JP2000164645A - Electronic part mounting film carrier tape and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a continuity failure from occurring in a film carrier tape by a method wherein a part of a solder resist layer near a flexure slit is formed thicker than the other part of the solder resist layer. SOLUTION: An electronic part mounting film carrier tap (TAB) is composed of an insulating film 10 and a wiring pattern 30 formed of an electrolytic copper foil pasted on the film 10 with an adhesive agent layer 12. A solder resist 20 is applied on the wiring pattern 30 to protect its surface. At this point, a part of the solder resist 20 adjacent to a flexure slit 45 is formed thicker than the other part of the resist 20. By this setup, a continuity failure can be restrained from occurring in a TAB tape, and a device can be surely mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film carrier tape (TAB (Tape Automated Bondin) for mounting an electronic component such as an IC or an LSI and bending it.
g) tapes) and a method for producing this tape.

[0002]

BACKGROUND OF THE INVENTION In recent years, electronic devices such as notebook personal computers have become smaller and lighter. Semiconductor I
The wiring of C is further miniaturized.

With the miniaturization of such electronic devices, TAB
Tape is being used. This TAB tape is manufactured as follows. For example, a copper foil is adhered to an insulating film such as a polyimide film, a photoresist is applied to the surface of the copper foil, and a portion of the photoresist other than a wiring pattern to be formed is exposed to light and the photoresist is exposed to light. Is removed. Next, the copper foil in the portion where the photoresist has been removed is removed by etching, and the photoresist is removed to form a wiring pattern. TAB with wiring pattern formed in this way
The tape is coated with a solder resist that becomes a protective layer of the circuit except for connection parts such as inner leads and solder ball terminals. After the solder resist is applied in this manner, a tin plating layer is formed on the exposed connection portion.

[0004] Such TAB tapes are used in various forms. One of the usage forms of such TAB tapes is to use a TAB tape to which a device is bonded by bending the tape. For example, a TAB tape for driving a liquid crystal element has one end of a lead bonded to the liquid crystal element.
After being bent twice, the lead at the other end goes around the back surface of the liquid crystal element and is bonded to the external wiring board.

[0005] In the TAB tape to be used in this manner, a flex slit is formed in advance in the portion of the insulating film to be bent. A wiring pattern is formed so as to extend over the flex slit formed in the bent portion. Since the flex slit portion has the insulating substrate cut out, the wiring pattern in the flex slit portion is supported only by the back solder resist, and the strength of the wiring pattern in this portion is the lowest. Become. In addition, in the bent portion, there is a problem that a pinhole is apt to be generated in the solder resist due to the bending during the application. In order to increase the strength of the wiring pattern at such a bent portion and further reduce the occurrence of pinholes, it is conceivable to apply a thick solder resist. The thickness of the solder resist in the lead portion is also increased, and the bonding between the outer lead and the terminal with solder of the device is hindered by the thick solder resist, and device mounting failure is likely to occur.

Therefore, in the TAB tape having such a bent portion, there has been a problem that poor conduction is likely to occur at the bent portion and at the joint between the outer lead and the soldered terminal.

[0007]

An object of the present invention is to provide a TAB tape having a bent portion with less occurrence of conduction failure, capable of reliably mounting devices, and hardly causing a defect in protection of a wiring pattern by a solder resist. And a method of manufacturing the same.

[0008]

SUMMARY OF THE INVENTION A film carrier tape for mounting an electronic component according to the present invention has a wiring pattern forming portion excluding a lead portion of a wiring pattern, in which a desired wiring pattern is formed on an insulating film having a bent slit. An electronic component mounting film carrier tape in which a solder resist layer is applied on an insulating film including: a solder resist layer in a portion other than the vicinity of the bending slit; It is characterized in that it is formed thicker than the layer thickness.

In such a film carrier tape for mounting electronic parts, a desired wiring pattern is formed on an insulating film in which a bending slit is formed, and then a wiring pattern forming portion excluding a lead portion of the formed wiring pattern is formed. After applying the solder resist on the insulating film containing
It can be manufactured by further applying a solder resist near the bending slit to which the solder resist has been applied.

[0010] In the film carrier tape for mounting electronic parts of the present invention, a bending slit is formed in a portion where the insulating film is bent. The wiring pattern is also formed in this slit portion, and since there is no insulating film in this portion, the strength of the wiring pattern at the bent portion becomes the lowest. Although the strength of the wiring pattern is low as described above, the TAB tape is bent at this portion, so that the wiring pattern is likely to be broken at this bent portion. Since the solder resist is thicker than other parts,
The wiring pattern at the bent portion is protected by the solder resist. In addition, this solder resist is thickened as described above at the bent portion, but the thickness is equal to the normal solder resist at the other parts, so when soldering the device to the outer lead, the solder resist is There is no hindrance to the connection between the soldered terminal and the lead.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Next, the film carrier tape for mounting electronic parts of the present invention and a method for manufacturing the same will be described in detail. In the drawings shown below, common members are assigned common numbers.

FIG. 1 is a front view showing an example of a film carrier tape for mounting electronic parts of the present invention, and FIG. 2 is a perspective view showing an example in which the film carrier tape for mounting electronic parts is bent and used. FIG. 3 is a sectional view taken along the line AA in FIG. 2 showing the state of the electronic component mounting film carrier tape which is used in such a bent state. FIG. 4 is a partial sectional view showing an example of a sectional structure of the bent portion.

On the film carrier tape 1 for mounting electronic parts of the present invention, an insulating film 10 and a wiring pattern 30 made of an electrolytic copper foil adhered to the surface by, for example, an adhesive layer 12 are laminated in this order. ing. The solder resist 20 is applied on the wiring pattern 30 so as to protect the surface.

The insulating film 10 constituting the electronic component mounting film carrier tape of the present invention is made of a flexible resin film. In addition, the insulating film 10 has chemical resistance that is not affected by such a chemical because it comes into contact with an acid or the like at the time of etching, and has heat resistance that does not deteriorate even by heating during bonding. Examples of the resin that forms such a flexible resin film include glass epoxy, BT resin, polyester, polyamide, and polyimide. Particularly, in the present invention, it is preferable to use a film made of polyimide.

Examples of the polyimide film forming the insulating film 10 include a wholly aromatic polyamide synthesized from pyromellitic dianhydride and an aromatic diamine, and a synthetic film formed from biphenyltetracarboxylic dianhydride and an aromatic diamine. 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 the insulating film 10 is usually 25 to 125.
μm, preferably in the range of 50 to 75 μm.

In such an insulating film 10, bent slit holes 45 (flex slits 45), sprocket holes 42, outer lead cut holes 43, and the like are formed by punching at positions corresponding to the device holes 41 and the bent portions. Have been.

The wiring pattern 30 is formed by applying an insulating adhesive to at least one surface of the insulating film 10 on which the predetermined holes 41, 42, 43, 45,. A layer 12 is formed, a copper foil is bonded by the adhesive layer 12, and the copper foil is etched to form a layer. Here, as the copper foil, any of an electrolytic copper foil and a rolled copper foil can be used, but in the present invention, it is preferable to use an electrolytic copper foil capable of coping with the recent fine pitch.

The adhesive used here needs properties such as heat resistance, chemical resistance, adhesive strength and flexibility. Examples of the adhesive having such characteristics include an epoxy-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 such an adhesive layer is usually in the range of 3.7 to 23 μm, preferably 10 to 21 μm. When the copper foil is attached to the insulating film 10 as described above, the copper foil can be attached without using an adhesive.

The adhesive layer 12 made of such an adhesive
May be applied to the surface of the insulating film 10 or provided on the surface of the electrolytic copper foil. As the electrolytic copper foil used here, a copper foil having a thickness usually used in the production of a TAB tape can be used, but in order to produce a fine pitch TAB tape, the copper foil is usually A copper foil having a thickness in the range of 6 to 75 μm, preferably 9 to 75 μm, more preferably 9 to 50 μm is used. By using such a thin electrolytic copper foil, it is possible to easily form inner leads having a narrow pitch width.

After the copper foil is attached to the surface of the insulating film, a photoresist is applied to the surface of the copper foil,
A desired wiring pattern is baked on the photoresist to cure the photoresist, and the uncured portions of the photoresist are removed. Conversely, a photoresist that can be dissolved in a specific medium by exposure to light can also be used.

The copper foil on which the desired wiring pattern has been formed is etched with the photoresist thus cured to dissolve and remove the copper foil in a portion where no photoresist is present, thereby forming a wiring pattern 3 made of copper foil on the surface of the insulating film.
0 is formed.

The wiring pattern 3 is thus etched.
After forming 0, the hardened photoresist is removed with, for example, an alkaline solution. In the present invention, after a predetermined wiring pattern is formed in this way, the solder resist is removed except for the tips of the inner lead 51 and the outer lead 52 (input outer lead 52a, output outer lead 52b) to be plated in the next step. Is applied. In the present invention, there are various methods for applying the solder resist. For example, the solder resist is applied uniformly over the entire surface (1).
After the second application), a method of applying the solder resist again near the flex slit 45 (second application),
A method of applying a solder resist in the vicinity of the flex slit 45 by using a coating apparatus in which the amount of the solder resist applied in the vicinity of the flex slit 45 is increased in advance can be exemplified.

In the method of applying the solder resist twice, the first coating thickness of the solder resist is usually 10 μm or more and less than 35 μm, preferably 15 μm or less, as a dry thickness.
〜30 μm. By applying the solder resist 20 to the entire thickness at such a thickness, the wiring pattern portion which is not bent is protected by the solder resist 20 having a sufficient thickness. For example, in the subsequent plating step, the solder resist 20 layer thus formed is formed. Functions as a masking agent layer. Further, since the solder resist 20 layer formed in this manner has an unusually thick coating thickness, for example, when bonding the outer lead 52 to a soldering portion of a device (not shown), the terminal with solder and the outer It does not hinder contact with the leads. Therefore, poor connection hardly occurs between the outer lead and the soldered terminal of the device.

As described above, the surface of the wiring pattern 30 at the bent portion (flex slit) portion is supported by the solder resist layer by the first coating, but the insulating film 10 is cut off the back surface of the wiring pattern 30 at this portion. Since the flex slit 45 is formed in a chipped manner, the flex slit 45 is not supported by the insulating film 10 and only the back solder resist 20b is present. That is, the surface of the wiring pattern 45 formed over the flex slit 45 is formed by the solder resist 20.
Only the back surface is covered with the back surface solder resist 20b. The TAB tape 1 of the present invention is used by being bent at the flex slit 45, as shown in FIGS. 2, 3 and 4, and the wiring pattern 30 of the flex slit 45 is located at the bent portion. , Despite the part where bending stress is applied,
Solder resist 20 and backside solder resist 20
only protected by b. Therefore, the strength of the wiring pattern 30 formed over the flex slit 45 is lower than that of the other portion due to the absence of the insulating film. The wiring pattern formed in the 45 parts is often damaged.

In the present invention, the flex slit 45
A solder resist is further applied on the coating layer of the solder resist 20 including the vicinity to form an overcoat solder resist layer 20a, thereby protecting the wiring pattern near the flex slit 45.

The thickness of the overcoated solder resist 20a is the total dry coating thickness of the solder resist 20 already applied, and the thickness of the solder resist layer near the flex slit 45 is usually 15 to 80
It is applied so as to be in the range of μm, preferably in the range of 25 to 60 μm (excluding the thickness of the backside solder resist layer). Therefore, when the overcoat solder resist 20a layer is overcoated as described above, the coating thickness of the overcoat solder resist 20a is usually 5 to 5 mm in dry coating thickness.
It is in the range of 45 μm, preferably 15-25 μm.

The overcoated solder resist 20a layer
Flex slit 45 formed by punching or the like
Is usually formed with a width and a length of 101 to 200%, preferably 101 to 150% with respect to the width and the length.

The flex slit 45 having such a thickness is used.
By thickening the solder resist in the vicinity, even if the TAB tape of the present invention is bent and used, since the solder resist in the vicinity of the flex slit 45 is thick,
The wiring pattern 30 formed in this portion is sufficiently protected, and disconnection or the like is unlikely to occur.

As described above, the overcoated solder resist 20
The layer a can be applied in a step after the solder resist 20 is applied to a portion to be applied in advance and the solder resist 20 layer is cured.
The coating amount can be partially changed so that the coating thickness in the vicinity of 5 is as described above, and the coating can be performed simultaneously with other portions.

When the number of times of application of the solder resist is one, usually, the solder resist is partially applied to the solder resist by a method such as changing a mesh size of a screen near the flex slit 45 by using a screen printing technique. It is possible to adjust the amount of application.

Examples of the solder resist used in the present invention include conventionally used solder resists such as an epoxy solder resist, a urethane solder resist, and a polyimide solder resist.

Further, in the present invention, the composition of the solder resist for forming the solder resist 20 layer to be applied first, and the overcoat solder resist 20a to be applied thereon
The composition of the solder resist forming the layer may be the same or different. For example, by blending different coloring agents into the overcoated solder resist layer and the previously applied solder resist layer, it can be confirmed that the overcoated solder resist layer has been reliably formed.

Also, since the TAB tape of the present invention is used by being bent, elasticity is imparted as an overcoating solder resist so that cracks and the like do not occur in the solder resist formed near the flex slit 45 due to such bending. It is preferable to use a solder resist.

As a method for imparting elasticity to the solder resist, for example, the above-mentioned epoxy-based solder resist, urethane-based solder resist, polyimide-based solder resist, or the like may be added to an elastic (co) polymer (eg, a rubber component). Etc.) can be included. Further, by partially copolymerizing an elastomer component with a component forming the solder resist as described above, the elasticity of the obtained solder resist itself can be improved.

After applying the solder resist near the flex slit 45 as described above to a greater thickness than other portions,
Usually, heating is performed to remove the solvent contained in the solder resist and to proceed with the curing reaction of the solder resist. At this time, the heating temperature is usually from room temperature to 200 ° C.
Hereinafter, the temperature is preferably 120 to 160 ° C., and it is preferable that the film be maintained in a reduced pressure state during or after the heating. By maintaining the reduced pressure state in this manner, the solvent or bubbles in the solder resist layer can be more reliably removed, and the generation of voids due to the removal of the solvent or bubbles can be effectively prevented.

After the formation of the solder resist layers 20 and 20a, the wiring pattern and the insulating film on which the solder resist layers 20 and 20a are formed are transferred to a plating bath, and a tin plating layer is formed on the surface of the wiring pattern. In the present invention, the plating layer can be formed of various metals.
It is a tin plating layer. The tin plating layer is formed by a method such as electroless tin plating or electric tin plating. The initial tin plating layer thus formed is usually substantially made of tin, but may contain other metals as long as the characteristics of the tin plating layer are not impaired.

The thickness of the tin plating layer is 0.01 to 0.8 μm.
It is preferably within the range of m. By forming the tin plating layer with such a thickness, when bonding the inner lead and the bump of the device, a metal such as gold forming the bump and tin form an appropriate amount of eutectic,
The inner lead and the bump can be satisfactorily bonded, and no excessive eutectic is formed. Even if the TAB tape has a fine pitch, a short circuit may occur at the inner lead during bonding. Few. This tin plating layer is formed on the entire wiring pattern exposed from the portion where the solder resist 20, 20a layer is formed. By heating after forming the tin plating layer in this way, a part of the copper forming the lead diffuses into the tin plating layer and generation of whiskers from the lead portion can be suppressed. In addition, the formation of whiskers can also be controlled by forming a tin plating layer as described above and then performing tin plating (flash plating) so that a thin tin plating layer is formed on the surface of the formed tin plating layer. .

In the TAB tape of the present invention, the plating layer is usually formed after forming the solder resist layer as described above, but the plating layer may be formed before the solder resist is applied. That is, after the wiring pattern is formed by etching, the insulating film on which the wiring pattern is formed is transferred to a plating tank to form, for example, a tin plating layer, and then a solder resist is applied from above the plating layer thus formed. Can be.

After tin plating in this manner, a solder resist can be applied so that the application thickness near the flex slit 45 is thicker than other portions.
By applying tin plating to the entire wiring pattern before applying the solder resist in this way, even if the solder resist layer has a poor adhesion part, even if the plating solution infiltrates from this poor adhesion part, the wiring pattern under the solder resist layer will be No pitting or the like occurs.

[0040]

The TAB tape of the present invention is a type of TAB tape which has a bending slit (flex slit) 45 formed therein and is used by being bent from the flex slit 45. And in the TAB tape of the present invention, the bending slit (flex slit) is used.
The wiring pattern 30 on the top 45 is protected by a solder resist applied more thickly than other parts, and even if the TAB tape of the present invention is bent and used, the wiring pattern 30 in this flex slit 45 is Less likely to be damaged. In addition, the thickness of the solder resist near the flex slit is increased, and the thickness of the solder resist layer at other portions, particularly near the outer leads, is not different from the thickness of the normal solder resist. And the soldering terminal of the same. Further, in the present invention, after the solder resist is applied to the entire portion to be coated with the solder resist, the solder resist is applied again in the vicinity of the flex slit, and the thickness of the solder resist in the vicinity of the flex slit is made thicker than other portions. Thereby, a solder resist layer with few defects of the solder resist such as voids can be formed.

According to the manufacturing method of the present invention, it is possible to easily manufacture a TAB tape in which a wiring pattern is hardly broken at a flex slit when the device is bent and used, and a device can be securely bonded to an outer lead. it can.

The TAB tape of the present invention can be suitably used as a TAB tape to be used by bending.
In particular, the TAB tape of the present invention is a TAB tape having solder terminals.
It is highly useful as a B tape.

[0043]

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 to these examples.

[0044]

Example 1 50 μm thick with epoxy adhesive applied
A device hole, a sprocket hole, and a flex slit were formed by punching in the polyimide film. Next, a copper foil having a thickness of 18 μm was attached to the surface of the polyimide film.

Further, a photoresist was applied on the copper foil, and the photoresist was exposed and etched to form a wiring pattern on the copper foil. Next, a urethane-based solder resist was applied to a dry thickness of 20 μm (first time) from above the formed wiring pattern except for the tips of the inner leads, the input outer leads, and the output outer leads.

Further, a urethane-based solder resist is applied to a flex slit provided at the side end of the sprocket hole in a range of 10% wider than the width and length of the flex hole so that the dry coating thickness becomes 10 μm. (2nd time)

After the solder resist was applied twice, the temperature was gradually raised to a temperature of 120 to 160 ° C. over 3 hours and heated to harden the solder resist. In addition,
This heating was performed under reduced pressure of 0.1 atm.

The thickness of the cured solder resist was 50 μm on the flex slit, and was 20 μm in other portions, for example, near the outer leads. After forming the solder resist layer in this manner, the film was transferred to an electroless tin plating bath, and a tin plating layer having a thickness of 0.4 μm was formed on the surface of the wiring pattern on which the solder resist was not applied.

After forming the tin plating layer, the TAB tape was heated and held. After bonding the device to the TAB tape thus obtained and further performing a bending durability test by bending it 100 times at the flex slit portion, the electrical characteristics of the TAB tape were measured.

As a result of the measurement of the bonding failure and the disconnection failure caused by the flex slit on the 30 TAB tapes as described above, the occurrence rate of the conduction failure due to such causes was 3%.

[0051]

Comparative Example 1 In Example 1, except that the first solder resist coating thickness was 40 μm and the second solder resist coating was not performed, a thick uniform solder resist layer having a total thickness of 40 μm was formed. Is the same as TAB
Tape was manufactured.

Example 1 of the obtained TAB tape
In the same manner as in the above, the electrical characteristics were measured. As a result, as a result of measuring the conduction failure due to the bonding failure with respect to the 30 TAB tapes, the occurrence rate of the conduction failure was 47%, and most of the causes of the conduction failure were due to the device bonding failure due to the thick coating of the solder resist. Met.

[0053]

Comparative Example 2 In Example 1, except that the first solder resist coating thickness was 15 μm, and a 15 μm thin uniform solder resist layer was formed as a whole without performing the second solder resist coating. A TAB tape was manufactured in the same manner.

Example 1 of the obtained TAB tape
In the same manner as in the above, the electrical characteristics were measured. As a result, as a result of measuring the bonding failure and the disconnection failure caused by the flex slit with respect to the 30 TAB tapes, the occurrence rate of the conduction failure due to these causes was 10%, and most of the causes of the conduction failure were flex. The wiring was broken at the slit. Further, since the solder resist was thin, defects in the solder resist layer such as voids were observed in 15% of the manufactured TAB tapes.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a film carrier tape (TAB tape) for mounting electronic components according to the present invention.

FIG. 2 is a perspective view schematically showing a state in which the above-mentioned film carrier tape (TAB tape) for mounting electronic components is bent and used.

FIG. 3 is a sectional view taken along the line AA in FIG. 2;

FIG. 4 is a cross-sectional view illustrating an example of a cross section of a bent portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Insulating film 12 ... Adhesive layer 20 ... Solder resist 20a ... Overcoat solder resist 20b ... Backside solder resist 30 ... Wiring pattern (copper foil) 41 ... Device hole 42・ ・ ・ Sprocket hole 43 ・ ・ ・ Cutting hole of outer lead 45 ・ ・ ・ Flex slit (bending slit) 51 ・ ・ ・ Inner lead 52a ・ ・ ・ Input outer lead 52b ・ ・ ・ Output outer lead

Claims (7)

[Claims] 1. A desired wiring pattern is formed on an insulating film in which a bending slit is formed, and a solder resist layer is applied on the insulating film including a wiring pattern forming portion excluding a lead portion of the wiring pattern. Electronic component mounting film carrier tape, wherein the layer thickness of the solder resist layer in the vicinity of the bending slit is formed to be thicker than the layer thickness of the solder resist layer in a portion other than the vicinity of the bending slit. Characteristic film carrier tape for mounting electronic components. 2. The solder resist layer in the vicinity of the bent slit has a thickness of 15 to 80 μm, and the thickness of the solder resist layer other than in the vicinity of the bent slit is 1
2. The film carrier tape for electronic component mounting according to claim 1, wherein the thickness is 0 μm or more and less than 35 μm. 3. The film carrier tape for mounting electronic parts according to claim 1, wherein at least the leads exposed from the solder resist layer are plated. 4. The film carrier tape for electronic component mounting according to claim 1, wherein the solder resist is made of a thermosetting resin containing an elastomer component. 5. A desired wiring pattern is formed on the insulating film on which the bending slit is formed, and then, a solder resist is applied on the insulating film including a wiring pattern forming portion excluding a lead portion of the formed wiring pattern. And then further applying a solder resist in the vicinity of the bending slit to which the solder resist has been applied, a method for manufacturing a film carrier tape for mounting electronic components. 6. A solder resist is applied so as to have a dry thickness of 10 μm or more and less than 35 μm on an insulating film including a portion where a wiring pattern is formed except for a lead portion. The method according to claim 4, wherein the coating is performed so as to have a thickness of 15 to 80 m. 7. The method according to claim 5, wherein a solder resist paint obtained by dissolving or dispersing a thermosetting resin containing an elastomer component in a solvent is applied.