JP2009084652A - Oxidation treatment method and oxidation treatment liquid for metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxidation treatment method of a metal (copper or copper alloy) which is free from treatment unevenness or is satisfactory by clarifying the component to impede the oxidation treatment of copper or copper alloy if the component coexists in an oxidation treatment liquid, and controlling the concentration of the impediment component which is of a problem in the oxidation treatment liquid down to a problem-less level or below, and an oxidation treatment liquid. <P>SOLUTION: In the oxidation treatment liquid of the metal including an oxidizing agent and a basic substance, the metal is the copper or copper alloy, and a silicic acid component concentration is ≤200 ppm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a metal (copper or copper alloy) oxidation treatment method and an oxidation treatment liquid that do not cause oxidation treatment unevenness.

  A multilayer printed wiring board is generally manufactured by alternately laminating inner layer wiring boards and prepregs serving as insulating layers and laminating them. At this time, in order to obtain sufficient adhesion between the inner layer copper wiring and the prepreg, an oxidation treatment solution is used to form a fine copper oxide uneven shape on the surface of copper or copper alloy, or a reduction treatment solution is used. A method of reducing this copper oxide to metallic copper is usually performed. In particular, in a package substrate for mounting a semiconductor, roughening with an oxidation treatment liquid or the like is applied not only to the inner layer copper but also to the outermost layer copper surface for the purpose of strengthening the adhesion between the copper wiring and the solder resist.

  The quality of this copper wiring oxidation process greatly affects the adhesion between the resin material such as prepreg and solder resist and the copper foil, and if uneven oxidation occurs, the quality of multilayer printed wiring boards and semiconductor mounting package substrates This leads to a decrease in reliability such as heat resistance. Conventionally, in the case where such processing unevenness occurs, it has been performed to redo from polishing and pickling in the previous step. However, when the series of steps are repeated, the efficiency is low and the copper oxide film once formed is removed, so that the copper foil becomes thin and the conductor thickness varies, which is not preferable.

  For this reason, various methods have been proposed that suppress uneven oxidation treatment and provide uniform copper surface treatment (see, for example, Patent Documents 1 and 2). Patent Document 1 replenishes the amount corresponding to the amount of consumption according to the surface area of the copper foil treated with potassium persulfate and sodium hydroxide, which are constituents of the oxidation treatment liquid, and Patent Document 2 discloses the oxidation treatment liquid. Prior to dipping, a small amount of dirt on copper is removed using a degreasing solution of alkali hydroxide. However, none mentions an inhibitory component in the oxidation treatment solution that induces treatment unevenness.

Japanese Patent Laid-Open No. 1-294771 JP-A-4-165597

  The object of the present invention is to clarify the components that inhibit the oxidation treatment of copper or a copper alloy when coexisting in the oxidation treatment solution, and to control the concentration of the inhibitory components that are problematic in the oxidation treatment solution to a level that does not cause a problem. An object of the present invention is to provide a good metal (copper or copper alloy) oxidation treatment method and oxidation treatment liquid without treatment unevenness.

As a result of intensive studies on the oxidation treatment method and the oxidation treatment liquid in order to solve the above-mentioned problems, the silicic acid component in the oxidation treatment liquid becomes an inhibitory component, and the concentration of the silicic acid component increases, and exceeds a certain level. It has been found that processing unevenness is likely to occur when the concentration reaches a concentration of 1, and that when the concentration of the silicic acid component is extremely high, it is significantly affected so that no oxidation treatment occurs at all, and the present invention has been completed. .
Thus, the present invention relates to the following.
(1) A metal oxidation treatment solution containing an oxidizing agent and a basic substance, wherein the metal is copper or a copper alloy and the silicic acid component concentration is 200 ppm or less.
(2) The metal oxidation treatment solution according to (1) above, which contains chlorite or persulfate as an oxidant and contains alkali hydroxide as a basic substance.
(3) A metal oxidation treatment method using the metal oxidation treatment liquid according to (1) or (2) above.

  The oxidation treatment method and oxidation treatment liquid of the present invention are used at a level where the silicic acid component concentration does not cause a problem, and provide a uniform surface treatment without causing uneven treatment in the oxidation treatment of copper or copper alloy. it can.

  The oxidation treatment liquid of the present invention contains an oxidizing agent and a basic substance, and may contain a buffer as necessary. As the oxidizing agent, chlorite, persulfate or the like can be used. Sodium chlorite can be used as the chlorite, and sodium persulfate, potassium persulfate, ammonium persulfate and the like can be used as the persulfate, and the concentration is preferably 30 to 120 g / l. As the alkali hydroxide, sodium hydroxide, potassium hydroxide and the like can be used, and the concentration is preferably 5 to 40 g / l.

  As the buffering agent, a phosphate such as trisodium phosphate can be used, and its concentration is preferably 3 to 20 g / l. 50-95 degreeC is suitable for the liquid temperature of an oxidation treatment liquid, and the to-be-processed object containing copper or a copper alloy should just contact an oxidation treatment liquid for 1 to 5 minutes. In order to bring the treatment object into contact with the oxidation treatment liquid, the treatment object may be immersed in the oxidation treatment liquid heated to a predetermined temperature, or the oxidation treatment liquid may be sprayed onto the treatment object using a spray machine or the like. .

  The structure of the silicic acid component which is an inhibitory component of the oxidation treatment is not particularly limited, and “ionic silica (ionic silicic acid)” and “dissolved and detected” detected by the analysis method described in JIS-K0101-44. “Colloidal silica”. For the analysis of the silicate component in the oxidation treatment solution, the molybdenum yellow absorptiometry and the molybdenum blue absorptiometry described in JIS-K0101-44 can be used, and other analysis methods such as ICP emission analysis can be used. It is also possible to use it. If the concentration of the silicic acid component in the oxidation treatment liquid is greater than 200 ppm, uneven treatment tends to occur. Therefore, the concentration of the silicic acid component is 200 ppm or less, and particularly preferably 30 ppm or less.

  There is no particular limitation on the route of mixing the silicic acid component into the oxidation treatment liquid. For example, an oxidizing agent, an alkali hydroxide, a complexing agent, and a silicic acid component as an impurity contained in water, which are constituents of the oxidizing treatment liquid during bathing or supply of necessary components, are targeted. In addition, materials such as ceramics and glass used for equipment and jigs such as treatment tanks and spray machines used for oxidation treatment are also targeted. Since the oxidation treatment liquid is alkaline, when it is eluted from these materials, it is mixed in the oxidation treatment liquid. Alternatively, contamination from the workpiece may occur. In particular, printed wiring board materials such as copper-clad laminates often use glass cloth as a base material or silica as a filler, and when eluted in an alkaline oxidation treatment solution, it is mixed into the oxidation treatment solution. .

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.
Example 1
After preparing a single-sided copper foil (thickness 35 μm) for printed wiring boards made by Furukawa Circuit Foil Co., Ltd., after physically polishing the copper foil as a pretreatment, 5 The sample was immersed for 1 minute, washed with running water, and further immersed in a 10% sulfuric acid aqueous solution for 2 minutes and washed with running water. This copper foil was oxidized under the following conditions.
(Composition and conditions of oxidation treatment liquid)
NaClO ₂ : 80 g / l, NaOH: 15 g / l, Na ₃ PO ₄ · 12H ₂ O: 10 g / l, pure water: 1 liter Amount of liquid temperature = 85 ° C.
Copper foil immersion time = 120 seconds Material of oxidation treatment tank = Warming time of glass oxidation treatment liquid (time from the time the liquid temperature reaches 85 ° C. until the copper foil is immersed) = 30 minutes of copper foil oxidized After washing with running water, it was dried at 80 ° C. for 30 minutes.

(Example 2)
The copper foil used in Example 1 was pretreated under the same conditions as in Example 1, and then oxidized under the following conditions.
Composition of oxidation treatment liquid = same liquid temperature as in example 1 = same copper foil immersion time as in example 1 = same oxidation treatment material as in example 1 = warming time of polytetrafluoroethylene oxidation treatment liquid (liquid temperature) Time until the copper foil is immersed after the temperature reaches 85 ° C.) = 10 hours After the oxidation treatment, it was washed with water and dried under the same conditions as in Example 1.

(Comparative Example 1)
The copper foil used in Example 1 was pretreated under the same conditions as in Example 1, and then oxidized under the following conditions.
Composition of oxidation treatment liquid = same liquid temperature as in example 1 = same copper foil immersion time as in example 1 = same oxidation treatment material as in example 1 = heating time of same oxidation treatment as in example 1 (liquid temperature Time until the copper foil is immersed after the temperature reaches 85 ° C.) = 5 hours After the oxidation treatment, it was washed with water and dried under the same conditions as in Example 1.

(Comparative Example 2)
The copper foil used in Example 1 was pretreated under the same conditions as in Example 1, and then oxidized under the following conditions.
Composition of oxidation treatment liquid = same liquid temperature as in example 1 = same copper foil immersion time as in example 1 = same oxidation treatment material as in example 1 = heating time of same oxidation treatment as in example 1 (liquid temperature Time until the copper foil is immersed after the temperature reaches 85 ° C.) = 10 hours After the oxidation treatment, it was washed with water and dried under the same conditions as in Example 1.

(Comparative Example 3)
The copper foil used in Example 1 was pretreated under the same conditions as in the Examples, and then oxidized under the following conditions.
Composition of oxidation treatment solution = NaClO ₂ : 80 g / l, NaOH: 15 g / l, Na ₃ PO ₄ · 12H ₂ O: 10 g / l, Na ₂ SiO ₃ : 1 g / l, pure water: 1 liter Temperature = same copper foil immersion time as in Example 1 = same oxidation treatment tank material as in Example 1 = warming time of polytetrafluoroethylene oxidation treatment solution (copper foil is immersed after the liquid temperature reaches 85 ° C.) Time) = 10 hours After the oxidation treatment, it was washed with water and dried under the same conditions as in Example 1.

(Comparative Example 4)
The copper foil used in Example 1 was pretreated under the same conditions as in Example 1, and then oxidized under the following conditions.
Composition of oxidation treatment liquid = NaClO ₂ : 80 g / l, NaOH: 15 g / l, Na ₃ PO ₄ .12H ₂ O: 10 g / l, Na ₂ SiO ₃ : 2 g / l, pure water: 1 liter Temperature = same copper foil immersion time as in Example 1 = same oxidation treatment tank material as in Example 1 = warming time of polytetrafluoroethylene oxidation treatment solution (copper foil is immersed after the liquid temperature reaches 85 ° C.) Time) = 10 hours After the oxidation treatment, it was washed and dried under the same conditions as in Example 1.

  About the glossy surface of the copper foil oxidized by the above Examples and Comparative Examples, the appearance was observed to examine the presence or absence and degree of processing unevenness. Furthermore, this oxidized copper foil was heated and pressure laminated with a glass cloth epoxy prepreg made by Hitachi Chemical Co., Ltd. to produce a copper-clad laminate, and the copper foil peel strength in the normal state (copper foil pulling) Stripping width: 10 mm, peeling speed: 50 mm / min) and solder heat resistance (288 ° C., 2 min) were measured. Moreover, the concentration of the silicic acid component contained in the oxidation treatment solution used in the examples and comparative examples was quantified. The analysis method was performed by molybdenum yellow absorptiometry and molybdenum blue absorptiometry according to JIS-K0101-44. The results are shown in Table 1.

なお、表中の記号は次を意味する。
処理ムラ・・・・○：均一な処理でムラ無、△：一部にムラ有、×：ムラかなり発生、
−：酸化処理が十分起こらないため、評価不可
はんだ耐熱性・・○：異常無、△：小さな膨れ発生、×：大きな膨れ発生

In addition, the symbol in a table | surface means the following.
Unevenness of processing ... ○: Uniform treatment with no unevenness, △: Some unevenness, ×: Unevenness occurs considerably,
-: Oxidation does not occur sufficiently, so evaluation is not possible Solder heat resistance ··: No abnormality, △: Small blisters, ×: Large blisters

  As is clear from Table 1, by making the concentration of the silicic acid component in the oxidation treatment solution 200 ppm or less, a copper foil having a uniform appearance without treatment unevenness can be obtained. If this copper foil is used, the copper foil is peeled off. It was found to be excellent in strength and solder heat resistance.

  The copper or copper alloy oxidation treatment method and oxidation treatment liquid of the present invention enhance the adhesion between the copper foil and a resin material such as a prepreg or solder resist in an electronic component such as a printed wiring board or a package substrate for mounting a semiconductor. The reliability can be improved. In addition, it is possible to prevent a reduction in processing efficiency due to the redoing of the oxidation treatment.

Claims (3)

  A metal oxidation treatment solution comprising an oxidant and a basic substance, wherein the metal is copper or a copper alloy and the silicate component concentration is 200 ppm or less.   The metal oxidation treatment solution according to claim 1, comprising chlorite or persulfate as the oxidizing agent, and alkali hydroxide as the basic substance.   A metal oxidation treatment method using the metal oxidation treatment liquid according to claim 1.