TWI710312B - High-frequency covering film with electromagnetic shielding function and preparing methods thereof - Google Patents

Abstract

The present invention provides a high-frequency covering film with electromagnetic shielding function comprising: an insulating layer, an adhesive layer, a copper foil layer, a high-frequency insulating layer with Dk less than 4.0 and Df (@ 10GHz) less than 0.015, first high-frequency adhesive layer and second high-frequency adhesive layer with Dk less than 4.0, Df (@ 10GHz) of 0.002 to 0.010, and water absorption of 0.001 to 0.5%. The present invention further provides a preparing method of high-frequency covering film as described. The high-frequency covering film of present invention has the electromagnetic shielding rate up to 100dB, and having the advantage of relatively good dielectric properties, mechanical properties and soldering heat resistance, thereby reducing the transmission loss of signal, and overcoming the problem of burst plate in assembly process of flexible printed circuit boards (FPC) and printed circuit boards (PCB).

Description

High-frequency covering film with high electromagnetic shielding function and preparation method thereof

The present invention relates to the technical field of cover films for printed circuit boards, and more particularly to a high-frequency cover film with high electromagnetic shielding function suitable for high-frequency and high-speed transmission circuit boards and a preparation method thereof.

Under the market demand of electronic and communication products tending to be multi-functional and complex, the structure of circuit substrates needs to be lighter, thinner, shorter, and smaller; and in terms of functions, powerful and high-speed signal transmission is required. Therefore, the line density is bound to increase, the distance between the carrier board lines is getting closer and closer, and the working frequency is going to be higher and wider, plus if the line layout and wiring are unreasonable, electromagnetic interference (EMI) situation More and more serious, so it is necessary to effectively manage electromagnetic compatibility (EMC), so as to maintain the normal signal transmission of electronic products and improve reliability.

With the advent of the 5G era, terminal products have higher and higher requirements for electromagnetic mask films. Electromagnetic mask films have good application prospects in high-end manufacturing fields such as mobile communications, medical displays, and military electronics. The demand for high-frequency cover film also creates demand in the design of electronic circuit boards. For example, it is applied to multi-layer board design to reduce the cost and difficulty of the manufacturing process. However, its thickness is required to be thick and has good dielectric properties, and it is attractive. Electricity is stable when wet. In addition, CN 205112572 U, CN 207014920 U, CN 105282959 B exposes a high-frequency cover film, while TWM555982 and CN 206067098U disclose a high-shielding EMI masking film using a metal layer.

On the other hand, the shielding rate of conventional EMI shielding films is generally around 55dB, which is difficult to reach 70dB. As 5G high-frequency applications require even higher shielding effects, in 5G application scenarios where the shielding ratio is greater than 75dB, 80dB or even 100dB, the current market EMI masking films are often difficult to achieve, and many EMI masking films should be increased as much as possible The thickness of the metal layer and the thickness of the conductive adhesive can meet the performance requirements of high shielding rate, but the problem of plate burst is often encountered in the manufacturing process.

In addition, when the EMI mask film is used in the FPC board processing process, there are multiple processes that are quite complicated. It is necessary to paste the cover film on the circuit and then open the EMI mask film to use. This is because the conventional cover film only has insulation. It does not have the effect of electromagnetic shielding after the EMI shielding film is turned on.

For this reason, it is urgent to develop a high-frequency cover film product with high electromagnetic shielding rate to meet the shielding requirements of 5G high-frequency applications and be effective in multi-layer board design.

The present invention provides a high-frequency cover film with high electromagnetic shielding function, and the high-frequency cover film is suitable for the use of 5G high-frequency high-speed transmission circuit boards, especially in multi-layer boards, so as to reduce process and manufacturing process problems. The shielding rate of the high-frequency covering film of the present invention can be up to 100dB or more; the dielectric performance is good, the dielectric loss is 0.003 to 0.010 and the dielectric constant is lower than 4.0 at a frequency of 10GHz; the mechanical performance is good, and it can handle drilling , Hole filling and other processing processes; a wide range of thickness, which can be used for thick dielectric layer design, which is beneficial to reduce signal transmission loss under high frequency; solder has good heat resistance, and does not produce plate burst through FPC and PCB assembly processes, and can be drilled and filled Process design such as holes is good for exhaust without occurrence of plate explosion.

In order to solve the above technical problems, the present invention provides a high-frequency cover film with high electromagnetic shielding function, which includes an insulating layer, an adhesive layer, a copper foil layer, a first high-frequency adhesive layer, a high-frequency insulating layer, and a second layer from top to bottom. Two high-frequency adhesive layers; wherein, the high-frequency insulating layer is an insulating layer with a dielectric constant lower than 4.0 and a dielectric loss (@ 10GHz) lower than 0.015; the first high-frequency adhesive layer and the second high-frequency adhesive layer The layers are all resin glue layers with a dielectric constant lower than 4.0, a dielectric loss (@ 10GHz) of 0.002 to 0.010, and a water absorption of 0.001 to 0.5%; the surface hardness of the insulating layer is greater than 4H; wherein, the insulating layer The thickness of the adhesive layer is 5 to 25 microns; the thickness of the bonding layer is 5 to 20 microns; the thickness of the copper foil layer is 2 to 105 microns; the thickness of the first high frequency bonding layer and the second high frequency The thickness of the subsequent layer is 8-50 microns; the thickness of the high-frequency insulating layer is 7.5-100 microns.

In an embodiment of the present invention, the materials for forming the first high-frequency adhesive layer and the second high-frequency adhesive layer respectively include selected from the group consisting of fluorine resin, epoxy resin, acrylic resin, and urethane At least one resin in the group consisting of a resin, a silicone rubber resin, a parylene resin, a bismaleimide resin, and a thermosetting polyimide resin.

In an embodiment of the present invention, the material for forming the high-frequency insulating layer includes selected from the group consisting of polyolefin, polyphenylene ether, polyphenylene sulfide, polyimide, and polyether ether ketone At least one of.

In an embodiment of the present invention, the copper foil layer can be a thin copper or carrier copper with a thickness of 2 to 18 microns. In another embodiment, the copper foil layer may be a thick copper layer with a thickness of 105 microns.

In a specific embodiment of the present invention, the insulating layer may be a non-ink layer, and the insulating layer may be a non-ink layer containing or not containing matting powder, wherein the material forming the insulating layer includes Selected from epoxy resin, acrylic resin, polyester, polyimide and polyimide-imine, polyether ether ketone, polysulfide, polybutylene hexamethylene diamine, polyurethane, polyphenylene sulfide , Polyether sulfide, polyether imide, polypropylene At least one resin in the group consisting of olefin, polystyrene, and polycarbonate. Examples of polyesters include polyethylene terephthalate, polyethylene terephthalate, and polyethylene naphthalate. In addition, the weight percentage of the matting powder in the non-ink layer is 5 to 20% by weight, and the matting powder system is selected from calcium sulfate, carbon black, silicon dioxide, titanium dioxide, zinc sulfide, zirconium oxide, and calcium carbonate. , Silicon carbide, boron nitride, alumina, talc powder, aluminum nitride, glass powder, quartz powder, at least one inorganic powder in the group consisting of emery and clay; or polyimide-based organic Powder; or containing at least one flame retardant compound selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds and boron-containing compounds.

In another specific embodiment, the insulating layer is an ink layer containing matting powder, and the weight percentage of the matting powder in the ink layer is 5 to 20% by weight; wherein, the matting powder system Selected from calcium sulfate, carbon black, silicon dioxide, titanium dioxide, zinc sulfide, zirconium oxide, calcium carbonate, silicon carbide, boron nitride, alumina, talc powder, aluminum nitride, glass powder, quartz powder, emery and At least one inorganic powder in the group consisting of clay; or polyimide-based organic powder; or containing selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds and boron-containing compounds At least one of the flame retardant compounds.

In a specific embodiment of the present invention, the adhesive layer contains selected from epoxy resin, acrylic resin, vinyl acetate resin, urethane resin, silicone rubber resin, parylene resin, double At least one resin in the group consisting of maleimide resin and polyimide resin.

In an embodiment of the present invention, the high-frequency cover film with high electromagnetic shielding function includes an upper release layer and a lower release layer, wherein the upper release layer is located on the outer surface of the insulating layer, The lower release layer is located on the outer surface of the second high frequency adhesive layer, and the thickness of the upper release layer and the thickness of the lower release layer are 25 to 100 microns, respectively.

In an embodiment of the present invention, the upper release layer and the lower release layer are respectively 25 to 100 microns thick release film, and the release film is selected from fluorine-containing polyterephthalene At least one of ethylene formate (PET) release film, PET release film containing silicone oil, PET matte release film and polyethylene (PE) release film.

In another embodiment, the upper release layer and the lower release layer are respectively 25 to 130 micron thick release paper, and the release paper is single-sided release PE coated paper or double-sided release paper PE coated paper.

The present invention further provides a method for preparing the aforementioned high-frequency cover film with high electromagnetic shielding function, and the above-mentioned preparation method is divided into two types according to the type of insulating layer, which are described in detail as follows.

The first preparation method is applicable when the insulating layer is an ink layer, and its steps include:

Coating on the upper release layer to form an insulating layer, and winding it for later use;

Coating and forming a first high-frequency bonding layer on the high-frequency insulating layer, and pressing a copper foil layer on the other surface of the first high-frequency bonding layer;

Coating on the other surface of the high-frequency insulating layer to form a second high-frequency adhesive layer, and attaching the lower release layer to the surface of the second high-frequency adhesive layer;

Coating the other surface of the copper foil layer to form an adhesive layer; and

Laminating and curing the insulating layer coated on the upper release layer.

The second preparation method is applicable when the insulating layer is a non-ink layer, and its steps include:

Coating and forming a first high-frequency bonding layer on the high-frequency insulating layer, and pressing a copper foil layer on the other surface of the first high-frequency bonding layer;

Coating on the other surface of the high-frequency insulating layer to form a second high-frequency adhesive layer, and attaching the lower release layer to the surface of the second high-frequency adhesive layer;

Coating the other surface of the copper foil layer to form an adhesive layer; and

Press and cure the insulating layer on the adhesive layer to obtain the high-frequency cover film with high electromagnetic shielding function.

The beneficial effects of the present invention

4H))、良好的機械性能、極低的介電損耗、極佳的耐熱性，並且具有良好的遮蔽效果；在後期儲存上，由於本發明將EMI包含在覆蓋膜中，存儲方式可以按照常規高頻覆蓋膜的方式進行存儲。 The high-frequency cover film with high electromagnetic shielding function of the present invention not only has the function of insulating the cover film from the surface of the electronic circuit, but also plays the role of shielding the signal transmission; in the manufacturing process, the cover film and The mask film is combined into one, does not affect the product function, reduces the process steps, and reduces the production cost; in terms of product physical properties, its surface has a higher hardness

4H)), good mechanical properties, extremely low dielectric loss, excellent heat resistance, and good shielding effect; in the later storage, because the present invention contains EMI in the cover film, the storage method can be conventional High-frequency cover film for storage.

Regarding the beneficial effects of the high-frequency cover film of the present invention, the details are as follows:

1. The high-frequency cover film with high electromagnetic shielding function provided by the present invention has extremely high electromagnetic shielding effect, and can reach a maximum of 100dB or more, and can meet the requirements of the shielding rate of high-frequency EMI shielding film.

2. The cover film provided by the present invention has excellent mechanical properties and electrical properties, is suitable for high-frequency and high-speed transmission circuit boards, as a thick dielectric layer for signal transmission, and at the same time satisfies the function of cover film line protection.

3. The high-frequency cover film with high electromagnetic shielding function of the present invention, combined with the function of the EMI mask film, greatly reduces the manufacturing process steps and reduces the production cost, and the combined use is Under ensuring low transmission loss of the circuit board, the total laminated thickness of the circuit board is reduced, which is conducive to high-density assembly and increases the design space of the multilayer board.

4. General high-frequency EMI masking film, in order to solve the high-performance requirements of electromagnetic shielding, the thickness of the conductive glue and the thickness of the metal layer are designed to increase the thickness, resulting in a burst; the conduction of the present invention does not rely on the conductivity of the colloid to complete , It does not have the problem of the general high-frequency EMI mask film bursting.

5. General high-frequency EMI masking film with 5G thick plate design or reliability and continuity problems caused by high step difference; and the technical path of the present invention has no step difference problem.

6. When the copper foil layer is 35μm or more, with the design of the number of conductive metal holes, it has good heat conduction and heat dissipation effects, and the heat generation problem can be improved under 5G high transmission.

100, 100’: High frequency cover film

101: insulating layer

102: Next layer

103: Copper foil layer

104: The first high frequency adhesive layer

105: high frequency insulation layer

106: second high frequency adhesive layer

107: Upper release layer

108: lower release layer

200: high frequency EMI masking film

201: Insulation layer

202: Next layer

203: Copper foil layer

204: conductive adhesive layer

205: upper release layer

206: lower release layer

300: high frequency cover film

301: high frequency insulation layer

302: High frequency adhesive layer

303: Release layer

The embodiments of the present invention will be described with reference to the drawings as an example:

Figure 1 is a schematic structural diagram of an embodiment of the cover film of the present invention;

Figure 2 is a schematic structural view of another embodiment of the cover film of the present invention;

Figure 3 is a schematic diagram of the structure of a prior art high-frequency EMI masking film; and

Figure 4 is a schematic diagram of the structure of a prior art high-frequency cover film.

The following is a specific embodiment to illustrate the implementation of the present invention. Those skilled in the art can easily understand the advantages and effects of the present invention from the content disclosed in this specification.

It should be noted that the structure, proportion, size, etc. shown in the accompanying drawings in this manual are only used to match the contents disclosed in the manual for the understanding and reading of those who are familiar with this technique. It is not used to limit the limited conditions for the implementation of the present invention, so it does not have any technical significance. Any structural modification, change in proportion or size adjustment does not affect the effect and the purpose of the present invention. The following should still fall within the scope of the technical content disclosed in the present invention. At the same time, the terms such as "first", "second", "upper", "lower" and "one" cited in this specification are only for convenience of description and are not used to limit the scope of the present invention. The scope of implementation and the change or adjustment of the relative relationship shall be regarded as the scope of the implementation of the present invention without substantively changing the technical content. In addition, all ranges and values herein are inclusive and combinable. Any value or point falling within the range described herein, for example, any integer can be used as the minimum or maximum value to derive the lower range and so on.

Please refer to Figures 1 and 2, which illustrate two implementations of the high-frequency cover film 100, 100' with high electromagnetic shielding function of the present invention, except for the upper release layer 107 and the lower release layer 108, from top to bottom, including: insulating layer 101, adhesive layer 102, copper foil layer 103, first high-frequency adhesive layer 104, high-frequency insulating layer 105, and second high-frequency adhesive layer 106; wherein, the insulating layer 101 and the adhesive layer 102 are on the outermost side of the high-frequency cover film 100 of the present invention. As a protective layer, they are mostly matte black to shield the circuit design and be beautiful. As for the use of the upper release layer 107 and the lower release layer 108, In addition to facilitating winding, it can also provide stiffness when used in FPC processing and facilitate the process. The release layer, insulating layer, and adhesive layer do not affect the overall signal transmission and electromagnetic shielding performance.

Regarding the above-mentioned high-frequency insulating layer, the high-frequency insulating layer is an insulating layer with a dielectric constant lower than 4.0 and a dielectric loss (@ 10GHz) lower than 0.015. Among them, the dielectric loss (@ 10GHz) is particularly The range of 0.003 to 0.010 is preferred.

In a specific embodiment, the material forming the high-frequency insulating layer includes at least one resin selected from the group consisting of polyolefin, polyphenylene ether, polyphenylene sulfide, polyimide and polyether ether ketone .

Regarding the above-mentioned first high-frequency adhesive layer and second high-frequency adhesive layer, they are all resin glues with a dielectric constant lower than 4.0, a dielectric loss (@ 10GHz) of 0.002 to 0.010, and a water absorption of 0.001 to 0.5% And the dielectric loss (@ 10GHz) of the first high-frequency adhesive layer and the second high-frequency adhesive layer is preferably in the range of 0.002 to 0.005.

In a specific embodiment, the materials for forming the first high-frequency adhesive layer and the second high-frequency adhesive layer respectively include selected from fluorine resin, epoxy resin, acrylic resin, urethane resin, silicon At least one resin in the group consisting of rubber resin, parylene resin, bismaleimide resin and thermosetting polyimide resin; wherein, the first high-frequency adhesive layer and the second The two high frequency adhesive layers are preferably thermosetting polyimide resin, and the content of the thermosetting polyimide resin is 40% to 80% by weight.

In another embodiment, the first high-frequency adhesive layer and the second high-frequency adhesive layer include a fluorine resin containing phosphorus resin (flame retardant), and the content of the fluorine resin is 8 to 50 weight. %.

Regarding the above-mentioned insulating layer, a non-ink layer or an ink layer can be selected as required, and the insulating layer should preferably have a surface hardness greater than 4H.

When the insulating layer is a non-ink layer, and its material is formed from epoxy resin, acrylic resin, polyester, polyimide, polyimide-imide, polyether ether ketone, poly Dimethyl hexamethylene diamine, polycyclohexane dimethyl terephthalate, polyurethane, polyphenylene sulfide, polyethylene terephthalate, polyethylene naphthalate, polyether diamine, At least one resin in the group consisting of polyetherimide, polypropylene, polystyrene, and polycarbonate. In addition, the insulating layer may be a non-ink layer containing or not containing matting powder, wherein the weight percentage of the matting powder in the non-ink layer is 5 to 20% by weight.

When the insulating layer is an ink layer, the ink layer of the insulating layer contains matting powder, and the weight percentage of the matting powder in the ink layer is 5 to 20% by weight.

Regarding the above matting powder system selected from calcium sulfate, carbon black, silicon dioxide, titanium dioxide, zinc sulfide, zirconia, calcium carbonate, silicon carbide, boron nitride, alumina, talc, aluminum nitride, At least one inorganic powder in the group consisting of glass powder, quartz powder, emery and clay; or polyimide-based organic powder; or containing selected from halogen-containing compounds, phosphorus-containing compounds, and nitrogen-containing At least one flame retardant compound in the group consisting of a compound and a boron-containing compound.

Regarding the above-mentioned copper foil layer, in one embodiment, the copper foil layer can be a thin copper or carrier copper with a thickness of 2 to 18 microns; in another embodiment, the copper foil layer can be 105 microns Thick thick copper layer.

Regarding the aforementioned adhesive layer, the adhesive layer is selected from epoxy resin, acrylic resin, vinyl acetate resin, urethane resin, silicone rubber resin, parylene resin, bismaleimide At least one resin in the group consisting of a resin and a polyimide resin.

The total thickness of the high frequency cover film with high electromagnetic shielding function of the present invention is 35.5 to 350 microns; wherein the thickness of the insulating layer is 5 to 25 microns; the thickness of the adhesive layer is 5 to 20 microns; the copper foil layer The thickness of the high-frequency adhesive layer is 2 to 105 microns; the thickness of the first high-frequency adhesive layer and the thickness of the second high-frequency adhesive layer are respectively 8-50 microns; the thickness of the high-frequency insulating layer is 7.5-100 microns, where, The high-frequency insulating layer is particularly preferably 12.5 to 50 microns.

In addition, the high-frequency cover film with high electromagnetic shielding function of the present invention includes an upper release layer and a lower release layer, and the upper release layer is located on the outer surface of the insulating layer, and the lower release layer is located on the The outer surface of the second high frequency adhesive layer; and the thickness of the upper release layer and the thickness of the lower release layer are 25 to 100 microns, respectively.

Regarding the release layer, it is divided into the following two structures:

1. The release layer is a 25-100 micron thick release film, and the release film is selected from fluorine-containing polyethylene terephthalate (PET) release film and silicone oil-containing PET release film At least one of the group consisting of type film, PET matt release film and polyethylene (PE) release film; and

2. The release layer is 25 to 130 microns thick release paper, and the release paper is single-sided release PE coated paper or double-sided release PE coated paper.

Referring to Fig. 3, the structure of the prior art high-frequency EMI masking film 200 is illustrated. It includes an insulating layer 201, a bonding layer 202, a copper foil layer 203, and a conductive adhesive layer 204 from top to bottom; and to facilitate processing , Are attached to the outer side of the insulating layer 201 and the conductive adhesive layer 204 with an upper release layer 205 and a lower release layer 206 respectively. In addition, referring to FIG. 4, it illustrates the structure of the high-frequency cover film 300 in the prior art, which includes a high-frequency insulating layer 301, a high-frequency adhesive layer 302, and a release layer 303 from top to bottom.

Compared with the above-mentioned prior art high-frequency EMI masking film 200 and high-frequency cover film 300, the high-frequency cover film with high electromagnetic shielding function of the present invention combines the function of EMI masking film and has an electromagnetic shielding effect of more than 100dB , It can even meet the requirement of 80dB shielding rate of high-frequency EMI masking film; and under the low transmission loss of the circuit board, the total laminated thickness of the circuit board is reduced, which is conducive to high-density assembly and increases the design space of the multilayer board. It can further reduce the process steps and production costs.

Furthermore, the conduction of the high-frequency cover film of the present invention does not depend on the conductivity of the colloid, so there is no problem of plate explosion caused by thickening of the existing high-frequency EMI shielding film for high electromagnetic shielding performance.

In addition, the high-frequency cover film of the present invention does not have the reliability and conductivity problems caused by the high step difference of the existing high-frequency EMI mask film.

In addition, the high-frequency cover film of the present invention also has excellent mechanical properties and electrical properties, and is suitable for high-frequency and high-speed transmission circuit boards, as a thick dielectric layer for signal transmission, and satisfies the role of cover film circuit protection.

The present invention further provides a method for preparing the aforementioned high-frequency cover film with high electromagnetic shielding function, and the above-mentioned preparation method is divided into two types according to the type of insulating layer, which are described in detail as follows.

The first preparation method is applicable when the insulating layer is an ink layer, and its steps include:

Coating on the upper release layer to form an insulating layer, and winding it for later use;

Coating and forming a first high-frequency bonding layer on the high-frequency insulating layer, and pressing a copper foil layer on the other surface of the first high-frequency bonding layer;

Coating on the other surface of the high-frequency insulating layer to form a second high-frequency adhesive layer, and attaching the lower release layer to the surface of the second high-frequency adhesive layer;

Coating the other surface of the copper foil layer to form an adhesive layer; and

The adhesive layer and the insulating layer coated on the upper release layer are laminated and cured to obtain the high frequency cover film with high electromagnetic shielding function.

The second preparation method is applicable when the insulating layer is a non-ink layer, and its steps include:

Coating and forming a first high-frequency bonding layer on the high-frequency insulating layer, and pressing a copper foil layer on the other surface of the first high-frequency bonding layer;

Coating on the other surface of the high-frequency insulating layer to form a second high-frequency adhesive layer, and attaching the lower release layer to the surface of the second high-frequency adhesive layer;

Coating the other surface of the copper foil layer to form an adhesive layer; and

Press and cure the insulating layer on the adhesive layer to obtain the high-frequency cover film with high electromagnetic shielding function.

The characteristics and effects of the present invention will be further described in detail below through specific embodiments, but the scope of the present invention is not limited by the description of the embodiments.

Example 1:

Due to the presence or absence of the insulating layer and the adhesive layer of the high-frequency cover film of the present invention, the resistance value, peel strength, electromagnetic shielding property, dielectric performance, solder heat resistance and other properties of the cover film of the comparative example described later are not affected. Therefore, the high-frequency cover film of the embodiment described later will omit the stacked structure including the insulating layer and the adhesive layer.

Preparation of high-frequency cover film : 12.5 micron thick polyimide film (SKCKOLONPI company, model FS) is used as the high-frequency insulating layer, wherein the high-frequency insulating layer has a dielectric constant of 3.1 and a dielectric loss of 0.005 .

Then, a thermosetting polyimide resin is coated on the high-frequency insulating layer to form a first high-frequency adhesive layer, and a 2 micron thick copper foil layer is laminated on the other surface of the first high-frequency adhesive layer, wherein , The thermosetting polyimide resin is composed of 70% polyimide resin, 8% sintered silica, 3% epoxy resin, 15% phosphorous flame retardant and 4% fluorine resin. The formed first high-frequency adhesive layer has a dielectric constant of 2.8, a dielectric loss value of 0.003, and a water absorption rate of 0.08%; and the other surface of the high-frequency insulating layer is coated to form the second highest layer with a thickness of 25 microns Frequency bonding layer, wherein the second high frequency bonding layer is selected from thermosetting polyimide resin with the same composition as the first high frequency bonding layer, and its dielectric constant is 2.8, dielectric loss value is 0.003, and water absorption rate It is 0.08%; after drying and winding, a high-frequency cover film without insulating layer and adhering layer is obtained.

Finally, the high frequency covering film prepared above was tested and analyzed as follows, and the results were recorded in Table 1:

(1) Resistance test: Use a multimeter to measure in accordance with the "Test Guidelines for Soft Board Assembly Essentials" (TPCA-F-002).

(2) Peel strength test: Use a universal tester to measure according to IPC-TM-650 2.4.9 (or according to TPCA-F-002).

(3) Electromagnetic shielding test: Measure in accordance with International Electrotechnical Commission (IEC) standards.

(4) Dielectric performance test: use a network analyzer and resonant cavity to measure in accordance with IPC-TM-650 2.5.5.13.

(5) Solder heat resistance test: use a lead-free tin furnace and measure it in accordance with the "Test Guidelines for Soft Board Assembly Essentials" (TPCA-F-002).

Examples 2 to 7:

The high-frequency cover film used was prepared as in Example 1, except that the thicknesses of the copper foil layer, the first high-frequency bonding layer, the high-frequency insulating layer, and the second high-frequency bonding layer are shown in Table 1, and the same Method to measure the resistance value, peel strength, electromagnetic shielding, dielectric properties, and solder heat resistance of the high-frequency cover film, and record the results in Table 1.

Comparative examples 1 to 2:

Except that the high-frequency cover film in Example 1 is replaced with the high-frequency cover film of the prior art, the resistance value, peel strength, electromagnetic shielding, dielectric properties, solder heat resistance and other performance measurement methods are the same as those in Example 1, wherein the The high-frequency cover film system includes a high-frequency insulating layer and a high-frequency adhesive layer, and is purchased from Asia Electronics HFC125 and HFC035.

Comparative examples 3 to 5:

Except that the high-frequency cover film in Example 1 is replaced with the prior art high-frequency EMI mask film, the resistance value, peel strength, electromagnetic shielding, dielectric properties, solder heat resistance and other performance measurement methods are the same as those described in Example 1. Among them, the high-frequency EMI masking film system includes a copper foil layer and a conductive adhesive layer, and is purchased from Tatsuta's SF-PC 8600, SF-PC 3300, and KNQ Technology's MW8900, respectively. .

Table 1

It can be seen from Table 1 that the high-frequency cover film of the present invention has a specific composition structure, so it can achieve a thicker thickness more easily than the comparative example, and in the field of high-frequency and high-speed transmission, it can meet the needs of thick dielectric layers while having a relatively high Ideal dielectric properties.

In addition, it can be seen from the test results that the present invention has a good shielding effect and better shielding performance in the structure of a thicker copper foil layer; at a frequency of 1GHz, its electromagnetic shielding rate can reach more than 80dB, even It is greater than 100dB, and under the conditions of 85℃ temperature and 85% relative humidity for 100 hours, it can also maintain excellent shielding effect and has excellent reliability. Since the technical path of the present invention is different from the general EMI masking film, and has good solder heat resistance, it can solve the problems of board explosion and high step difference encountered by circuit board manufacturers in the circuit assembly and other manufacturing processes.

In summary, the high-frequency cover film with high electromagnetic shielding function of the present invention can not only meet the design requirements of low transmission loss, but also has the function of insulating and protecting the circuit surface, and its electromagnetic shielding effect is extremely high. Preferably, compared with the prior art high-frequency cover film and high-frequency EMI mask film, the present invention can reduce the number of processes, so it can be used as a design solution to replace the high-frequency cover film with high-frequency EMI mask film on the market.

The above-mentioned embodiments are only illustrative and not used to limit the present invention. Anyone familiar with this technique can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention is defined by the scope of the patent application attached to the present invention. As long as it does not affect the effect and implementation purpose of the present invention, it should be covered in the technical content of this disclosure.

100: high frequency cover film

101: insulating layer

102: Next layer

103: Copper foil layer

104: The first high frequency adhesive layer

105: high frequency insulation layer

106: second high frequency adhesive layer

107: Upper release layer

108: lower release layer

Claims (15)

A high-frequency cover film with high electromagnetic shielding function, including in order: An insulating layer with a thickness of 5 to 25 microns and a surface hardness greater than 4H; A bonding layer of 5 to 20 microns thick formed on the insulating layer; A copper foil layer of 2 to 105 microns thick formed on the adhesive layer; A first high frequency adhesive layer formed on the copper foil layer; A high frequency insulating layer with a thickness of 7.5 to 100 microns, a dielectric constant lower than 4.0 and a dielectric loss (@ 10GHz) lower than 0.015 formed on the first high-frequency adhesive layer; and A second high-frequency adhesive layer formed on the high-frequency insulating layer; Wherein, the thickness of each of the first high-frequency bonding layer and the second high-frequency bonding layer is 8-50 microns, and the dielectric constant is lower than 4.0, the dielectric loss (@ 10GHz) is 0.002 to 0.010, and the water absorption The rate is 0.001 to 0.5%. The high-frequency cover film with high electromagnetic shielding function as described in the first item of the scope of patent application, wherein the materials for forming the first high-frequency adhesive layer and the second high-frequency adhesive layer respectively include those selected from fluorine-based resin and ring Oxygen resin, acrylic resin, urethane resin, silicone rubber resin, parylene resin, bismaleimide resin and thermosetting polyimide resin At least one resin. The high-frequency cover film with high electromagnetic shielding function as described in the first item of the scope of patent application, wherein the material forming the high-frequency insulating layer includes selected from polyolefin, polyphenylene ether, polyphenylene sulfide, polyphenylene oxide At least one resin in the group consisting of amine and polyetheretherketone. The high-frequency cover film with high electromagnetic shielding function as described in the first item of the scope of patent application, wherein the insulating layer is a non-ink layer, and the material forming the insulating layer is selected from epoxy resin, acrylic Resin, polyester, polyimide and polyimide-imide, polyether ether ketone, poly sulfide, polyhexamethylene At least one resin in the group consisting of butylene diamine, polyurethane, polyphenylene sulfide, polyether sulfide, polyether imide, polypropylene, polystyrene, and polycarbonate. The high-frequency cover film with high electromagnetic shielding function as described in the first item of the patent application, wherein the insulating layer is an ink layer containing matting powder, and the weight of the matting powder in the ink layer The percentage is 5 to 20% by weight. As described in item 5 of the scope of patent application, the high-frequency cover film with high electromagnetic shielding function, wherein the matting powder system is selected from calcium sulfate, carbon black, silicon dioxide, titanium dioxide, zinc sulfide, zirconium oxide, calcium carbonate, At least one inorganic powder in the group consisting of silicon carbide, boron nitride, aluminum oxide, talc powder, aluminum nitride, glass powder, quartz powder, emery and clay. The high-frequency cover film with high electromagnetic shielding function as described in item 5 of the scope of patent application, wherein the matting powder system is a polyimide-based organic powder. The high-frequency cover film with high electromagnetic shielding function as described in item 5 of the scope of patent application, wherein the matting powder system contains selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds and boron-containing compounds At least one of the flame retardant compounds. The high-frequency cover film with high electromagnetic shielding function as described in the first item of the scope of patent application, wherein the adhesive layer is selected from epoxy resin, acrylic resin, vinyl acetate resin, urethane resin, silicon At least one resin selected from the group consisting of rubber-based resin, parylene-based resin, bismaleimide-based resin, and polyimide resin. The high-frequency cover film with high electromagnetic shielding function as described in item 1 of the scope of patent application includes an upper release layer and a lower release layer, wherein the upper release layer is located on the outer surface of the insulating layer, and the The lower release layer is located on the outer surface of the second high frequency adhesive layer, and the thickness of the upper release layer and the thickness of the lower release layer are 25 to 100 microns, respectively. The high-frequency cover film with high electromagnetic shielding function as described in item 10 of the scope of patent application, wherein the upper release layer and the lower release layer are respectively 25 to 100 microns thick release film, and the release film The film is selected from the group consisting of fluorine-containing polyethylene terephthalate (PET) release film, silicone oil-containing PET release film, PET matte release film and polyethylene (PE) release film At least one of the group. The high-frequency cover film with high electromagnetic shielding function described in item 10 of the scope of patent application, wherein the upper release layer and the lower release layer are respectively 25 to 130 microns thick release paper, and the release paper is It is single-sided release PE coated paper or double-sided release PE coated paper. A method for preparing a high-frequency cover film with high electromagnetic shielding function as described in item 1 of the scope of patent application, including: Coating and forming a first high-frequency bonding layer on the high-frequency insulating layer, and pressing a copper foil layer on the other surface of the first high-frequency bonding layer; Coating on the other surface of the high-frequency insulating layer to form a second high-frequency adhesive layer, and attaching the lower release layer to the surface of the second high-frequency adhesive layer; Coating the other surface of the copper foil layer to form an adhesive layer; and Press and cure the insulating layer on the adhesive layer. The method for manufacturing a high-frequency cover film with high electromagnetic shielding function as described in item 13 of the scope of patent application, wherein the insulating layer is a non-ink layer. The manufacturing method of a high-frequency cover film with high electromagnetic shielding function as described in item 13 of the scope of patent application, wherein, when the insulating layer is an ink layer, the insulating layer is first coated and formed on the upper release layer, and it is to be completed After the bonding layer, the insulating layer on the upper release layer and the bonding layer are laminated and cured.

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