JP4222001B2 - Copper coated plastic substrate - Google Patents

Description

【００４３】
表１から明らかなように、実施例１〜７では、クロム層（第一シード層）の膜厚が５Å以上２５Å以下であり、かつクロム濃度が１５重量％未満であるニッケルクロム合金層（第二シード層）の膜厚が１０Å以上３００Å以下であるとき、また、クロム層（第一シード層）の膜厚が５Å以上２５Å以下であり、かつクロム濃度が１５重量％以上４０重量％以下であるニッケルクロム合金層（第二シード層）の膜厚が１０Å以上１５０Å以下であるとき、リード周辺のエッチング状態はシード層の残留がなく良好で、初期密着力が６００Ｎ／ｍ以上、高温耐熱密着力が５００Ｎ／ｍ以上である銅被覆ポリイミド基板が得られることが分かる。これに対して、比較例１〜６では、シード層の構成、または膜厚がこれらの条件に合わないため、リード周辺のエッチング状態、又は高温耐熱密着力のいずれかに満足すべき結果が得られないことが分かる。
【００４４】
【発明の効果】
以上説明したように、本発明の銅被覆プラスチック基板は、塩化鉄溶液や塩化銅溶液を用いたエッチング法によってパターニング可能で、かつ銅導電体の厚み８μｍにおいて、初期密着力、および、３５０℃から４５０℃の温度範囲で１０秒間の熱圧着後の高温耐熱密着力が、いずれも５００Ｎ／ｍ以上となる高耐熱性の２層メッキ基板であり、その工業的価値は極めて大きい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper-coated plastic substrate, and more specifically, it can be patterned not only to a copper layer but also to a seed layer by an etching method using an iron chloride solution or a copper chloride solution, and has an initial adhesion force and a high-temperature heat-resistant adhesion force. Relates to a large copper-coated plastic substrate. Such a copper-coated plastic substrate is used as a flexible substrate for electronic components such as a printed wiring board, a flexible printed wiring board, a TAB tape, and a COF tape.
[0002]
[Prior art]
Copper-coated plastic substrates are widely used as substrates for electronic components such as printed wiring boards (PWB), flexible printed wiring boards (FPC), tape automatic bonding tapes (TAB), and chip-on-film (COF).
These PWB, FPC, TAB, COF, etc. are obtained by processing a metal-coated plastic substrate mainly coated with copper as a metal conductor layer on at least one surface of a plastic film such as polyimide. Such metal-coated plastic substrates include a three-layer substrate in which a plastic film and a metal foil such as a copper foil are bonded via an adhesive, and a two-layer substrate in which a metal layer is directly formed on the plastic film.
[0003]
The most widely used two-layer copper polyimide substrate is a substrate by casting that forms a polyimide film on a commercially available copper foil, and a dry plating method such as sputtering, vacuum evaporation, or ion plating on a commercially available polyimide. A substrate by a plating method (hereinafter referred to as a two-layer plating substrate) in which a seed layer is formed and a copper layer is formed by dry plating, wet plating (electroplating or electroless plating), or a combination thereof. is there.
[0004]
Conventionally, in a two-layer plated substrate, the adhesion between the plastic film and the copper layer is low in the manufacturing process of PWB, FPC, etc., which is a subsequent process, for example, metal lamination and etching process by electroplating in the circuit forming process. There was a problem of lowering.
As a solution to this, a method of forming a seed metal layer having better adhesion than copper between a plastic and a copper layer has been proposed. As typical seed layer metal types and film formation methods, Such a thing is mentioned.
(1) Nickel or a nickel alloy is formed by an ion plating method (see Patent Document 1),
(2) Nickel, cobalt, zirconium, palladium or an alloy containing these is formed by an ion plating method (see Patent Document 2).
(3) One of nickel, cobalt, zirconium, and palladium is formed by physical vapor deposition (see Patent Document 3).
(4) Nickel, tin, manganese, and indium are formed by vapor deposition (see Patent Document 4).
(5) forming a deposited metal chromium layer of 50 to 500 angstroms (see Patent Document 5);
(6) Nickel or nickel-chrome is formed by vapor deposition (see Patent Document 6),
(7) A chromium layer of 0.01 to 5 μm is formed by a sputtering method (see Patent Document 7).
[0005]
However, in the adhesion between a plastic film such as polyimide and a copper layer, these proposals were effective in improving the adhesion (initial adhesion) after circuit formation, but the adhesion after heat load at high temperature. It does not meet the requirements for strength (high temperature and heat resistance).
Recently, especially as portable electronic devices become smaller and thinner, the above-mentioned TAB and COF are also required to be smaller and thinner, that is, higher density, and the wiring pitch (wiring width / space width) has become increasingly narrower. Therefore, a two-layer plated substrate that can be freely controlled with a thin conductor layer (copper coating) has attracted particular attention. At the same time, the required performance for heat resistance is increasing.
[0006]
Therefore, solutions aimed at improving heat resistance have been proposed, and typical methods include, for example, the following.
(1) A chromium / chromium oxide layer having a thickness of 25 to 150 mm is formed by a sputtering method (see Patent Document 8).
(2) A cobalt layer is formed by a sputtering method in such a thickness that the decrease in adhesion strength between the metal layer and the polyimide layer is suppressed to within 5% even when heated at 150 ° C. for 4 hours (see Patent Document 9). ,
(3) A titanium layer is formed by a sputtering method to such a thickness that a decrease in adhesive strength between the metal layer and the polyimide layer is suppressed to within 5% even when heated at 150 ° C. for 4 hours (see Patent Document 10).
(4) A molybdenum layer is formed by a sputtering method in such a thickness that a decrease in adhesive strength between the metal layer and the polyimide layer is suppressed to within 5% even when heated at 150 ° C. for 4 hours (see Patent Document 11). ,
(5) An alloy layer including at least two of titanium, cobalt, molybdenum, and nickel is formed by a sputtering method (see Patent Document 12).
(6) A nichrome alloy having a thickness of 50 to 500 angstroms is formed by a sputtering method (see Patent Document 13).
(7) At least one selected from the group consisting of nickel, copper-nickel alloy, chromium, and chromium oxide is formed by a dry plating method such as sputtering, vacuum deposition, or ion plating (Patent Document 14). reference).
[0007]
These proposals have contributed to the improvement of heat resistance in each application, but further, it is required to cope with more severe high temperature heat resistance and film characteristics that are easily etched. For example, a method of forming a chromium / chromium oxide sputtering layer having a thickness of 25 to 150 mm on an electrically insulating support film such as polyimide and further forming a copper layer has been proposed (see Patent Document 8). In the case of such a two-layer plating substrate having a chromium / chromium oxide seed layer of 25 mm or more, in order to remove the remaining chromium seed layer after etching the copper layer with an iron chloride solution or a copper chloride solution in the patterning process. In addition, it is necessary to use environmentally damaging chemicals such as potassium permanganate solution.
[0008]
However, along with recent social demands for environmental protection, COF processing does not use potassium permanganate solution, but uses more environmentally friendly iron chloride solution and copper chloride solution as well as copper layer as seed. There is a need for a two-layer plated substrate that can be etched down to a layer.
Further, in the COF processing step, Sn plating is performed on the Cu leads of the two-layer plating substrate after the patterning. The Sn plated Cu lead is electrically and mechanically connected to the Au bump on the Si chip. This connection is called an ILB (Inner Lead Bonding) connection. In this case, the two-layer plated substrate is exposed to a high temperature of 200 ° C. or higher, and in some cases, 350 ° C. to 450 ° C.
[0009]
However, the conventional two-layer plated substrate has a problem that the adhesion after a high temperature heat load by ILB connection is remarkably lowered. For example, the high-temperature heat-resistant adhesion after a thermocompression bonding of a two-layer plated substrate having an initial adhesion of 500 N / m or more for 10 seconds in a temperature range of 350 ° C. to 450 ° C. is reduced to 500 N / m or less. .
In view of the above situation, the market demands a two-layer plated substrate that can be etched with an iron chloride solution or a copper chloride solution and has high adhesion between the copper layer and the plastic film after high-temperature heat load. .
[0010]
[Patent Document 1]
Japanese Examined Patent Publication No.57-18356 (first page)
[Patent Document 2]
Japanese Examined Patent Publication No. 57-18357 (first page)
[Patent Document 3]
Japanese Patent Publication No.57-33718 (first page)
[Patent Document 4]
JP 61-128593 A (page 2)
[Patent Document 5]
JP 62-62551 A (first page)
[Patent Document 6]
Japanese Patent Laid-Open No. 62-181488 (first page)
[Patent Document 7]
Japanese Unexamined Patent Publication No. 02-98994 (first page)
[Patent Document 8]
Japanese Examined Patent Publication No. 04-65558 (first page)
[Patent Document 9]
Japanese Patent Application Laid-Open No. 08-330693 (2nd page)
[Patent Document 10]
Japanese Patent Application Laid-Open No. 08-330694 (2nd page)
[Patent Document 11]
Japanese Patent Laid-Open No. 08-330695 (2nd page)
[Patent Document 12]
Japanese Patent Application Laid-Open No. 08-332697 (page 2)
[Patent Document 13]
JP 09-83134 A (page 2)
[Patent Document 14]
JP-A-10-256700 (page 2)
[0011]
[Problems to be solved by the invention]
The object of the present invention is to be able to pattern not only the copper layer but also the seed layer by an etching method using an iron chloride solution or a copper chloride solution in view of the above-mentioned problems of the prior art, and the thickness of the copper conductor layer is 8 μm. It is an object of the present invention to provide a copper-coated plastic substrate having both initial adhesion strength and high-temperature heat-resistant adhesion strength after thermocompression bonding for 10 seconds in a temperature range of 350 ° C. to 450 ° C. of 500 N / m or more.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the inventors have conducted extensive research on the structure of the seed layer formed between the plastic film and the copper layer in the copper-coated plastic substrate, and as a result, optimized the structure of the seed layer. That is, the seed layer has a two-layer structure composed of a chromium layer and a nickel chromium alloy layer, and the film thickness of these seed layers is appropriately controlled while maintaining the chromium concentration in the nickel chromium alloy within a specific range. The inventors have found that this can be solved, and completed the present invention.
[0013]
That is, according to the first aspect of the present invention, a copper coating is formed by forming a seed layer directly on both sides or one side of a plastic film without using an adhesive, and forming a copper conductor layer on the seed layer. In the plastic substrate, the seed layer includes a first seed layer made of a chromium layer having a thickness of 5 mm to 25 mm formed on a plastic film, and nickel having a chromium concentration of 40% by weight or less formed on the first seed layer. The second seed layer is composed of a chromium alloy layer , and the second seed layer has a film thickness of 10 to 300% and a chromium concentration of 15 when the chromium concentration in the nickel chromium alloy is less than 15% by weight. When the content is not less than 40% by weight and not more than 40% by weight , a copper-coated plastic substrate characterized by being 10 to 150% is provided.
According to the second invention of the present invention, in the first invention, the impurity concentration of chromium as the first seed layer is 2 wt% or less, and the impurity concentration of the nickel chromium alloy as the second seed layer Is 1% by weight or less, a copper-coated plastic substrate is provided.
[0014]
According to a third aspect of the present invention, there is provided a copper-coated plastic substrate according to the first or second aspect , wherein the first seed layer and the second seed layer are formed by a sputtering method. .
[0015]
According to a fourth aspect of the present invention, there is provided the copper-coated plastic substrate according to any one of the first to third aspects , wherein the plastic film is a polyimide film.
[0016]
According to the fifth invention of the present invention, in any one of the first to fourth inventions, the high-temperature heat-resistant adhesive strength after thermocompression bonding for 10 seconds at a temperature range of 350 to 450 ° C. is obtained at a copper conductor layer thickness of 8 μm. A copper-coated plastic substrate characterized by being 500 N / m or more is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the copper-coated plastic substrate of the present invention will be described in detail.
[0018]
The copper-coated plastic substrate according to the present invention has environmentally friendly etching processability and is excellent in high-temperature heat resistance. Specifically, it can be patterned by an etching method using an iron chloride solution or a copper chloride solution, and when the copper conductor layer has a thickness of 8 μm, the initial adhesive force and the thermocompression bonding for 10 seconds at a temperature range of 350 ° C. to 450 ° C. The subsequent high-temperature heat-resistant adhesion is 500 N / m or more.
[0019]
The plastic film used in the present invention is not particularly limited, and for example, heat-resistant films such as polyethylene terephthalate, polyether ketone, polyether imide, polyphenylene sulfide, polyarylate, polyamide, polyimide are used. Among these, a polyimide film that is particularly excellent in heat resistance and that is inferior to other plastic materials in mechanical, electrical, and chemical characteristics is preferable. The polyimide film used in the present invention may be a commercially available polyimide film having a trade name such as Kapton, Apical, or Upilex, and preferably has a thickness of 5 to 75 μm.
[0020]
In the present invention, a seed layer is formed directly on both sides or one side of a plastic film without using an adhesive, and a copper conductor layer is formed on the seed layer. This seed layer is composed of two layers, a first seed layer formed on the plastic film and a second seed layer formed on the first seed layer, and can be made into two different metal (alloy) layers. It is essential. By forming the seed layer with this configuration, the object of the present invention relating to adhesion is achieved.
[0021]
As the first seed layer, chromium is used, and the film thickness is 5 to 25 mm, preferably 10 to 20 mm. This is because if the film thickness of the chromium layer is less than 5 mm, it is impossible to maintain the desired high-temperature heat resistance, and if it exceeds 25 mm, the efficiency of the etching process in the patterning process is reduced or an etching residue occurs.
[0022]
As the second seed layer, a nickel chromium alloy is used, and the film thickness varies depending on the chromium concentration in the nickel chromium alloy. The chromium concentration in the nickel chromium alloy used as the second seed is 40% by weight or less. This is because if the amount exceeds 40% by weight, the efficiency of the etching process in the patterning step is reduced, or an etching residue occurs.
When the chromium concentration is less than 15% by weight, the film thickness is 10 to 300 mm, preferably 30 to 200 mm. This is because if the thickness of the nickel-chromium alloy is less than 10 mm, it is impossible to maintain the desired high-temperature heat resistance, and if it exceeds 300 mm, the efficiency of the etching process in the patterning process is reduced or an etching residue occurs.
When the chromium concentration is 15% by weight or more and 40% by weight or less, the film thickness is 10 to 150%, preferably 15 to 100%. This is because if the thickness of the nickel-chromium alloy is less than 10 mm, it is impossible to maintain the desired high-temperature heat resistance, and if it exceeds 150 mm, the efficiency of the etching process in the patterning process decreases.
[0023]
The impurity concentration of chromium as the first seed layer is preferably 2% by weight or less, and the impurity concentration of the nickel chromium alloy as the second seed layer is preferably 1% by weight or less. When the impurity concentration of chromium as the first seed layer exceeds 2 wt% and / or the impurity concentration of the nickel chromium alloy as the second seed layer exceeds 1 wt%, the etching process during the patterning process becomes difficult. This is because the adhesive strength varies.
[0024]
The seed layer is preferably formed directly on the surface of the plastic film by a dry plating method such as sputtering, vacuum deposition, or ion plating. In particular, the sputtering method is preferable from the viewpoint of adhesion to a plastic film and stability of film thickness control. In the sputtering method, there are no specific conditions, and DC sputtering, high frequency sputtering, ion beam sputtering, magnetron sputtering, or the like is used.
[0025]
Prior to the formation of the seed layer, chemical treatment with acid, alkali, organic solvent, etc., or plasma treatment in a vacuum or air atmosphere may be performed as a modification treatment of the plastic film surface. Moreover, you may put a heating process as a drying process.
[0026]
In the copper-coated plastic substrate of the present invention, the copper layer is formed on the second seed layer by a dry plating process such as sputtering, vacuum deposition, or ion plating, or by electrolytic copper plating or electroless copper plating. It is formed by a wet plating process such as a method. The copper layer may be formed by combining the dry process and the wet process. For example, a copper layer having a layer thickness of 200 to 5,000 mm is formed on the second seed layer by a dry plating process in order to reduce pinhole defects and ensure electric conductivity. A copper layer is formed by a wet plating process up to a predetermined thickness in order to ensure the desired performance.
The film thickness of the copper layer is not particularly limited because an optimal film thickness may be selected according to the application, but is preferably 800 mm or more and 35 μm or less. This is because if the thickness is less than 800 mm, the conductivity and the mechanical strength are lowered, and if it exceeds 35 μm, the wiring pitch is hindered and the productivity is lowered.
[0027]
Since the copper-coated plastic substrate of the present invention has two kinds of first seed layer and second seed layer of different metals as the seed layer, it is excellent in high-temperature heat-resistant adhesion. That is, the heat resistance at a high temperature of 350 to 450 ° C. is imparted, and the initial adhesion strength and the high temperature heat adhesion strength after the thermocompression bonding for 10 seconds in the temperature range of 350 to 450 ° C. are both 8 μm thick. In this case, it is 500 N / m or more, preferably 530 N / m or more.
As described above, the chromium concentration and film thickness in the nickel chromium alloy layer used for the second seed layer are properly formed, and the surface properties of the film, such as the type and brand of plastic film used, and the surface modification status as a pretreatment Can be added to obtain a copper-coated plastic substrate with higher temperature and heat resistance adhesion. [0028]
【Example】
EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the use polyimide film used by the Example and the comparative example, the sample preparation methods, and the evaluation method are as follows.
(1) Polyimide film used Kapton EN manufactured by Toray DuPont Co., Ltd., a 38 μm-thick polyimide film was used after being heated and dried in a vacuum.
(2) Sample preparation method and evaluation method A test piece was taken out from the manufactured copper-coated polyimide substrate, and was first patterned. A lead with a width of 1 mm was formed using an iron chloride solution as an etching solution to prepare a sample for adhesion measurement. After patterning, it was confirmed by elemental analysis using an EPMA (electron beam microanalyzer) whether the portion around the lead of the adhesion measurement sample where the metal layer should be removed and the polyimide should be exposed is properly etched. . The sample for adhesion measurement was measured by a 90 degree peel test. This adhesion was defined as the initial adhesion.
Next, another sample for adhesion measurement produced in the same manner was thermocompression bonded at a pressure of 3 MPa from the polyimide side with a ceramic head heated to 400 ° C. in the atmosphere for 10 seconds to give a thermal load. The adhesion after thermocompression bonding at 400 ° C. was defined as a high temperature heat resistant adhesion.
In addition, since each said adhesive force tends to show a high value, so that copper thickness becomes thick, the measurement of the adhesive force in this invention was implemented on the basis of the measurement by the copper thickness of 8 micrometers currently used widely. The measurement of adhesive force was implemented according to JPCA BM01-11.5.3.
[0029]
Example 1
A chromium layer was formed as a first seed layer on one side of the polyimide film to a thickness of 8 mm by sputtering. Next, a nickel chromium alloy layer having a chromium concentration of 7% by weight was formed on the first seed layer to a thickness of 100 mm by a sputtering method. Subsequently, a copper layer was first formed to a thickness of 1500 mm by a sputtering method, and then a copper layer was formed to have a total thickness of 8 μm by an electrolytic copper plating method, thereby manufacturing a copper-coated polyimide substrate. An evaluation sample was prepared from a part of the substrate, and the etching state around the lead, the initial adhesion, and the high-temperature heat-resistant adhesion were measured. The results are shown in Table 1.
[0030]
Example 2
A copper-coated polyimide substrate was produced under the same conditions as in Example 1 except that the chromium layer was formed to a thickness of 20 mm as the first seed layer. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0031]
Example 3
A copper-coated polyimide substrate was produced under the same conditions as in Example 1 except that the chromium layer was formed to a thickness of 15 mm as the first seed layer. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0032]
Example 4
Example 1 except that a chromium layer was formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy layer with a chromium concentration of 7 wt% was formed as a second seed layer with a thickness of 250 mm. A copper-coated polyimide substrate was manufactured under the conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0033]
Example 5
Example 1 except that a chromium layer was formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy layer with a chromium concentration of 20 wt% was formed as a second seed layer with a thickness of 20 mm. A copper-coated polyimide substrate was manufactured under the conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0034]
Example 6
The same conditions as in Example 1 were used except that a chromium layer was formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy with a chromium concentration of 20 wt% was formed as a second seed layer with a thickness of 120 mm. A copper-coated polyimide substrate was produced. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0035]
Example 7
Example 1 except that a chromium layer was formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy layer with a chromium concentration of 35 wt% was formed as a second seed layer with a thickness of 50 mm. A copper-coated polyimide substrate was manufactured under the conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0036]
Comparative Example 1
The copper-coated polyimide substrate was formed under the same conditions as in Example 1 except that the chromium layer of the first seed layer was not formed and a nickel chromium alloy layer having a chromium concentration of 7% by weight and a thickness of 100 mm was directly formed on the polyimide. Manufactured. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0037]
Comparative Example 2
A copper-coated polyimide substrate was produced under the same conditions as in Example 1 except that the chromium layer was formed to a thickness of 35 mm as the first seed layer. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0038]
Comparative Example 3
A copper-coated polyimide substrate was manufactured under the same conditions as in Example 1 except that the chromium layer was formed to a thickness of 15 mm as the first seed layer and the nickel-chromium alloy layer as the second seed layer was not formed. . Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0039]
Comparative Example 4
Example 1 except that a chromium layer is formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy layer with a chromium concentration of 7 wt% is formed as a second seed layer with a thickness of 400 mm. A copper-coated polyimide substrate was manufactured under the conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0040]
Comparative Example 5
Example 1 except that a chromium layer is formed as a first seed layer with a thickness of 15 mm and a nickel chromium alloy layer with a chromium concentration of 35 wt% is formed as a second seed layer with a thickness of 300 mm. A copper-coated polyimide substrate was manufactured under the conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0041]
Comparative Example 6
The same as in Example 1 except that the chromium layer was formed as a first seed layer with a thickness of 15 mm and the nickel chromium alloy layer with a chromium concentration of 45 wt% was formed as a second seed layer with a thickness of 100 mm. Manufactured under conditions. Table 1 shows the etching conditions around the leads, and the measurement results of initial adhesion and high-temperature heat-resistant adhesion.
[0042]
[Table 1]

[0043]
As is clear from Table 1, in Examples 1 to 7, a nickel chromium alloy layer (first layer) in which the film thickness of the chromium layer (first seed layer) is 5 to 25 mm and the chromium concentration is less than 15% by weight. The second seed layer) is 10 to 300 mm thick, the chromium layer (first seed layer) is 5 to 25 mm thick, and the chromium concentration is 15 wt% to 40 wt%. When the thickness of a nickel chrome alloy layer (second seed layer) is 10 mm or more and 150 mm or less, the etching condition around the lead is good with no seed layer remaining, initial adhesion is 600 N / m or more, and high temperature heat resistant adhesion It can be seen that a copper-coated polyimide substrate having a force of 500 N / m or more can be obtained. On the other hand, in Comparative Examples 1-6, since the structure of the seed layer or the film thickness does not meet these conditions, a satisfactory result is obtained in either the etching state around the lead or the high-temperature heat-resistant adhesion. I can't understand.
[0044]
【The invention's effect】
As described above, the copper-coated plastic substrate of the present invention can be patterned by an etching method using an iron chloride solution or a copper chloride solution, and has an initial adhesion force of 350 μC at a copper conductor thickness of 8 μm. It is a high heat-resistant two-layer plating substrate in which the high-temperature heat-resistant adhesion after 10 seconds of thermocompression bonding in the temperature range of 450 ° C. is 500 N / m or more, and its industrial value is extremely large.

Claims (5)

In a copper-coated plastic substrate in which a seed layer is formed directly on both sides or one side of a plastic film without using an adhesive, and a copper conductor layer is formed on the seed layer, the seed layer is formed on the plastic film. The first seed layer made of a chromium layer having a thickness of 5 to 25 mm and the second seed layer made of a nickel chromium alloy layer having a chromium concentration of 40% by weight or less formed on the first seed layer. Moreover, the thickness of the second seed layer is 10 to 300% when the chromium concentration in the nickel chromium alloy is less than 15% by weight, and 10% or more when the chromium concentration is 15% to 40% by weight. A copper-coated plastic substrate characterized by being 150 mm or less . The impurity concentration of chromium as the first seed layer is 2 wt% or less, and the impurity concentration of the nickel chromium alloy as the second seed layer is 1 wt% or less. Copper coated plastic substrate. The copper seed plastic substrate according to claim 1 or 2 , wherein the first seed layer and the second seed layer are formed by sputtering. The copper-coated plastic substrate according to any one of claims 1 to 3, wherein the plastic film is a polyimide film. The high-temperature heat-resistant adhesive strength after thermocompression bonding for 10 seconds in a temperature range of 350 to 450 ° C in a thickness of 8 µm of the copper conductor layer is 500 N / m or more, according to any one of claims 1 to 4. The copper-coated plastic substrate as described.