention is an electronic component mounting film carrier tape having a copper foil attached to an insulating film, and etching the copper foil to form a desired wiring pattern. The tin plating layer (a) in which copper is diffused by tin plating is formed, and the protective layer which consists of hardened | cured material of a soldering resist is formed in the predetermined position except the terminal part of the said wiring pattern, and copper is diffused in the said terminal part. A copper-tin-containing region in which the copper concentration is continuously lowered is formed from the tin-plated layer (a) and the tin-plated layer (b) substantially free of tin on the surface of the tin-plated layer (a) where copper is diffused. It is characterized in that it is formed so as to be continuous with the tin plating layer (b) which does not contain copper substantially.

In the film carrier tape for mounting the second electronic component of the present invention, a copper foil is attached to an insulating film, the copper foil is etched to form a desired wiring pattern, and tin plating is performed almost on the formed pattern. A method of manufacturing a film carrier tape for mounting an electronic component having a process of applying a solder resist to a predetermined portion except for the terminal portion of the substrate, and curing the solder resist, and then tin plating the terminal portion of the wiring pattern again. To

In the terminal portion, copper diffusion is gradually reduced toward the surface of tin-plated layer (a) in which copper is diffused and tin-plated layer (b) substantially free of copper in the tin-plated layer (a) in which copper is diffused. It can be produced by forming the containing region and forming the region so as to be continuous with the tin plating layer (b) which does not substantially contain copper.

As described above, by forming the copper-tin-containing region in which copper concentration continuously decreases from the copper diffusion tin plating layer (a) to the pure tin plating layer (b) so as to be continuous with the pure tin plating layer, the above cavity becomes hard to be formed further. At the same time, the formation of whiskers can be almost permanently prevented.

[Detailed Description of the Invention]

Next, the film carrier tape for mounting an electronic component of the present invention will be specifically described in accordance with the manufacturing method thereof with reference to the drawings. In addition, in the drawing shown below, the common code | symbol is attached | subjected to a common member.

1: is sectional drawing which shows typically the cross section of the film carrier tape for electronic component mounting of this invention.

In the film carrier tape 1 for mounting electronic components of the present invention, the insulating film 10 and the wiring pattern 30 made of, for example, an electrolytic copper foil adhered to the surface by an adhesive layer 12 are laminated in this order. Is done. In order to protect the surface of the wiring pattern 30, a layer (cured product) made of solder resist 20 is applied and disposed.

The insulating film 10 constituting the film carrier tape for mounting electronic components of the present invention is made of a flexible resin film. In addition, since the insulating film 10 contacts acid or the like when etching, the insulating film 10 has chemical resistance that does not corrode such chemicals, and heat resistance that does not deteriorate by heating when bonding. As an example of resin which forms such a flexible resin film, glass epoxy, BT resin, polyester, polyamide, polyimide, etc. are mentioned. In particular, in the present invention, it is preferable to use a film made of polyimide.

Examples of the polyimide film constituting the insulating film 10 include all aromatic polyamides synthesized from pyromellitic dianhydride and aromatic diamine, and all aromatic polyamides having a biphenyl skeleton synthesized from biphenyltetracarboxylic dianhydride and aromatic diamine. Amides may be enumerated. In particular, in the present invention, all aromatic polyamides having a biphenyl backbone (e.g. trade name: Eupyrex, manufactured by Uderoku) are preferably used. The thickness of such insulating film 10 is usually in the range of 25 to 125 mu m, preferably 50 to 75 mu m.

In this insulating film 10, device holes, sprocket holes, cutting holes of external leads, and the like are formed by punching.

The wiring pattern 30 forms an adhesive layer 12 by applying an insulating adhesive to the insulating film 10 in which the predetermined holes are formed as described above, adhering the copper foil to the adhesive layer 12, and applying the copper foil. It is formed by etching. As the copper foil, any one of an electrolytic copper foil and a rolled copper foil can be used, but it is preferable to use an electrolytic copper foil capable of coping with the recent fine pitch.

Moreover, when sticking copper foil to the above insulating film, it can also stick without using an adhesive agent, and can also stick using an adhesive agent. It is preferable that the adhesive agent used here has characteristics, such as heat resistance, chemical resistance, adhesive force, and flexibility. Examples of the adhesive having such characteristics include epoxy adhesives and phenolic adhesives. Such an adhesive may be modified with urethane resin, melamine resin, polyvinyl acetal resin, or the like, and the epoxy resin itself may be rubber modified. Such adhesives are thermosetting. The thickness of such an adhesive bond layer is normally 8-23 micrometers, Preferably it exists in the range of 10-21 micrometers. The adhesive layer 12 made of such an adhesive may be applied and disposed on the surface of the insulating film 10 or may be applied and disposed on the surface of the electrolytic copper foil. As the electrolytic copper foil used here, although the copper foil of the thickness normally used for manufacture of the film carrier tape for electronic component mounting can be used, in order to manufacture the film carrier tape for electronic component mounting of fine pitch, it is usually a range of 6-25 micrometers. It is preferable to use the copper foil which exists in the range of 9-18 micrometers preferably. By using such a thin electrolytic copper foil, it becomes easy to form an internal lead with a narrow pitch width.

After sticking copper foil to the surface of an insulating film in this way, a photoresist is apply | coated on the surface of this copper foil, the desired wiring pattern is hardened to this pot resist, and the photoresist of the uncured part is removed. do. It is also possible to use a photoresist which becomes soluble in a specific medium by reverse exposure.

In this way, the laminated film of the insulating film and copper foil in which the desired wiring pattern was formed by the hardened photoresist is etched, and copper foil of the part in which the hardened photoresist does not exist is melted and removed, and the wiring pattern of copper foil is formed in the surface of an insulating film. do.

After the wiring pattern is formed by etching in this manner, the cured photoresist is removed, for example, with an alkaline solution.

In the present invention, after forming the wiring pattern as described above, the insulating film on which the wiring pattern is formed is transferred to a plating bath, and a tin plating layer (a) 31 is formed on the surface of the wiring pattern. In the present invention, the tin plating layer is formed by a method such as electroless tin plating or electrolytic tin plating. Although the original tin plating layer (a) 31 formed in this way is generally shape | molded substantially with tin, another metal may contain in the range which does not impair the characteristic of this tin plating layer (a) 31. FIG.

If the thickness of the tin plating layer (a) 31 is 0.01 µm or more, preferably 0.1 µm or more, it is localized to the wiring pattern made of copper foil even when the plating liquid penetrates into the bottom surface of the solder resist in the plating process after applying the solder resist. A battery is not formed and the wiring pattern made of copper foil can be effectively protected.

The tin plating layers (a) 31 are formed on the entire surface of the wiring pattern except for the wiring pattern surface in contact with the adhesive 12.

When the thickness of the tin plating layer (a) 31 is thicker than 0.5 mu m, the tin plating layer (b) 33 formed later and the thick tin plating layer having a total thickness of more than 0.6 mu m are used when the internal lead and pitch are connected. Relaxation may occur and short circuit may occur. For this reason, the thickness of the tin plating layer (a) 31 is usually 0.01 µm or more, preferably 0.1 µm or more, particularly preferably 0.3 µm or more, and the upper limit of the thickness of the tin plating layer (a) 31 is above. ) Is usually 0.5 μm.

The tin plating layers (a) 31 are formed on the entire surface of the wiring pattern except for the wiring pattern in contact with the adhesive 12.

Whisker formation can be prevented by diffusing copper into the tin plating layers (a) 31 thus formed. As a method of diffusing copper into the tin plating layers (a) 31, a method of heating the tin plating layers (a) 31 together with the wiring pattern is mentioned. At this time, the heating temperature is usually 70 to 200 ° C, preferably 100 to 150 ° C, and the heating time depends on the thickness of the tin plating, but is usually 30 seconds to 120 minutes, preferably 30 minutes to 60 minutes. . By heating in this way, the initial stage of formation is made of tin and copper diffuses into the tin plating layer (a) 31 which does not substantially contain other metal, so that the layer (a) becomes a tin-copper diffusion layer.

In addition, the heating for forming the said tin-copper diffusion layer is not necessarily performed here, and after apply | coating the next soldering resist, when the time until the heating for hardening of the soldering resist 20 is short, soldering resist 20 is carried out. You may heat when hardening). In this case, the tin plating layers (a) 31 are tin plating layers (a) 31 through which copper can be diffused.

Thus, the solder resist 20 is apply | coated on the tin plating layer (a) 31 in which copper was spread | diffused, or the tin plating layer (a) 31 in which copper may be spread. As this soldering resist 20, it is preferable to use a thermosetting resin having high heat resistance. Usually, a thermosetting resin such as an epoxy resin, a polyimide resin, or a urethane resin is used, but an ultraviolet photosensitive solder resist can also be used. Such solder resist exhibits good adhesion to the tin-plated layer (a) 31 and the insulating film 10 in which the formed copper is diffused (or can be diffused). Such solder resist is applied to the surface of the tin plated layer (a) using, for example, a screen printing technique. However, such a solder resist 20 is not applied to the electrical junction portion of the wiring pattern 30 and its vicinity. The coating thickness of the soldering resist 20 is usually 5-50 micrometers, Preferably it is in the range of 10-40 micrometers. By applying the solder resist at such a thickness, the wiring pattern can be physically protected and the electrical insulation between the wiring patterns can be more reliably achieved.

In this way, after apply | coating a soldering resist, in the case of a thermosetting resin, this soldering resist is heated and hardened. The heating temperature for curing the solder resist varies depending on the type of solder resist used, but is usually 100 to 180 ° C, preferably 130 to 160 ° C, and the heating time is usually 40 minutes to 180 minutes, preferably 60 minutes-120 minutes. Moreover, you may heat by the heating process (step cure) which raises a heating temperature step by step in order to prevent the void in a soldering resist, etc. In this drying, a vacuum drying method, an ultraviolet drying method, or the like can be adopted. As mentioned above, when the soldering resist 20 fully hardens by the heating at the time of drying, the tin plating layer (a) 31 is also heated at the same time, and further copper diffusion will advance.

If the heat treatment is not performed prior to applying the solder resist, the heat treatment conditions for curing the solder resist are suitable for curing the solder resist. This can be done continuously.

After applying and curing the solder resist 20 as described above, in the present invention, tin plating is again performed on the wiring pattern surface of the portion where the solder resist 20 is not applied.

This tin plating layer (b) 33 does not contain substantially metal components other than tin, and differs from the tin plating layer (a) 31 in which the said copper was diffused in this point.

The thickness of the tin plated layer (b) 33 thus formed is usually in the range of 0.01 to 0.5 µm, preferably 0.1 to 0.5 µm, and particularly preferably 0.1 to 0.3 µm.

The formation of the thin tin plating layers (b) 33 by the electroless plating method is also described in the present invention as flash plating in particular. By making the thickness of this tin plating layer (b) 33 into the said range, reliable bonding is attained and plating loosening does not occur and a short circuit does not occur easily.

In the case where the solder resist is an ultraviolet photosensitive photosolder resist, the solder resist is applied to the surface of the tin plating layer (a) by screen printing, and then temporarily dried, the coated portion and the plated portion. It develops by exposing to the pattern of and heats in order to improve the adhesiveness of a tin plating layer (a) and a photosolder resist. In this case, heating temperature is 100-180 degreeC normally, Preferably it is 130-160 degreeC, Heating time is 40 minutes-120 minutes normally, Preferably it is 60-90 minutes.

The tin plating layer (b) 33 is a surface of the tin plating layer (a) in which the copper is diffused, and is formed on the surface not covered by the solder resist 20. That is, in the film carrier tape for mounting the electronic component of the present invention, a tin-plated layer (a) in which copper is diffused on the surface of the wiring pattern 30 made of copper foil on the portion where the solder resist of the wiring pattern is not applied, especially the lead portion ( 31) is formed, and on the surface of the tin-plated layer (a) 31 in which copper is diffused, a tin-plated layer (b) 33 substantially free of copper is formed.

The sum [(a) + (b)] of the thickness of the tin-plated layer (a) with copper diffused on the surface of the wiring pattern made of copper and the tin-plated layer (b) substantially free of copper is usually 0.02 to 0.6. It is in the range of m, preferably in the range of 0.2 to 0.6 m, particularly preferably in the range of 0.4 to 0.5 m.

By forming the thin tin plating layers (b) 33 by flash plating as described above, the growth of the whisker from the wiring pattern can be almost completely prevented. In addition, the tin plating layer (b) 33 is substantially made of tin. For example, in the case of mounting a device having a gold bump electrode, the tin and gold form a process compound. As a result, the bump electrode and the wiring pattern 30 (lead) are firmly and reliably bonded together.

However, in the case of forming the tin plating layer (b) by the flash plating, the solder resist is firmly bonded to the tin plating layer (a) in which copper is diffused, and the tin plating layers (a) 31 and the solder resist 20 are firmly bonded. Since it is bonded, the plating liquid and the like rarely penetrate between the bottom surface of the solder resist 20 and the top surface of the tin plating layer a, and even if the plating liquid penetrates therebetween, the surface of the wiring pattern 30 is Since it is covered with the tin plating layer (a) 31 and copper is not exposed, no local battery is formed by the infiltrating plating solution. Therefore, according to the present invention, the cavity at the time of tin plating is coated on a film carrier tape for mounting a conventional electronic component. (Formula) 35 or the like does not occur, and lead breakage or the like is unlikely to occur.

By forming the tin plating layers (b) 33 by flash plating in this manner, it is possible to almost permanently prevent the generation of tin whiskers.

In addition, unlike the tin plating layers (a) 31, the tin plating layers (b) 33 do not need to be heat treated. In addition, since the tin plating layer (a) 31 is formed on the wiring pattern, and copper is diffused in the tin plating layer (a) 31, the growth of the whisker is controlled by the tin plating layer (a) 31 in a short time. The performance of the film carrier tape for mounting electronic components does not deteriorate even after a certain time until application of the solder resist and formation of the tin plating layers (b) 33 by flash plating. Therefore, according to this invention, management of a manufacturing process becomes easy.

The pure tin plating layer (b) 33 is usually manufactured by one plating process, but the plating process may be divided into a plurality of times to form the tin plating layer (b) 33. Thus, in this case, tin The plating layers (b) 33 consist of a composite of a plurality of tin plating layers.

The plating layer in the present invention consisting of the tin plated layer (a) in which the copper thus formed is diffused and the tin plated layer (b) substantially free of copper, and the conventional tin plated layer by using an X-ray diffraction method, an AES analysis method, or the like Can be distinguished. For example, X-ray diffraction intensity of Cu ₃ Sn and Cu ₆ Sn ₅ in a layer by X-ray diffraction is measured, and in the plating layer of the film carrier tape for mounting an electronic component of the present invention, it is usually 1: 0.3 to 0.5. On the other hand, in the conventional plating layer, it exists in the range of 1: 1-1.5. In addition, according to the AES analysis, in the vicinity of the surface of the plating layer in the present invention, it is confirmed that copper is diffused to the vicinity of the surface in the conventional plating layer, while the pure tin plating layer is used.

The film carrier tape for mounting an electronic component of the present invention is suitably formed by the above-described method, and is a film carrier tape for mounting electronic components on which a copper foil is attached to an insulating film, and the copper foil is etched to form a desired wiring pattern. The tin plating layer (a) in which copper was diffused by tin-plating almost all of this wiring pattern was formed, and the protective layer which consists of hardened | cured material of a soldering resist is formed in the predetermined position except the terminal part of this wiring pattern. Although the tin-plated layer (b) which does not contain copper substantially is formed in the surface of the tin-plated layer (a) which copper spread | diffused, the terminal part can be variously deformed in the range which does not impair the characteristic.

For example, not only copper foil but copper alloy foil can be used as copper foil, It is preferable that tin plating is pure tin plating, However, These tin plating layers may contain another metal within the range which does not impair the characteristic.

In the film carrier tape for mounting the first electronic component of the present invention, a tin plating layer (a) in which copper is diffused over almost the entire surface of the wiring pattern as described above (also referred to herein as simply "copper diffusion tin plating layer (a)"). In the film carrier tape for mounting the second electronic component of the present invention, copper and tin in which the copper content gradually decreases from the copper diffusion tin plating layer (a) to the pure tin plating layer (b) over almost the entire wiring pattern. The containing area is formed.

The copper-tin-containing region contains copper so that the copper concentration gradually decreases toward the pure tin plated layer (b). The copper-tin-containing region is a pure tin plated layer by transferring copper from the tin plated layer (a) to the pure tin plated layer (b) to a pure tin plated layer (b) plated on the copper diffusion tin plated layer (a). It is formed continuously with (b).

In the film carrier tape for mounting the second electronic component, the insulating film, the adhesive layer, the solder resist, and the wiring pattern are the same as in FIG.

The copper diffusion tin plating layer a formed on the wiring pattern is also formed by tin plating on the surface of the wiring pattern formed by etching before applying the solder resist as in FIG. In this way, the copper diffusion tin plating layer (a) is formed of tin almost immediately after tin plating, but copper forming a terminal by heating or the like when the solder resist is applied and cured is diffused in the tin plating layer (a) to form this layer. Becomes a highly diffused tin plated layer (a).

The average thickness of the copper diffusion tin plated layer (a) is usually 0.01 µm or more, preferably 0.1 µm or more, particularly preferably 0.3 µm, and the upper limit of the thickness of the layer 31 is Usually 0.5 micrometer. After the plating layers (a) 31 are formed in this manner, a solder resist is applied and heat cured, leaving the terminal portion as described above.

After the tin plating layer (a) is formed by heating or the like accompanying the curing of the solder resist, the copper forming the wiring pattern is gradually diffused into the tin plating layer (a) formed as described above, and finally the layer is formed. Copper spreads.

After applying the copper diffusion tin plating layer (a) and the solder resist in this manner, a second tin plating is applied to the surface of the copper diffusion tin plating layer (a) formed on the surface of the wiring pattern (terminal portion) extending from the solder resist. To form a pure tin plated layer (b). This pure tin plated layer (b) is an almost pure tin plated layer which does not contain other metals immediately after formation, or the tin plated layer (a) present as a lower layer of the tin plated layer (b) is a copper diffusion layer. Part of the copper moves from the surface in contact with the copper diffusion tin plating layer (a) of (b) to the tin plating layer (b) to form a copper-tin-containing region. In the copper-tin-containing region, the copper content gradually decreases toward the surface, and finally, the copper content becomes zero (0) and changes to the pure tin plating layer (b). That is, when the copper concentration in the thickness direction in the copper-tin-containing region is measured, the copper concentration at the portion that is in contact with the surface of the copper diffusion tin plating layer (a) is the highest and is far from the copper diffusion tin plating layer (a). Therefore, its tin concentration is lowered, and finally, the content of copper becomes 0%, resulting in a pure tin plated layer (b).

By forming the copper-tin containing region in this way, it becomes difficult to form a cavity part in a terminal remarkably, and the occurrence of a whisker can be suppressed.

The thickness of the pure tin plated layer (b) is usually in the range of 0.01 to 0.5 µm, preferably 0.1 to 0.5 µm, and particularly preferably 0.1 to 0.3 µm, as shown in FIG. By making the thickness of the pure tin plated layer (b) within the above range, it is possible to securely bond and at the same time prevent the occurrence of whiskers without causing plating loosening, and short circuiting is unlikely to occur.

The film carrier tape for mounting the second electronic component of the present invention has a copper diffusion tin plating layer (a), a copper and tin containing region, and a pure tin plating layer (b) as described above, and the thickness of each layer has its effect. In consideration, it can set suitably within the said range.

Further, in the film carrier tape for mounting the second electronic component of the present invention, the sum of the thicknesses of the copper diffusion tin plating layer (a), the copper-tin-containing region, and the pure tin plating layer (b) is usually 0.02 to 0.6. It is in the range of 탆, preferably 0.03 to 0.6 탆, particularly preferably in the range of 0.2 to 0.6 탆, more preferably in the range of 0.4 to 0.5 탆. By forming the tin plated layer as described above, bonding reliability is high even in the film carrier tape for electronic component mounting of fine pitch, and by forming such a tin plated layer, the mechanical strength of the lead can be improved and whiskers can be completely prevented. The incidence of short circuits is significantly reduced.

EXAMPLE

Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

Example 1

A wiring pattern made of copper foil having a thickness of 18 µm was formed on the polyimide film. A 0.4-micrometer-thick tin plating layer was formed on the whole surface of the wiring pattern of this carrier tape, and it heat-processed at 125 degreeC for 60 minutes. Next, the solder resist was applied, leaving the lead portion of the wiring pattern, heated at 80 ° C for 45 minutes, exposed for 8 seconds, developed for 40 seconds, and heated at 150 ° C for 60 minutes to completely cure the solder resist.

After curing the solder resist in this manner, tin plating was applied to the lead portions exposed to a thickness of 0.2 µm, followed by heat treatment at 120 캜 for 60 minutes.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the cavity part was not formed in the lead part. Moreover, the phenomenon which plating penetrates into the bottom surface of a soldering resist was not seen, either.

In addition, the growth of the whisker in the lead portion thus formed was not seen.

Example 2

A 0.4-micrometer-thick tin plating layer was formed on the entire surface of the wiring pattern of the carrier tape formed in the same manner as in Example 1, and was heat treated at 125 ° C for 60 minutes. Next, the solder resist was applied, leaving the lead portion of the wiring pattern, heated at 80 ° C. for 45 minutes, exposed for 8 seconds, developed for 40 seconds, and heated at 150 ° C. for 60 minutes to completely cure the solder resist.

After hardening a soldering resist in this way, the tin plating layer was formed in the lead part exposed by the thickness of 0.2 micrometer.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the cavity part was not formed in the lead part. Moreover, the phenomenon which plating penetrates into the bottom surface of a soldering resist was not seen, either.

In addition, the growth of the whisker in the lead portion thus formed was not seen for a long time.

Example 3

A tin plated layer having a thickness of 0.2 μm was formed on the wiring pattern of the carrier tape formed in the same manner as in Example 1, and was then heat treated at 125 ° C. for 60 minutes. Solder resist was completely cured by applying solder resist, leaving the lead portion of this wiring pattern, heating at 80 ° C. for 45 minutes, exposing for 8 seconds, developing for 40 seconds, and heating at 150 ° C. for 60 minutes.

After curing the solder resist in this manner, tin plating was applied to the lead portions exposed to a thickness of 0.4 µm, followed by heat treatment at 125 ° C. for 60 seconds.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the cavity part was not formed in the lead part.

In addition, the growth of the whisker in the lead portion thus formed was not seen for a long time.

Example 4

A tin plated layer having a thickness of 0.2 μm was formed on the wiring pattern of the carrier tape formed in the same manner as in Example 1. Next, the solder resist was applied, leaving the lead portion of the wiring pattern, heated at 80 ° C. for 45 minutes, exposed for 8 seconds, developed for 40 seconds, and heated at 150 ° C. for 60 minutes to completely cure the solder resist.

After curing the solder resist in this manner, tin plating was applied to the lead portions exposed to a thickness of 0.4 µm, followed by heat treatment at 125 ° C. for 60 seconds.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the cavity part was not formed in the lead part.

In addition, the growth of the whisker in the lead portion thus formed was not seen for a long time.

[Examples 5-10]

The tin plating layer (a) of the thickness shown in Table 1 was formed in the wiring pattern of the carrier tape formed similarly to Example 1, and was heat-processed at 125 degreeC for 60 minutes. Next, in the same manner as in Example 1, the solder resist was applied and cured while leaving the lead portion of the wiring pattern.

After hardening a soldering resist in this way, the tin plating layer (b) was formed in the exposed lead part. After forming the tin plating layer (b) in this way, the sum of the thicknesses of the tin plating layer (a) and the tin plating layer (b) was measured using fluorescent X-rays, and the results are shown in Table 1.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the growth of the whisker was not seen. Moreover, the cavity part was not formed in the lead part. In addition, plating was not penetrated into the bottom of the solder resist.

Plating layer (a) Plating layer thickness Plating time (seconds) Plating temperature (℃) Plating layer (a) (μm) Plating layer [(a) + (b)] (µm) Example 5 One 30 0.023 0.542 Example 6 3 30 0.033 0.525 Example 7 One 45 0.041 0.543 Example 8 3 45 0.044 0.543 Example 9 One 70 0.040 0.581 Example 10 3 70 0.043 0.598

Example 11

A wiring pattern made of copper foil having a thickness of 18 µm was formed on the polyimide film. A tin-plated layer having a thickness of 0.04 占 퐉 is formed on the entire surface of the wiring pattern of the carrier tape. Then, a solder resist is applied, leaving the lead portion of the wiring pattern, heated at 80 DEG C for 45 minutes, exposed for 8 seconds, and then exposed for 40 seconds. After development, the solder resist was completely cured by heating at 150 DEG C for 60 minutes. During the thermosetting, copper in the wiring pattern was diffused into the tin plating layer to form a copper diffusion tin plating layer (a).

After curing the solder resist as described above, a tin plated layer having a thickness of 0.40 탆 is formed on the lead portion, and thermally sensitized to transfer a part of the copper in the copper diffusion tin plated layer (a) and the copper in the wiring pattern to the formed tin plated layer. Copper and tin-containing regions were formed with a thickness of 0.19 mu m. Therefore, the thickness of the pure tin plating in this film carrier tape for electronic component mounting is 0.21 micrometer.

The sum of the thicknesses of the copper diffusion tin plated layer (a), the copper-tin-containing region, and the pure tin plated layer (b) in the film carrier tape for mounting an electronic component is 0.44 m.

In addition, the sum of the thickness of the tin plating layer in this invention was measured using the fluorescent X-ray film thickness measuring apparatus.

When the obtained film carrier tape for electronic component mounting was observed using the electron microscope, the cavity part was not formed in the lead part. Moreover, the phenomenon which a plating liquid penetrates into the bottom surface of a soldering resist was not seen.

Moreover, the growth of the whisker from the lead portion thus formed was not seen.

In addition, the thickness of the pure tin plated layer measured using a cockle film thickness measuring apparatus was 0.21 µm, and the copper diffusion tin plated layer (a), copper and tin containing regions, and pure tin measured using a fluorescent X-ray film thickness measuring apparatus. The sum of the thicknesses of the plating layer (b) is 0.44 µm, and the thickness of the copper diffusion tin plating layer is 0.04 µm as described above, so that the thickness of the copper-tin-containing diffusion region is 0.19 µm.

In addition, the cockle film thickness measuring apparatus adds an electrolytic solution to a predetermined area of the tin plated layer and electrolyzes it, stops electrolysis at the time when the potential rises, calculates the amount of tin from the amount of current per unit area at this time, and measures the amount. It is a device for calculating the thickness of the pure tin plated layer from the specific area and specific gravity of tin.

The cavity was not generated in the film carrier tape for mounting electronic components obtained as described above, and the whisker was not generated in the film carrier tape for mounting electronic components.

According to the film carrier tape for mounting an electronic component of the present invention, the growth of the whisker in the wiring pattern can be almost completely prevented, and the bump electrodes and the wiring pattern are firmly and securely bonded. According to the present invention, a plating liquid or the like rarely penetrates between the bottom surface of the solder resist and the tin plating layer (a), and even if the plating liquid penetrates therebetween, the surface of the wiring pattern is covered with the tin plating layer (a). Since copper is not exposed, the cavity 35 (formula) 35 during tin plating on a conventional TAB tape does not occur, and the film carrier tape lead for mounting electronic components of the present invention is broken. It is hard to produce a back.

Moreover, whiskers are hard to grow in the film carrier tape for electronic component mounting of this invention.

In particular, the film carrier tape for mounting the second electronic component of the present invention in which copper and tin-containing regions are formed can almost completely prevent the occurrence of a cavity and at the same time almost prevent the occurrence of whiskers.

According to the manufacturing method of the present invention, whiskers do not grow during manufacturing, so that the manufacturing process can be easily managed.

Claims (19)

As a film carrier tape for mounting electronic components, a copper foil is attached to an insulating film, and the copper foil is etched to form a desired wiring pattern. A tin plating layer (a) formed by diffusion of copper by tin plating the entire wiring pattern; A protective layer formed of a cured body of solder resist at a position other than the terminal portion of the wiring pattern; The terminal portion has a tin plating layer (b) formed so as not to substantially contain copper on the surface of the tin plating layer (a). Film carrier tape for mounting electronic components comprising a. The method of claim 1, An average thickness of the tin-plated layer (a) in which copper is diffused is in the range of 0.01 to 0.5 µm. The method of claim 1, An average thickness of the tin-plated layer (b) containing substantially no copper is in the range of 0.01 to 0.5 占 퐉. The method of claim 1, The electronic component characterized in that the sum of the thickness of the tin-plated layer (a) in which copper formed on the surface of the wiring pattern made of copper and the tin-plated layer (b) substantially free of copper is in the range of 0.02 to 0.6 µm. Film carrier tape for mounting. A film carrier tape for mounting electronic components in which a copper foil is attached to an insulating film, and the copper foil is etched to form a desired wiring pattern. A tin plating layer (a) formed by diffusion of copper by tin plating on the entire wiring pattern; A protective layer formed of a cured body of solder resist at a position other than the terminal portion of the wiring pattern; The terminal portion has a tin plating layer (b) formed so as not to substantially contain copper on the surface of the tin plating layer (a). Including; In the terminal portion, the copper diffusion concentration gradually decreases from the surface of the tin plating layer (a) toward the surface of the tin plating layer (b), and copper and tin-containing regions are formed so as to be continuous with the tin plating layer (b). Film carrier tape for mounting electronic components. The method of claim 5, An average thickness of the tin-plated layer (a) in which copper is diffused is in the range of 0.01 to 0.5 µm. The method of claim 5, An average thickness of the tin-plated layer (b) containing substantially no copper is in the range of 0.01 to 0.5 占 퐉. The method of claim 5, The sum of the thickness of the tin-plated layer (a) in which copper formed on the surface of the copper wiring pattern is diffused, the copper-tin-containing region, and the tin-plated layer (b) substantially free of copper ranges from 0.02 to 0.6 µm. Film carrier tape for mounting electronic components, characterized in that the inside. Adhering copper foil to an insulating film, Etching the copper foil to form a desired wiring pattern; Forming a tin plating layer (a) in which copper is diffused in the entire wiring pattern; Hardening by applying a solder resist to a portion of the wiring pattern other than the terminal portion; After the solder resist is cured, tin plating is performed on the terminal portion of the wiring pattern to form a tin plating layer (b) substantially free of copper. Method of manufacturing a film carrier tape for mounting electronic components comprising a. The method of claim 9, After forming the tin plating layer (a) in which copper is diffused throughout the wiring pattern by electroless tin plating, the wiring pattern is heated to 80 to 150 ° C. before the solder resist is applied. Method of Making Tape. The method of claim 9, An average thickness of the tin-plated layer (b) containing substantially no copper is in the range of 0.01 to 0.5 µm. The method of claim 9, The electronic component characterized in that the sum of the thickness of the tin-plated layer (a) in which copper formed on the surface of the wiring pattern made of copper and the tin-plated layer (b) substantially free of copper is in the range of 0.02 to 0.6 µm. Manufacturing method of film carrier tape for mounting. Adhering copper foil to an insulating film, Etching the copper foil to form a desired wiring pattern; Tin-plating the entire wiring pattern; Hardening by applying a solder resist to a portion of the wiring pattern other than the terminal portion; After the solder resist is cured, tin plating the terminal portions of the wiring patterns again. In the manufacturing method of the film carrier tape for mounting electronic components comprising: In the terminal portion, the copper diffusion concentration gradually decreases toward the surface of the tin-plated layer (a) in which copper is diffused and the tin-plated layer (b) substantially free of copper from the surface of the tin-plated layer (a). And forming a copper-tin-containing region so as to be continuous with the tin-plated layer (b) which does not contain. The method of claim 13, After forming the tin plating layer (a) in which copper is diffused throughout the wiring pattern by electroless tin plating, the wiring pattern is heated to 80 to 150 ° C. before the solder resist is applied. Method of Making Tapes. The method of claim 13, An average thickness of said tin plating layer (a) is in the range of 0.01-0.5 micrometer, The manufacturing method of the film carrier tape for electronic component mounting. The method of claim 13, An average thickness of the tin-plated layer (b) containing substantially no copper is in the range of 0.01 to 0.5 µm. The method of claim 13, A method for producing a film carrier tape for mounting electronic components, characterized in that the average thickness of the copper-tin-containing region in which the copper diffusion concentration gradually decreases is in the range of 0.01 to 0.5 µm. The method of claim 13, The electronic component characterized in that the sum of the thickness of the tin plating layer (a) in which copper formed on the surface of the wiring pattern made of copper diffuses and the tin plating layer (b) substantially free of copper are in the range of 0.02 to 0.6 µm. Manufacturing method of film carrier tape for mounting. The method of claim 13, Manufacture of a film carrier tape for mounting an electronic component, characterized in that the average copper concentration in the copper of the copper-tin-containing region where the copper diffusion concentration gradually decreases is lower than the average copper concentration in the tin-plated layer (a) on which copper is diffused. Way.