JPH03292796A - Manufacture of copper plated laminar board for printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method of manufacturing copper-clad laminates for printed wiring boards, and is a method of manufacturing copper-clad laminates for printed wiring boards with high productivity. The present invention relates to a method for manufacturing a copper-clad laminate for printed wiring boards having a three-layer structure of resin and copper foil.

(Prior Art) Conventionally, for example, a laminate having a structure made of R4 temporary, insulating resin, and copper foil has been manufactured by a hot pressing method using heating and pressing.

That is, multiple sheets of materials such as steel plates, insulating resin (sheets), and copper foil (or steel plates and copper foil with insulating resin) are stacked by hand and inserted into a hot press, where they are heated and pressurized. Thereafter, it is cooled and then taken out from the hot press to form a copper-clad laminate for printed wiring boards.

On the other hand, in Japanese Patent Application Laid-Open No. 62-139392, a steel plate, an insulating resin, and a copper foil are coated with an insulating resin and then heated and dried. A method for producing a three-layer structure has been proposed, using epoxy, polyamide/imide, silicone, acrylic, polyester, and polyurethane resins.

(Problem to be solved by the invention) This hot pressing method applies a large amount of pressure to the material of the laminate, so it may adhere to the copper foil surface that becomes the surface of the laminate and the surface of the material that is in contact with the copper foil surface. This method has problems in that it cannot be said to be a highly productive manufacturing method because it requires removing dust and the like and manually stacking the materials one by one. Furthermore, the adhered dust is pressed against the copper foil surface by the pressure of the hot press, causing so-called indentation flaws, resulting in a reduction in yield.

Next, the latter method disclosed in JP-A-62-139392 is an invention intended to improve the hot press method, but the adhesive (insulating resin) is only applied in one layer painted on the steel strip side. As a result, uneven thickness of the adhesive layer painted on the steel strip and defects in the coating film are transferred directly to the ultra-thin copper foil.
It was difficult to form a copper foil layer with good quality.

The present invention advantageously seeks to overcome the drawbacks of the prior art methods mentioned above.

(Means for Solving the Problems) The method for manufacturing a copper-clad laminate for printed wiring boards according to the present invention is characterized by using a steel strip coated with semi-hardened ultraviolet curable resin (insulating resin) on one side. The semi-cured ultraviolet curing resin is preheated and the semi-cured insulating resin coated on one side of the copper foil strip is pressed together to create a laminate with a three-layer structure of steel strip, insulating resin, and copper foil strip. This is then cut into appropriate dimensions, and the cut laminate having a three-layer structure is heated and hardened in a heating furnace.

A method for manufacturing a copper-clad laminate for printed wiring boards according to the present invention will be described below.

First, the materials used in the method for manufacturing a copper-clad laminate for printed wiring boards according to the present invention will be explained.

The thickness of the copper foil is preferably 10 to 70 cm. The insulating resin coated on the copper foil strip is made of epoxy resin, for example, which has good soldering heat resistance, but the thickness of the entire insulating resin does not exceed the required electrical insulation. It is best to decide based on the property, and the total weight of the ultraviolet curable insulating resin coated on the steel plate strip described later and the insulating resin coated on the copper foil may be 30 to 120 un. It is preferable to use an ordinary steel plate or a silicon steel plate with a thickness of 0.2 to 2.0 mm as the steel strip.As a pretreatment of the steel strip, for example, both sides are electrolytically galvanized, and then both sides are subjected to chromate treatment, and then It is possible to use a material coated with an organic polymer on both sides.

Next, a method for manufacturing a copper-clad laminate for a printed wiring board according to the present invention will be explained using an example shown in FIG.

The steel strip 2 drawn out from the steel plate coil 1 shown in FIG.
Using roll coater 3, apply ultraviolet curing resin 3' to the top surface of the steel strip (the side that will be crimped to the insulating resin coated on the copper foil).
Then, the insulating resin is brought into a semi-hardened (B stage) state using the ultraviolet irradiation device 4.

The purpose of coating the steel strip with insulating resin is to remove the hard material of the steel strip,
Even when the soft insulating resin formed on the surface of the copper foil is bonded to the surface of the copper foil, defect-free crimping is not possible because defective spots are observed in the appearance of the copper foil, even if the crimping conditions using heated rolls are used. Therefore, soft materials are crimped together.

That is, the steel strip is coated with an insulating resin, and this resin is crimped to the insulating resin coated on the copper foil strip to improve the crimping properties between the insulating resins. The type of insulating resin applied to the steel strip for the purpose of improving crimpability must have the same moisture resistance and soldering heat resistance as the insulating resin applied to the copper foil strip. There are no restrictions on the type.

Next, the reason for using ultraviolet curing resin is that it cures in a short time compared to conventional thermosetting resins. ■ Seconds t11. It is a compact drying device.

■Space saving and ■equipment costs can be reduced.

2) Contribute to the prevention of working ring burial mounds and air pollution. ■Since it is a solvent-free coating, there is no contamination caused by the use of solvents.

■Ultraviolet irradiation lamps are powered by electricity, so there is no pollution from combustion gases, such as in thermosetting, which obtains energy from fossil fuels. 3) Energy saving will be achieved. ■Since the UV irradiation lamp only needs to be turned on when necessary, energy can be saved compared to heat drying types. It has the following characteristics.

Types of coaters include roll coaters, curtain flow coaters, knife coaters, etc., and may be selected based on the thickness of the insulating resin to be coated, the viscosity of the resin, the speed of threading the steel strip, etc.

On the other hand, the ultraviolet irradiation device is desirably selected based on the degree of semi-curing of the insulating resin after irradiation. In other words, the intensity of ultraviolet rays is determined by the output of the lamp, the distance between the lamp and the material to be coated, and the speed at which the steel strip is threaded.If the intensity of ultraviolet rays is insufficient, multiple irradiation devices may be installed in series on the line. Good too.

Furthermore, the interval (distance) between the roll coater and the ultraviolet irradiation device is preferably determined based on the time required to ensure the smoothness of the coated insulating resin (referred to as setting).

Next, this steel strip is preheated in a far-infrared furnace 5, and then heated and pressed with a heating roll 8 to a semi-hardened (B stage) insulating resin coated copper foil strip 7 pulled out from a copper foil 6 coil. , a three-layer structure 9 consisting of a steel strip, an insulating resin, and a copper foil strip.

The temperature of the rolls in this heat-pressing process can cause defects in the appearance of the copper foil, or peeling between the insulating resins when cutting into appropriate dimensions using a shearing machine, which will be described later. The insulating resin flows excessively, causing unevenness and flaws on the appearance of the copper foil. On the other hand, if the temperature is low, the bonding force between the semi-cured insulating resins will be insufficient, so when cutting with a shearing machine (described later), a shearing stress with an impact peculiar to a shearing machine will act, causing the resin to come into contact with the shearing machine blade. A peeling phenomenon occurs between the insulating resin on the end face. Therefore, it is best to set the roll temperature based on the progress of semi-hardening of the insulating resin, that is, the degree of hardening of the resin.When hardening is progressing, set the roll temperature high, and when hardening is not progressing, set the roll temperature high. It is best to lower the roll temperature.

Note that the degree of hardening of the insulating resin may be determined by so-called pencil hardness, which is obtained by rubbing a pencil lead against the resin surface.

In addition, if the thickness of the copper foil and the thickness of the insulating resin change, even if the degree of curing of the insulating resin is the same, the crimped interface between the ultraviolet curing resin painted on the steel strip and the insulating resin painted on the copper foil strip will change. Since the temperature changes, it is recommended to change the roll temperature and set it in order to manage the pressure bonding temperature range.

Furthermore, the selection of the heating roll 8 in the heat-press bonding process is to ensure heat-press bonding (contact between the material to be laminated and the roll).
It should be determined based on the time, therefore, the surface material of the O-ru may be either iron core rubber covered or iron.
The iron-core rubber-lined roll is advantageous in uniformly applying pressure to materials to be laminated, including copper foil. The heat and pressure bonding time is determined by the threading speed of the steel strip, the diameter of the roll, and the pressure applied to the roll, and in the case of iron-cored rubber-coated coal, it is also determined by the hardness of the rubber, or is not limited by any of these factors. do not have.

Furthermore, the tension applied to the copper foil strip 7 when the copper foil coil 6 is drawn in by the heating roll 8 affects the appearance of the laminate, and if the tension is weak, the appearance of the copper foil strip after heat-pressing may bulge. If the tension is too strong, the resulting laminate will have wrinkles in the copper foil strip.

Next, the method for completely curing the insulating resin is to cut the three-layered laminate 9 into appropriate dimensions using a shearer 10 while heat-pressing the laminate 11. The semi-hardened insulating resin is completely cured by stacking it up and inserting it into the heating furnace 13 and passing it through the heating furnace 13 in a free state without applying pressure, as shown in FIG. Form a resin layer.

14 in FIG. 2 is a spacer plate.

In FIG. 2, the number of materials for the three-layer structure is two, or may be any number.

The length of the heating furnace is determined by the time required for curing the resin.
Depending on the amount of 40 units of curing agent, the temperature of the heating furnace, etc., it takes about 2 hours when a short-curing resin is used, and about 5 hours at maximum. In the present invention, the stacking and heating curing after cutting is performed using hot pressing stones, and the continuous heating curing method in the same line is performed by stacking the laminate 9 as it is when the speed of the heating pressing process is 1 m/min. (Uncut) Even if it is inserted into the heating furnace and the curing time is 2 hours, the length of the heating furnace is 120 m, making it an extremely long heating furnace, which has disadvantages such as high equipment costs and taking up a lot of space. It is.

In other words, the laminates II are stacked and placed in a heating furnace with a cutting length of 1.
When inserted at a speed of 1.5 m, it is necessary to stack 60 sheets per hour due to the line speed mentioned above, but the maximum thickness of the steel plate is as thin as 2 m, and the thickness of the copper foil and insulating resin Even if the height is added, the stacking height is not considered to be a problem in terms of stacking workability or equipment.

The required length of the heating furnace is that the laminates that have been inserted into the heating furnace are stopped in the heating furnace for one hour while the laminates are being stacked, but the laminates are moved by 1m, equivalent to the cutting length, every hour. from,
The required length is 5 hours if the heat curing time is up to 5 hours.
m, which is possible with shorter equipment than the above-mentioned continuous type.

On the other hand, the heating conditions are 150 to 200°C, but if the heating temperature is less than 150°C, the resin will not be sufficiently cured.
Good soldering heat resistance cannot be obtained, and the surface of the copper foil is oxidized at temperatures exceeding 200° C., which adversely affects the removal of the oxide film and the soldering work in the mounting process of IC components and the like.

According to the method of manufacturing a copper-clad laminate for a printed wiring board according to the present invention, a steel plate, an insulating layer (consisting of an ultraviolet curing resin coated on a steel plate and a resin coated on a copper foil), and a copper foil. The three-layer laminated board is made by crimping the soft insulating resin formed on the steel plate side and the copper foil side, so that the copper foil does not have any uneven appearance, has good moisture resistance and soldering heat resistance, and is resistant to pressure. There are no scratches caused by the pressure of the hot press (
A copper-clad laminate for printed wiring boards without the occurrence of dents or scratches can be obtained.

(Example) A steel strip (thickness 1.0 mm, width 500m+s), a roll coater is used to coat the upper surface of the UV curable resin to a thickness of 50 knots, and irradiation with UV light (lamp output 80W/am, distance between lamp and steel strip 100+AM) is carried out. Cured resin (pencil hardness 5H) and semi-hardened resin (pencil hardness 5H), which was previously coated on a copper foil strip with a roll coater and dried in a heating oven, were passed through the sheet at a threading speed of 1 m.
/win (both upper and lower rolls are rubber-lined, roll diameter 200 mm, roll temperature +50'C1 copper foil strip tension is 3kg for copper foil width 500cm), and then heat and press the three-layer structure. From I [100
Cut to x 500 city.

60 pieces of the cut material were stacked and inserted into a heating furnace, and the semi-hardened insulating resin was completely cured by passing through the heating furnace (temperature 150°C, 4 hours) to produce copper for printed wiring boards. I made a stretched laminate.

Copper-clad laminates for printed wiring boards manufactured under various conditions,
? The iF' values are shown in Table 1.

Appearance of copper foil After storage at room temperature for 24 hours, the occurrence of dents on the copper foil surface was observed according to JIS C8481 evaluation, and a score was determined according to the size of the dents, and the total score was ○: 250 Ryukaku. 25 points or less in X: 35 or more points in a 250 mm square Moisture resistance was evaluated according to the method for measuring peel strength. After being stored at room temperature for 24 hours, it was immersed in boiling distilled water for 60 minutes, and then cooled for 30 minutes in flowing clean water kept at a temperature of 20°C. Evaluate the crimping (adhesion) status of the interface. O: No blistering or peeling at the interface, good. After cooling for 30 minutes in flowing clean water kept at a temperature of Good, good (according to the method) O: There is no uneven color or striped pattern ×: There is uneven color or striped pattern (Effects of the invention) According to the method for manufacturing a copper-clad laminate for printed wiring boards according to the present invention, The appearance of the copper foil is superior to that produced by conventional methods, the moisture resistance and soldering heat resistance are ensured, and the copper foil exhibits an excellent effect of high productivity.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention, FIG. 2 is an explanatory diagram of a three-layer structure heating furnace for copper-clad laminates for printed wiring boards according to the present invention, and FIG. 3 is a schematic diagram of the heating method. 1. Steel plate coil 3: Roll coater 5. 2. Preheating furnace 7. Copper foil strip 9. Laminated plate (strip shape) ll: Laminated plate (cutting) 13. Heating furnace Steel strip ultraviolet irradiation device Copper foil coil heating roll shearing machine interval Board Figure 1 Figure 2/3

Claims (1)

[Claims] A steel strip coated with a semi-cured ultraviolet curable resin on one side is preheated, and this semi-cured ultraviolet curable resin is pressure bonded to a semi-cured insulating resin coated on one side of the copper foil strip.
A laminate with a three-layer structure of a steel strip, an insulating resin, and a copper foil strip is prepared, the laminate with a three-layer structure is cut into appropriate dimensions, and then the laminate with a three-layer structure is heated in a heating furnace. A method for manufacturing a copper-clad laminate for printed wiring boards, which comprises completely curing an insulating resin.