JP2005116910A - Method for manufacturing printed circuit board of composite conductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing technology of a composite conductor printed circuit board having a sensor function. <P>SOLUTION: A method for manufacturing the printed circuit of the composite conductor includes a step of forming a base material having a nickel layer on one side surface and a copper layer on the other side surface; a step of forming a copper plating layer after perforating at the base material; a step of coating photoresists on both surfaces of the base material, and disposing a first film for forming a circuit on the nickel layer side and a complete exposure film for entire surface exposure at the copper layer side to exposure-develop them; a step etching the exposed copper plating layer and the nickel layer disposed under the copper plating layer; a step of coating again after the photoresists are released, and disposing a second film for forming the circuit at the nickel layer side and a third film for forming the circuit at the copper layer side to exposure-develop them; a step of forming a solder plating layer on the exposed copper plating layer; a step of alkali-etching the photoresist with the solder plating layer as a mask after the photoresists are released; a step of removing the exposed copper plating layer and the copper layer disposed under the copper plating layer; and a step of removing the solder plating layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a composite conductor printed wiring board having different metal conductors, and in particular, a conductor made of nickel on one side and copper on the other side is formed, and these conductors are connected by through holes, and a temperature sensor It is related with the printed wiring board of a suitable composite conductor as.

  Conventionally, a thermocouple that measures temperature using a thermoelectromotive force generated by a temperature difference when different metals are connected is known as a temperature sensor. In recent years, temperature sensors are arranged at various locations, and various controls such as an air temperature and a liquid temperature are often performed by detecting and feeding back an environmental temperature or the like.

A typical example of the use of such a temperature sensor is an air conditioner. In an air conditioner, an appropriate temperature control is performed while detecting a room temperature with a temperature sensor. In recent years, air conditioners are also provided as standard equipment in automobiles, and in-vehicle air conditioners are similarly controlled using temperature sensors (see Patent Document 1).
JP-A-6-80009

  The temperature sensor used in this on-vehicle air conditioner is also a conventionally known thermocouple type. On the other hand, in a recent automobile, most of various controls are electrically performed, and electronic control using a printed wiring board is performed for the control. And this printed wiring board is also evolving, and it has various on-board electronic parts such as IC and memory, and has a function capable of performing a great deal of control by the wiring board itself.

  Under such circumstances, there has been a proposal to give the printed wiring board itself the function of a temperature sensor for controlling an on-vehicle air conditioner. In other words, if the printed wiring board itself becomes a temperature sensor, there is no need to separately arrange the temperature sensor and the printed wiring board as in the conventional thermocouple type, and only the printed wiring board needs to be mounted on the automobile. In addition, work efficiency can be improved and space can be saved.

  In order for the printed wiring board itself to be a temperature sensor, it is necessary to form a wiring board in which different metals (conductors) are connected, such as a thermocouple. That is, a technique for manufacturing a printed wiring board so that a thermocouple is formed in the printed wiring board is required. As far as the present inventor is aware, there is no technique for manufacturing a printed wiring board having such a temperature sensor function.

  The present invention has been made against the background described above, and provides a technique for manufacturing a printed wiring board of a composite conductor having a function as a temperature sensor.

  In order to solve the above problems, the present inventor has studied various conventional printed wiring board technologies using nickel and copper as conductors to realize a thermocouple similar to a temperature sensor, that is, a thermocouple. As a result, the present invention has been conceived.

  The method for producing a printed wiring board according to the present invention comprises a step of laminating a nickel foil on one side of a substrate and a copper foil on the other side by press molding to form a substrate having a nickel layer on one side and a copper layer on the other side. Then, after drilling the base material, a copper plating layer is formed by plating treatment, a photoresist is coated on both surfaces of the base material, and a first film for circuit formation is provided on the base material surface side provided with a nickel layer. , A fully exposed film for full surface exposure is arranged on the substrate surface side provided with a copper layer, and exposure and phenomenon treatment are performed, and the exposed copper plating layer and the nickel layer therebelow are treated with a cupric chloride solution. Alternatively, after etching with an iron chloride solution and peeling off the remaining photoresist, the photoresist is coated again, and a second film for forming a circuit is formed on the substrate surface side having a nickel layer, and a base having a copper layer is provided. A third film for circuit formation is placed on the material side. After each placement, exposure, phenomenon treatment, solder plating treatment is performed on the exposed copper plating layer to form a solder plating layer, the remaining photoresist is peeled off, and then alkali etching is performed using the solder plating layer as a mask Thus, the exposed copper plating layer and the copper layer below the copper plating layer are removed, and the solder plating layer is removed.

  According to the manufacturing method of the present invention, it is possible to easily manufacture a printed wiring board of a composite conductor characterized in that a nickel conductor and a copper conductor are connected via a base material.

  The method for producing a printed wiring board of a composite conductor according to the present invention, when forming a circuit in order to form conductors on different metal conductor layers on both sides of the substrate, that is, a nickel layer and a copper layer, On the nickel layer side, a circuit is formed on the nickel layer by a so-called tenting method, and on the copper layer side, a circuit is formed on the copper layer by a so-called solder peeling method. By this manufacturing method, on both surfaces of one base material, a conductor made of nickel is formed on one side and a conductor made of copper is formed on the other side.

  The tenting method is a method of using a photoresist such as a dry film, covering a copper plated through hole including necessary circuits and lands with a photoresist like a tent, and performing an etching process. More specifically, after drilling a base material provided with a nickel layer on one side and a copper layer on the other side, a copper plating layer is formed by plating, and a photoresist is coated on both sides of the base material. The first film for circuit formation is arranged on the substrate surface side provided with a layer, and the fully exposed film for full exposure is arranged on the substrate surface side provided with a copper layer, respectively, and exposed, phenomenon-treated, and exposed copper plating. The layer and the nickel layer therebelow are etched with a cupric chloride solution or an iron chloride solution.

  Thereby, on the nickel layer side, a pattern such as a circuit printed on the first film is formed, and a conductor made of nickel having a predetermined shape is formed. On the other side, that is, on the copper layer side, the completely exposed photoresist remains, so that the etching process with the cupric chloride solution or the iron chloride solution is not performed. In the present invention, a manufacturing method using a negative type photoresist is shown, but a positive type photoresist can also be used as a matter of course.

  The solder peeling method is a method of using solder plating as an etching resist, forming a circuit, a land, and the like and then dissolving and removing the solder plating that has become the etching resist. More specifically, after removing the remaining photoresist on the substrate on which the conductor circuit was formed by nickel by the above-described tenting method, the photoresist was coated again, and the substrate surface provided with the nickel layer was coated. The second film for circuit formation is placed on the substrate side with the copper layer, and the third film for circuit formation is placed on each side, exposed and processed, and the exposed copper plating layer is solder plated. After forming the solder plating layer and removing the remaining photoresist, the exposed copper plating layer and the underlying copper layer are removed by alkali etching using the solder plating layer as a mask, and the solder plating layer is removed. It is.

  An etching solution used for alkali etching using the solder plating layer as an etching resist is an alkaline aqueous solution mainly composed of a copper ammonium complex ion, such as an aqueous ammonium hydroxide solution. This alkaline etching solution dissolves copper, but does not dissolve nickel. Therefore, the exposed copper plating layer and the copper layer below it can be etched on the copper layer side, and only the exposed copper plating layer can be etched on the nickel layer side. Thereafter, by removing the solder plating layer as an etching resist, a conductor made of nickel is formed on one side, a conductor made of copper is formed on the other side, and different metals are formed depending on the copper plating layer of the through hole. This is because the conductor is connected with the base material interposed therebetween.

  As described above, according to the manufacturing method of the present invention, a conductor made of nickel is formed on one side and copper is formed on the other side, and these conductors are connected by through holes. A wiring board can be provided.

  Hereinafter, preferred embodiments of the present invention will be described. 1 (A) to (E), FIGS. 2 (F) to (J), and FIGS. 3 (K) to (O) sequentially show the steps of the manufacturing process of the printed wiring board according to this embodiment according to the schematic cross-sectional views. It is shown in.

  First, as shown in FIG. 1A, a copper foil (35 μm thickness) is bonded to a prepreg (glass epoxy material) 1 as an interlayer insulating material, and the copper foil is etched to form a circuit. A core substrate 3 provided with the inner layer pattern 2 was prepared. Then, by placing 18 μm-thick nickel foil on one side of the core base material 3 and 35 μm-thick copper foil on the other side and press-molding, the nickel layer 4 on one side and copper on the other side A core substrate 3 comprising a layer 5 was formed.

Thus, the drilling process was performed to the predetermined position of the core base material 3 provided with a different metal conductor layer, and the drilling part 6 was formed (FIG.1 (B)). And the electroless copper plating process and the electroplating process (electrolytic plating conditions: liquid temperature 25 ° C., 0.9 A / dm ² , 68 min) were performed to form a copper plating layer (thickness 25 μm) 7 having a predetermined thickness ( FIG. 1C).

  After the copper plating layer 7 is formed, a dry film 8 having a thickness of 40 μm is laminated (FIG. 1D), and a first pattern film 9 for forming a predetermined pattern is disposed on the nickel layer 4 side. On the side 5, a full exposure film 10 for whole surface exposure was disposed, and ultraviolet exposure (arrow) was performed (FIG. 1E).

  After the development process (FIG. 2 (F)), the exposed copper plating layer (7 ′) and the nickel layer 4 therebelow are etched with a cupric chloride etchant (liquid temperature 28 ° C., 60 sec). (FIG. 2G). Thereafter, the remaining dry film 8 'was removed (FIG. 2 (H)), and the dry film 8 was again laminated on both sides (FIG. 2 (I)).

  Then, the second pattern film 11 is arranged on the nickel layer 4 side of the core base material 3 so that the dry film 8 other than the land portion of the perforated portion 6 is exposed, and a predetermined pattern is formed on the copper layer 5 side. The 3rd pattern film 12 for performing was arrange | positioned, and the ultraviolet exposure was performed (FIG.2 (J)).

After the development processing (FIG. 3K), a solder plating solution (organic acid <alkyl sulfonic acid> base bath, plating conditions: liquid temperature 28 ° C., 1.26 A / dm ² ) on the exposed copper plating layer 7 ′. , 15 min), a solder plating layer 13 was formed (FIG. 3L). Subsequently, the remaining dry film 8 ′ was removed (FIG. 3 (M)), and the exposed copper plating layer 7 ′ was etched by an alkaline etching solution of ammonium hydroxide solution (liquid temperature 50 ° C., 90 sec). And the copper layer 5 under it was removed (FIG. 3 (N)). Thereafter, the solder plating layer 13 was removed. The solder plating layer 13 was removed with a nitric acid solution (liquid temperature 27 ° C., 120 sec) (FIG. 3 (O)).

  By performing the process steps as described above, a printed wiring board of a composite conductor having a conductor made of nickel on one side and a conductor made of copper on the other side and these conductors connected by a copper plating layer 7 is obtained. It was.

  The peel strength and solder heat resistance characteristics of the nickel layer 4 were measured on the composite conductor printed wiring board thus manufactured. The peel strength was measured by forming a 10 mm wide circuit in the nickel layer and peeling the circuit. Moreover, the solder heat resistance was performed by observing the adhesion state between the nickel layer and the base material visually after the manufactured printed wiring board sample was floated in a 260 ° C. solder bath for 20 seconds. As a result, the peel strength of the nickel layer (18 μm) was 1.1 kN / m, and in the solder heat resistance test, no particular change was observed in the adhesion state between the nickel layer and the substrate, and it was found that there was no practical problem. .

The cross-sectional schematic diagram which shows the procedure (AE) of the manufacturing method of the printed wiring board in this embodiment. Sectional schematic which shows the procedure (FJ) of the manufacturing method of the printed wiring board in this embodiment. Sectional schematic which shows the procedure (KO) of the manufacturing method of the printed wiring board in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Inner layer pattern 3 Core base material 4 Nickel layer 5 Copper layer 6 Drilling part 7 Copper plating layer 8 Dry film 9 First pattern film 10 Film for full exposure 11 Second pattern film 12 Third pattern film 13 Solder plating layer

Claims (2)

Laminating nickel foil on one side of the base material and copper foil on the other side by press molding, forming a base material comprising a nickel layer on one side and a copper layer on the other side,
After drilling the base material, a copper plating layer is formed by copper plating treatment,
A photoresist is coated on both sides of the substrate, and a first film for circuit formation is disposed on the substrate surface side provided with a nickel layer, and a fully exposed film for full exposure is disposed on the substrate surface side provided with a copper layer. And exposure, phenomenon processing,
Etching the exposed copper plating layer and the nickel layer below it with cupric chloride or iron chloride solution,
After removing the remaining photoresist, coat the photoresist again,
Arrange the second film for circuit formation on the side of the base material provided with the nickel layer, and arrange the third film for circuit formation on the side of the base material surface provided with the copper layer.
Solder plating treatment is performed on the exposed copper plating layer to form a solder plating layer,
After removing the remaining photoresist, by performing alkali etching using the solder plating layer as a mask, the exposed copper plating layer and the copper layer below it are removed,
A method for producing a printed wiring board of a composite conductor, comprising removing a solder plating layer. A printed wiring board of a composite conductor, wherein a nickel conductor and a copper conductor are connected via a base material.

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