JP4906332B2 - Curling correction method for composite foil, composite foil and composite foil-clad laminate - Google Patents

Description

  The present invention relates to a method for correcting a curling phenomenon that occurs in a composite foil, particularly an ultrathin electrolytic copper foil with a carrier copper foil, to an extent that does not hinder handling in a subsequent process. (The “curl” referred to in the present application indicates a phenomenon in which the sheet edge is lifted from the desktop plane when the sheet-like foil is left on the plane desk.)

  Conventionally, metal foil has been widely used as a basic material for forming a conductor of a printed wiring board. In addition, electronic and electrical devices in which printed wiring boards are frequently used are required to be so-called light and thin, such as miniaturization and weight reduction. Conventionally, in order to realize such a light, thin and small electronic and electrical equipment, in order to make the signal circuit as fine pitch as possible, a thinner copper foil is used and overetching when forming a circuit by etching. Therefore, it has been demanded to shorten the set time and improve the etching factor of the circuit to be formed.

  On the other hand, electronic and electrical devices that are reduced in size and weight are also requested to be highly functional as represented by mobile phones. Accordingly, in order to secure the component mounting area as much as possible within the limited substrate area, it has been required to improve the etching factor of the circuit. Of these circuit boards, tape automated bonding (TAB) boards and chip-on-flexible (COF) boards that directly mount IC chips and the like have a small drive current for the mounted components, so the power consumption due to the conductor resistance is low. When the increase can be ignored, it is said that a conductor layer thickness of 4 microns is sufficient.

  Therefore, when making a copper clad laminate with the minimum necessary conductor layer thickness, it is difficult to handle an extremely thin conductor layer, so it is necessary to use composite foil or prepare a thick conductor layer. A technique such as thinning by etching to a suitable thickness was used. When a composite foil is used, the support layer is provided with a function for facilitating handling by attaching the conductor layer side having a necessary thickness, which is one of its constituent elements, to the dielectric layer. (In the present application, this support layer is hereinafter referred to as “carrier”) mechanically or chemically removed (generally, the former is referred to as peelable type and the latter is referred to as etchable type). It has been adopted. However, these composite foils initially employ low-cost aluminum foil as a carrier and have an ultra-thin conductor layer made of copper, so the curl phenomenon easily occurs due to the composite of metals having different characteristics. When used in the process, it was a cause of problems such as problems in handling on the production line.

  As the demand for ultra-thin copper foil increases, efforts to supply copper foil as thin as possible without a carrier are continuing, and the thickness of the conductive foil used in printed wiring boards has also changed. It has been accomplished. The 35 μm-thick copper foil, which was said to be a general-purpose product when printed wiring boards started to spread, has already been recognized as a thick product, and 12 μm-thick copper foil has already been positioned as a part of a general-purpose product that can be handled. Yes. Therefore, an ultra-thin electrolytic copper foil with a carrier copper foil, which is a peelable type composite foil having a three-layer structure of carrier copper foil / peeling layer / ultra-thin electrolytic copper foil, developed in consideration of preventing the occurrence of curling phenomenon However, although it started with a carrier copper foil thickness of 35 μm, the process of disposing of the carrier copper foil has become more important than the handling property as the awareness of environmental issues has increased. The demand for a thickness of 18 μm is becoming stronger. As a result of thinning the carrier copper foil, the curl of the composite foil has increased.

  Let us consider why curling occurs despite the combination of the same electrolytic copper foils. In the manufacturing process of a general peelable type ultra-thin electrolytic copper foil with carrier copper foil, in order to obtain an ultra-thin electrolytic copper foil with carrier copper foil having a three-layer structure of carrier copper foil / peeling layer / ultra-thin copper foil First, an interfacial layer that has adhesive properties to the extent that the carrier-side copper and ultra-thin copper can be peeled off so that the carrier can be mechanically removed from the surface of the copper foil that will be the carrier copper foil in the subsequent process (this case) In the application, the interface layer formed for this purpose is referred to as a “peeling layer.”) Is formed using an inorganic substance or an organic substance. And, taking the case of using an organic release layer as an example, there are few precipitation sites when trying to deposit copper directly on the organic release layer, so it has a good conductivity and orientation. Precipitation with a denser crystal structure with less crystal orientation than when it precipitates on the surface of metallic copper is obtained. Therefore, as the thickness increases, the crystal grains become enlarged, but the ultrathin electrolytic copper foil layer to be obtained here is thin, so it is desirable before the crystal grains are enlarged. The electrolytic deposition of thickness is completed. Accordingly, the ultrathin electrolytic copper foil generally becomes an electrolytic copper foil having only a dense structure. Therefore, as a result, the mechanical strength (tensile strength) is larger than that of the carrier copper foil, and at the same time, the strain at the time of deposition of this ultra-thin electrolytic copper foil is increased and the curling phenomenon occurs. is there.

  At this time, if the thickness of the carrier copper foil is sufficiently larger than the thickness of the ultrathin electrolytic copper foil, the distortion on the ultrathin electrolytic copper foil side has a small effect on the composite foil, and as a result, curl can be reduced. When the thickness difference is reduced, the difference in physical properties is greatly reflected, and the curl as a composite foil is inevitably increased. In addition, nickel, cobalt, chromium, or the like, which is a metal that easily forms a passive metal oxide film on the surface, can be used as the material constituting the release layer. In this case, the metal oxide film is used as the inorganic release layer. Considering that it is functioning and has no orientation, the curl phenomenon is caused by a large crystal structure and a large strain of precipitation on the surface to some extent compared to the organic release layer. It is guessed that it will happen.

  However, even if the layer structure is the same, for example, when an ultrathin electrolytic copper foil layer is formed on a rough surface such as the rough surface side of the electrolytic copper foil, it is formed even if the deposited crystal is fine. The layer itself has an accordion shape, and this shape functions as an effect to alleviate the effect of stress on the composite foil due to the strain possessed by the ultra-thin electrolytic copper foil. The above problem does not occur.

However, the occurrence of curling in the composite material is, of course, a composite material in which different materials such as a resin base material and a metal foil are bonded together by heat treatment, and it is a typical composite material in which different metals are bonded in the technical field related to metals. Taking bimetal as an example, the use of changes in the amount of deflection (curl) due to temperature changes with a smooth joint interface, the existence of curl is considered to be natural. Various measures have been proposed for the solution. However, it is difficult to say that sufficient research has been made on the curl phenomenon that occurs in a composite material having a combination of the same materials and having an interface like the ultrathin electrolytic copper foil with carrier copper foil.

  Moreover, even if the cause of occurrence is different, the curling problem is a phenomenon that has been proposed to occur easily in a variety of products having a high mechanical strength in the manufacturing process of a rolled product that is a single-type metal layer product. However, the manufacturing process of rolled products is a system that adjusts the thickness and shape while passing many rolls, and the basic metal characteristics such as annealing characteristics are the same, so the curl is the direction of travel of the rolling mill (When handling strip-shaped products, this direction is generally referred to as MD: MACHINE DIRECTION, and the direction perpendicular to this direction is referred to as TD: TRANSVERSE DIRECTION, and this abbreviation may be used in this application) However, it was not difficult to add a process for correcting curl during the production line. That is, it is a method called a leveling process disclosed in Patent Documents 1 to 3, such as a method of annealing under tension, a tension leveler that performs correction under high tension, and correction under low tension. There were many options such as a method combining roller levelers to perform.

  That is, taking a rolled copper strip as an example, the rolling oil is attached to the surface of the copper strip passing through the straightening process, and slipping also occurs when passing through a small diameter roll such as a tension leveler. It is easy to do and it is hard to do damage such as scratches on the surface. In addition, since the thickness of the strip is about 0.4 mm to several mm, it is easy to receive mechanical correction, and the width is about 1 m at the maximum. It's hard to get up.

  As described above, the curl correction is generally performed by applying a mechanical stress, but the thickness of the conductor foil used for the printed wiring board is already less than 35 μm and 12 μm thick as described above. Some products can be handled, and some products have a maximum width exceeding 2 m. Therefore, even if a simple proportional calculation is performed from the product thickness, if a straightening operation based on mechanical stress is to be applied, the roll diameter applied to the rolled product is reduced to 1/100 to 1/10 and a long straightening roll is used. Therefore, by applying the line tension necessary for curl correction, the correction roll is bent, and the adverse effects such as the generation of wrinkles due to the deflection are greatly highlighted.

  Moreover, even if the deflection problem of the straightening roll is solved, considering that the product is used for the production of printed wiring boards by being laminated with an insulating resin, the oil content used in the mechanism that can be adopted as a solution means. If it adheres, it will adversely affect the adhesive strength and heat resistance with the resin, and if scratches etc. occur, scraping may cause short circuits and problems with long-term heat resistance, etc. It is difficult to deal with on the extension line.

JP-A-8-132138 Japanese Patent Laid-Open No. 9-295047 Japanese Patent Laid-Open No. 10-100016

  From the above, the composite foil, especially the ultra-thin electrolytic copper foil with carrier copper foil used for printed wiring boards, is different from straightening technology such as rolling strips, and does not cause surface contamination and damage such as scratches. There was a need for a technique for correcting curl while satisfying the basic characteristics required for wiring board applications.

  Means for solving the above problems will be described below.

The present invention is a method of correcting a curl by heat-treating a composite foil , wherein the composite foil has a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil. A curling correction method for a composite foil is provided, wherein the composite foil is heat-treated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours while being continuously run, and then wound up .

The present invention is also a method for correcting curl by heat treatment of a composite foil, wherein the composite foil has a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil. Provided is a method for correcting curling of composite foil, which is an electrolytic copper foil, wherein the composite foil is wound up and heat-treated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours with the composite foil being wound up. To do.

The present invention is also a method for correcting curl by heat treatment of a composite foil, wherein the composite foil has a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil. Provided is a method for correcting curl of a composite foil, which is an electrolytic copper foil, and is heat-treated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours in a state of being stacked in a sheet form .

Then, it is not further preferred to heat for 1 hour to 7 hours the composite foil at atmosphere temperature 0.99 ° C. to 200 DEG ° C..

  Furthermore, when winding the heat-treated composite foil, it is preferable to wind it in an inert gas atmosphere.

  And when the said composite foil is heat-processed, it is also preferable to heat in inert gas atmosphere.

  Furthermore, it is preferable that the said heat processing exceeds the minimum temperature and makes the subsequent temperature increase rate 50 degrees C / hr or less.

The present invention is an ultrathin electrolytic copper foil with a carrier copper foil obtained by the curl correction method, wherein the composite foil has a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil,
The value of Ca Lumpur to provide a composite foil, characterized in that at 10mm or less.

  The present invention provides a composite foil-clad laminate in which the composite foil is laminated with an insulating resin.

  The curl of the composite foil is reduced by the composite foil curl correction method according to the present invention, so that it can be used without discomfort in handling the same production line as 12 μm copper foil and 18 μm copper foil that have been used as conventional products. As a result, it has become possible to produce fine pattern circuits with higher yields without the need for major process changes.

  The present invention provides a method for correcting curling of a composite foil, which comprises heat-treating the composite foil. As described above, the cause of curling is the strain that the metal structure on the ultrathin foil side precipitates in a fine state, so that strain relief by heat treatment is effective for curling correction. It is.

Its to a method of curl correction described above, the particularly effective against ultrathin electrolytic copper foil with carrier copper foil having a three-layer structure of the carrier copper foil / peel layer / ultrathin electrolytic copper foil of the composite foil Demonstrate. When the carrier and the ultrathin foil are made of different metals, the curl condition changes due to the heat treatment temperature as well as the bimetal, and the correction effect tends to vary. can the impact to a minimum, Ru preferred Nodea to easy to obtain the expected effect as planned.

  The composite foil is preferably heated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours, more preferably 150 ° C. to 200 ° C. for 1 hour to 7 hours. As a general knowledge about changes in physical properties when a metal material is heat-treated, it is known that the annealing effect appears as a function of temperature and time (heat penetration flow rate). Considering the case where copper is the material here, it is recognized that the copper crystal structure obtained by the electrolytic method is difficult to anneal because of the incorporation of additives and oxygen into the grain boundaries. Although rolled copper foil depends on the type and design of the pass schedule of the rolling process, it is said that annealing is particularly likely to occur with tough pitch copper.

  However, even if it is an electrolytic copper foil, it is clear in the literature that annealing effect appears and a decrease in tensile strength and an increase in elongation rate are observed after high-temperature treatment for a long time. Even if it is a composite foil, a problem arises in handling properties. However, if the setting is made too low to avoid the manifestation of the annealing effect, it will take a long time to obtain the desired effect, which will increase the cost to supply as an industrial product. is there. Therefore, a preferable condition is heating at 120 ° C. to 250 ° C. for 1 hour to 10 hours, and a more preferable condition is heating at 150 ° C. to 200 ° C. for 1 hour to 7 hours. The temperature range and the heating time may be appropriately adjusted in consideration of the productivity from the degree of curling and the amount of the composite foil introduced into the furnace. And when raising the temperature to the above temperature condition range, it is recommended that the upper limit of the rate of temperature rise after the lower limit temperature is about 50 ° C./hour. When a sudden temperature rise is given in the above range, a temperature unevenness is generated inside a heated body having a large capacity especially in a roll shape, and this causes variation in distortion correction depending on the position. As a result, not only the purpose of curl correction cannot be achieved, but also abnormal phenomena such as the occurrence of undulations appear in the sheet, which is not preferable.

And in the curl correction method of the composite foil which concerns on this invention, it is preferable to heat-process, and to wind up after curl correction, making the said composite foil run continuously. The method of heating the foil at a constant temperature by continuously passing the foil through a floating furnace or the like is a method in which the heat capacity of the object to be heated in the treatment process becomes the smallest as the heat treatment process, so that the heating is finely set. It is preferable because it can be processed. When a straightening roll is disposed in the heating furnace, more effective curl correction can be achieved. In addition, as a method for heating the metal foil, there is a field where a technique for generating heat by energization is put into practical use, and this is also a heating technique that can be targeted when considering continuous heating.

In the method for correcting curl of a composite foil according to the present invention, it is also preferable to heat-treat the composite foil in a wound state. In particular, winding in the direction of curling is slightly applied, but tensile stress is applied to the composite foil, and the correction effect by heat treatment can be enhanced. At this time, in order to reduce the temperature unevenness inside the roll, it is recommended to use a metal winding core also from an example of annealing of a rolled product.

When winding the composite foil is the heat treatment, it is more preferred to wind in an inert gas atmosphere. There is a certain amount of air adsorbing layer on the surface of the composite foil to be heat-treated, and it cannot be guaranteed that the metal will not oxidize at all, although it depends on the heat-resistant rust prevention treatment. Therefore, it is preferable to replace the air with an inert gas in order to prevent oxidation of the metal surface.

Alternatively, in the method for correcting curl of the composite foil according to the present invention, it is also preferable to heat-treat the composite foil in a sheet form and stacked. By stacking sheets, a load due to its own weight is applied, and heat treatment is performed in a state where the curl is corrected, which is preferable. The batch method requires a small amount of capital investment, and at the same time, if the lot size is almost the same under the same condition setting, the desired effect can be obtained stably. In this case, the sheet foils are stacked, but in order to obtain a correction effect by their own weight, it is preferable that the curls are stacked in a convex direction, and the MD direction and the TD of the ultra-thin electrolytic copper foil manufacturing apparatus with carrier copper foil are stacked. The effect can be enhanced by appropriately changing the direction of the direction or further applying a weight to increase the load.

  And it is also preferable to heat in the inert gas atmosphere when heat-treating the said composite foil. Although this can contribute to the prevention of oxidation of the metal surface as described above, in the case of using a batch-type heating furnace, not only mere purging of the inert gas but also a method of sealing the inert gas after the decompression process Is more preferable.

The present invention is an ultrathin electrolytic copper foil with a carrier copper foil obtained by the curling correction method for the composite foil and having a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil, and the curl is 10 mm or less. Provide composite foil. The curl level of 10 mm shown here is a level at which no trouble occurs in an automatic line for producing a general printed wiring board or copper-clad laminate, and a more preferable level is 5 mm or less. Then, it is preferable that the curl value after correction is less than 50% of the initial value, Ru Nodea which may be an indicator of this that variations in lot less.

  More preferably, the ultrathin electrolytic copper foil with carrier copper foil has an organic release layer. The presence of the organic release layer at the interface means that the interface has some flexibility, and this flexible interface exists as a buffer zone between the carrier copper foil and ultrathin electrolytic copper foil layer with different physical properties. By doing so, the effect of curl correction by heat treatment is easily obtained.

  The present invention provides a composite foil-clad laminate in which the composite foil is laminated with an insulating resin. Bonding the composite foil with reduced curl through the heat treatment step with the insulating resin means that the crystal structure of the composite foil has already received the heat history originally received for the first time at the time of thermocompression bonding, and the distortion has been relaxed. For example, an effect can be expected to improve the dimensional stability of the laminated board, for example, when the thickness of the substrate is reduced.

  In this example, carrier copper foil (18 μm and 35 μm of electrolytic copper foil classified as grade 3 in the IPC standard) / organic release layer (CBTA (carboxybenzotriazole)) / ultra thin electrolytic copper foil (of carrier copper foil) An ultrathin electrolytic copper foil with a carrier copper foil having a layer structure of 3 μm thickness and 5 μm thickness on the glossy surface side was used.

<Method for producing ultrathin electrolytic copper foil with carrier copper foil>
It is a manufacturing process of the above-mentioned ultra-thin electrolytic copper foil with carrier copper foil, but after unwinding the carrier copper foil, an organic peeling layer is formed by dipping while running in multiple meandering treatment tanks. After forming an ultra-thin electrolytic copper foil layer on the organic release layer by an electrolytic method, it was subjected to a roughening treatment and a rust prevention treatment by a conventional method, followed by drying.

[Manufacture of carrier copper foil]
The carrier copper foil is manufactured as follows, and the glossy surface is necessarily formed on the electrolytic copper foil. The production of the electrolytic copper foil is carried out by flowing an acidic copper sulfate solution between the electrodes using an apparatus having a drum-shaped rotating cathode and an anode arranged so as to face the rotating cathode. Is deposited on the drum surface of the rotating cathode with a predetermined thickness, and is continuously peeled off from the rotating cathode and wound up. The copper foil obtained in this state is called a separating foil, and this is used as a carrier copper foil.

The surface peeled off from the state of contact with the rotating cathode of the separation foil is a mirror-finished surface of the rotating cathode, which is a glossy and smooth surface. Yes. On the other hand, the surface shape of the separating foil on the side that was the precipitation side shows a mountain-shaped uneven shape because the crystal growth rate differs depending on the crystal surface of the deposited copper metal surface. It is called. This rough surface is generally a bonding surface with an insulating material when manufacturing a copper-clad laminate, but it can also be a surface on which an ultra-thin electrolytic copper foil is electrodeposited as described above. can Nodea Ru.

[Manufacture of ultra-thin electrolytic copper foil with carrier copper foil]
Below, it demonstrates according to the order of the manufacturing process which advances as it sequentially passes the various tanks arrange | positioned continuously in series using carrier foil.
The unrolled carrier copper foil (deposited foil) first entered the pickling bath to remove oil and fat components attached to the carrier copper foil, and also removed the surface oxide film.

  The carrier copper foil exiting the pickling bath entered an organic release layer forming bath and was immersed in a CBTA aqueous solution to form an organic release layer on the surface of the carrier copper foil.

When the organic release layer was formed, a bulk copper layer as a base of the ultrathin electrolytic copper foil was subsequently formed on the release layer formed on the glossy surface. The bulk copper forming tank is filled with an acidic copper sulfate solution, and when a 3 μm ultrathin electrolytic copper foil layer is formed, the current density is 8 A / dm ² , and when a 5 μm ultrathin electrolytic copper foil layer is formed, smooth plating is performed with a current density of 15 A / dm ² . The bulk copper layer was obtained by electrolysis under conditions for 60 seconds.

  When the bulk copper layer formation is completed, the surface of the bulk copper layer is then subjected to a roughening treatment to form fine copper grains for anchors to secure the adhesive strength by biting into the base material when processed into a copper-clad laminate. Carried out. This treatment consists of a baking plating process in which fine copper grains for anchoring are deposited on a bulk copper layer using an acidic copper sulfate solution, and a covering plating process for preventing the fine copper grains for anchoring from falling off. Has been.

  Next, rust prevention treatment was performed using zinc as the rust prevention element, and the ultrathin electrolytic copper foil with carrier copper foil after the rust prevention treatment was completed by heating and drying with an electric heater in the drying treatment section. It wound up in roll shape as ultra-thin electrolytic copper foil. At this time, a SUS tube was used as the winding core, and three types of roll products having a product width of 1350 mm and a length of 800 m (a carrier copper foil having a thickness of 18 μm and an ultrathin electrolytic copper foil having a thickness of 3 μm and 5 lots (L1 to L5) and ultrathin electrolytic copper) One lot (L6) having a foil thickness of 5 μm, and one lot (L7) having an ultrathin electrolytic copper foil thickness of 3 μm was obtained at a carrier copper foil thickness of 35 μm.

<Curl measuring method>
The curl measurement methods implemented in the examples and comparative examples according to the present invention are shown below.

〔sampling〕
Samples of 10 cm square were collected from three locations in the TD direction of the ultrathin electrolytic copper foil product roll with carrier copper foil before and after curl correction. A specific sampling position and a curl measurement position in the sample are shown in FIG.

[Curl measurement]
The sampled 10 cm square specimen is placed on a horizontal table with the ultrathin electrolytic copper foil side up. Then, the height (mm) of lifting from the four corners (A, B, C, D) of the specimen is measured. At this time, when the center part of the specimen is lifted, the specimen is inverted and measured, and the measured value is a negative value.

<Curl correction test>
In this example, when the target lot is a carrier copper foil thickness of 18 μm, an ultra-thin electrolytic copper foil thickness of 3 μm is the main test object, and lots L1 to L5 and lots of ultrathin electrolytic copper foil thickness of 5 μm are produced following L5. One lot of L6, and one lot of L7 with ultra-thin electrolytic copper foil thickness of 3μm was produced with the carrier copper foil thickness of 35μm, and the test was conducted with the roll shape that is most difficult to perform stable heat treatment. . As an evaluation item, in addition to the curl value, we decided to look at the change in the physical properties of the copper foil layer to confirm the occurrence of annealing phenomenon, but because it is a composite foil, it lacks the reliability of physical property measurement. The presence or absence of changes in physical properties was evaluated using the difference in handling properties as an alternative characteristic.

[Heating oven]
In this example, a big batch oven BL-2515C (manufactured by Asahi Kagaku Co., Ltd.) was used as the heating oven, and the ambient temperature was set to 195 ° C.

[Test-1]
First, as test-1, the lot L1 was carried into a heating oven, and samples were collected from the outer periphery for 6 hours, 8 hours, and 10 hours after the set temperature reached 195 ° C., and the curl values before and after heating were determined. Measured and evaluated the status of correction. The results are shown in Table 1.

  As is apparent from Table 1, the curl value after the heat treatment at an oven temperature of 195 ° C. is 5.3 to 9.1 mm on average and 8.2 to 9.8 mm on the maximum, clearing the target value of 10 mm. It is done. From this result, it is clear that the heating time around 6 hours is the minimum required time for the size of the roll subjected to the test at the carrier copper foil thickness of 18 μm, the ultrathin copper foil thickness of 3 μm, and the oven temperature of 195 ° C.

[Test-2]
Subsequently, curling before and after holding for 10 hours at a set temperature of the oven of 195 ° C. was measured for the remaining 6 lots (L2 to L7) to be tested, and the correction status was evaluated. The results are shown in Table 2. In addition, it was confirmed that the temperature of the ultrathin electrolytic copper foil with carrier copper foil itself was maintained at 175 ° C. or higher for 5.0 hours. The temperature profile of the ultrathin electrolytic copper foil with carrier copper foil itself is shown in FIG.

<Influence of ultrathin copper foil thickness>
In Table 2, when compared with the carrier copper foil thickness of 18 μm, the curl before heating of the ultrathin electrolytic copper foil thickness of 3 μm was 21.6 mm and the maximum value was 30.0 mm, whereas the ultrathin electrolytic copper foil thickness was 30.0 mm. In the copper foil thickness 5 μm product, the average value of the curl is 34.5 mm, and the maximum value is 40.0 mm. Therefore, the ultrathin electrolytic copper foil layer obtained based on the experience of the inventors etc. The finding that the thinner the thickness, the smaller the curl value immediately after manufacture is supported.

<Influence of carrier copper foil thickness>
When the influence of the carrier thickness is compared with an ultrathin electrolytic copper foil thickness of 3 μm, the average curl value before heating is 8.3 mm for the 35 μm thickness carrier product, and the average curl value of the 18 μm thickness carrier product is 21.6 mm. The maximum value is about 30 mm with respect to 15 mm and about 1/2, and the influence of the carrier copper foil thickness on the curl is clear. Also, the curl value after heating is 0.8 mm on the average for the carrier copper foil thickness of 35 μm, and the curl value on the carrier copper foil thickness of 18 μm is 3.5 mm on average. The influence of the thickness of the copper foil is observed.

<Curl correction effect by heat treatment>
Then, looking at the data after curling correction by heating for the sample of the carrier copper foil thickness 18 μm, the average value in the ultrathin electrolytic copper foil thickness 3 μm product is 3.5 mm, the maximum value is 8.0 mm, Even with a thin electrolytic copper foil thickness of 5 μm, the average value of the curl is 4.6 mm, the maximum value is 9.0 mm, and the target value can be cleared. From this data, although the difference in curl level before heating was large, the difference after heating was 1 mm, and it can be said that it is almost equivalent considering the variation existing between lots. Therefore, the thickness of the ultrathin electrolytic copper foil part has a great influence on the ease of occurrence of curling after production, but the correction effect by heating is almost equal regardless of the thickness of the ultrathin copper foil layer. It can be said that That is, it is clear that the adjustment of the heat treatment condition according to the thickness of the ultrathin copper foil is small. And since there was almost no change in the results of evaluating the handling properties of the ultra-thin electrolytic copper foil with carrier copper foil before and after heating, it is considered that there was no heat flow through which annealing was applied under the above heating conditions. The effectiveness of curling correction effect of the composite foil by heating was confirmed.

  With the method for correcting curl of composite foil according to the present invention, it has been clarified that curl of composite foil can be corrected by appropriate heat treatment when the composite foil is made of the same metal. Therefore, with ultra-thin electrolytic copper foil using electrolytic copper foil as a carrier, curling can be corrected by heating, and it can be handled on the same production line as 12 μm copper foil and 18 μm copper foil that have been used as conventional products. This makes it possible to insert and use it without a sense of incongruity, and to produce fine pattern circuits that are higher than conventional ones with a high yield without any major process changes.

It is a schematic diagram for demonstrating the collection position of a measurement specimen, and a curl measurement position . It is a graph which shows the temperature profile of the composite foil itself during an orthodontic test .

Claims (10)

A method of correcting the curl by heating the composite foil,
The composite foil is an ultrathin electrolytic copper foil with a carrier copper foil having a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil,
A curling correction method for a composite foil, wherein the composite foil is heat-treated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours while being continuously run, and then wound . A method of correcting the curl by heating the composite foil,
The composite foil is an ultrathin electrolytic copper foil with a carrier copper foil having a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil,
  A curling correction method for a composite foil, wherein the composite foil is wound and heat-treated at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours in a state where the composite foil is wound. A method of correcting the curl by heating the composite foil,
The composite foil is an ultrathin electrolytic copper foil with a carrier copper foil having a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil,
  A curling straightening method for a composite foil, characterized by heat-treating at an ambient temperature of 120 ° C. to 250 ° C. for 1 hour to 10 hours in a stacked state in a sheet form. The method for correcting curl of a composite foil according to any one of claims 1 to 3, wherein the composite foil is heat-treated at an ambient temperature of 150C to 200C for 1 hour to 7 hours. The said heat processing is the curl correction method of the composite foil in any one of Claims 1-4 which makes a temperature increase rate after that exceeding a minimum temperature 50 degrees C / hour or less. The curling correction method for a composite foil according to claim 2 , wherein the composite foil to be heat-treated is wound up under an inert gas atmosphere. The method for correcting curl of a composite foil according to any one of claims 1 to 6, wherein the composite foil is heat-treated in an inert gas atmosphere. Resulting et is the curl straightening method of a composite foil according to any one of claims 1 to 7,
The composite foil is an ultrathin electrolytic copper foil with a carrier copper foil having a three-layer structure of carrier copper foil / peeling layer / ultra thin electrolytic copper foil,
Composite foil value of mosquito Lumpur is characterized in that it is 10mm or less. The composite foil according to claim 8 , wherein the ultrathin electrolytic copper foil with a carrier copper foil has an organic release layer. A composite foil-clad laminate obtained by bonding the composite foil according to claim 8 or 9 with an insulating resin.