JPH05283888A - Printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To get an electromagnetic wave shielding structure small in sheet resistance and reliable in aging. CONSTITUTION:The area excluding the earth land 4 of a board 1 and the connection land 3 of a part 5 is covered with an insulating layer 8, and an electromagnetic shield layer 9 is provided on the insulating layer 8, and the electromagnetic shield layer 9 is protected with a solder resist 10. The electromagnetic shield layer 9 and the earth land 4 are connected by a jumper member 4 in the shape of a flat package, and the electromagnetic shield layer 9 is kept at earth potential. The sheet resistance is made small by using a copper as the electromagnetic shield layer 9, and the stability in aging is ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having an electromagnetic wave shield layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art In information processing equipment, electronic office equipment, etc., it is necessary to prevent malfunctions due to external electromagnetic waves, and to prevent leakage of electromagnetic waves that cause noise. A metallized layer is formed on the inner surface. Even in a printed wiring board mounted in such a device, there is a need to suppress electromagnetic noise in order to increase the speed and reliability of operation.

Therefore, in the conventional printed wiring board, the electromagnetic wave countermeasure is taken by applying the conductive paste. FIG. 11 shows this conventional printed wiring board, in which a circuit 110 formed by etching a copper foil and a connection land 120 for an electronic component are provided on both surfaces of an insulating substrate 100. 130 is the substrate 100
Conductive through-holes for connecting circuits on both sides of
Reference numeral 140 is a ground land formed on a predetermined portion of both surfaces of the substrate. The insulating layer 15 is formed on both surfaces of the substrate 100 except the connection land 120 and the through hole 130.
The electromagnetic wave shield layer 160 made of a conductive paste is formed on the insulating layer 150. The electromagnetic wave shield layer 160 is the insulating layer 15 of the substrate 100.
0 is applied by printing or the like, but by contacting with the ground land 140 on the substrate 100, the voltage is held at the ground level and electromagnetic wave shielding is performed. 170
Is a protective layer made of a solder resist provided so as to cover the electromagnetic wave shield layer 160.

By providing the electromagnetic wave shield layer 160 made of a conductive paste as described above, it is possible to reduce the emission of electromagnetic waves from the circuit 110 patterned on the substrate 100 and prevent malfunction of the circuit 110 due to external electromagnetic noise. can do.

[0005]

However, since the conductive paste used in the conventional electromagnetic wave shield layer is obtained by kneading a conductive metal powder such as copper with a polymer,
There is a problem that the sheet resistance cannot be made sufficiently small and sufficient electromagnetic wave shielding cannot be performed. Further, since the conductive paste deteriorates due to a change in environmental temperature, humidity, etc., the sheet resistance increases with time and the resistance value becomes unstable, as well as the adhesion with the insulating layer 150 and the ground land 140.
There is also a problem that the reliability of the connectivity with

The present invention has been made in consideration of the above circumstances, and it is possible to provide a reliable and good electromagnetic wave shield without using a conductive paste and to provide a print having a reliable shield ability for a long period of time. An object is to provide a wiring board and a manufacturing method therefor.

[0007]

In order to achieve the above object, the printed wiring board of the present invention is an electromagnetic wave made of copper foil with an insulating layer on one or both sides of the substrate excluding the circuit portion which does not require the electromagnetic wave shield. It is characterized in that a shield layer is laminated. Since the electromagnetic wave shield layer made of such a copper foil has a sufficiently small sheet resistance, it has a good shield power. In this case, by connecting the electromagnetic wave shield layer made of copper foil and the ground land on the substrate with a jumper member, the electromagnetic wave shield layer can be set to the ground level and reliable shielding can be performed. Further, by forming the jumper member into a flat package shape, it is possible to arrange the electronic component on the board at the same time as mounting the electronic component.

The method of the present invention for producing such a printed wiring board comprises a step of coating an insulating layer on one side or both sides of a substrate on which a circuit is formed, and a substrate surface excluding a circuit portion which does not require an electromagnetic wave shield. The method is characterized by including a step of punching a copper foil into a pattern and a step of adhering the punched copper foil to the insulating layer. Further, the manufacturing method of the present invention, a step of coating an insulating layer on one side or both sides of the substrate on which the circuit is formed, a step of joining a copper foil to this insulating layer, a circuit that does not require electromagnetic shielding on the substrate. And a step of etching away the copper foil portion corresponding to. A printed wiring board can be satisfactorily manufactured by any of the above methods.

[0009]

EXAMPLES The present invention will be described in detail below with reference to illustrated examples. In each of the embodiments, the same elements are designated by the same reference numerals, and overlapping description will be omitted.

FIG. 1 shows a printed wiring board according to a first embodiment of the present invention, in which a circuit 2, a connection land 3 and a ground land 4 are patterned on both surfaces of an insulating substrate 1. These circuits 2, connection lands 3 and ground lands 4 are simultaneously formed by printing a copper clad laminate having copper foil laminated on both sides of the substrate, exposing it, and then etching it. Here, the connection land 3 is to be mounted with the electronic component 5, and the lead 5a of the component 5 or the component 5 is directly reflow-soldered to the connection land 3. The ground land 4 has its potential maintained at the ground level. Reference numeral 6 is a through hole for connecting the circuits 2 on both surfaces of the substrate 1, and a conductive material 7 for filling the through hole 6 is filled therein.

As described above, predetermined portions on both surfaces of the substrate 1 on which the circuit 2, the connection land 3 and the ground land 4 are formed are covered with the insulating layer 8, and the electromagnetic wave shield layer 9 is provided on the insulating layer 8. There is. The insulating layer 8 and the electromagnetic wave shield layer 9 are applied to the substrate portion except the circuit portion where the electromagnetic wave shield is unnecessary. In the illustrated example, it is provided on the substrate 1 except the connection land 3 on which the electronic component 5 is mounted and the portion where the through hole 6 for conducting both surfaces of the substrate 1 is formed. Here, the electromagnetic wave shield layer 9 is formed by bonding a copper foil onto the insulating layer 8. By thus forming the electromagnetic wave shield layer 9 with the copper foil, a shield layer having a small sheet resistance can be obtained, and reliable electromagnetic wave shield can be performed. Further, since the copper foil does not deteriorate due to environmental conditions such as temperature and humidity, it is possible to have sufficient reliability over time.

Numeral 10 is a solder resist which is applied and cured on the electromagnetic wave shield layer 9 made of such a copper foil and functions as a protective layer for preventing the electromagnetic wave shield layer 9 from being peeled off and oxidized.

In addition to the above structure, the electromagnetic wave shield layer 9 made of copper foil and the ground land 4 on the substrate 1 are connected by a jumper member 11, which brings the potential of the electromagnetic wave shield layer 9 to the ground level. Is held. By holding the electromagnetic wave shield layer 9 at the ground level in this way, a sufficient electromagnetic wave shield force can be ensured, and radiation of electromagnetic waves from the circuit 2 on the substrate 1 and invasion of foreign electromagnetic waves into the circuit 2 can be reliably prevented. can do.

Next, the manufacturing method of this embodiment will be described. First, the insulating layer 8 is coated on the substrate 1 on which the circuit 2, the connection land 3 and the ground land 4 are formed. On the other hand, a copper foil laminated with an adhesive on the lower surface is punched to punch out portions corresponding to the connection lands 3, the ground lands 4 and the through holes 6, the copper foil is adhered to the insulating layer 8, and the electromagnetic wave shield layer 9 is formed. And And this electromagnetic wave shield 9
A solder resist 10 is applied on the top to form a printed wiring board. After that, the electronic component 5 and the jumper member 11
Is mounted, and the terminals are reflow-soldered to complete the assembly.

FIG. 2 shows a jumper member 11, which is a conductive material 14 having both ends serving as leads 12 and 13 for connection.
And a package material 15 formed by molding plastic in the central portion of the conductive material 14, and the whole is molded in a flat package shape. By forming the jumper member 11 in a flat package shape, it can be handled in the same manner as an electronic component having the same shape. Therefore, the jumper member 11 can be mounted at the same time as the mounting of the electronic component, which is advantageous in that the mounting can be automated. Here, the lead 12 is the electromagnetic wave shield layer 9
While the lead 13 is soldered to the ground land 13 on the substrate 1, the lead 12 is formed to be higher than the lead 13 by a dimension h. The dimension h corresponds to a step (for example, 100 μm) between the ground land 8 and the electromagnetic wave shield layer 9 on the substrate 1. By forming the dimension h corresponding to the step in the leads 12 and 13 in this manner, the jumper member 11
It is possible to surely connect the leads and to prevent the leads from being deformed.

FIG. 3 and FIG. 4 show another example of the jumper member 11, in which each of the leads 12 and 13 is composed of four leads and two of the leads 12 connected to the electromagnetic wave shield layer 9 are arranged outside. The inner two leads 12a are higher than the leads 12b by the dimension h. In the printed wiring board shown in FIG. 1, the leads 12a higher by the dimension h are soldered to the electromagnetic wave shield layer 9. There is. A plurality of leads 1 are attached to the jumper member 11 having such a configuration.
2, 13 corresponding electromagnetic wave shield layer 9, ground land 3
Can be connected to, thus improving the reliability of the connection.

5 and 6 show another example of the jumper member 11, in which the conductive material 11 as a whole has a wide shape, whereby the resistance value of the conductive material 11 is further reduced, and the jumper member 11 is formed. Functions are highly efficient. In this example, a support lead 16 having the same height as the lead 13 is provided outside the lead 12 for connection with the electromagnetic wave shield layer 9. The support lead 16 allows the jumper member 11 to be held horizontally, which enables good mounting. The jumper member 11 does not have to have a flat package shape, and may be a conductive wire soldered, screwed, or welded.

FIG. 7 shows the second embodiment of the present invention.
The ground land 4 is formed only on one surface of the substrate 1. In this embodiment, the insulating layer 8 covering the formation portion of the circuit 2
An adhesive layer 20 is provided on the upper side, and an electromagnetic wave shield layer 9 made of copper foil is provided on the adhesive layer 20.
In this case, the circuit 2 and the ground land 4 are largely separated from each other, and the adhesive layer 20 is applied up to the substrate 1 in the separated portion between the circuit 2 and the ground land 4. In such a printed wiring board, since the step between the electromagnetic wave shield layer 9 and the ground land 4 is as small as 30 to 50 μm, the leads 12 and 13 of the jumper member 11 connecting these are generally the same height. Flat package shape can be used. Therefore, the jumper member 11 can be handled in the same manner as an electronic component, and its automatic mounting can be performed more smoothly.

8 to 10 show another example of the jumper member 11 for connecting the ground land 4 on the substrate 1 and the electromagnetic wave shield layer 9 made of copper foil. 8 and 9
Is to use the conductive paste as the jumper member 11. After forming the electromagnetic wave shield layer 9 made of copper foil, the conductive paste is applied to form the jumper member 11, and then the electromagnetic wave shield layer 9 and the jumper member 11 are formed. The solder resist 10 is applied so as to cover the. The jumper member 11 in FIG. 8 is in the form of a wide flange at the top and is in contact with the electromagnetic wave shield layer 9. In FIG. 9, a recess is formed in the electromagnetic wave shielding layer 9, and the recess is filled with the jumper member 11, and the periphery of the ground land 4 is also filled with the jumper member 11. Therefore, in any case, the jumper member 11 and the electromagnetic wave shield layer 9 or / and the ground land 4 are
The contact area with is large, the connection is reliable, and the sheet resistance is also small.

The jumper member 11 shown in FIG. 10 is used for thermocompression bonding a conductive adhesive film, and is used for the electromagnetic wave shield layer 9
Also, the two are surely contacted with each other by being bonded so as to hang over the ground land 4.

The present invention can be variously modified without being limited to the above embodiments. As the copper foil as the electromagnetic wave shield layer 9, it is not necessary to use the one in which the shield unnecessary portion is punched out, and the copper foil may be directly coated on the entire insulating layer. In this case, after the copper foils are joined together, an electronic component can be mounted by etching and removing the copper foils in the shield-free portions such as the connection lands. Moreover, you may use a copper clad flexible board as an electromagnetic wave shield layer. Furthermore, by performing a predetermined process on a portion of the electromagnetic wave shield layer made of copper foil that does not require shielding, inductance and
Circuits such as capacitors and resistors can be formed, and connection lands for mounting electronic components can be formed. further,
Further, as the electromagnetic wave shield layer, a laminate of a metal foil having a high magnetic permeability such as nickel and a copper foil can be used, whereby electromagnetic wave shield can be performed in a wide frequency band from low frequency to high frequency. The site where the through hole 6 (see FIG. 1) is formed may be covered with the electromagnetic wave shield layer 9 made of copper foil via the insulating layer 8 to provide the shielding property.

[0022]

As described above, according to the present invention, since the electromagnetic wave is shielded by using the copper foil, it is possible to surely shield and to make the shield stable with time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a side view of a jumper member.

FIG. 3 is a side view of another example of the jumper member.

FIG. 4 is a plan view of FIG.

FIG. 5 is a plan view of still another example of the jumper member.

FIG. 6 is a side view of FIG.

FIG. 7 is a cross-sectional view of a second embodiment of the present invention.

FIG. 8 is a sectional view of a modified example of the jumper member of the present invention.

FIG. 9 is a cross-sectional view of another modified example of the jumper member of the present invention.

FIG. 10 is a cross-sectional view of still another modified example of the jumper member of the present invention.

FIG. 11 is a cross-sectional view of a conventional printed wiring board.

[Explanation of symbols]

 1 substrate 2 circuit 4 ground land 8 insulating layer 9 electromagnetic wave shield layer 11 jumper member

Front Page Continuation (72) Inventor Junzaburo Hii 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Japan CMK Corporation (72) Inventor Mikiya Kojima 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture Japan CMK Corporation

Claims (10)

[Claims] 1. A printed wiring board characterized in that an electromagnetic wave shield layer made of copper foil is laminated on one or both sides of a substrate excluding a circuit portion which does not require an electromagnetic wave shield, with an insulating layer interposed therebetween. 2. The printed wiring board according to claim 1, wherein the electromagnetic wave shield layer is a copper-clad flexible board joined to a substrate such that the copper foil is on the outside. 3. The printed wiring board according to claim 1, wherein the electromagnetic wave shield layer made of the copper foil and the ground land on the substrate are connected by a jumper member. 4. The jumper member is formed in a flat package shape, and is arranged so as to connect the electromagnetic wave shield layer and a ground land in a component mounting process on a substrate. Printed wiring board. 5. The printed wiring board according to claim 4, wherein in the flat package-shaped jumper member, the height of the lead is different depending on the step between the electromagnetic wave shield layer and the ground land. 6. The printed wiring board according to claim 3, wherein the jumper member is a conductive paste or a conductive film provided so as to bridge the electromagnetic wave shield layer and the ground land. 7. A step of coating an insulating layer on one side or both sides of a board on which a circuit is formed, a step of punching out a copper foil so as to form a pattern covering the surface of the board excluding a circuit portion where an electromagnetic wave shield is unnecessary, and punching. And a step of adhering the removed copper foil to the insulating layer. 8. The method for manufacturing a printed wiring board according to claim 7, wherein the copper foil and the ground land of the substrate are connected by a jumper member after the copper foil is adhered to the insulating layer. 9. A step of coating an insulating layer on one side or both sides of a substrate on which a circuit is formed, a step of joining a copper foil to this insulating layer, and a copper corresponding to a circuit which does not require electromagnetic wave shielding on the substrate. And a step of etching away the foil portion. 10. The method of manufacturing a printed wiring board according to claim 9, wherein the copper foil and the ground land of the substrate are connected by a jumper member after the etching.