A shielding film with multi-layer metal structure

Abstract

The present invention provides a shielding film with a multi-layer metal structure, including an insulating layer and a multi-layer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of the multi-layer metal layers is 2 to 10; and a conductive adhesive layer is provided between the multi-layer metal layers. The present invention provides a multi-layer metal to control the thickness of each metal layer, and the metal layers are bonded by the conductive adhesive layer, so that the shielding film has good flexibility and excellent shielding effect. In addition, the use of the conductive adhesive layer makes the bonding force between the metal layers better, and while ensuring the high-frequency signal shielding performance greater than 80db@10ghz, the shielding film has good flexibility, which meets the flexibility requirements of the flexible circuit board, and at the same time has good high temperature resistance, and can still keep the bonding force of the metal layer from decreasing and stable and reliable when subjected to high temperature impact.

Description

Technical Field

[0001] The invention belongs to the technical field of shielding films, and in particular relates to a shielding film with a multi-layer metal structure. Background Art

[0002] The existing shielding film materials are copper-aluminum foil tape and shielding film materials with more than 50db within 1ghz. Because of their low price, easy material acquisition and good shielding effect, they have always been the preferred materials of various electronic factories. However, when applied to flexible circuit boards, copper foil and aluminum foil cannot meet the performance requirements of thickness and bending resistance, and ordinary shielding films cannot meet the shielding performance requirements of more than 65db at high frequencies above 1ghz. There are high-frequency shielding films on the market that use copper foil directly as a shielding layer, but the bending resistance and high temperature resistance cannot meet the production requirements of flexible boards, and it also virtually increases the production cost and has no use value. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a shielding film with a multi-layer metal structure, which has good flexibility and good shielding performance.

[0004] The present invention provides a shielding film with a multi-layer metal structure, comprising an insulating layer and a multi-layer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of layers of the multi-layer metal is 2 to 10;

[0005] A conductive bonding layer is provided between the multiple metal layers.

[0006] Preferably, the thickness of the insulating layer is 2-20 μm.

[0007] Preferably, the thickness of the conductive adhesive layer is 1-10 μm.

[0008] Preferably, the shielding film is composited with the flexible plate and has an overall bending resistance of more than 20 times under GB / T2679.5, 135 degree, Radius 0.38 mm.

[0009] Preferably, each layer of metal is independently selected from nickel, gold, silver, copper, aluminum or tin.

[0010] Preferably, the insulating layer comprises resin, additives, fillers and pigments in a mass ratio of 70-80:5-10:0-20:0-15;

[0011] The resin is selected from one or more of polyurethane, epoxy, polyimide, modified silica gel and polyethylene terephthalate;

[0012] The auxiliary agent is selected from one or more of a curing agent, a dispersant and a modifier of the corresponding resin;

[0013] The filler is selected from one or more of titanium dioxide, thermal conductive powder, silicon dioxide and carbon powder.

[0014] Preferably, the conductive adhesive layer comprises glue, metal powder, curing agent and auxiliary agent in a mass ratio of 50-80:5-70:5-10:5-10.

[0015] Preferably, the shielding film has a thickness of 10 to 50 microns.

[0016] Preferably, the multi-layer metal is 0.25-0.35 μm silver-0.25-0.35 μm nickel in sequence;

[0017] or 0.45-0.55μm copper-0.2-0.25μm silver-0.95-1.05μm copper-0.2-0.25μm Ni-0.2-0.25μm silver;

[0018] Or 0.95~1.05μm copper-0.55~0.55μm copper-0.2~0.3μm silver-0.25~0.35μm nickel.

[0019] Preferably, the adhesive is selected from epoxy thermosetting conductive adhesive, acrylic thermosetting conductive adhesive or polyurethane thermosetting conductive adhesive commonly used in the market.

[0020] The present invention provides a shielding film with a multi-layer metal structure, including an insulating layer and a multi-layer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of layers of the multi-layer metal is 2 to 10; and a conductive adhesive layer is provided between the multi-layer metal. The present invention arranges multiple layers of metal to control the thickness of each metal layer, and the metal layers are bonded by the conductive adhesive layer, so that the shielding film has good flexibility and excellent shielding effect. In addition, the use of the conductive adhesive layer makes the bonding force between the metal layers better, the high temperature resistance is good, and the bonding force of the metal layers can still be kept stable and reliable when subjected to high temperature impact. The experimental results show that when the thickness of the shielding film is 20-35μm and there are 2-7 layers of metal, the shielding test at 10hgz reaches more than 80db; the shielding test at 100ghz reaches more than 70db; the shielding film after laminating the flexible plate can pass the high temperature resistance test of immersion at 288℃ for 30s and the bending resistance test at GB / T2679.5, 135degree, Radius 0.38mm for more than 50 times, which can meet the basic requirements of flexible plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of the shielding film with a multi-layer metal structure provided by the present invention. DETAILED DESCRIPTION

[0022] The present invention provides a shielding film with a multi-layer metal structure, comprising an insulating layer and a multi-layer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of layers of the multi-layer metal is 2 to 10;

[0023] A conductive bonding layer is provided between the multiple metal layers.

[0024] The present invention sets multiple layers of metal, controls the thickness of each metal layer, and bonds the metal layers together through a conductive adhesive layer, so that the shielding film has good flexibility and excellent shielding effect. In addition, the use of a conductive adhesive layer makes the bonding force between the metal layers better, and while ensuring the high-frequency signal shielding performance of more than 80db@10ghz, the shielding film has good flexibility to meet the flexibility requirements of the flexible circuit board; it has good high temperature resistance, and can still maintain the metal layer bonding force without decreasing and stable and reliable when subjected to high temperature impact. While ensuring the basic requirements of the flexible board material (flexibility, high temperature resistance), the metal used in the present invention does not need to be very thick, but can also achieve a shielding performance of more than 80db (10ghz), which is equivalent to the shielding performance of a pure metal layer >2μm thick, and can also reduce costs.

[0025] See also Figure 1 , Figure 1 A schematic structural diagram of a shielding film of a multi-layer metal structure provided by the present invention; wherein 1 is an insulating layer, 2 is a first metal layer, 3 is a conductive adhesive layer, 4 is a second metal layer, 5 is a last metal layer, 6 is a grounded conductive adhesive layer, and 7 is a protective film.

[0026] The shielding film of the multilayer metal structure provided by the present invention comprises an insulating layer 1; the thickness of the insulating layer is preferably 2 to 20 μm. The insulating layer preferably comprises resin, additives, fillers and pigments in a mass ratio of 70 to 80:5 to 10:0 to 12:0 to 15; the fillers and pigments are added as appropriate according to the actual situation. The insulating layer preferably comprises resin, additives, fillers and pigments in a mass ratio of 70 to 80:5 to 10:8 to 12:5 to 15; the resin is preferably selected from one or more of polyurethane, epoxy, polyimide, modified silica gel and polyethylene terephthalate; in a specific embodiment, the resin in the insulating layer is a toughened polyester. 891, ZY-3600R or Petpur adhesive. The auxiliary agent in the insulating layer is selected from one or more of the curing agent, dispersant and modifier of the corresponding resin;

[0027] The filler is selected from one or more of titanium dioxide, thermal conductive powder, silicon dioxide and carbon powder. In a specific embodiment, the filler is selected from titanium dioxide.

[0028] In the present invention, the pigment in the insulating layer allows the insulating layer to be transparent, white or black, which can be selected according to customer needs.

[0029] In one embodiment of the present invention, the insulating layer specifically comprises a 70:20:5:5 ratio of the mass ratio of the 1,2-dimethyl- ... 891. Titanium dioxide, additives and black color paste;

[0030] or the insulating layer specifically includes ZY-3600R, Taisheng general oily black paste, titanium dioxide and ZY-3600R curing agent in a mass ratio of 70:10:10:10;

[0031] Or the insulating layer specifically includes Petpur adhesive, titanium dioxide, Petpur curing agent and Taisheng general oily black slurry in a mass ratio of 70:10:10:10.

[0032] The thickness of the insulating layer is specifically 3 μm, 5 μm or 7 μm.

[0033] The shielding film of the multi-layer metal structure provided by the present invention comprises a multi-layer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of layers of the multi-layer metal is 2 to 10. The thickness of each metal layer is preferably 0.05 to 2 μm; the number of layers of the multi-layer metal is specifically 2 layers, 3 layers, 4 layers, 5 layers, 6 layers, 7 layers, 8 layers, 9 layers or 10 layers. In a specific embodiment, each metal layer is independently selected from nickel, gold, silver, copper, aluminum or tin. The multi-layer metal comprises a first metal layer 2, a second metal layer 4, and finally a last metal layer 5.

[0034] In the present invention, a conductive adhesive layer 3 is provided between the multiple layers of metal; the conductive adhesive layer plays a role of conduction. As a non-metallic layer, the conductive adhesive layer can effectively improve flexibility. The conductive adhesive layer includes glue, metal powder, curing agent and auxiliary agent in a mass ratio of 50-80:5-70:5-10:5-10; the glue in the conductive adhesive layer is preferably selected from one or more of epoxy glue, acrylic glue, polyester and silicone; the metal powder is preferably selected from one or more of nickel powder, silver copper powder, copper powder, gold powder, silver powder and aluminum powder; the curing agent in the conductive adhesive layer is preferably selected from one or more of the curing agents of the corresponding resin system; the auxiliary agent in the conductive adhesive layer is selected from one or more of the curing agent, filler dispersant and surfactant of the corresponding resin; the auxiliary agent in the conductive adhesive layer is added as appropriate according to the actual situation. In the present invention, the glue in the conductive adhesive layer is selected from the commonly used conductive glues such as epoxy thermosetting conductive glue, acrylic thermosetting conductive glue and polyurethane thermosetting conductive glue on the market. The thickness of the conductive adhesive layer is preferably 1-10 μm, more preferably 3-8 μm; in a specific embodiment, the thickness of the conductive adhesive layer is 8 μm, 5 μm or 3 μm.

[0035] In the present invention, the multilayer metal is preferably 0.25-0.35 μm silver-0.25-0.35 μm nickel; or 0.45-0.55 μm copper-0.2-0.25 μm silver-0.95-1.05 μm copper-0.2-0.3 μm Ni-0.2-0.3 μm silver; or 0.95-1.05 μm copper-0.45-0.55 μm copper-0.2-0.3 μm silver-0.25-0.35 μm nickel. In a specific embodiment, the multilayer metal is 0.3 μm silver-0.3 μm nickel; or 0.5 μm copper-0.2 μm silver-1 μm copper-0.2 μm Ni-0.2 μm silver; or 1 μm copper-0.5 μm copper-0.2 μm silver-0.3 μm nickel.

[0036] In the present invention, the topmost layer of the multi-layer metal is preferably a composite grounding conductive adhesive layer 6, and then covered with a protective film 7; the protective film is preferably selected from a PP protective film or a PET release film.

[0037] The various properties of the shielding film provided by the present invention meet the IPC standard, and the shielding test effect reaches above 65db.

[0038] The shielding film of the multi-layer metal structure provided by the present invention is preferably prepared according to the following method:

[0039] An insulating layer is coated on the release film, and after drying, a first metal layer is set, and then a conductive adhesive layer is coated on the first metal layer. The metal layer and the conductive adhesive layer are repeatedly set, and then a grounded conductive adhesive layer 6 is set on the last metal layer, and finally covered with a protective film 7 to obtain a shielding film with a multi-layer metal structure.

[0040] In the present invention, the drying temperature is preferably 100-200° C. The metal layer is provided by thermal bonding, vacuum plating or water plating. The protective film is selected from PP film or PET release film.

[0041] The present invention adopts GB / T30142-2013 to test the shielding performance of the shielding film;

[0042] GB / T2679.5, (135 degree, Radius 0.38 mm) is used to test the bending resistance of the shielding film composite flexible circuit board;

[0043] The high temperature resistance of the shielding film composited with the flexible plate was tested by immersing it at 288°C for 30 seconds.

[0044] The test results show that: after being bonded to a flexible plate, the shielding film provided by the present invention has good resistance to SMT high-temperature soldering and bending resistance; and the bonding force between the metal layers is good.

[0045] In order to further illustrate the present invention, a shielding film with a multi-layer metal structure provided by the present invention is described in detail below in conjunction with embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0046] Example 1

[0047] 1) Polyurethane insulation layer formula (based on 100 parts by weight):

[0048] Renchi 891 (Guangdong Pusaida Sealing Adhesive Co., Ltd.): 70

[0049] Titanium dioxide: 20

[0050] Additives (Renchi 891 curing agent): 5

[0051] Color paste: Black: 5

[0052] Will Renchi 891. Titanium dioxide, additives and black color paste are mixed to obtain black ink;

[0053] 2) Black glue coating on raw film: Unwind the prepared release film on the coating line and pass it through the coating head, evenly coat it with a 3μm thick layer of black glue, dry the butanone solvent in an oven at 100℃~200℃, and then roll it up.

[0054] 3) Vacuum plating of 0.3 μm silver layer;

[0055] 4) applying a 3 μm thick conductive adhesive layer; the conductive adhesive layer includes epoxy glue, nickel powder, polyurethane curing agent and additives in a mass ratio of 70:10:10:10, and drying and curing;

[0056] 5) Then plate a 0.3 μm layer of second metal nickel on the adhesive surface;

[0057] 6) Apply a 10μm thick grounding conductive adhesive layer on the second metal layer, and then cover it with a PP protective film;

[0058] 8) Then inspect and cut to obtain a shielding film with a multi-layer metal structure.

[0059] Example 2

[0060] 1) Epoxy insulation layer formula (based on 100 parts by weight):

[0061] ZY-3600R (Zhongshan Zhuyi Electronic Materials Co., Ltd.): 70;

[0062] Taisheng general oily black paste (Dongguan Taisheng Pigment Co., Ltd.): 10;

[0063] Titanium dioxide: 10;

[0064] ZY-3600R curing agent: 10;

[0065] Mix ZY-3600R, Taisheng universal oily black paste, titanium dioxide and curing agent to obtain black glue;

[0066] Unwind the prepared release film on the coating line and pass it through the coating head, evenly coat it with a 5μm thick layer of black glue, dry the solvent in an oven at 100℃~200℃, and then rewind it;

[0067] 3) Vacuum coating with 0.5 μm copper;

[0068] 4) applying a 5 μm thick conductive adhesive layer; the conductive adhesive layer includes epoxy glue, nickel powder, polyurethane curing agent and additives in a mass ratio of 70:10:10:10, and drying and curing;

[0069] 5) Then plate a 0.2μm layer of second metal silver on the adhesive surface;

[0070] 6) Repeat 4) and 5), and sequentially plate 1 μm of the third metal copper, 0.2 μm of the fourth metal Ni, and 0.2 μm of the fifth metal layer silver;

[0071] 7) Apply a layer of grounding conductive adhesive on the fifth metal layer and cover it with a layer of PET release film;

[0072] 8) Inspect and cut the product to obtain a shielding film with a multi-layer metal structure.

[0073] Example 3

[0074] 1) Adjustment of the acrylic ink insulation layer formula (based on 100 parts by weight):

[0075] Petpur adhesive (Chongqing Luchuan): 70

[0076] Titanium dioxide: 10

[0077] Petpur curing agent: 10;

[0078] Taisheng general oily black paste (Dongguan Taisheng Pigment Co., Ltd.): 10;

[0079] Mixing petpur adhesive, titanium dioxide, petpur glue curing agent and black color paste to obtain black glue;

[0080] 2) Black glue coating on raw film: unwind the prepared release film on the coating line and pass it through the coating head, evenly coat it with a layer of 7μm thick black glue, dry the solvent in an oven at 100℃~200℃, and rewind it;

[0081] 3) Vacuum plating of 1 μm copper layer;

[0082] 4) applying a conductive adhesive layer 8 μm thick; the conductive adhesive layer includes epoxy glue, nickel powder, polyurethane curing agent and additives in a mass ratio of 70:10:10:10, and drying and curing;

[0083] 5) Then plate a 0.5μm layer of second metal copper on the adhesive surface;

[0084] 6) Repeat 4) and 5) to plate a 0.2 μm thick third metal layer of silver; then plate a 0.3 μm thick fourth metal layer of nickel;

[0085] 7) Apply a grounding conductive adhesive layer on the fourth metal layer and cover it with a PP protective film;

[0086] 8) Inspect and cut the product to obtain a shielding film with a multi-layer metal structure.

[0087] Comparative Example 1

[0088] 1) Polyurethane insulation layer formula (based on 100 parts by weight):

[0089] Renchi 891 (Guangdong Pusaida Sealing Adhesive Co., Ltd.): 70

[0090] Titanium dioxide: 20

[0091] Additives (Renchi 891 curing agent): 5

[0092] Color paste: Black 5

[0093] Will Renchi 891. Titanium dioxide, additives and black color paste are mixed to obtain black glue;

[0094] 2) Black glue coating on raw film: Unwind the prepared release film on the coating line and pass it through the coating head, evenly coat it with a 3μm thick layer of black glue, dry the solvent in an oven at 100℃~200℃, and then roll it up.

[0095] 3) Use a thermal bonding machine to bond a 2μm thick copper foil at 120°C, then apply a 10μm thick grounding conductive adhesive layer on the surface of the copper foil, and then cover it with a layer of PP protective film;

[0096] 4) Then inspect and cut to obtain a shielding film with a single-layer metal structure.

[0097] The present invention performs performance tests on the shielding films prepared in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 1. Table 1 is the performance test results of the shielding films prepared in Examples 1 to 3 and Comparative Example 1 of the present invention:

[0098] Table 1 Performance test results of shielding films prepared in Examples 1 to 3 of the present invention and Comparative Example 1

[0099]

[0100] It can be seen from the above embodiments that the present invention provides an insulating layer and a multilayer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of layers of the multilayer metal is 2 to 10; and a conductive adhesive layer is provided between the multilayer metals. The present invention controls the thickness of each metal layer by providing multiple layers of metal, and the metal layers are bonded by the conductive adhesive layer, so that the shielding film has good flexibility and excellent shielding effect. In addition, the use of the conductive adhesive layer makes the bonding strength between the metal layers better, and the high temperature resistance is good. When subjected to high temperature impact, the bonding strength of the metal layers can still be maintained without decreasing and is stable and reliable. The experimental results show that when the thickness of the shielding film is 20-35μm and there are 2-7 layers of metal, the shielding test reaches 78-85db at 10hgz, and the shielding test reaches 71-79db at 100ghz. After the shielding film is pressed onto the flexible plate, the overall performance can pass the high temperature resistance test of immersion at 288℃ for 30s and the bending resistance test of GB / T2679.5, 135degree, Radius 0.38mm for more than 50 times, which can meet the basic requirements of the flexible plate.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A shielding film with a multi-layer metal structure, characterized in that: It comprises an insulating layer and a multilayer metal compounded on the insulating layer; the thickness of each metal layer is 0.05 to 5 μm; the number of the multilayer metal layers is 2 to 10; A conductive bonding layer is provided between the multiple metal layers; The thickness of the insulating layer is 2 to 20 μm, and the thickness of the conductive adhesive layer is 1 to 10 μm; Each layer of metal is independently selected from nickel, silver or copper; The insulating layer comprises resin, additives, fillers and pigments in a mass ratio of 50 to 80:5 to 10:0 to 20:0 to 15; The resin is selected from one or more of polyurethane, epoxy, polyimide, modified silica gel and polyethylene terephthalate; The auxiliary agent is selected from one or more of a curing agent, a dispersant and a modifier of the corresponding resin; The filler is selected from one or more of titanium dioxide, thermal conductive powder, silicon dioxide and carbon powder; The conductive adhesive layer includes glue, metal powder, curing agent and auxiliary agent in a mass ratio of 50-80:5-70:5-10:5-10; the glue is selected from epoxy thermosetting conductive glue, acrylic thermosetting conductive glue or polyurethane thermosetting conductive glue commonly used in the market; The multi-layer metal is 0.25-0.35 μm silver-0.25-0.35 μm nickel in sequence; or 0.45-0.55μm copper-0.2-0.25μm silver-0.95-1.05μm copper-0.2-0.3μm Ni-0.2-0.3μm silver; Or 0.95 to 1.05 μm copper - 0.45 to 0.55 μm copper - 0.2 to 0.3 μm silver - 0.25 to 0.35 μm nickel.

2. The shielding film according to claim 1, characterized in that After the shielding film is pressed onto the flexible plate, the overall bending resistance under GB / T2679.5, 135 degree, Radius 0.38 mm is greater than 20 times.

3. The shielding film according to claim 1, characterized in that The thickness of the shielding film is 10 to 50 microns.

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