TW201925403A - Multi-layered anisotropically piercing conductive adhesive tape and preparing method and FPC with shield-enhanced structure using the same - Google Patents

Abstract

The present invention provides a multi-layered anisotropically piercing conductive adhesive comprising an upper conductive adhesive layer, an ultrathin conductive fabric with two sides and a lower conductive adhesive layer; wherein both the upper conductive adhesive layer and the lower conductive adhesive layer comprises a plurality of metal conductive particles, and a metal plating layer is form on one side of the ultrathin conductive fabric. The present invention also provides a flexible printed circuit (FPC) with shield-enhanced structure using the conductive adhesive above. Even if no reserved grounding hole is form in the FPC, it also performs excellent grounding effect and good shielding. Therefore, the multi-layered anisotropically piercing conductive adhesive tape of the present invention has good electrical properties, good adhesive strength, better tin soldering, reliability and flame resistant. In additions, the method for producing multi-layered anisotropic conductive adhesive could simplify the process, and save cost.

Description

Multi-layer anisotropic puncture type conductive tape manufacturing method thereof and flexible printed circuit board reinforcing shielding structure using the same

The invention relates to the technical field of conductive cloth for printed circuit boards, in particular to a multi-layer anisotropic puncture type conductive tape and a reinforcing shielding structure.

With the development of electronic and communication products, the circuit board components are moving toward light, thin, short and high integration, and the transmission signal frequency band is wider and wider, resulting in more and more serious electromagnetic interference. In addition, the safety of electronic circuit components is also included. Considering the new requirements for circuit component grounding reliability and circuit board design freedom in electronic products, the conductive adhesive products popular in the market often have the grounding holes filled too much by conductive adhesive to affect the design and installation of other components. Or, if the conductive adhesive is not filled, there is a gap in the connecting portion during reflow soldering, and a defect such as a blasting plate is generated.

1 is a prior art flexible printed circuit board (FPC) reinforcing shield structure, including a steel sheet 200; a flexible printed circuit board 300; a first grounding hole 301 formed in a flexible printed circuit board 300; electromagnetic wave shielding (EMI) ) a film 400; and a conductive film 600; the conductive film 600 covers the first ground hole 301 and a portion of the flexible printed circuit board 300, and presses the steel sheet 200 over the conductive film 600. After being hot pressed, the conductive adhesive film 600 is melted and flows into the first grounding hole 301 to form a conduction with the flexible printed circuit board 300, and is used for grounding shielding. However, the current FPC process in the market has less and less requirements on the grounding aperture, and the technical requirements for the downstream punching process are becoming more stringent. However, the flowability of the conductive adhesive and other factors affect the conductive adhesive material in a very small aperture. The conduction effect is not ideal. In view of this, it is not necessary to provide a new material for the grounding hole (the aperture is less than or equal to 0.5 mm) to improve the grounding effect and stability. Although some existing new technologies and patents have been disclosed in the conductive adhesive layer to provide a thin metal plating layer to improve the conductivity of the conductive adhesive product, so that the powder content is reduced and the cost is reduced, but in the actual production process, due to the flexibility of the metal itself Poor, resulting in the product filling ability after pressing can not achieve the expected effect or even worse, and because of the poor permeability of the thin metal coating, there is a burst in the SMT (Surface Mount Technology) process of the flexible printed circuit board Board risk.

To this end, the present invention provides an anisotropic multi-layer conductive tape having a high conductivity of an ultra-thin conductive cloth layer and a plurality of shapes of a plurality of metal particles.

The technical problem to be solved by the present invention is to provide a multi-layer anisotropic puncture-type conductive adhesive tape, which can be applied to a flexible printed circuit board by using the conductive adhesive tape of the present invention, and can obtain good grounding and electromagnetic wave shielding effects even if the FPC has no reserved grounding holes. . Compared with the general conductive adhesive, the conductive adhesive tape of the invention has good electrical properties, good bonding strength, good solderability, high reliability and resistance. Good flammability and other characteristics, and its production method can reduce production processes and save production costs, and its market application prospects are broad.

In order to solve the above technical problem, the present invention adopts a multi-layered anisotropic puncture-type conductive tape comprising: an upper conductive adhesive layer having a thickness of 15 to 25 μm; and a lower conductive adhesive layer having a thickness of 35 to 45 μm, wherein The upper conductive adhesive layer and the lower conductive adhesive layer each comprise a plurality of conductive metal particles having a particle diameter of 40 to 100 μm, and the plurality of conductive metal particles are selected from the group consisting of dendritic, chain, needle, and flake. At least two shapes of a group consisting of spheres; and an ultrathin conductive layer of 5 to 15 micrometers thick and having upper and lower sides formed between the upper conductive adhesive layer and the lower conductive adhesive layer, wherein At least one side of the ultra-thin conductive cloth layer has a metal plating layer.

In one embodiment, the upper conductive adhesive layer and the lower conductive adhesive layer are both thermosetting adhesive layers, and each comprises an adhesive resin and the plurality of conductive metal particles, wherein each of the upper conductive adhesives The adhesive layer of the agent layer and the lower conductive adhesive layer is 20 to 75% by weight, the content of the plurality of conductive metal particles is 25 to 70% by weight, and the plurality of conductive metal particles and the adhesive resin are The weight ratio is 1:1 to 4:1.

In one embodiment, the ultra-thin conductive cloth layer is a fiber cloth, and the fiber cloth may be selected from the group consisting of mesh cloth, plain woven cloth or non-woven fabric, wherein the fiber cloth is A plurality of micropores having a size that allows the smallest conductive metal particles in the upper conductive adhesive layer and the lower conductive adhesive layer to pass through the fiber cloth.

In another embodiment, the plurality of micropores of the fiber cloth have a size of not less than 5 micrometers.

In one embodiment, the metal plating on the surface of the ultra-thin conductive cloth layer may be a copper-plated nickel layer, a copper-plated cobalt layer, a copper-plated tin layer, a copper-plated silver layer, a copper-plated iron-nickel layer, or a copper-plated gold. Layer or copper plating.

In one embodiment, the plurality of conductive metal particles are composed of a plurality of acicular conductive metal particles and a plurality of spherical conductive metal particles, and the plurality of acicular conductive metal particles and the plurality of spherical conductive metal particles The weight ratio is 1:4 to 4:1.

In another embodiment, the material of the plurality of conductive metal particles comprises alloy conductive particles.

In one embodiment, the conductive adhesive tape comprises two 25-100 micrometer-thick release layers respectively formed under the lower conductive adhesive layer and above the upper conductive adhesive layer. The layer may be a single-sided release film or a double-sided release film, and the release layer may be a fluorine-containing polyester release layer, an oil-containing polyester release layer, a matte polyester release layer, and a polyethylene release type. Layer or polyethylene coated paper layer.

The invention provides a flexible printed circuit board (FPC) reinforcing shielding structure comprising: a steel sheet having a thickness of 0.05 to 0.2 mm; and a 10 to 20 micrometer thick electromagnetic wave shielding (EMI) film comprising 5 to 10 micrometers thick. a conductive adhesive layer and a 5 to 10 micron thick ink layer on the conductive adhesive layer; the conductive adhesive tape of the present invention is located between the electromagnetic wave shielding film and the steel sheet; and a flexible printed circuit board is attached The electromagnetic wave shielding film is disposed between the conductive adhesive tape and the flexible printed circuit board on the lower surface of the electromagnetic wave shielding film.

In one embodiment, the steel sheet is 0.05 to 0.2 mm thick Nickel plated steel sheet.

The present invention provides a method for preparing the above-mentioned multi-layered anisotropic puncture-type conductive tape, which comprises: mixing a plurality of conductive metal particles and an adhesive resin having a particle diameter of 40 to 100 μm in a weight ratio of 1:1 to 4:1; To form a mixture, wherein the plurality of conductive metal particles have at least two shapes selected from the group consisting of dendritic, chain, needle, flake and spherical; the coating is applied to the design of the release layer The release surface forms a lower conductive adhesive layer; the ultra-thin conductive cloth layer is bonded and cured on the surface of the lower conductive adhesive layer; and the other side of the ultra-thin conductive cloth layer is coated with 1:1 to 4:1 The weight ratio is a mixture of a plurality of conductive metal particles and an adhesive resin having a particle diameter of 40 to 100 μm to form an upper conductive adhesive layer; and a release layer is adhered to the surface of the upper conductive adhesive layer.

The effect of the present invention has at least the following points: 1. The multilayer conductive tape of the present invention comprises a plurality of conductive metal particles of at least two shapes, and a conductive metal particle having a particle diameter of 40 to 100 μm, due to the plural The conductive metal particles are of various shapes, and the thickness of the ultra-thin conductive cloth layer is extremely thin. Therefore, when the FPC reinforcing shielding structure is formed by pressing, the plurality of conductive metal particles in the conductive adhesive cloth are subjected to hot pressing through the ultra-thin. a plurality of micropores of the conductive layer to make the upper conductive adhesive layer and the lower conductive adhesive layer conductive; on the other hand, the conductive metal particles in the conductive adhesive can pierce the ink layer of the EMI film during pressing Directly forming conduction with the conductive adhesive layer of the EMI film, compared with the prior art, the process of reserving the grounding hole in the FPC can be omitted, that is, the process of reinforcing the shielding structure by the FPC without punching, and also the grounding and electromagnetic shielding. Effect, effective solution The FPC process has defects in the continuity and stability caused by the extremely small grounding hole (the aperture is less than or equal to 0.5 mm), and saves the cost of the FPC process by eliminating the original punching process and Human; of course, the present invention is also applicable to the case where a small aperture grounding hole is reserved in the FPC process, in which case the conduction effect is better than that of the ordinary conductive film; 2. The upper conductive adhesive layer and the lower layer of the present invention The conductive adhesive layer includes at least two shapes of the plurality of conductive metal particles. Since the plurality of conductive metal particles have various shapes, the processing tends to flow in multiple directions when the processing is subjected to hot pressing deformation, so that after pressing, the plurality of conductive metals The distribution of the particles in the conductive adhesive layer has multi-directionality and high dispersibility, and further forms a conduction circuit with the grounding holes on the flexible board, so that the upper conductive adhesive layer and the lower conductive adhesive layer have good transconductivity, which is large Improve the electrical conductivity and reduce the grounding resistance of the soft board; 3. The ultra-thin conductive cloth layer of the invention is advantageous for the upper conductive adhesive layer and the lower layer due to its fibrous or mesh structure. The plurality of conductive metal particles in the electro-adhesive layer pass through the micropores to realize the conduction of the upper and lower conductive adhesive layers, and at the same time, since the conductive cloth layer has good gas permeability, the surface mounting technology process on the flexible printed circuit board does not The occurrence of the blasting phenomenon can effectively solve the problem of the explosion of the existing conductive adhesive and the conductive adhesive introduced into the thin metal layer; Fourth, since the conductive cloth layer of the invention is based on the fiber cloth, it has good flexibility and wear resistance. Therefore, it can be avoided that the conductive adhesive is deformed when the flexible circuit board is subjected to hot pressing due to excessive hardness, which affects the performance, and the plurality of conductive metal particles of the upper conductive adhesive layer and the lower conductive adhesive layer are hot pressed to cause the adhesive. The resin material is deformed and flows to achieve the opposite conduction, and there may be The utility model avoids the defects that the traditional conductive adhesive of the rabbit and the conductive adhesive introduced into the thin metal layer have poor conduction effect; fifth, since the surface of the ultra-thin conductive cloth layer of the invention is treated by electroplating metal plating to form a metal plating layer, the same conduction force is In the case, the amount of the plurality of conductive metal particles of the upper conductive adhesive layer and the lower conductive adhesive layer can be correspondingly reduced, and the dust pollution is reduced, the cost is reduced, and the subsequent strength of the product is greatly improved; After the combination, the multi-directional plurality of conductive metal particles can improve the electrical and mechanical properties of the adhesive resin after complete crosslinking and curing; 7. When the conductive tape and the steel sheet of the present invention are used to cover the printed circuit When the reinforcing member is formed on the board, the external electromagnetic wave interference can be effectively shielded due to good grounding stability; 8. The conductive metal particles of the present invention may comprise a plurality of alloy conductive particles, which have excellent oxidation resistance and conductivity, and are favorable for Product storage and handling, does not affect the physical properties of the product, so that the product has good stability and high reliability; and The conductive tape is bonded to the steel sheet or other reinforcing members to form a flexible printed circuit board (FPC) reinforcing shield structure, which can effectively prevent the deformation of the mounting portion due to factors such as bending, and because the steel sheet has good stiffness. It is beneficial to the installation and handling of FPC parts; by pressing and the puncture effect of a plurality of large particles of conductive metal particles in the conductive adhesive tape, even if the FPC has no reserved grounding holes, it has good grounding and Block the effects of external signal interference.

The above description is merely an overview of the technology of the present invention, in order to be clearer. The technical means of the present invention can be implemented in accordance with the contents of the specification, and the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings.

100‧‧‧conductive tape

101‧‧‧Upper conductive adhesive layer

102‧‧‧Ultra-thin conductive fabric

103‧‧‧Under conductive adhesive layer

104‧‧‧ release layer

200‧‧‧ steel sheet

300‧‧‧Soft Printed Circuit Board (FPC)

301‧‧‧First grounding hole

302‧‧‧Second grounding hole

400‧‧‧Electromagnetic wave shielding (EMI) film

401‧‧‧Ink layer

402‧‧‧conductive adhesive layer

500‧‧‧Single-sided copper clad laminate

600‧‧‧conductive film

1011‧‧‧ Conductive metal particles

1012‧‧‧Adhesive resin

Embodiments of the present invention are described by way of example with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a conventional FPC reinforcing shield structure including a common conductive film; and FIG. 2 is a release-free type of the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing a conductive tape containing a release layer according to a first embodiment of the present invention; and FIG. 4A is a FPC reinforcing shield structure according to a second embodiment of the present invention; FIG. 4B is a cross-sectional view showing the FPC reinforcing shield structure of the third embodiment of the present invention; FIG. 5 is a schematic view showing the test of the multi-layer anisotropic puncture type conductive tape of the present invention; and FIG. A schematic diagram of testing the second embodiment of the multi-directional anisotropic puncture type conductive tape.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention from the disclosure.

It should be noted that the structures, proportions, sizes, etc. shown in the drawings of the present specification are only used in conjunction with the contents disclosed in the specification to familiarize themselves with the art. The understanding and reading of the person is not intended to limit the conditions for the implementation of the present invention, and therefore does not have technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size may not be affected by the present invention. The efficacies and the achievable objectives should still fall within the scope of the technical content disclosed in the present invention. In the meantime, the terms "a", "lower" and "upper" are used in this specification for the purpose of description and are not intended to limit the scope of the invention. Substantially changing the technical content is also considered to be within the scope of the invention. In addition, all ranges and values herein are inclusive and combinable. Any value or point falling within the ranges recited herein, such as any integer, may be the minimum or maximum value to derive the lower range and the like.

A multilayer anisotropic puncture-type conductive tape 100, as shown in FIGS. 2 and 3, comprises: an upper conductive adhesive layer 101 having a thickness of 15 to 25 μm; and a lower conductive adhesive layer 103 having a thickness of 35 Up to 45 μm, wherein the upper conductive adhesive layer 101 and the lower conductive adhesive layer 103 each comprise a plurality of conductive metal particles 1011 having a particle diameter of 40 to 100 μm and an adhesive resin 1012, and the plurality of conductive metal particles 1011 Having at least two shapes selected from the group consisting of dendrites, chains, needles, flakes, and spheres; and an ultrathin conductive fabric layer 102 having a thickness of 5 to 15 μm and having upper and lower faces formed thereon Between the conductive adhesive layer 101 and the lower conductive adhesive layer 103, at least one side of the ultra-thin conductive cloth layer has a metal plating layer.

If the ultra-thin conductive cloth layer is too thick, the upper conductive conductive material layer 101 and the plurality of conductive metal particles 1011 in the lower conductive adhesive layer 103 cannot be contacted, and the contact is poor; if the ultra-thin conductive cloth Layer 102 too Thin, it is not conducive to production and increase production costs.

In one embodiment, the plurality of conductive metal particles have a particle diameter of 40 to 80 micrometers; in another specific embodiment, the plurality of conductive metal particles have a particle diameter of 51 to 80 micrometers; The plurality of conductive metal particles are composed of a plurality of acicular conductive metal particles and a plurality of spherical conductive metal particles, and the weight ratio of the plurality of acicular conductive metal particles to the plurality of spherical conductive metal particles is from 1:4 to 4:1. If the weight ratio of the plurality of acicular conductive metal particles to the plurality of spherical conductive metal particles is less than 1:1, the conductivity is not good, and excessive adhesive resin causes problems such as sticking to the downstream operation; if the plurality of needles When the weight ratio of the conductive metal particles to the plurality of spherical conductive metal particles is higher than 4:1, the dispersion of the powder is disadvantageous, and the adhesion and the subsequent strength of the conductive adhesive are also affected.

If the conductive adhesive layer is too thin, the shielding effect is not good; if the conductive adhesive layer is too thick, the thinning requirements are not met, and the coating processability is unfavorable, which indirectly increases the production cost.

Typically, only a single shape of conductive particles in the conductive adhesive layer and the lower conductive adhesive layer tend to flow and distribute in the same direction during dispersion and compression flow, so that the conductive adhesive layer tends to be conductive. In the same direction, the conductivity of the overall conductive adhesive layer is poor, thereby affecting the shielding effect of the conductive adhesive layer. The plurality of shaped conductive metal particles of the present invention are dispersed in the conductive adhesive layer and subjected to hot pressing. The deformation is generated, and the directional flow and distribution are performed, so that the conductive adhesive layer has good transconductivity and improves the shielding performance.

The upper conductive adhesive layer and the lower conductive adhesive layer are both hot a solid adhesive layer, each of which comprises an adhesive resin and the plurality of conductive metal particles, wherein the adhesive resin content of each of the upper conductive adhesive layer and the lower conductive adhesive layer is 20 to 75% by weight, The content of the plurality of conductive metal particles is 25 to 70% by weight, and the weight ratio of the plurality of conductive metal particles to the adhesive resin is 1:1 to 4:1. The upper conductive adhesive layer and the lower conductive adhesive layer of the present invention may include some excipients (such as a hardener or a thickener, etc.) and non-conductive metal particles (such as graphite or a conductive compound, etc.).

In one embodiment, the weight ratio of the plurality of conductive metal particles of the upper conductive adhesive layer and the lower conductive adhesive layer is 35 to 55% by weight.

The adhesive resin is selected from the group consisting of an epoxy resin, an acrylic resin, a urethane resin, a ruthenium rubber resin, a poly-p-xylene resin, a bismaleimide resin, a phenol resin, At least one of the group consisting of a melamine resin and a polyimide resin, and particularly preferably an acrylic resin.

If the adhesive resin is too small, the viscosity is too low, which is not conducive to on-line production; if there is too much adhesive resin, the produced product is more viscous, and the content of the plurality of conductive metal particles is relatively lowered, resulting in conductivity. Not good.

The ultra-thin conductive cloth layer 102 is a fiber cloth, and the fiber cloth may be selected from the group consisting of a mesh cloth, a plain woven cloth or a non-woven fabric, wherein the fiber cloth has a plurality of micropores, and The size allows the smallest conductive metal particles in the upper conductive adhesive layer and the lower conductive adhesive layer to pass through the fiber cloth.

The metal plating on the surface of the ultra-thin conductive cloth layer may be a copper-plated nickel layer and plated Copper-cobalt layer, copper-plated tin layer, copper-plated silver layer, copper-plated iron-nickel layer, copper-plated gold layer or copper-plated layer.

In one embodiment, the metal plating on the surface of the ultra-thin conductive layer is a copper-plated nickel layer or a copper-plated silver layer.

The plurality of conductive metal particles are composed of a plurality of acicular conductive metal particles and a plurality of spherical conductive metal particles, and the weight ratio of the plurality of acicular conductive metal particles to the plurality of spherical conductive metal particles is 1:4 to 4 :1.

The material of the plurality of conductive metal particles includes alloy conductive particles. The material for forming the plurality of conductive metal particles includes at least one of a single metal conductive metal particle and an alloy conductive particle, and the plurality of conductive metal particles are particularly preferably an alloy conductive particle.

The conductive metal particles of the single metal may be at least one selected from the group consisting of gold particles, silver particles, copper particles, and nickel particles, but are not limited thereto; the conductive particles of the alloy may be selected from silver-plated copper particles, At least one of the group consisting of silver-plated gold particles, silver-plated nickel particles, gold-plated copper particles, and gold-plated nickel particles, but is not limited thereto.

The conductive particles of the alloy have good oxidation resistance and conductivity, and the product is advantageous for storage and handling, and does not affect the physical properties of the product, so that the product has good stability and high reliability.

The conductive adhesive tape 100 further comprises two 25-100 micrometer-thick release layers 104 respectively formed under the lower conductive adhesive layer 103 and above the upper conductive adhesive layer 101, and each of the release layers may be a single a release film or a double-sided release film, and the release layer may be a fluorine-containing polyester release layer, an eucalyptus-containing polyester Release layer, matte polyester release layer, polyethylene release layer or polyethylene coated paper layer.

In a specific embodiment, the release layer is preferably a double-sided release film having a thickness of 25 to 100 μm, and the thickness is too thin or too thick to be detrimental to subsequent processing and punching.

The color of the release layer is pure white, milky white or transparent color, especially the pure white release film or the milky white release film, because the CNC automatic equipment engraves the line, under the infrared induction, the pure white release film or milky white The problem of no-light reflection of the release film can be quickly and accurately positioned, and the processing operation, and the manual operation, pure white or milky white has a recognition function, reducing the situation of artificial leakage.

The invention provides a method for preparing the above-mentioned multi-layered anisotropic puncture-type conductive adhesive tape, comprising the following steps: Step 1: screening a powder of conductive metal particles of various shapes to obtain a desired particle diameter, and then mixing the conductive metal particles of each shape. Uniform, the ball milling method can be selected when mixing, and the ball milling speed should not be too high (the rotation speed is especially 200 to 300 rpm), otherwise the surface alloy layer of the metal particles will be destroyed, or the stirring method is selected (the rotation speed is 700 to 2000) The rotation/min is preferred. The mixing speed is high, the mixing uniformity is good, and after mixing, a plurality of conductive metal particle mixture is obtained; Step 2: adding the above plurality of conductive metal particle mixture to the adhesive resin and mixing well In the mixing period, it is necessary to add a plurality of conductive metal particles while stirring and mixing, and the mixing conditions are similar to those in the first step; Step 3: coating the mixture obtained in the second step on the designated release surface of the release layer, that is, forming the lower conductive adhesive layer; Step 4: attaching the ultra-thin conductive cloth layer with the carrier to the lower conductive adhesive layer and pre-curing The pre-curing temperature of the lower conductive adhesive layer should not exceed the curing temperature of the adhesive resin itself. The pre-curing temperature selected in the present invention is between 80 and 100 ° C, and the carrier is peeled off after pre-curing to form an ultra-thin film. Conductive cloth layer; Step 5: Apply the mixture prepared in the second step on the other side of the ultra-thin conductive cloth layer to form an upper conductive adhesive layer. Of course, another mixture of different compositions and ratios may be additionally prepared; Step 6: curing the upper conductive adhesive layer by the pre-curing conditions of the fourth step, and then winding up, that is, the finished product.

As shown in FIG. 4A, the present invention provides a flexible printed circuit board (FPC) reinforcing shield structure comprising: a steel sheet 200 having a thickness of 0.05 to 0.2 mm; and a 10 to 20 micrometer thick electromagnetic wave shielding (EMI) film. 400, comprising a 5 to 10 micron thick ink layer 401 and a 5 to 10 micron thick conductive adhesive layer 402. In this aspect, the ink layer 401 is located on the conductive adhesive layer 402, and may of course be oppositely disposed; The conductive tape 100 of the invention is located between the electromagnetic wave shielding film 400 and the steel sheet 200, and the conductive tape is attached to the lower surface of the steel sheet 200; and the flexible printed circuit board 300 is attached to the electromagnetic wave shield. The lower surface of the film 400.

In one embodiment, the steel sheet is a nickel-plated steel sheet having a thickness of 0.05 to 0.2 mm. In one embodiment, the nickel-plated steel sheet has a total thickness of 0.1 mm.

In the specific embodiment shown in FIG. 4A, the flexible printed circuit board 300 located under the conductive adhesive tape has no reserved grounding holes, which is different from the typical flexible printed circuit board (FPC) of FIG. Reinforce the shield structure.

In the FPC reinforcing shield structure, after the conductive adhesive tape 100 is pressed against the steel sheet 200, the conductive metal particles 1011 in the adhesive resin 1012 pierce the EMI film and the ink layer 401 is directly connected to the conductive adhesive layer 402 of the EMI film. And passing through the conductive adhesive layer 402 to the second ground hole 302 of the flexible printed circuit board 300 which is not covered by the conductive tape 100 and the EMI film, and then grounded, compared with the typical FPC reinforcing shield structure. As shown in FIG. 1 , the process of reserving the first grounding hole 301 of the small aperture below the coverage of the EMI film of the typical FPC reinforcing shielding structure can be omitted, that is, the process of reinforcing the shielding structure by the FPC without punching, The effect of grounding and electromagnetic wave shielding effectively solves the defects of insufficient continuity and stability caused by the minimum grounding hole (the aperture is less than or equal to 0.5 mm) in the FPC process, and the original punching process is omitted. It also saves the cost and manpower of the FPC process.

In another embodiment, a flexible printed circuit board (FPC) reinforcing shield structure includes a steel sheet 200 as shown in FIG. 4B, and an electromagnetic wave shielding (EMI) film 400 including an ink layer 401 and a conductive adhesive layer. 402, wherein the ink layer 401 is located on the conductive adhesive layer 402; the flexible printed circuit board 300 includes a first ground hole 301 and a second ground hole 302; and the conductive tape 100 is covered by the first a grounding hole 301 and a part of the flexible printed circuit board 300, and pressing the steel in the conductive adhesive tape 100 Slice 200.

After the thermocompression bonding, the conductive adhesive layer and the lower conductive adhesive layer on the conductive adhesive tape are melted and flowed into the first grounding hole 301 to form a conduction with the FPC for grounding shielding. Compared with the prior art, the present invention can be The overflow fluidity of the ordinary conductive film itself is avoided, and the conduction effect of the present invention is also better than that of the ordinary conductive film.

Test Method 1: Continuity Analysis

As shown in Fig. 5, the multi-layer anisotropic puncture-type conductive tape after peeling off the release layer was subjected to a conductivity analysis test by a Takahashi tester, and the surfaces of the upper conductive adhesive layer 101 and the lower conductive adhesive layer 103 were respectively bonded. After the nickel plated steel sheet 200 and the flexible printed circuit board 300 are pressed and cured, the test pieces are respectively tested for the conductivity resistance before and after reflow soldering. As an embodiment, the conductive property of the general product is tested by the same method as a comparison. For example, the measured conductivity results are reported in Table 1.

Test Method 2: Peel Force Analysis

As shown in Fig. 6, the peeling force test was performed on the multi-layered anisotropic puncture-type conductive tape after peeling off the double-sided release film by a universal tensile machine, and the surfaces of the upper conductive adhesive layer 101 and the lower conductive adhesive layer 103 were respectively faked. After attaching the nickel-plated steel sheet 200 and the single-sided copper clad 500, after pressing and curing, the sample is taken out to test the peeling force value. As an example, the peeling force of the general product is tested in the same manner as a comparative example, and the test will be performed. The resulting peel force results are reported in Table 1.

As can be seen from Table 1, the multilayer anisotropic puncture-type conductive tape of the present invention has a good electrical conductivity, stability, and good adhesion strength compared to general products. In contrast, the general conductive adhesive is not conductive because the FPC is not opened and has no piercing effect.

The above embodiments are merely illustrative and are not intended to limit the invention. The equivalent structures made by the description of the present invention and the contents of the drawings are directly or indirectly applied to other related technical fields, and are included in the scope of patent protection of the present invention.

Claims (10)

A multi-layer anisotropic puncture-type conductive adhesive tape comprising: a conductive adhesive layer of 15 to 25 micrometers thick; a conductive adhesive layer of 35 to 45 micrometers thick, wherein the upper conductive adhesive layer and the lower conductive adhesive Each of the layers includes a plurality of conductive metal particles having a particle diameter of 40 to 100 μm, and the plurality of conductive metal particles have at least two shapes selected from the group consisting of dendritic, chain, needle, flake, and spherical; An ultra-thin conductive cloth layer of 5 to 15 micrometers thick and having upper and lower sides is formed between the upper conductive adhesive layer and the lower conductive adhesive layer, wherein at least one side of the ultra-thin conductive cloth layer has a metal plating layer. The conductive adhesive tape of the first aspect of the invention, wherein the upper conductive adhesive layer and the lower conductive adhesive layer are both thermosetting adhesive layers, and each comprises an adhesive resin and the plurality of conductive metal particles, wherein The adhesive resin content of each of the upper conductive adhesive layer and the lower conductive adhesive layer is 20 to 75% by weight, the content of the plurality of conductive metal particles is 25 to 70% by weight, and the plurality of conductive metal particles and the The weight ratio of the adhesive resin is 1:1 to 4:1. The conductive tape according to claim 1, wherein the ultra-thin conductive cloth layer is a fiber cloth, and the fiber cloth may be selected from the group consisting of mesh cloth, plain woven cloth or non-woven fabric. Wherein the fiber cloth has a plurality of micropores sized to allow the smallest conductive metal particles of the upper conductive adhesive layer and the lower conductive adhesive layer to pass through the fiber cloth. The conductive tape of claim 1, wherein the ultra-thin The metal plating on the surface of the conductive layer may be a copper-plated nickel layer, a copper-plated cobalt layer, a copper-plated tin layer, a copper-plated silver layer, a copper-plated iron-nickel layer, a copper-plated gold layer or a copper-plated layer. The conductive tape according to claim 1, wherein the plurality of conductive metal particles are composed of a plurality of acicular conductive metal particles and a plurality of spherical conductive metal particles, and the plurality of acicular conductive metal particles and the plural The spherical conductive metal particles have a weight ratio of 1:4 to 4:1. The conductive tape according to claim 1, wherein the material of the plurality of conductive metal particles comprises alloy conductive particles. The conductive tape of claim 1 or 2, further comprising a 25-100 micron thick release layer formed under the lower conductive adhesive layer and above the upper conductive adhesive layer. Each of the release layers may be a single-sided release film or a double-sided release film, and the release layer may be a fluorine-containing polyester release layer, an oil-containing polyester release layer, and a matte polyester release layer. , polyethylene release layer or polyethylene coated paper layer. A flexible printed circuit board (FPC) reinforcing shielding structure comprising: a steel sheet of 0.05 to 0.2 mm thick; an electromagnetic wave shielding (EMI) film of 10 to 20 micrometers thick, comprising a conductive adhesive layer of 5 to 10 micrometers thick and located a 5 to 10 micron thick ink layer on the conductive adhesive layer; the conductive adhesive tape according to claim 1 is located between the electromagnetic wave shielding film and the steel sheet; and a flexible printed circuit board The electromagnetic wave shielding film is disposed between the conductive adhesive tape and the flexible printed circuit board. The flexible printed circuit board (FPC) reinforcing shield structure according to claim 8, wherein the steel sheet is a nickel-plated steel sheet. A method for preparing a conductive adhesive tape according to claim 7, comprising: mixing a plurality of conductive metal particles and an adhesive resin having a particle diameter of 40 to 100 μm in a weight ratio of 1:1 to 4:1; Forming a mixture, wherein the plurality of conductive metal particles have at least two shapes selected from the group consisting of dendrites, chains, needles, flakes, and spheres; and coating the mixture on the release layer Forming a lower conductive adhesive layer; bonding an ultra-thin conductive cloth layer to the surface of the lower conductive adhesive layer; coating the other side of the ultra-thin conductive cloth layer with a ratio of 1:1 to 4:1 The mixture of the plurality of conductive metal particles and the adhesive resin having a particle diameter of 40 to 100 μm is mixed to form an upper conductive adhesive layer; and the release layer is adhered to the surface of the upper conductive adhesive layer.