JP6049482B2 - Circuit board for mounting electronic components - Google Patents

Description

  The present invention relates to an electronic component mounting circuit board capable of mounting an electronic component on a circuit board by soldering.

  Conventionally, as a circuit board for mounting an electronic component, a substrate in which a copper wiring pattern is formed on one side or both sides of a resin-containing base material such as a composite base material of a glass nonwoven fabric and an epoxy resin or a polyimide resin base material is widely used. It is used. Here, as a method of mounting an electronic component on a copper line, soldering that is excellent in productivity and reliability of a joint is common.

  Examples of the electronic components include resistors, capacitors, transistors, various power elements, high-density integrated circuits such as MPU and CPU, light emitting elements such as LED chips and laser diodes, and array elements thereof.

  In recent years, for the purpose of reducing the cost and weight of circuit boards, there has been an increasing movement to switch the conductor forming the wiring pattern from copper to aluminum. However, since it is difficult to mount an electronic component by soldering in an aluminum circuit, unlike a copper circuit, development of a method for joining an aluminum circuit and an electronic component (mounting component) is an issue.

  In response to the above problem, Patent Document 1 discloses “a surface-treated Al plate in which a Zn layer, a Ni layer, and a Sn layer are formed in this order from the substrate surface side on the Al substrate surface”. Since the Ni layer and Sn layer are formed on the substrate by plating, the adhesion between the Al substrate and the plating layer is excellent, and since the Sn layer is provided on the outermost surface, it has excellent solder wettability and high solder It is described that strength can be obtained (claim 1, [0025] paragraph, etc.).

  Further, Patent Document 2 contains “Ge: 0.1-5 wt%, Cu: 0.1-4 wt%, Sn: 10-70 wt%, Al: 0.5-10 wt%, and consists of the balance Zn and inevitable impurities. A material for joining Al, characterized in that, by soldering with the Zn-Sn alloy, an Al joined component and a joined component such as copper, iron, nickel, cobalt, silver, gold, etc. It is described that it is advantageous in joining of the above (claim 1, [0015] paragraph).

  However, when Zn plating, Ni plating, and Sn plating are performed on an aluminum circuit as in Patent Document 1, it is necessary to perform a water washing operation after each plating process in addition to the three types of plating processes, which is a complicated process. This is not practical. In addition, when a Zn—Sn alloy is used as solder as in Patent Document 2, it is necessary to use a strong flux to remove the oxide film of the aluminum circuit, and the aluminum circuit is likely to be corroded after soldering. There's a problem. Furthermore, since the Zn—Sn alloy is highly reactive, it is difficult to form a solder paste, and there is a problem that improvement in productivity cannot be expected. It is to be noted that a known Pb—Sn alloy, Sn—Ag—Cu alloy, etc. used for mounting electronic components on a copper circuit can be easily obtained as solder paste solder.

  Therefore, even when a known Pb-Sn alloy, Sn-Ag-Cu alloy, etc. are used as solder, electronic components can be easily mounted on an aluminum circuit by soldering. Development of circuit boards is desired.

JP 2004-263210 A JP 7-96387 A

  The present invention provides an electronic component that can be easily mounted on an aluminum circuit by soldering even when a known Pb-Sn alloy, Sn-Ag-Cu alloy, or the like is used as solder. An object is to provide a circuit board for mounting.

  As a result of intensive studies to achieve the above object, the present inventor, when forming a specific zinc-containing plating film on an aluminum circuit, known Pb-Sn alloy, Sn-Ag-Cu alloy, etc. The present inventors have found that an electronic component can be easily mounted on an aluminum circuit by soldering even when the solder is used as solder, and the present invention has been completed.

That is, the present invention relates to the following electronic component mounting circuit board.
1. An electronic component mounting circuit board in which an aluminum layer of a circuit pattern is laminated on one side or both sides of a resin-containing base material via an adhesive resin layer,
(1) A zinc-containing plating film is formed on the surface of the aluminum layer,
(2) The zinc-containing plating film has a film weight of 0.8 to 4.5 g / m ² and a zinc content of 60 to 97% by weight.
A circuit board for mounting electronic components.
2. 2. The electronic component mounting circuit board according to Item 1, wherein the electronic component is an LED chip.
3. 3. An LED mounting circuit board, wherein an LED chip is mounted on the surface of the zinc-containing plating film of the electronic component mounting circuit board according to Item 1 or 2 by soldering.

  Hereinafter, the present invention will be described in detail.

An electronic component mounting circuit board of the present invention is an electronic component mounting circuit board in which an aluminum layer of a circuit pattern is laminated on one side or both sides of a resin-containing base material via an adhesive resin layer,
(1) A zinc-containing plating film is formed on the surface of the aluminum layer,
(2) The zinc-containing plating film has a film weight of 0.8 to 4.5 g / m ² and a zinc content of 60 to 97% by weight.

  The circuit board for mounting an electronic component according to the present invention having the above characteristics has a zinc-containing plating film having a specific weight and zinc content formed on an aluminum layer (hereinafter also referred to as “aluminum circuit”) of a circuit pattern. Thus, even when a known Pb—Sn alloy, Sn—Ag—Cu alloy or the like is used as solder, electronic components can be easily mounted on the aluminum circuit by soldering. In the present invention, when forming a zinc-containing plating film, it is not necessary to use a strong flux or the like, and since the zinc-containing plating film can be formed by a single plating process, it is easier to use aluminum. Electronic components can be mounted on the circuit by soldering.

  Examples of the resin-containing base material (insulating base material) include at least one kind of epoxy, polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl chloride, polyimide, amorphous polyethylene terephthalate, liquid crystal polymer, and the like. Examples include a substrate containing a resin. As a composite material containing resin, the composite base material of a glass nonwoven fabric and an epoxy is mentioned, for example. Among these, the composite base material of a glass nonwoven fabric and an epoxy, a polyimide containing board | substrate, etc. are preferable from a heat resistant point.

  The thickness of the resin-containing base material is usually selected depending on the purpose and application of the finally produced circuit board. From the viewpoint of using a circuit board as a flexible printed board or handling characteristics, a thickness of 25 to 50 μm is usually preferable.

  The aluminum circuit is formed by processing an aluminum foil by a known pattern forming method such as a photolithography method or an etching resist method. Aluminum foil is not limited to pure aluminum foil, but also includes aluminum alloy foil. Specifically, as the aluminum foil, for example, a pure aluminum foil or aluminum alloy foil such as 1030, 1N30, 1050, 1100, 8021, 8079 or the like with a symbol of JIS (AA) can be adopted.

  The aluminum circuit is laminated on one side or both sides of the resin-containing substrate. Specifically, an aluminum foil is laminated on one side or both sides of the resin-containing substrate via an adhesive resin layer, and then a known pattern forming method The aluminum foil may be processed into an aluminum circuit.

  The thickness of the aluminum circuit is not limited, but is preferably about 7 to 60 μm, and more preferably about 15 to 50 μm.

  The adhesive resin layer may be any resin that can bond the resin-containing substrate and the aluminum foil, and examples thereof include epoxy resin-based, urethane resin-based, polyimide, acrylic resin-based, vinyl chloride resin solution-based adhesives, and the like. It is done. Although the thickness of adhesive resin (adhesive resin layer) is not limited, about 1-10 micrometers is preferable and about 3-7 micrometers is more preferable.

In the present invention, a zinc-containing plating film is formed on the surface of the aluminum circuit. The zinc-containing plating film has a film weight of 0.8 to 4.5 g / m ² and a zinc content of 60 to 97% by weight.

When the coating weight of the zinc-containing plating film is less than 0.8 g / m ² , the surface of the aluminum circuit is not sufficiently covered with the plating film, and the solderability may be lowered. On the other hand, when the coating weight exceeds 4.5 g / m ² , the plating coating itself becomes brittle, and there is a possibility that the plating coating is destroyed after the electronic parts are joined by soldering, and the joining is likely to come off. Coating weight may be in 0.8~4.5g / m ² but, 1.5~3.2g / m ² are preferable among them. Conventionally, Zn plating is exclusively used as a base plating when plating Sn, Cr, etc. on an aluminum substrate, and the coating weight of the conventional Zn plating is about 0.05 to 0.30 g / m ² , and the present invention Compared with the zinc-containing plating film used in the above, it is clearly distinguished in terms of the film weight. The zinc-containing plating film of the present invention does not necessarily have to be formed on the entire surface of the aluminum circuit. As long as the predetermined film weight requirement is satisfied, the zinc-containing plating film is partially applied to the area where electronic components are mounted by soldering. It may be formed. However, when the zinc-containing plating film is formed by immersing the aluminum circuit board in a known zinc-displacement plating agent, the zinc-containing plating film is usually formed on the entire surface of the aluminum circuit.

  If the zinc content of the zinc-containing plating film is less than 60% by weight, the adhesion between the plating film and the aluminum circuit will be reduced, and after joining the electronic parts by soldering, they will be bonded at the interface between the aluminum circuit and the plating layer May easily come off. On the other hand, when the zinc content exceeds 97% by weight, the solder wettability may be reduced by promoting the oxidation reaction of the plating film by the heat of soldering.

  Examples of components other than Zn contained in the zinc-containing plating film include, for example, Ni, Fe, Cu and the like, and metals other than Zn are particularly effective in suppressing the oxidation reaction of the plating film due to the heat of soldering. It is necessary to contain 3 to 40% by weight of the component, preferably 5 to 15% by weight. In other words, the zinc content in the zinc-containing plating film may be 60 to 97% by weight, and preferably 80 to 90% by weight. Preferred plating compositions include Zn: 80.0-90.0 wt%, Ni: 0-2.0 wt%, Fe: 2.0-4.5 wt%, Cu: 0-1.5 wt%.

  In the present invention, the zinc-containing plating film can be formed by using a known zinc displacement plating agent or the like. In addition, in order to suppress oxidation of the zinc-containing plating film and a decrease in solder wettability, the surface of the zinc-containing plating film may be rust-proofed with benzotriazole or the like.

  Although the thickness of the zinc-containing plating film depends on the film weight per unit area, it is preferably about 6 to 80 μm, more preferably about 30 to 50 μm in the present invention.

  The circuit board for mounting an electronic component of the present invention becomes an electronic component mounting circuit board by mounting the electronic component on the surface of the zinc-containing plating film by soldering.

  Examples of the electronic components include resistors, capacitors, transistors, various power elements, high-density integrated circuits such as MPU and CPU, light emitting elements such as LED chips and laser diodes, and array elements thereof.

  In the present invention, a known Pb—Sn alloy, Sn—Ag—Cu alloy or the like can be suitably used as the solder. These solders can be easily obtained as commercial products of solder paste. When these solders are used, the soldering temperature is preferably about 230 to 250 ° C., and the aluminum circuit and the electronic component can be conducted and bonded with sufficient solder strength (die shear strength) by such soldering.

  The circuit board for mounting electronic components according to the present invention has a known Pb-Sn alloy and Sn-Ag-Cu alloy by forming a zinc-containing plating film having a specific weight and zinc content on an aluminum circuit. Even when soldering is used as solder, electronic components can be easily mounted on the aluminum circuit by soldering. In the present invention, when forming a zinc-containing plating film, it is not necessary to use a strong flux or the like, and since the zinc-containing plating film can be formed by a single plating process, it is easier to use aluminum. Electronic components can be mounted on the circuit by soldering.

It is a top view of the wiring pattern (aluminum circuit) used by the Example and the comparative example. A hatched portion is a portion where a wiring pattern (Pattern) is formed, and a slit portion indicated by 0.15 (unit mm) is a gap where no wiring pattern is formed.

  The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

Example 1
On one side of a 50 μm thick aluminum foil (Toyo Aluminum Co., Ltd .: 1N30 material, hard foil), adhesive resin (DIC Co., Ltd .: 100 parts of LX500 and 10 parts of KW75, a curing agent) The mixture was coated so that the thickness after solvent evaporation was 5 μm. Next, the adhesive resin coated surface was bonded to a polyimide film (manufactured by Toray DuPont Co., Ltd .: Kapton 100H, thickness 25 μm).

  Next, an aluminum foil was formed into a wiring pattern (aluminum circuit) shown in FIG. 1 by photolithography.

Next, a zinc-containing plating film (film weight: 1.5 g / m ² , zinc is formed on the aluminum circuit by immersing the aluminum circuit in a zinc replacement plating agent (manufactured by Dipsol: IC-0313) at 25 ° C. for 180 seconds. Content: 85% by weight).

  Next, the LED chip was mounted on the slit portion of FIG. 1 by soldering using a solder paste (Nihon Superior Co., Ltd .: Sn-95.2 wt%, Ag-3.8 wt%, Cu-1.0 wt%).

  Next, the light emission of the mounted LED chip was confirmed and the die shear strength was measured (JIS Z 3198-7). The results are shown in Table 1. The die shear strength measurement is a measurement of the solder joint shear strength of the mounted LED chip, and is performed to evaluate the soldering strength.

Example 2
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 0.8 g / m ² and a zinc content: 85% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Example 3
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 4.5 g / m ² and a zinc content: 85% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Example 4
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 1.5 g / m ² and a zinc content: 60% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Example 5
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight of 1.5 g / m ² and a zinc content of 97% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Example 6
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 4.5 g / m ² and a zinc content: 60% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 1
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight of 0.6 g / m ² and a zinc content of 85% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 2
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 4.8 g / m ² and a zinc content: 85% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 3
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight of 1.5 g / m ² and a zinc content of 55% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 4
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight of 1.5 g / m ² and a zinc content of 99% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 5
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 4.5 g / m ² and a zinc content: 55% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

Comparative Example 6
An LED chip was mounted in the same manner as in Example 1 except that the zinc-containing plating film was changed to a film weight: 4.8 g / m ² and a zinc content: 60% by weight.

  Table 1 shows the results of confirmation of light emission of the mounted LED chip and measurement of die shear strength.

As is apparent from the results in Table 1, an LED chip of an example in which a zinc-containing plating film having a film weight of 0.8 to 4.5 g / m ² and a zinc content of 60 to 97% by weight was formed on an aluminum circuit. It can be seen that all the mounting boards have a large die shear strength, and the soldering strength is sufficiently ensured. In the present invention, if the die shear strength is about 800 gf, it is evaluated that practical strength can be secured even in actual use. Moreover, since it is conducted through soldering, chip light emission is recognized. On the other hand, the LED chip mounting substrate of the comparative example in which the zinc-containing plating film that does not satisfy the provisions of the present invention is significantly inferior to the examples in terms of die shear strength, and in particular, Comparative Examples 1, 4 and 5 Then, it turns out that soldering is not substantially completed.

Claims (3)

An electronic component mounting circuit board in which an aluminum layer of a circuit pattern is laminated on one side or both sides of a resin-containing base material via an adhesive resin layer,
(1) A zinc-containing plating film is formed on the surface of the aluminum layer,
(2) The zinc-containing plating film has a film weight of 0.8 to 4.5 g / m ² and a zinc content of 60 to 97% by weight.
A circuit board for mounting electronic components.   The electronic component mounting circuit board according to claim 1, wherein the electronic component is an LED chip.   The LED mounting circuit board by which the LED chip is mounted by soldering on the surface of the said zinc containing plating film of the circuit board for electronic component mounting of Claim 1 or 2.

Images