TWI486103B - Flexible printed circuit board with attached plate and method for manufacturing the same - Google Patents

Description

Flexible printed circuit board with strong plate and manufacturing method thereof

The present invention relates to a flexible printed circuit board with a strong plate and a method of manufacturing the same.

In an hard disk drive (hereinafter simply referred to as "HDD"), an actuator that holds the magnetic head element portion is assembled. The actuator is rotated by the rotation axis as a center, and the head element portion is a desired track that is positioned on the disk. In this actuator, an FPC unit that performs signal transmission between the head element portion and the control circuit is fixed. This FPC unit is a preamplifier integrated circuit having a flexible printed circuit board (hereinafter, simply referred to as "FPC board") and a predetermined bump portion mounted on the FPC board.

The FPC substrate is a signal transmission between the control circuit and the preamplifier integrated circuit. The preamplifier integrated circuit is connected to the magnetic head element portion by the transmission wiring, and the current output from the preamplifier integrated circuit is transmitted to the magnetic head element portion by the transmission wiring (for example, refer to Patent Document 1) .

In recent years, with the speeding up of HDDs, the transfer speed of data has rapidly increased. Along with this, the amount of heat generated by the preamplifier integrated circuit is increased. Then, as a countermeasure against heat dissipation, a reinforcing plate made of a metal having excellent thermal conductivity is provided on the back surface of the FPC board on which the preamplifier integrated circuit is mounted (see, for example, Patent Document 2). Generally, as such a reinforcing plate, a reinforcing plate made of aluminum is used (hereinafter, also referred to as "aluminum reinforcing" board".

In order to bond the aluminum reinforcing plate layer to the FPC board to produce an FPC board with a strong plate, various adhesives such as acrylic, epoxy, and urethane can be used. When an HDD application or the like is required to be pure in terms of external air characteristics, an acrylic adhesive is used. The acrylic binder is recognized as a standard binder in applications such as HDD, and is non-contaminating to the periphery.

In order to bond the aluminum reinforcing plate layer to the FPC board, it is necessary to pressurize and heat the FPC board and the aluminum reinforcing board which are laminated via the bonding agent.

Acrylic binders are designed to exhibit sufficient adhesion and must be processed for a longer period of time (eg, 45 to 120 minutes) in the properties of the material. Here, the method of performing the press processing in such a long time is referred to as "long-term forming method". The press device used to perform the press process is relatively expensive, and the number of introductions is limited. Therefore, if the press device is occupied for a long time by the one-time press process, there is a problem that the production efficiency of the FPC board with the strong plate is lowered.

On the other hand, in the above-described long-term molding method, there is a method in which the press is processed for a short period of time (hereinafter referred to as "rapid forming method". In this rapid forming method, the time of the press processing is regarded as a short time (10 minutes or less). To the extent that the heat treatment called post-baking heat treatment is performed after the press processing, the forming pressure and the forming temperature of the press forming process of the rapid forming method are approximately the same as those of the press processing of the long-time forming method. The post-baking heat treatment after the treatment is, for example, at 150 ° C or more for two hours or more. Under the conditions.

In the rapid forming mode, the press is processed for a short period of time, so that the press device does not occupy the press device for a long time in one press process. Further, after the press processing, it is not necessary to lower the temperature of the FPC board when the FPC board is to be taken out from the press device. That is, the post-baking heat treatment in the next step can be carried out with a cooling process which is necessary in a long time forming mode. Therefore, the occupation time of the press device is made shorter. Further, the post-baking heat treatment can be carried out in a large amount, for example, by using a plurality of furnaces in parallel. Therefore, according to the rapid prototyping method, compared with the long-time forming method, there is an advantage that the production efficiency of the FPC board with the strong plate can be greatly improved.

However, when the rapid prototyping method is applied in the past, since the pressurization time (press treatment) is short, it is impossible to ensure proper curing conditions of the acrylic binder. As a result, even after the post-baking heat treatment, there is a problem that sufficient adhesion cannot be obtained. Moreover, the method of improving the adhesion by the fixing effect by the roughening of the surface of the aluminum plate has been known in the past, but even when this method is used, sufficient bonding strength cannot be obtained under the normal state (normal temperature, normal humidity). (Hereinafter, it is called "stripping strength".

In addition, the FPC substrate with the strong plate produced by the conventional rapid prototyping method has a high adhesion property between the aluminum reinforcing plate and the FPC substrate in a imaginary humid environment which is an environment in which the FPC substrate is used. reduce. That is, in the conventional art, there is also a problem that water-resistant adhesion is deteriorated.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-287197

Patent Document 2: Japanese Laid-Open Patent Publication No. 2002-314207

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flexible printed circuit board and a method for producing the same, which are applicable to a rapid forming method and have excellent adhesion.

According to a first aspect of the present invention, a flexible printed circuit board with a strong plate is provided, comprising: a flexible printed circuit having a substrate and a wiring pattern formed on one surface of at least one of the substrates; a circuit board and a metal plate for reinforcing the flexible printed circuit board, and a chemical treatment film containing zirconia in a mask facing the flexible printed circuit board is bonded to the substrate via an acrylic adhesive layer Metal plate.

According to a second aspect of the present invention, a flexible printed circuit board with a strong plate is provided, comprising: a first mounting region including a convex rail portion formed on a surface of the substrate; and a second solid And a mounting region that is disposed between the first mounting region and the second mounting region, and includes the protruding rail electrically connecting the first mounting region and the protruding rail of the second mounting region a flexible printed circuit board in a wiring area of the wiring of the portion; and an acrylic adhesive layer formed on the back surface of the substrate in the first mounting region and/or the second mounting region; A mask corresponding to the flexible printed circuit board contains a chemically treated film of zirconia, and is bonded to the aluminum reinforcing plate of the substrate via the acrylic adhesive layer.

According to a third aspect of the present invention, a flexibility of an attached strong plate is provided A method for producing a printed circuit board, characterized in that a chemical treatment film containing zirconium oxide is formed on a surface of an aluminum plate, and the aluminum plate on which the chemical treatment film is formed is subjected to the chemical treatment film and the acrylic system via an acrylic adhesive. a plastic film deposited on the flexible printed circuit board in a manner of contacting the adhesive layer, whereby the laminated body of the aluminum plate and the plastic film is laminated via the acrylic adhesive, and heated by a press device The press processing for pressurizing the above-mentioned laminated body is performed by using a furnace apparatus for a post-baking heat treatment for heating the laminated body longer than the above-described press processing.

In the present invention, a metal plate on which a chemical treatment film containing zirconium oxide is formed on the surface is used as a reinforcing plate for a flexible printed circuit board. The metal plate having this chemical treatment film is bonded to the flexible printed circuit board via the acrylic adhesive layer. In the heat treatment of the hardened acrylic binder, the hydroxyl group in the chemically treated film containing zirconium oxide is chemically reacted with a carboxyl group or a hydrocarbon group in the acrylic binder. Thereby, a strong chemical chain is formed at a high density. This chemical chain constitutes a crosslink that spans the interface between the chemical treatment film and the acrylic binder layer. Therefore, according to the present invention, high bonding strength can be obtained even when the rapid forming method is employed.

Further, the chemical chain constituting the above cross-linking has a strong adhesive strength and is not affected by the hydroxyl group having water molecules, so that sufficient adhesion can be ensured even in a wet environment. That is, according to the present invention, high water-resistant adhesion can be obtained.

Hereinafter, the FPC unit to which the strong plate is attached according to the embodiment of the present invention will be described with reference to the drawings. In addition, constituent elements having the same functions are denoted by the same reference numerals, and detailed description thereof will be omitted. The pattern is model, the relationship between the thickness and the plane size, the ratio of the thickness of each layer, etc. are different from the actual one.

An FPC board with a strong plate according to an embodiment of the present invention will be described with reference to Fig. 1 . Fig. 1(a) is a cross-sectional view showing the FPC board 1 of the reinforcing plate of the present invention, and Fig. 1(b) is a bottom view showing the FPC board 1 to which the strong board is attached.

The FPC board 1 with a strong plate has an FPC board 2 having a wiring pattern on its surface, and an acrylic adhesive layer 3 provided on the back surface of the FPC board 2, and is adhered to the FPC board via the acrylic adhesive layer 3. 2 aluminum reinforcement plate 4 on the back.

As can be seen from the first (a) and the first (b), the FPC board 2 is composed of the mounting regions 2a, 2b and the wiring region 2c. The mounting areas 2a, 2b are convex rail portions 22a, 22b for mounting electronic components. The wiring area 2c is provided so as to be sandwiched between the mounting area 2a and the mounting area 2b, and has wiring for performing signal transmission between the mounting area 2a and the mounting area 2b.

The acrylic adhesive layer 3 is provided between the substrate 21 of the FPC board 2 and the aluminum reinforcing plate 4. The acrylic adhesive layer 3 is an acrylic adhesive which is subjected to pressure treatment and heat treatment.

As described in detail below, the aluminum reinforcing plate 4 is an aluminum plate to which a chemical treatment by a zirconia chemical treatment liquid is applied to a predetermined shape. As described above, the aluminum reinforcing plate 4 is a chemical treatment film 4a containing zirconium oxide (ZrO ₂ ) at least on the side opposite to the FPC board 2 .

As can be seen from the first (a) and the first (b), the aluminum reinforcing plate 4 is adhered to the back surface of the FPC board 2 of the mounting regions 2a, 2b via the acrylic adhesive layer 3. That is, the chemical treatment film 4a is in contact with the acrylic adhesive layer 3, and the aluminum reinforcing plate 4 is adhered to the back surface of the FPC board 2. The aluminum reinforcing plate 4 can function as a reinforcing plate for reinforcing the FPC board 2 without buckling the FPC board 2 of the mounting areas 2a, 2b, and can also be functionally mounted as heat sink on the rail portions 22a, 22b. The heat sink of the electronic parts. Moreover, the aluminum reinforcing plate 4 is not attached to the back surface of the FPC board 2 of the wiring area 2c. As such, the wiring region 2c is configured to have flexibility.

Hereinafter, a detailed configuration of the FPC board 2 will be described.

As can be seen from Fig. 1(a), the FPC board 2 is a substrate 21 having a plastic film, a wiring pattern 22 formed on one side of the substrate 21, and a plastic provided via the adhesive layer 23. The cover film 24 formed by the film.

The wiring pattern 22 is made of a conductive material such as copper (Cu). This wiring pattern 22 is formed into a predetermined circuit pattern shape by using a subsidized subtractive method, a semi-additive method, a printing method, or the like. As can be seen from Fig. 1(a), a part of the wiring pattern 22 is covered by the cover film 24, and constitutes the convex rail portions 22a, 22b for mounting the electronic components. Further, the wiring pattern 22 may be laminated on the substrate 21 via a bonding agent or may be laminated on the substrate 21 without using a bonding agent.

The cover sheet 24 is insulated and covered by the adhesive layer 23 except for the convex Wiring patterns 22 of the rail portions 22a, 22b. Further, as the material of the binder layer 23, various binders such as acrylic, epoxy or urethane can be used. As described above, an acrylic adhesive excellent in non-contaminating property to the periphery is preferably used.

Further, as the plastic film used for the substrate 21 and the cover sheet 24, there are exemplified by a polyimide film, a polyester film, a polyethylene naphthalate film, a polyether sulfon film, a polyether quinone film, and a polyether. An ether ketone film or a poly-strand acid film.

Hereinafter, the state of adhesion between the FPC board 2 and the aluminum reinforcing plate 4 will be described in detail using FIG. 2 . Fig. 2 is an enlarged cross-sectional view showing a portion A of Fig. 1(a).

As shown in Fig. 2, a chemical treatment film 4a containing zirconia is formed on the surface of the aluminum reinforcing plate 4. Further, the chemical treatment film 4a is bonded to the acrylic adhesive layer 3, and the aluminum reinforcing plate 4 is adhered to the substrate 21 via the acrylic adhesive layer 3. Further, strictly speaking, aluminum water and an oxide layer (not shown) are naturally formed on the surface of the aluminum reinforcing plate 4, and a chemical treatment film 4a is formed on the aluminum water and the oxide layer.

In the vicinity of the interface (Al/Ad) between the acrylic binder layer 3 and the chemical treatment film 4a, a strong chemical chain (crosslinking) is formed across the interface. This reason will be explained.

On the surface of the chemically treated film 4a containing zirconia, a hydroxyl group (OH group) is present at a high density. When the aluminum reinforcing plate 4 is bonded to the FPC substrate 2, the hydrocarbon group on the surface of the chemical treatment film 4a and the carboxyl group (COOH group) contained in the acrylic binder applied to the substrate 21 are subjected to heat treatment. Or a hydroxyl group (OH group) for chemical reaction. As a result of this chemical reaction (dehydration chain), in the vicinity of the interface between the chemical treatment film 4a and the acrylic binder layer 3, "-C(=O)-O-" "-O-" or the like is formed at a high density. Indicates the crosslinks formed by the strong chains. Therefore, the bonding strength between the aluminum reinforcing plate 4 and the FPC board 2 becomes large.

Hereinafter, the configuration of the FPC unit to which the strong plate is attached will be described.

Fig. 3(a) is a cross-sectional view showing the FPC unit 100 to which the strong plate is attached. The FPC unit 100 of the attached strong plate is a bump portion 22a, 22b which is mounted on the preamplifier integrated circuit 101 using a solder material and attached to the mounting region 2a of the FPC board 1 to which the strong plate is attached. In the FPC board 100 to which the strong board is attached, the heat generated by the preamplifier integrated circuit 101 is radiated by the aluminum reinforcing plate 4 adhered to the back surface of the FPC board 2 of the mounting area 2a.

As described above, the FPC board 1 to which the strong board is attached and the FPC unit 100 to which the strong board is attached will be described.

Further, the FPC board to which the strong plate is attached is not limited to the above-described constituents.

For example, the aluminum reinforcing plate 4 may be provided only on the back surface of the substrate 21 of either of the mounting area 2a or the mounting area 2b.

Further, instead of the FPC board 2 in which wiring is formed only on one surface of the substrate 21, a double-sided FPC board 2' in which wiring is formed on the front and back surfaces of the substrate 21 may be used. Fig. 3(b) is a cross-sectional view showing the FPC unit 200 with a strong plate when the double-sided FPC board 2' is used. The double-sided FPC board 2' has wiring patterns 22A and 22B which are respectively formed on the front and back surfaces of the substrate 21. The wiring patterns 22A and 22B are respectively passed through the adhesive layer 23A and The cover films 24A and 24B provided in 23B are insulated and protected.

Further, as shown in Fig. 3(b), the aluminum reinforcing plate 4 may not be on the substrate 21, but may be laminated to the cover film 24B via the acrylic adhesive layer 3.

Further, instead of the cover film 24, a predetermined portion of the wiring pattern 22 may be covered with a surface layer made of a varnish-like resin. The surface layer may be formed into a desired pattern by a printing method, or may be formed by photolithography using a photosensitive resin. When photolithography is used, a photosensitive resin film is applied to a predetermined portion of the substrate 21 and the wiring pattern 22, and then the resin film is exposed and developed to form a surface layer by a desired shape of the pattern. As an advantage of using the surface layer, a highly precise pattern can be cited as compared with the surface layer. Therefore, for example, an aperture portion or the like can be formed with high precision. Further, a cover film and a top layer may be used in combination as needed. For example, a surface layer is used for a portion where high-precision pattern formation is required, and a cover film is used for a portion other than the pattern to improve production efficiency.

Hereinafter, an embodiment of the present invention will be described. The method of manufacturing the FPC substrate with the reinforcing plate of the present embodiment will be described, and then the measurement result of the peeling strength test will be described.

First, a copper foil on which a copper foil is deposited on a single side of a substrate of polyimide by a binder is prepared. Then, after the dry film was laminated on the copper clad plate, exposure development was performed. Thereby, the photoresist of the predetermined negative pattern is formed on the copper plate. Then, this photoresist is used as an etching mask to etch the copper foil of the copper plate to form a wiring pattern. Further, a cover film coated with a binder on one side of the polyimide film is prepared, and a predetermined portion of the cover film is formed. Aperture section. Then, a cover film provided with an aperture portion is laminated so as to cover the wiring pattern. At this time, the aperture portion of the cover film is covered with a film so as to correspond to a portion to be exposed such as a convex portion. Through the above steps, the FPC board of the present embodiment was produced. Hereinafter, a method of manufacturing an aluminum reinforcing plate will be described.

First, an aluminum plate is prepared to remove the oleaginous substance (degreasing treatment) adhering to the surface of the aluminum plate. Then, after washing the aluminum plate with water, it was immersed in an alkali solution to remove an aluminum oxide layer (alkaline degreasing treatment) naturally formed on the surface of the aluminum plate. Thereafter, the aluminum plate was washed with water, and then immersed in a weakly acidic (pH=5 to 6) zirconia chemical treatment liquid. As the zirconia chemical treatment liquid, a zirconium compound having no added phosphoric acid can be used. The zirconium compound having no phosphoric acid added is, for example, a hydrofluoric acid added to fluorozirconic acid (or an ammonium salt thereof).

Then, the aluminum plate was pulled up from the zirconia chemical treatment liquid, washed with water, and then dried in a furnace. Through the steps up to this point, an aluminum plate in which a chemical treatment film containing zirconium oxide is formed on the surface is obtained. Here, two kinds of samples containing cerium oxide in a chemical treatment film and those not containing cerium oxide were prepared. For this reason, in the use of the FPC board, in order to obtain an anti-rust effect, it is required to contain a flaw, and on the other hand, there is a request for a defect.

After the above chemical treatment, the thickness of the chemical treatment film formed on the surface of the aluminum plate was measured, and the thickness of the chemical treatment film was 5 nm regardless of the presence or absence of cerium oxide.

An aluminum plate which has not been subjected to chemical treatment (hereinafter referred to as "untreated aluminum plate") and an aluminum plate which is treated with boehmite (hereinafter referred to as "Bohmite" are prepared in comparison with the chemically treated aluminum plate. Processing aluminum board". Further, in the untreated aluminum plate, the above-described degreasing treatment and alkali degreasing treatment were also applied. Further, the boehmite treatment is performed by treating the surface of the aluminum plate at a temperature of 80 ° C to 90 ° C.

The thickness of the aluminum oxide layer formed on the surface of the comparative aluminum plate was measured to be 6 nm in the untreated aluminum plate and 238 nm in the untreated aluminum plate.

Further, the thicknesses of the chemical treatment film and the aluminum oxide layer described above were all measured by a scanning transmission electron microscope (STEM).

Then, the above four kinds of aluminum plates (chemically treated aluminum plates containing yttria, chemically treated aluminum plates not containing yttria, untreated aluminum plates and boehmite treated aluminum plates) are respectively punched into a predetermined shape and formed to be adhered to the FPC substrate. Aluminum reinforcement board.

Thereafter, the FPC substrate and the aluminum reinforcing plate produced as described above were laminated via an acrylic binder, whereby a laminate in which an FPC substrate and an aluminum reinforcing plate were laminated was formed. Then, the press process of heating and pressurizing the laminated body is performed using a press apparatus or the like. This press treatment was carried out in a rapid forming manner under the conditions of a pressure of 1 MPa, a temperature of 190 ° C, and a time of 5 minutes. Thereafter, a post-baking heat treatment temperature of the heated laminate was performed using a furnace apparatus or the like for a period longer than the press treatment: 180 ° C, time: 3 hours.

Through the above steps, samples of FPC substrates of four kinds of reinforcing plates each of which is laminated and bonded to the above four kinds of aluminum reinforcing plates were completed. Hereinafter, for the sake of convenience, a strong plate of an aluminum plate which is chemically treated with zirconia (containing cerium oxide) will be used. The FPC substrate is referred to as type A, and the FPC substrate of the aluminum plate which is chemically treated with zirconia (not containing yttrium oxide) is referred to as type B, and the FPC substrate using the unafficked aluminum plate is referred to as type C, The FPC substrate using the reinforcing plate of the boehmite-treated aluminum plate is referred to as type D.

Hereinafter, an evaluation test of the peel strength peel strength performed on the FPC board to which the reinforcing plate is attached will be described.

The evaluation of the peel strength was carried out in accordance with the IPC specification (TM650 2.4.9.). The measurement temperature was 25° C., and the peeling speed was 50 (mm/min). As shown in Fig. 4, the aluminum reinforcing plate of the FPC board with the strong plate attached was fixed to the stage with a peeling angle of 90° ( Pull the FPC board in the direction just above the figure in Figure 4.

The test results of the peel strength are shown in Table 1.

The conditions of "before mounting" and "after mounting" in Table 1 will be described. "Before mounting" is a result of indicating an FPC board with a strong plate in a state where the history of the heat is not evaluated. On the one hand, “after installation” means evaluation As a result of applying an FPC board attached to a strong plate which is heat-treated in the same manner as the heat history of the FPC board. As a heat history of the component mounting, a virtual welding leveling process and a lower feeding process are performed. Specifically, the imaginary welding leveling step was carried out at 220 ° C for 5 minutes, and then the hypothetical lower feeding step was performed at 165 ° C for 30 minutes.

The conditions of "Dry" and "Soak" in Table 1 are explained. "Dry" means a case where the test is carried out at normal temperature and normal humidity, and "Soak" means a case where the sample is immersed (50 ° C, 1 hour) in warm water and then tested. Further, "average" and "σ" in Table 1 are the average value and standard deviation (σ) of the measured peeling strength. The number of samples is six (N=6).

The "peeling interface" in Table 1 will be described. This "peeling interface" is a state indicating the peeling interface after the peeling test. The state of the peeling interface is: peeling of the interface between the aluminum reinforcing plate (Al) and the acrylic adhesive layer (Al/Ad), and the interface between the substrate of the FPC substrate and the acrylic adhesive layer (FPC/Ad) The situation of the three types of the detachment, and the mixture of the two (Mixture). Fig. 5 is a view showing the state of the surface of the aluminum reinforcing plate after the peeling test. Fig. 5(a) shows a state in which peeling occurs at the Al/Ad interface, Fig. 5(b) shows a state where peeling occurs at the FPC/Ad interface, and Fig. 5(c) shows a situation where both interfaces are mixed. The condition of the stripping. Peeling occurs at an interface where the bond strength is relatively weak. Therefore, when the peeling interface is Al/Ad, it is understood that the bonding force at the interface between the aluminum reinforcing plate and the acrylic adhesive layer is relatively lower than the bonding strength between the FPC substrate and the acrylic adhesive layer. On the one hand, if the stripping interface is FPC/Ad, It is understood that the bonding force between the aluminum reinforcing plate and the acrylic adhesive layer is relatively higher than the bonding strength between the FPC substrate and the acrylic adhesive layer.

As shown in Table 1, for Type A and Type B subjected to zirconia chemical treatment, "before mounting" and "after mounting" have a high peeling strength and a small deviation. In addition, after "installation", the peel strength is improved compared with "before mounting". This may be because the chemical reaction between the reactive group (hydroxyl group) in the chemical treatment film and the reactive group (carboxyl group, hydroxyl group) in the acrylic adhesive layer is further performed by heat treatment of the imaginary part, and the crosslinking density is increased.

Further, with respect to Type A and Type B which are subjected to zirconia chemical treatment, the peel strength is not lowered in a wet environment, and the same peel strength as in a normal humidity environment is obtained. This is because the bonding strength of the chemical chain constituting the crosslink is strong, and the chemical chain is not affected by the moisture immersed in the bonding interface in a humid environment. That is, the adhesion constituting the cross-linking is stronger than the reactivity of the hydroxyl group having the water molecule, so the FPC substrate of the type A and the type B with the strong plate does not lower the bonding strength in a wet environment.

On the one hand, as can be seen from Table 1, for the type C using the untreated aluminum plate, the peeling interface is the FPC/Ad interface or the mixture in the state before "pre-installation". However, in the "after mounting" state, the Al/Ad interface is peeled off, and the bonding strength between the aluminum reinforcing plate and the acrylic adhesive layer is low. Moreover, in the wet environment after the "installation" state, the average peel strength is 352, which is larger than the state before "pre-installation". Decrease in magnitude. In this case, water molecules are immersed in the bonding interface between the aluminum reinforcing plate and the acrylic adhesive layer, and the water molecules may reduce the crosslinking density by reacting with a chemical chain exhibiting bonding strength.

Further, the type D of the aluminum plate treated with boehmite was peeled off at the FPC/Ad interface in the state before the mounting, and the bonding strength between the aluminum reinforcing plate and the acrylic adhesive layer was high. However, as shown in Table 1, in the wet environment in the state after mounting, the standard deviation σ of the peel strength was 123, and the deviation was large and unstable. This refers to the case where the sample having a small strength is peeled off and the yield is lowered.

From the evaluation results of the peel strength described above, it is understood that when the type A and the type B of the aluminum reinforcing plate subjected to the zirconia chemical treatment are used, it is "before mounting" and "after mounting" regardless of the condition containing cerium oxide. In the "dry", "wet"), sufficient peel strength can be stably obtained. As a result, according to the present embodiment, it has been proved that an FPC board with a strong bonding strength that exhibits sufficient bonding strength can be obtained in a practically imaginary environment.

The embodiments and examples of the present invention have been described above. As described above, in the embodiment of the present invention, the metal plate made of aluminum is chemically treated, and the chemically treated film containing zirconium oxide is formed on the surface thereof. Further, the chemically treated metal plate was bonded to the FPC substrate via an acrylic adhesive. Then, a short-time press treatment and a post-baking heat treatment in a rapid forming manner are performed. As a result, the hydroxyl group on the surface of the chemically treated film containing zirconium oxide is chemically reacted with a carboxyl group or a hydroxyl group in the acrylic binder, and a strong chemical chain is formed at a high density. The chemical chain is formed across the interface between the chemically treated film and the acrylic adhesive layer. Cross-linking. As a result, according to the present invention, high bonding strength can be obtained even when the rapid forming method is employed.

Further, the chemical chain constituting the above cross-linking has a strong adhesive strength and is not affected by the hydroxyl group having water molecules, so that sufficient adhesion can be ensured even in a wet environment. That is, according to the present invention, high water-resistant adhesion can be obtained.

Further, in the chemical treatment of the present invention, the chromate treatment using hexavalent chromium does not adversely affect the environment, and there is no problem in industrial use.

In addition, in the above description, the FPC board to which the strong board is attached is an example of the FPC unit used for the HDD, but the present invention is not limited thereto, and can be applied to an FPC of an attached strong plate for any use. Substrate.

Further, in the above description, an aluminum plate is used as the reinforcing plate, but the present invention is not limited thereto, and another metal plate which can be subjected to zirconia chemical treatment may be used.

According to the above description, the additional effects or various modifications of the present invention may be conceived by those skilled in the art, but the form of the present invention is not limited to the above embodiments. Various additions, modifications, and partial deletions can be made without departing from the scope of the present invention and the scope of the present invention.

1‧‧‧FPC substrate with strong board

2‧‧‧FPC substrate (single-sided FPC substrate)

2'‧‧‧ two-sided FPC substrate

2a, 2b‧‧‧ Served area

2c‧‧‧Wiring area

21‧‧‧ substrates

22,22A,22B‧‧‧Wiring pattern

22a, 22b‧‧‧ convex rail

23,23A,23B‧‧‧Binder layer

24,24A,24B‧‧‧ Cover film

3‧‧‧Acrylic adhesive layer

4‧‧‧Aluminum reinforcing plate

4a‧‧‧Chemical treatment membrane

100,200‧‧‧FPC unit with strong board

101‧‧‧Preamplifier integrated circuit

102‧‧‧Welding materials

Fig. 1(a) is a cross-sectional view showing an FPC board with a strong plate according to an embodiment of the present invention, and Fig. 1(b) is a view showing an embodiment of the present invention. A bottom view of the FPC board of the strong board.

Fig. 2 is an enlarged cross-sectional view showing a portion A of Fig. 1(a).

Fig. 3(a) is a cross-sectional view showing the FPC unit of the reinforcing plate according to the embodiment of the present invention, and Fig. 3(b) is a view showing the FPC unit of the reinforcing plate according to the modification of the embodiment of the present invention. Surface map.

Fig. 4 is a view showing the peeling test.

5(a), (b), and (c) are drawings for explaining the surface state of the aluminum reinforcing plate after the peeling test.

1‧‧‧FPC substrate with strong board

2‧‧‧FPC substrate (single-sided FPC substrate)

2a, 2b‧‧‧ Served area

2c‧‧‧Wiring area

21‧‧‧ substrates

22‧‧‧Wiring pattern

22a, 22b‧‧‧ convex rail

23‧‧‧Binder layer

24‧‧‧ Cover film

3‧‧‧Acrylic adhesive layer

4‧‧‧Aluminum reinforcing plate

4a‧‧‧Chemical treatment membrane

Claims (10)

A flexible printed circuit board with a strong plate, comprising: a flexible printed circuit board having a substrate and a wiring pattern formed on one surface of at least one of the substrates; and reinforcing the flexibility A metal plate of the printed circuit board is bonded to the metal plate of the substrate via an acrylic adhesive layer on a mask facing the flexible printed circuit board. The flexible printed circuit board with a strong plate according to the first aspect of the invention, wherein the metal plate is an aluminum plate. The flexible printed circuit board with a strong plate according to the first or second aspect of the invention, wherein the chemically treated film contains cerium oxide. The flexible printed circuit board with a strong plate according to claim 1, wherein the metal plate is bonded to a cover film that insulates the wiring pattern in place of the substrate. A flexible printed circuit board with a strong plate, comprising: a first mounting region and a second mounting region including a convex rail portion formed on a surface of the substrate; and being disposed to be sandwiched The first mounting region and the second mounting region include a wiring region electrically connecting the protruding portion of the first mounting region and the wiring portion of the protruding portion of the second mounting region a printed circuit board; and formed in the first mounting area and/or the second mounting area An acrylic adhesive layer on the back surface of the substrate; and a chemical treatment film containing zirconia in a mask opposite to the flexible printed circuit board, and the aluminum bonded to the substrate via the acrylic adhesive layer Reinforce the board. The flexible printed circuit board with a strong plate according to claim 5, wherein the chemical treatment film comprises ruthenium oxide. The flexible printed circuit board with a strong plate according to the fifth or sixth aspect of the invention, comprising a preamplifier integrated circuit mounted on the protruding rail portion. A method for producing a flexible printed circuit board with a strong plate, wherein a chemical treatment film containing zirconium oxide is formed on a surface of an aluminum plate, and the aluminum plate on which the chemical treatment film is formed is passed through an acrylic adhesive layer. a plastic film laminated on the flexible printed circuit board so as to be in contact with the acrylic adhesive layer, whereby the laminated body of the aluminum plate and the plastic film is laminated via the acrylic adhesive The press apparatus is used to heat and pressurize the laminate of the laminate, and the post-baking heat treatment for heating the laminate is performed using a furnace device for a longer period of time than the press treatment. The method for producing a flexible printed circuit board according to the eighth aspect of the invention, wherein the chemically treated film is obtained by immersing the aluminum plate in hydrofluoric acid or fluorozirconium. Acid ammonium salt It is formed by a zirconia chemical treatment solution without added phosphoric acid. The method for producing a flexible printed circuit board with a strong plate according to the invention of claim 8 or claim 9, wherein the plastic film is a polyimide film, a polyester film, or a polyethylene naphthyl ester. Film, polyether sulfonate film, polyether quinone film, polyetheretherketone film, or poly-extension film.