CN209462700U - Free ground film and wiring board - Google Patents

Abstract

The utility model embodiment provides a kind of free ground film and wiring board, and free ground film includes the first conductor layer being cascading, conductive adhesive layer, the second conductor layer, third conductor layer and adhesive film, is equipped with protrusion at the first through hole of the second conductor layer；Instantaneous cooling is formed after protrusion flow to the other side by the side of first through hole under fusion temperature by conductive adhesive layer；Third conductor layer covering protrusion, to form lug boss in the outer surface of third conductor layer position corresponding with protrusion；When free ground film is used for the ground connection of printed wiring board, free ground film is mutually pressed by adhesive film with the electromagnetic shielding film in printed wiring board, the insulating layer of lug boss puncture adhesive film and electromagnetic shielding film, and it is electrically connected with the shielded layer of electromagnetic shielding film, to which effectively the interference charge for accumulating in shielded layer be exported, it avoids the accumulation of interference charge and forms interference source, and then the integrality of signal transmission is effectively ensured.

Description

Free ground film and wiring board

Technical field

The utility model relates to electronic fields, more particularly to a kind of free ground film and wiring board.

Background technique

With the rapid development of electronics industry, electronic product is further to miniaturization, lightweight, assembling densification hair Exhibition greatly pushes the development of flexible electric circuit board, to realize component arrangement and conducting wire connecting integration.Flexible electric circuit board can be wide It is general to be applied to the industries such as mobile phone, liquid crystal display, communication and space flight.

Under the promotion of international market, function flexible electric circuit board is occupied an leading position in flexible electric circuit board market, and is evaluated One important indicator of function flexible electric circuit board performance is electromagnetic shielding (Electromagnetic Interference Shielding, abbreviation EMI Shielding).With the integration of the communication apparatus function such as mobile phone, internal component sharply high frequency High speed.Such as: for cell-phone function other than original audio communication function, camera function has become necessary function, and WLAN (Wireless Local Area Networks, WLAN), GPS (Global Positioning System, the whole world Positioning system) and function of surfing the Net popularized, along with the integration of following sensing component, sharply high-frequency high-speed becomes component Gesture is more inevitable.The component internal and the electromagnetic interference of outside, signal caused under the driving of high frequency and high speed exists Decaying and insertion loss and jitter problem are gradually serious in transmission.

Currently, commonly free ground film generally comprises conductor layer and conductive adhesive layer to existing line plate, conductor layer is by leading Electric glue-line contacts conducting with the shielded layer of electromagnetic shielding film, so that can pass through when printed wiring board is applied to electronic equipment Free ground film is electrically connected with the shell of electronic equipment, so that the interference charge of electromagnetic shielding film be exported.But implementing this During utility model, at least there are the following problems in the prior art for utility model people discovery: at high temperature, due to conducting resinl Layer expansion, so that the conducting particles that contacts with each other pulls open or script is in contact with electromagnetic shielding film originally in conductive adhesive layer Conducting particles pulls open, and leads to the Joint failure of free ground film and electromagnetic shielding film, to will effectively can not build up in electromagnetism Interference charge export on screened film, and then interference source is formed, influence the signal transmission of wiring board.

Utility model content

The purpose of the utility model is to provide a kind of free ground film and wiring boards, can be realized free ground film and electromagnetism Screened film is reliably connected, to guarantee the interference charge export in electromagnetic shielding film, to guarantee the complete of signal transmission Whole property.

In order to solve the above-mentioned technical problem, the utility model provides a kind of free ground film, including what is be cascading First conductor layer, conductive adhesive layer, the second conductor layer, third conductor layer and adhesive film, second conductor layer, which is equipped with, runs through it The first through hole of upper and lower surface is equipped with protrusion at the first through hole；The protrusion is by the conductive adhesive layer under fusion temperature Instantaneous cooling is formed after flowing to the other side by the side of the first through hole；The third conductor layer covers the protrusion, thus Lug boss is formed in the outer surface of third conductor layer position corresponding with the protrusion, the lug boss protrudes into the glue film Layer；

When the free ground film is used for the ground connection of printed wiring board, it is equipped with electromagnetic shielding film, institute on a printed-wiring board Stating electromagnetic shielding film includes the shielded layer and insulating layer being stacked, and the free ground film passes through the adhesive film and the electricity Magnetic shield film mutually presses, and the lug boss pierces through the adhesive film and the insulating layer and is electrically connected with the shielded layer.

As an improvement of the above scheme, the surface of the lug boss is equipped with the conductive particles of convex.

As an improvement of the above scheme, the height of the conductive particles is 20 μm -100 μm.

As an improvement of the above scheme, the adhesive film includes the adhesion layer containing conducting particles；Or the adhesive film packet Include the adhesion layer without conducting particles.

As an improvement of the above scheme, first conductor layer, the second conductor layer and third conductor layer respectively include metal One of conductor layer, carbon nanotube conductor layer, ferrite conductor layer and graphene conductor layer are a variety of.

As an improvement of the above scheme, the number of the first through hole in first conductor layer every square centimeter is 5- 10⁶It is a；And/or the cross-sectional area of the first through hole is 0.01 μm²-1mm²。

As an improvement of the above scheme, the free ground film further includes antioxidation coating, and the antioxidation coating is set to described In one side of first conductor layer far from the conductive adhesive layer.

As an improvement of the above scheme, the free ground film further includes peelable protective film layer, the peelable protection Film layer is set in one side of the adhesive film far from the third conductor layer.

Compared with prior art, the utility model embodiment discloses a kind of free ground film, by leading described second Protrusion is set at the first through hole on body layer, and the third conductor layer is made to cover the protrusion, is led with realizing in the third The outer surface of body layer position corresponding with the protrusion forms lug boss, and the lug boss is made to protrude into the adhesive film, so that When the free ground film is mutually pressed by its adhesive film with electromagnetic shielding film, the lug boss can successively pierce through the glue The insulating layer of film layer and the electromagnetic shielding film, and connect with the shielded layer of the electromagnetic shielding film, thus effectively will accumulation Interference charge export in the electromagnetic shielding film, and then ensure that the ground connection of electromagnetic shielding film, it efficiently avoids in height Wen Shi leads to free ground film and electromagnetic shielding film since free ground film is mutually pressed by conductive adhesive layer with electromagnetic shielding film Joint failure and can not by interference charge export rapidly the problem of, therefore ensure that signal transmission integrality.

In order to solve identical technical problem, the utility model also provides a kind of wiring board, including printed wiring board, electromagnetism Screened film and above-mentioned free ground film, the electromagnetic shielding film are set in the printed wiring board, the electromagnetic shielding film Including the shielded layer and insulating layer being stacked, the free ground film is mutually pressed by the adhesive film with the electromagnetic shielding film It closes, the lug boss pierces through the adhesive film and the insulating layer and is electrically connected with the shielded layer.

Compared with prior art, the utility model embodiment discloses a kind of wiring board, and the wiring board includes track Free ground film described in road plate, electromagnetic shielding film and above-mentioned any one, the free ground film by its adhesive film with When electromagnetic shielding film mutually presses, the lug boss can successively pierce through the insulating layer of the adhesive film and the electromagnetic shielding film, And connect with the shielded layer of the electromagnetic shielding film, thus effectively export the interference charge in the electromagnetic shielding film, into And ensure that the ground connection of electromagnetic shielding film, it efficiently avoids at high temperature, since free ground film passes through conductive adhesive layer and electricity Magnetic shield film mutually presses, lead to free ground film and electromagnetic shielding film Joint failure and can not will interference charge be derived rapidly asks Topic, therefore avoid the accumulation for interfering charge and the normal work for influencing printed wiring board, it ensure that the integrality that signal transmits.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of an angle of the free ground film in the utility model embodiment one；

Fig. 2 is the structural schematic diagram of another angle of the free ground film in the utility model embodiment one；

Fig. 3 is the structural schematic diagram of the free ground film in the utility model embodiment two；

Fig. 4 is the structural schematic diagram of the wiring board in the utility model embodiment three；

Fig. 5 is the flow diagram of the preparation method of the free ground film in the utility model embodiment four.

Wherein, the 1, first conductor layer；2, conductive adhesive layer；21, raised；3, the second conductor layer；31, first through hole；4, third Conductor layer；41, lug boss；42, conductive particles；5, adhesive film；6, peelable protective film layer；7, antioxidation coating；8, it is electromagnetically shielded Film；81, insulating layer；82, shielded layer；9, printed wiring board.

Specific embodiment

The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without creative efforts Every other embodiment obtained, fall within the protection scope of the utility model.

Embodiment one

Referring to figs. 1 and 2, the free ground film, including be cascading the first conductor layer 1, conducting resinl The 2, second conductor layer 3 of layer, third conductor layer 4 and adhesive film 5, second conductor layer 3 are equipped with the through its upper and lower surface One through-hole 31 is equipped with protrusion 21 at the first through hole 31；Described raised 21 by the conductive adhesive layer 2 under fusion temperature by institute State first through hole 31 side flow to the other side after instantaneous cooling formed；The third conductor layer 4 covers described raised 21, thus Lug boss 41 is formed with the raised 21 corresponding position in the outer surface of the third conductor layer 4, the lug boss 41 protrudes into The adhesive film 5；

As shown in figure 4, being equipped with electricity in printed wiring board 9 when the free ground film is used for the ground connection of printed wiring board Magnetic shield film 8, the electromagnetic shielding film 8 include the shielded layer 82 and insulating layer 81 being stacked, and the free ground film passes through The adhesive film 5 is pressed with 8 phase of electromagnetic shielding film, and the lug boss 41 pierces through the adhesive film 5 and the insulating layer 81 And it is electrically connected with the shielded layer 82.

In the utility model embodiment, by the way that protrusion 21 is arranged at the first through hole 31 in second conductor layer 3, And the third conductor layer 4 is made to cover described raised 21, to realize in the outer surface and described raised 21 of the third conductor layer 4 Corresponding position forms lug boss 41, while the lug boss 41 being made to protrude into the adhesive film 5, so that in the free ground film When being pressed by its adhesive film 5 and 8 phase of electromagnetic shielding film, the lug boss 41 can successively pierce through the adhesive film 5 and described The insulating layer 81 of electromagnetic shielding film 8, and connect with the shielded layer 82 of the electromagnetic shielding film 8, to will effectively accumulate in institute The interference charge export in electromagnetic shielding film 8 is stated, and then ensure that the ground connection of electromagnetic shielding film 8, is efficiently avoided in high temperature When, since free ground film is mutually pressed by conductive adhesive layer with electromagnetic shielding film, free ground film and electromagnetic shielding film is caused to connect It connects and fails to the problem of charge being interfered to export rapidly, therefore ensure that the integrality of signal transmission.

Specifically, during forming described raised 21, specific manifestation are as follows: under fusion temperature, make the conducting resinl Layer 2 melts；And after the conductive adhesive layer 2 flow to the other side close to the side of the conductive adhesive layer 2 from the first through hole 31, Make 2 instantaneous cooling of conductive adhesive layer, to form the protrusion close to the side of the adhesive film 5 in the first through hole 31 21。

In the utility model embodiment, it should be noted that raised 21 shape shown in the drawings is only to show Example property, described raised 21 in the utility model are not limited by the shape illustrated, as long as convex with penetration ability It rises, both is within the protection scope of the present invention.

In the utility model embodiment, it should be noted that the shape of the lug boss 41 can be with described raised 21 Shape it is identical, can also be different from raised 21 shape, the shape of the lug boss 41 shown in the drawings is only to show Example property.

In the utility model embodiment, ensures that and form described raised 21 at the first through hole 31, together When guarantee that second conductor layer 3 is not easily broken, it is preferable that the cross-sectional area of first through hole 31 described in the present embodiment is 0.01μm²-1mm²。

In addition, enough described raised 21 are formed in order to guarantee, to ensure that the third conductor layer 4 can pass through The lug boss 41 successively pierces through the insulating layer 81 of the adhesive film 5 and the electromagnetic shielding film 8, thus with the shielded layer 82 Connection, while guaranteeing that second conductor layer 3 is not easy to rupture, in the present embodiment in second conductor layer 3 every square centimeter The first through hole 31 number be 5-10¹⁰It is a.Correspondingly, the protrusion in second conductor layer 3 every square centimeter 21 number is 5-10¹⁰It is a；It should be noted that since the third conductor layer 4 covers described raised 21, thus described The outer surface of three conductor layers 4 forms lug boss 41 with the raised 31 corresponding position, therefore, the number of the lug boss 41 with Raised 21 number is corresponding, to ensure that the lug boss 41 can successfully pierce through the adhesive film 5 and described The insulating layer 81 of electromagnetic shielding film 8.

As shown in Fig. 2, the first through hole 31 can be regularly or irregularly distributed in second conductor layer 3；Its In, the first through hole 31, which is regularly distributed in second conductor layer 3, refers to that the shape of each first through hole 31 is identical, and It is evenly distributed in second conductor layer 3；The first through hole 31 is irregularly distributed in second conductor layer 3 Refer to the different of each first through hole 31, and is disorderly distributed in second conductor layer 3.Preferably, each first is logical The shape in hole 31 is identical, and each first through hole 31 is evenly distributed in second conductor layer 3.In addition, the first through hole 31 can be circular through hole, can also be the through-hole of other arbitrary shapes, the utility model attached drawing is only with the first through hole 31 It is that circular through hole is illustrated, but the first through hole 31 of other any shapes is all in the protection scope of the utility model Within.

In the utility model embodiment, the thickness of first conductor layer 1 is preferably 2 μm -45 μm；Second conductor The thickness of layer 3 is preferably 2 μm -45 μm；The thickness of the third conductor layer 4 is preferably 2 μm -45 μm, to guarantee described first Conductor layer 1, second conductor layer 3 and the third conductor layer 4 are not easy to rupture and have good flexibility.In addition, being Guarantee first conductor layer 1, second conductor layer 3 and the third conductor layer 4 have good electric conductivity, and described the One conductor layer 1, second conductor layer 3 and the third conductor layer 4 include metal conductor layer, carbon nanotube conductor layer, iron One of oxysome conductor layer and graphene conductor layer are a variety of.Wherein, the metal conductor layer include monometallic conductor layer and/ Or alloy conductor layer；Wherein, the monometallic conductor layer is by any one in aluminium, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold Kind of material is made, the alloy conductor layer by any two kinds or two kinds in aluminium, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold with On material be made.

In the utility model embodiment, first conductor layer 1 includes the first surface and second surface being oppositely arranged, The first surface is in contact with the conductive adhesive layer 2；The second surface is in contact with the antioxidation coating 7.It needs to illustrate , the first surface and the second surface may each be the surface of any shape, for example, can be as shown in Figure 1 Flat surface, or contoured non-smooth surface or other rough surfaces；In addition, the first surface and described Two surfaces can be the surface of rule, be also possible to irregular surface.The utility model attached drawing only with the first surface and The second surface is that flat surface is illustrated, and the first surface and second surface of other any shapes are all in this reality Within novel protection scope.

In the utility model embodiment, second conductor layer 3 includes the third surface and the 4th surface being oppositely arranged, The third surface is in contact with the third conductor layer 4；4th surface is in contact with the conductive adhesive layer 2.It needs Bright, the third surface and the 4th surface can be the surface of any shape, for example, can be as shown in Figure 1 Flat surface, or contoured non-smooth surface or other rough surfaces；In addition, the third surface and described Four surfaces can be the surface of rule, be also possible to irregular surface.The utility model attached drawing only with the third surface and 4th surface is that flat surface is illustrated, and the third surface of other any shapes and the 4th surface all exist Within the protection scope of the utility model.

In the utility model embodiment, it should be noted that first conductor layer 1 of the present embodiment attached drawing, described Second conductor layer 3 and the third conductor layer 4 all can be single layer structures, or multilayered structure.In addition, according to practical life The needs for producing and applying, first conductor layer 1, second conductor layer 3 and the third conductor layer 4 of the present embodiment attached drawing It may be configured as latticed, foaming shape etc..

In the utility model embodiment, one of structure of the adhesive film 5, specific manifestation are as follows: the adhesive film 5 Including the adhesion layer containing conducting particles.By making the adhesive film 5 include the adhesion layer containing conducting particles, so that the glue Film layer 5 not only has the function of bonding, so that the electromagnetic shielding film 8 and the free ground film closely bind, while described Adhesive film 5 also has the function of conduction, with first conductor layer 1, the conductive adhesive layer 2, second conductor layer 3 and institute It states third conductor layer 4 to match, interference electronics is gone out rapidly.Wherein, the conducting particles of the adhesive film 5 can be to be separated from each other Conducting particles, or bulky grain conducting particles made of reunion；When the conducting particles is the conductive particle being separated from each other The period of the day from 11 p.m. to 1 a.m can further improve the area of electrical contact, improve the uniformity of electrical contact；And when the conducting particles be reunite and At bulky grain conducting particles, puncture intensity can be increased.

In the utility model embodiment, another structure of the adhesive film 5, specific manifestation are as follows: the adhesive film 5 wraps Include the adhesion layer without conducting particles.By making the adhesive film 5 include the adhesion layer without conducting particles, so that the glue film Layer 5 has the function of bonding, so that the electromagnetic shielding film 8 and the free ground film closely bind, simultaneously because the glue Film layer 5 includes being free of conducting particles, therefore reduce the insertion loss of wiring board in use process, improves the bending of wiring board Property.

In the utility model embodiment, the adhesive film 5 with a thickness of 0.1 μm -80 μm.Material used in the adhesive film 5 Material is selected from following several: modified epoxy class, acrylic compounds, modified rubber class, modified thermoplastic polyimide.In addition, The outer surface of the adhesive film 2 can be the flat surface without fluctuating, be also possible to the non-smooth surface gently to rise and fall.

Referring to figs. 1 and 2, in order to protect the adhesive film 5, free ground film described in the present embodiment further includes can Protective film layer 6 is removed, the peelable protective film layer 6 is set in one side of the adhesive film 5 far from the third conductor layer 4. The peelable protective film layer 6 plays a protective role, and is using preceding generation damaged to avoid the adhesive film 5, so that it is guaranteed that institute Stating free ground film can be pressed by the adhesive film 5 and 8 phase of electromagnetic shielding film.It should be noted that will be described When free ground film is pressed on the electromagnetic shielding film 8, need to remove on the peelable protective film layer 6, then make the freedom Ground film is pressed by the adhesive film 5 and 8 phase of electromagnetic shielding film.

In addition, the peelable protective film layer 6 is thin including PPS film layer, PEN film layer, laminated polyester film, polyimides It is film layer that film layer that film layer, epoxy resin ink are formed after solidifying, polyurethane ink are formed after solidifying, acrylic resin modified solid The film layer that the film layer or polyimide resin formed after change is formed after solidifying.

In the utility model embodiment, in order to protect first conductor layer 1, to guarantee charge will be interfered to lead Out, free ground film described in the present embodiment further includes antioxidation coating 7, and it is remote that the antioxidation coating 7 is set to first conductor layer 1 In one side from the conductive adhesive layer 2.By first conductor layer 1 far from the conductive adhesive layer 2 one side setting described in Antioxidation coating 7 is aoxidized with preventing first conductor layer 1 from contacting with air, to guarantee freely to be grounded by described Film exports the interference charge in the electromagnetic shielding film 8.

In a kind of wherein preferred embodiment, the material of the antioxidation coating 7 is metal material, ferrite, graphite, carbon nanometer One of pipe, graphene, silver paste；Wherein, the metal material is aluminium, in titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, gold, molybdenum Any one；Or the metal material be aluminium, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, gold, two kinds or two kinds in molybdenum with The alloy of upper formation；At this point, the antioxidation coating 7 with a thickness of 0.01 μm -5 μm, the thickness of the antioxidation coating 7 is preferably 0.1μm-1μm.In addition, the antioxidation coating 7 can be plated by chemical plating, physical vapour deposition (PVD), chemical vapor deposition, evaporation, be splashed At least two combination process penetrated in one of plating, plating or process above is formed.

In another preferred embodiment, the antioxidation coating 7 is made of the mixture of glue and conducting particles；Wherein, described to lead Charged particle and the volume ratio of the glue are 5%-80%；At this point, the thickness of the antioxidation coating 7 is preferably 0.1 μm -5 μm.Separately Outside, which can be formed by cured technique after coating.

Embodiment two

As shown in figure 3, the free ground film in the present embodiment, difference from the first embodiment is that the protrusion The surface in portion 41 is equipped with the conductive particles 42 of convex.By the way that the conductive particles 42 are arranged on the surface of the lug boss 41, into One step guarantees that during pressing, the lug boss 41 can successfully pierce through the adhesive film 5 and the insulating layer 81, into And guarantee the normal export of interference charge.

Preferably, on the position outwardly protruded on surface of 42 integrated distribution of conductive particles in the lug boss 41, It is easier to pierce through the adhesive film 5 in this way.Certainly, the non-protrusion on the surface of the lug boss 41 can also have conductive particles 42 to divide Cloth.In addition, the conductive particles 42 can also be distributed in the third conductor layer 4 close to the adhesive film 5 one side other On position, and it is not only distributed in the surface of the lug boss 41, as shown in Figure 3.Certainly, the conductive particles 42 can also only divide It is distributed in the lug boss 41.

In specific implementation, it can be initially formed the third conductor layer 4, then again by other techniques in the third Conductor layer 4 forms the conductive particles 42 far from the side of second conductor layer 3.Certainly, the third conductor layer 4 and conductor Particle 42 is also possible to the overall structure formed by one-shot forming technique.

In the utility model embodiment, the conductive particles 42 can exist certain with the outer surface of the adhesive film 5 Distance can also be in contact with the outer surface of the adhesive film 5 or extend the outer surface of the adhesive film 5.

In the utility model embodiment, the highly preferred of the conductive particles 42 is 20 μm -100 μm, the adhesive film 5 Thickness be preferably 0.1 μm -80 μm, the thickness of the insulating layer 81 is preferably 1 μm -20 μm.By the way that the conductive particles are arranged 42 highly preferred is 20 μm -100 μm, and the thickness of the adhesive film 5 is preferably 0.1 μm -80 μm, to ensure the conductive particles 42 can pierce through the insulating layer 81 of the adhesive film 5 and the electromagnetic shielding film 8, ensure that the free ground film can The interference charge gathered on the electromagnetic shielding film 8 is exported.

In the utility model embodiment, the conductive particles 42 include metallic particles, carbon nanotube particulate and ferrite One of particle is a variety of.In addition, the metallic particles includes monometallic particle and/or alloying pellet；Wherein, the Dan Jin Metal particles are made of any one material in aluminium, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, the alloying pellet by aluminium, Two or more any material in titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold is made.It should be noted that described Conductive particles 42 can be identical as the material of the third conductor layer 4, can not also be identical.

In the utility model embodiment, it should be noted that the shape of the conductive particles 42 as shown in Figure 3 is only It is exemplary, due to the difference on process means and parameter, the conductive particles 42 can also be cluster-shaped, extension ice-like, clock The other shapes such as mammary calculus shape, dendroid.In addition, the conductive particles 42 in the utility model are not illustrated and above-mentioned shape Limitation, as long as have pierce through and conducting function conductive particles, both be within the protection scope of the present invention.

In addition, the other structures and working principle of the free ground film of the embodiment of the present invention are the same as example 1, herein It does not do and more repeats.

Embodiment three

As shown in figure 4, the utility model embodiment also correspondence provides a kind of wiring board, including printed wiring board 9, electromagnetism Screened film 8 and free ground film as described in embodiment 1 or 2, the electromagnetic shielding film 8 are set in the printed wiring board 9, The electromagnetic shielding film 8 includes the shielded layer 82 and insulating layer 81 being stacked, and the free ground film passes through the adhesive film 5 With 8 phase of electromagnetic shielding film press, the lug boss 41 pierce through the adhesive film 5 and the insulating layer 81 and with the shielding Layer 82 is electrically connected.

In the present embodiment, the implementation about free ground film can refer to the description of above-described embodiment, herein no longer It repeats.

Preferably, the printed wiring board 9 is flexible single-side, flexibility double face, flexible multi-layer plate, one in rigid-flex combined board Kind.

It, can be by making the free ground film when the wiring board is applied to electronic equipment in specific implementation It is electrically connected with the shell of electronic equipment, to be exported the interference charge in the electromagnetic shielding film 8 is built up.

In the utility model embodiment, by above structure, pass through its adhesive film 5 and electromagnetism in the free ground film During 8 phase of screened film presses, the glue film can be successively pierced through using the lug boss 41 in the third conductor layer 4 The insulating layer 81 of layer 5 and the electromagnetic shielding film 8, so that outer surface at least part of the third conductor layer 4 and institute The shielded layer 82 for stating electromagnetic shielding film 8 connects, and then realizes and export the interference charge in the electromagnetic shielding film 8, to guarantee The ground connection of electromagnetic shielding film 8.

Example IV

As shown in figure 5, this method is suitable for the preparation of free ground film described in embodiment one, comprising steps of

S1, the first conductor layer is formed；

In step sl, in a kind of wherein preferred embodiment, first conductor layer can be formed in the following manner:

Antioxidation coating is formed on a carrier film；

First conductor layer is formed far from the side of the carrier film in the antioxidation coating.

In another preferred embodiment, first conductor layer can be formed in the following manner:

Strippable coating is formed on a carrier film；

First conductor layer is formed far from the side of the carrier film in the strippable coating；

After first conductor layer forms antioxidation coating far from the side of the strippable coating, the strippable coating is shelled From.

S2, conductive adhesive layer is formed in the side of first conductor layer；

S3, the second conductor layer is formed far from the side of first conductor layer in the conductive adhesive layer；Wherein, described second Conductor layer has the first through hole through its upper and lower surface；

In the utility model embodiment, the cross-sectional area of the first through hole of formation is 0.01 μm²-1mm²；Often put down The number of the first through hole in square centimetre of second conductor layer is 5-10⁶It is a.

S4, under fusion temperature, moment is cold after so that the conductive adhesive layer is flow to the other side from the side of the first through hole But, to form protrusion far from the side of the conductive adhesive layer in the first through hole；

S5, third conductor layer is formed in the side that second conductor layer is formed with the protrusion, and leads the third Body layer covers the protrusion, to form lug boss in the outer surface of third conductor layer position corresponding with the protrusion；

S6, adhesive film is formed far from the side of second conductor layer in the third conductor layer；The free ground film When ground connection for printed wiring board, it is equipped with electromagnetic shielding film on a printed-wiring board, the electromagnetic shielding film includes that stacking is set The shielded layer and insulating layer set, the free ground film are mutually pressed by the adhesive film with the electromagnetic shielding film, the gold Belong to protrusion to pierce through the adhesive film and the insulating layer and be electrically connected with the shielded layer.

It is specifically, described to form adhesive film in the side that first conductor layer is formed with the metal bump specifically:

It is coated with adhesive film on release film, adhesive film pressing is then transferred to third conductor layer far from described second The side of conductor layer, to form adhesive film far from the side of second conductor layer in the third conductor layer；Or

It directly is coated with adhesive film far from second conductor layer side in the third conductor layer, to lead in the third Body layer forms adhesive film far from the side of second conductor layer.

Suitable for another preferred embodiment for preparing free ground film described in embodiment two, after step s 5, And it before step S6, further comprises the steps of:

It plated by physics feather plucking, chemical plating, physical vapour deposition (PVD), chemical vapor deposition, evaporation, sputter plating, be electroplated and is mixed It closes one of plating or kinds of processes and forms conductive particles in the outer surface of the lug boss.

In the utility model embodiment, the preparation method of the free ground film is led by sequentially forming described first Body layer, conductive adhesive layer and the second conductor layer, and under fusion temperature, make the conductive adhesive layer from second electrically conductive film The side of one through-hole flow to instantaneous cooling behind the other side, to be formed in the first through hole far from the side of the conductive adhesive layer Protrusion, while third conductor layer is formed in the side that second conductor layer is formed with the protrusion, to realize in the third The outer surface of conductor layer position corresponding with the protrusion forms lug boss, finally in the third conductor layer far from described second The side of conductor layer forms adhesive film, so that when the free ground film is mutually pressed by its adhesive film with electromagnetic shielding film, The lug boss can successively pierce through the insulating layer of the adhesive film and the electromagnetic shielding film, and with the electromagnetic shielding film Shielded layer connection, exports the interference charge in the electromagnetic shielding film to realize.

To sum up, the utility model embodiment provides a kind of free ground film and wiring board, the free ground film include according to Secondary the first conductor layer 1 being stacked, conductive adhesive layer 2, the second conductor layer 3, third conductor layer 4 and adhesive film 5, described second leads Body layer 3 is equipped with the first through hole 31 through its upper and lower surface, is equipped with protrusion 21 at the first through hole 31；Described raised 21 by Instantaneous cooling is formed after the conductive adhesive layer 2 flow to the other side by the side of the first through hole 31 under fusion temperature；It is described Third conductor layer 4 covers described raised 21, thus in outer surface and the raised 21 corresponding position of the third conductor layer 4 Lug boss 41 is formed, the lug boss 41 protrudes into the adhesive film 5；The free ground film is used for the ground connection of printed wiring board When, electromagnetic shielding film 8 is equipped in printed wiring board 9, the electromagnetic shielding film 8 includes the shielded layer 82 being stacked and insulation Layer 81, the free ground film is pressed by the adhesive film 5 and 8 phase of electromagnetic shielding film, and the lug boss 41 pierces through institute It states adhesive film 5 and the insulating layer 81 and is electrically connected with the shielded layer 82, to will effectively accumulate in the electromagnetic shielding Interference charge export in film 8, and then ensure that the ground connection of electromagnetic shielding film 8, it efficiently avoids at high temperature, due to freedom Ground film is mutually pressed with electromagnetic shielding film by conductive adhesive layer, lead to free ground film and electromagnetic shielding film Joint failure and can not The problem of interference charge is exported rapidly, therefore ensure that the integrality of signal transmission.

The above is only the preferred embodiment of the utility model, it is noted that for the common skill of the art For art personnel, without deviating from the technical principle of the utility model, several improvement and replacement can also be made, these change It also should be regarded as the protection scope of the utility model into replacement.

Claims (9)

1. a kind of free ground film, which is characterized in that including be cascading the first conductor layer, conductive adhesive layer, second lead Body layer, third conductor layer and adhesive film, second conductor layer be equipped with through its upper and lower surface first through hole, described first Through hole is equipped with protrusion；The protrusion is flow under fusion temperature by the side of the first through hole another by the conductive adhesive layer Instantaneous cooling is formed behind side；The third conductor layer covers the protrusion, thus outer surface and institute in the third conductor layer It states the corresponding position of protrusion and forms lug boss, the lug boss protrudes into the adhesive film；

When the free ground film is used for the ground connection of printed wiring board, electromagnetic shielding film, institute are equipped in the printed wiring board Stating electromagnetic shielding film includes the shielded layer and insulating layer being stacked, and the free ground film passes through the adhesive film and the electricity Magnetic shield film mutually presses, and the lug boss pierces through the adhesive film and the insulating layer and is electrically connected with the shielded layer.

2. free ground film as described in claim 1, which is characterized in that the surface of the lug boss is equipped with the conductor of convex Grain.

3. free ground film as claimed in claim 2, which is characterized in that the height of the conductive particles is 20 μm -100 μm.

4. free ground film as described in claim 1, which is characterized in that the adhesive film includes sticking together containing conducting particles Layer；Or the adhesive film includes the adhesion layer without conducting particles.

5. free ground film according to any one of claims 1-4, which is characterized in that first conductor layer, the second conductor Layer and third conductor layer respectively include in metal conductor layer, carbon nanotube conductor layer, ferrite conductor layer and graphene conductor layer It is one or more.

6. free ground film according to any one of claims 1-4, which is characterized in that first conductor layer every square centimeter In the first through hole number be 5-10⁶It is a；And/or the cross-sectional area of the first through hole is 0.01 μm²-1mm²。

7. free ground film according to any one of claims 1-4, which is characterized in that the free ground film further includes oxygen Change layer, the antioxidation coating is set in the one side of first conductor layer far from the conductive adhesive layer.

8. free ground film according to any one of claims 1-4, which is characterized in that the free ground film further includes peelable From protective film layer, the peelable protective film layer is set in one side of the adhesive film far from the third conductor layer.

9. a kind of wiring board, which is characterized in that including any one of printed wiring board, electromagnetic shielding film and claim 1-8 institute The free ground film stated, the electromagnetic shielding film are set in the printed wiring board, and the electromagnetic shielding film includes being stacked Shielded layer and insulating layer, the free ground film mutually pressed with the electromagnetic shielding film by the adhesive film, the protrusion It pierces through the adhesive film and the insulating layer and is electrically connected with the shielded layer in portion.