CN1191623A

CN1191623A - Method and apparatus for surface-mountable device for protection against electrostatic damage to electronic components

Info

Publication number: CN1191623A
Application number: CN96195759A
Authority: CN
Inventors: 安德鲁J·纽哈尔芬
Original assignee: Littelfuse Inc
Current assignee: Littelfuse Inc
Priority date: 1995-06-07
Filing date: 1996-06-06
Publication date: 1998-08-26
Also published as: ATE193149T1; MX9709973A; AU6597296A; CA2223746A1; WO1996041356A2; JPH11507766A; DE69608440T2; WO1996041356A3; EP0834180A2; DE69608440D1; EP0834180B1

Abstract

The thin film, circuit device is a subminiature overvoltage protection device in a surface mountable configuration for use in printed circuit board or thick film hybrid circuit technology. The surface mountable device (SMD) is designed to protect against electrostatic discharge (ESD) damage to electronic components. The circuit protection device comprises three material subassemblies. The first subassembly generally includes a substrate carrier, electrodes, and terminal pads for connecting the protection device (60) to a PC board. The second subassembly includes a voltage variable polymer material with non-linear characteristics, and the third subassembly includes a cover coat for protecting the circuit protection device.

Description

The protection electronic unit is avoided the surface-mountable device method and apparatus of electrostatic damage

The present invention relates generally to be used to the surface-mount devices (SMD) of protecting electric circuit to use.More particularly, the present invention relates to be used for the static discharge in the electric circuit is carried out the surface-mount devices of protection.

The application of printed circuit (PC) plate in all kinds of Electrical and Electronic equipment is more and more many.The electric circuit that forms on these PC plates, for example large scale integrated circuit and conventional electric circuit need be carried out protection to overvoltage.This kind protection is provided by the known physics static discharge device that is installed on the PC plate usually.

The example of this kind equipment comprises silicon diode and metal oxide variable resistor (MOV) device.Yet these devices have some problems.At first, well-known, exist and the connected many problem of aging of this class device.The second, also be well-known, this class device can experience the catastopic fault.The 3rd, may burn out or lose efficacy under this class device short-circuit condition.Also can there be many other shortcomings in the time of in using these productions that are installed on the PC plate.

The material that has been found that some type in the past can provide protection to the pulse of the speed of the piece in electronic circuit instantaneous overvoltage.These materials comprise those at least at U.S. Patent number 4,097, that class material in 834,4,726,991,4,977,357 and 5,262,754.Yet, in microelectronic circuit, comprise and when using these materials effectively, used time and expense are considerable.The present invention can relax and address these and other problems.

The present invention is a film static discharge surface-mount devices (ESD/SMD), and it comprises three material subassemblies.First subassembly comprises substrate carrier.

First or the substrate carrier subassembly comprise at the bottom of the carrier with two electrodes on its end face that these two electrodes are separated by a control width gap, this subassembly also comprises the side that is positioned at the bottom of the carrier and the takeup type dististyle on the bottom surface.Second subassembly or apply with the voltage variable polymeric material and to be added between two electrodes and to cover effectively on the interelectrode gap.The 3rd subassembly or cover layer be positioned at polymeric material and first or substrate subassembly end face on electrode on.The protective layer that the 3rd subassembly provides one deck to be used to the part of the dististyle that covers second subassembly and electrode and be connected to electrode so that as below will provide the protection of impact, oxidation and other influence with describing.

The 3rd subassembly or protective layer are preferably made by polymeric material, for example polyurethane or Merlon.In addition, highly preferred rest substrate is FR-4 epoxy resin or polyimides.

Another aspect of the present invention is the film surface mounting structure of ESD/SMD.Specifically, this device comprises the electrode of being made by conducting metal.First conducting metal is best, but not uniquely, is selected from the element set of the alloy that comprises copper, silver, nickel, titanium, aluminium or these metals.A kind of preferable alloy that the ESD/SMD electrode is used is a copper.

First conducting metal or electrode can multiple shape be deposited on first subassembly.Photoetching, mechanical can be used for forming the electrode of very little intricate profile with laser processing technology, and forms suitable gap width.This ability is added the very thin films cover layer that forms with electrochemistry and physical vapor deposition (PVD) technology and is made gap and protective circuit between these microminiature protective devices 60 energy control electrodes avoid the superpotential influence of quite big level.

The position of electrode on ESD/SMD substrate end face allow people with laser processing as a kind of high accuracy secondary operation, thereby with gap width thereby also will install rated value and finely tune.

To make further feature of the present invention and advantage more obvious by doing below in conjunction with accompanying drawing to describe.

Fig. 1 is the perspective view that is used to make according to the copper facing FR-4 epoxy resin board of microminiature ESD/SMD of the present invention;

Fig. 2 is that the part of plate among Fig. 1 is along 2-2 profile that line is got among Fig. 1;

Fig. 3 is the perspective view of FR-4 epoxy resin board among Fig. 1, has wherein removed its copper plate, and to mill out width in the different quadrants of this plate be that W1 and length are a plurality of notches of L;

Fig. 4 is the amplification profile perspective view of the plate part that mills out among Fig. 3, but copper plate plates again.

Fig. 5 is the birds-eye perspective of the several sections after the light tight material pattern mask of usefulness ultraviolet ray (UV) on the smooth surface that makes progress of copper facing plate hides again among Fig. 4;

Fig. 6 is the perspective view of Fig. 5 reverse side.But in Fig. 5, remove the band-like portions of copper plate again on the copper facing plate;

Fig. 7 be among Fig. 6 with the perspective view of 26 end faces 57, be used to show the linearity region 40 of marking by dotted line;

Band 26 among Fig. 8 is to immerse the nickel plating pond again after immersing the copper facing pond, the result on basic copper layer dististyle part deposit additional copper layer and nickel dam;

Fig. 9 is the band among Fig. 8 forms another layer again on the copper and mickel layer at dististyle after immersing the plumbous pond of tin a perspective view;

Band in Figure 10 displayed map 9, elaboration will form the zone of variable voltage polymer belt;

Figure 11 shows the band among Figure 10, but existing polymeric material 43 is inserted with in 26 the gap 25;

Figure 12 shows the band among Figure 11, but existing cover layer 56 is covered on electrode 21 and the polymeric material 43;

Figure 13 show make at last according to single ESD/SMD of the present invention, it has passed through so-called cutting operation, along parallel surface band is cut into single assembly with diamond saw in this operation;

Figure 14 is a front view that is used for finishing the wire printer of ESD/SMD manufacture process template print steps.

Though the present invention can have many different embodiment that form, and show in the drawings and be described in detail herein, but should know that the disclosure of the preferred embodiment of the present invention only is considered to the example of the principle of the invention, is not used as a kind of restriction in the embodiment that perspective of the present invention is confined to be set forth.

Figure 13 shows a preferred embodiment of the present invention.This thin film circuit device is an interior microminiature overvoltage protection of surface installation structure that is used for printed circuit board or thick film hybrid technology.A name of this device is called static discharge surface-mount devices (ESD/SMD).The design of this surface-mount devices (SMD) is used for protecting electronic unit to avoid the Electrostatic Discharge damage.The layout of this ESD/SMD device and structure allow with many size manufacturings.A standard industry size of surface-mount devices generally is that 125mil is long and 60mil is wide.This size can be used for the present invention, and is called " 1206 " size device for simplifying purpose.Yet should understand on all other standard sizes that the present invention can be used for surface-mount devices, as 1210,0805,0603 and 0402 device also can be used for off-standard size.Protective device design of the present invention is used for replacing being generally used for the silicon diode and the MOV technology of underpower protection purposes.

Protective device generally comprises three material subassemblies.To see that below first subassembly generally comprises a substrate carrier or substrate 13, electrode 21 and be used for protective device 60 is connected to

dististyle

34,36 on the PC plate.Second subassembly comprises with voltage variable polymeric material 43, and the 3rd subassembly comprises cover layer 56.

First or the substrate carrier subassembly comprise at the bottom of the carrier 13, two electrodes 21 are arranged on its upper surface, these two electrodes are separated by the gap 25 of a control width W 2, there is

takeup type dististyle

34,36 end face 57 of first subassembly 13, bottom surface 58 and side 59.Second subassembly or variable voltage polymeric material 43 are between these two electrodes 21 and effectively on gap 25.Cover layer 56 is positioned on the electrode 21 of end face 57 of polymeric material 43 and substrate subassembly, and partly covers the end face 57 of dististyle 34,36.Impact when the 3rd subassembly is used to protect assembly to avoid assembling automatically, and the protection assembly is in use avoided oxidation and other influence.

More particularly, first or the substrate subassembly comprise at the bottom of the carrier of making by semi-rigid epoxide resin material 13.This material have with printed board industry in the similar identical physical property of used standard substrate material, therefore very the heat and the mechanical performance of coupling are provided between device and plate.

First subassembly also comprises two metal electrodes, and they are the parts as one deck pantostrat or film dististyle 34,36.To see that below

dististyle

34,36 is made up of multilayer, comprises the basic copper layer 44 that also is used to form electrode 21, auxiliary copper layer 46, nickel dam 48 and be used to form the tin lead layer 52 of

dististyle

34,36 remainders.In another embodiment, auxiliary copper layer 46 also is the second bronze medal layer (not shown) of forming electrode 21, thereby increases the thickness of electrode 21.The basic copper layer of dististyle and electrode form with the deposit simultaneously of one of laxative remedy simultaneously: the processing of (1) electrochemistry, as the plating described in the following embodiment; Or (2) physical vapor deposition (PVD).This while deposition process guarantees to guarantee at

dististyle

34,36 when over-voltage condition occurring, has a good conductive passage between the electrode 21 and second subassembly 43.This deposition process also is convenient to make processing, can very accurately control each layer thickness that comprises electrode 21.After putting basic copper layer 44 to substrate or chip 13 at first, as described above with conducting metal

extra play

46,48 and 52 deposited adding on the dististyle.These extra plays can add on these dististyles with photoetching and deposition technology respectively.

These two metal electrodes, no matter be that one deck or bilayer (or multilayer) are thick, all the gap by control width W 2 is separated.This substrate subassembly also comprises and supports two

dististyles

34,36 that protective device is used, on end face 57, bottom surface 58 and side 59.These bottom surfaces 58 of

dististyle

34,36 and/or side 59 be used for being fixed to device on the plate and provide one from plate the electric path to electrode 21.Also have, electrode 21 and dististyle comprise that one deck is stacked in the copper sheet 44 above the backing material 13.Other each layer or form with electrochemical process or with physical vapor deposition method (PVD) deposit simultaneously is to guarantee existing a good continuous conduction passage between the

dististyle

34,36 on electrode on the substrate end face and substrate 13 bottom surfaces.This structure is convenient to the production process of mounted on surface mounting technology, makes dististyle have the takeup type structure.The gap width W2 that electrode is 21 forms by photoetching technique and etching process, and photoetching process is characterised in that and can carries out point-device control for the width W 2 of spaced-apart electrodes metallide.Stretch at substrate 13 end face upper edge straight lines in the gap 25 that is used for spaced-apart electrodes 21.The suitable dimension in gap and structure provide suitable trigger voltage and clamping voltage, and quick response and reliable operation are provided under over-voltage condition simultaneously.The electrode metal compound can be selected from different element materials or alloy material, i.e. Cu, Ag, Ni, Ti, Al, NiCr, Tin or the like are to obtain cover layer with required physics, electricity and metallographic performance.

Photoetching, machinery or laser processing technology be used to form the physical size and the width of gap 25 and dististyle 34,36.Photoetching subsequently and deposition run are used for the additional metal compounds of specific thicknesses is deposited to dististyle (being CU, Ni and Sn/Pb).

Provide protection with voltage variable polymeric material 43 for quick transient overvoltage pulse.Polymeric material 43 provides a non-linear electroresponse for overvoltage.Polymer 43 is a kind of materials, and it comprises the tiny separating particles that is dispersed in organic resin or the dielectric.Polymeric material 43 is by homodisperse conductive particle in insulating binder.The nonlinear resistance property that this polymeric material 43 is had is decided by the electric property of grain spacing and adhesive.This polymeric material can be taken pride in multi-source and be obtained, and obtains open in the above in the different patents of mentioning.

Cover layer 56 subassemblies are being determined through metal deposit, figure and are being added to after the painting process on polymer 43 on the end face of substrate/polymer subassembly, are being used to protect the device of polymeric material 43 and are provided at the flat top surface that adopts simple and easy mounting process to use on the automatic assembly equipment to provide one.This cover layer 56 prevents the over oxidation of electrode 21 and polymer 43, reduces protective device 60 superior functions.Cover layer 56 can be made up of different materials, comprising plastics, and conformal coating, polymer and epoxy resin.Cover layer 56 also is used as the mark chromatophore of protective device 60, or makes marks on the surface of each layer and cover layer 56 by printing ink transmission operation or laser labelling operation.

This protective device 60 can be made with following operation.Shown in Fig. 1 and Fig. 2 is a FR-4 epoxy resin solid slab 10 that is covered with copper facing plate 12.The copper facing plate 12 and the FR-4 epoxy resin chip 13 of this solid slab 10 are high-visible in Fig. 2.This copper facing FR-4 epoxy resin board 10 can have been bought in Signal Laminate Systems company from the Allied of the Hoosick Falls of New York, and its production number is 0200BED 130C1/C1 GFN0200C1/C1A2C.Though FR-4 epoxy resin is preferred material, any other material of performance that other can similarly be used to make the material of PC plate with its chemistry, physics and the structural behaviour of the above all is a suitable material.Therefore another kind of suitable material for these solid slab 10 usefulness is a polyimides.FR-4 epoxy resin and polyimides are two kinds of materials in similar identical that class material of used standard substrate material property in its physical property and the industry of PC plate.Consequently protective device 60 and the PC plate that protective device 60 is fixed thereon have mate extraordinary thermal technology and mechanical performance.The substrate of protective device 60 of the present invention also provides required electric arc tracking characteristics, meanwhile has enough mechanical flexibility, be subjected to relevant with overvoltage be kept perfectly when releasing energy rapidly harmless.

Next step is with conventional etching process copper facing plate 12 to be carried out etching on solid slab 10 in making the protective device process.In this conventional etching process, use ferric chloride solution with copper etching on substrate.

Though be appreciated that after this step finishes, the copper layer 12 of all Fig. 2 is the FR-4 epoxy resin etching in the heart of solid slab 10 since then all, but the epoxy resin heart 13 that is left on this FR-4 epoxy resin board 10 is not identical with " totally " FR-4 epoxy resin board of not crossing with the copper plate initial treatment.Specifically, after 12 corruption of copper layer being gone, stayed one deck chemical etching treated side on the epoxy resin heart 13 surfaces by etching.The easier acceptance of this treated side of the epoxy resin heart 13 processing operation subsequently.And these processing operate in the manufacture process of mounted on surface microminiature protective device 60 of the present invention is essential.

As shown in Figure 3, the FR-4 epoxy resin board 10 with no copper face of this processing then mills out or goes out groove 14 in four quadrants of plate 10.Four quadrants are separated significantly by dotted line among Fig. 3.The width W 1 of groove 14 (Fig. 4) is about 0.0625 inch.The length L of every groove (Fig. 3) of groove 14 is about 5.125.When finish mill or dash processing after, in the plate 10 (Fig. 3) that milled or broke through plated with copper again.Etching and the plate (Fig. 3) that milled are immersed in the copper facing pond of not having electricity and copper can be plated.This copper electroplating method is well-known technology.

The result of this copper facing step has plated the uniform copper layer of last layer thickness on the exposed surface of plate 10.For example, as shown in Figure 4, as copper coating 18 the flat upper surfaces 22 of the achievement of this step with (1) plate 10; (2) vertical calking district 16 boths that are used to form at least a portion groove 14 are covered.These calking districts 16 necessary copper facing are because they finally will form the

dististyle

34,36 of last protective device 60.The uniform thickness of copper coating is decided by user's final demand.

After finishing copper facing, for realizing the plated copper structure of Fig. 4, the whole exposed surface of this structure all uses so-called light resist polymer to apply.

After copper facing plate 20 was again used up thing against corrosion and applied, the part of this clean mask of mask that other parts of its top placement are clean was at interval a pattern line equably on whole.These pattern lines are made by the light tight material of UV, and its size and dimension is corresponding to the size and dimension of figure shown in Fig. 5 30.Main is, be put in again this mask on the copper facing plate 20 with these lines after, the flat several portions towards last surface 22 of copper facing plate 20 can mask the UV luminous effect effectively again.

The shape and size of can find out 30 figure major decision from following discussion electrode 21 and polymer belt 43.Next step forms the remainder of dististyle 34,36.Can know, can change width, length and the shape of electrode 21 and polymer belt 43 by the size and dimension that changes the light tight bargraphs of UV.Specifically, one embodiment of the invention need not shown in acute angle 19 and with arc chord angle 19 (not shown).In fact found out and preferably made angle 19 become circular arc.

Therefore, in this step, form the gap 25 of 21 at electrode and the breach 23 in the electrode 21.As mentioned above, photoetching, machinery can be used for forming the very little staggered and complicated electrode 21 and the geometric figure in gap 25 with laser processing technology.Can change electrode 21 structures easily, to obtain the specific electrical characteristic of final protective device 60.Can change gap width, so that control is carried out in triggering under the overload situations and clamping voltage.The apparatus structure that is indicated can obtain being similar to the triggering and the clamping voltage rated value of the device with first pre-structure.Used crest voltage to be 2KV, the ESD waveform of 4KV and 8KV carried out test.The gap width of 2mil and 4mil can obtain the trigger voltage of 100-150V and the clamping voltage of 30-50V.

Be coated in the back side of copper facing plate 20 in this step again with one deck light erosion resistant, and after it applies with the light erosion resistant, put the clean mask of lastblock other parts.The rectangle lines are parts of this clean mask.These rectangle lines are made by the light tight material of UV.Its size is corresponding to the size of lines shown in Fig. 6 28.Mainly this mask with these lines is positioned over again on the copper facing plate 20, this plays the effect of effective shielding UV light in flat downward surface 28 of copper facing plate 20 again.

Rectangle lines

major decision dististyle

34 and 36 width and with the shape and size of the lower end mid portion 28 of 26 bottoms 58.Therefore determined by light mask against corrosion with the copper facing part of 26 bottom surfaces 58.Specifically, with the copper plate of the lower end mid portion 28 of 26 bottom surfaces 58 by eating away.Fig. 6 shows this copper facing plate 20 these a part of perspective views again.

The copper-plated again plate 20 that covers with photoresist of monoblock, i.e. the end face 57 of this plate 20, the UV rayed is then used in bottom surface 58 and side 59.Answer long enough with the UV rayed time of copper facing plate 20 again, to guarantee not to be subjected to the square sheet of mask and all sclerosis fully of photoresist of rectangle lines covering.The mask that after this will cover these side's sheets and rectangle lines is from taking off on the copper facing plate again.Before be positioned at the not sclerosis of photoresist of these side's sheets and bar below.This photoresist that had not hardened can be with solution flush away on copper facing plate 20 again.

Again the sclerosis photoresist on copper facing plate 20 remainders provides protective effect at the next step of processing.Specifically, hard photochemical resist does not allow the copper below it be removed.Before be positioned at the then not sclerosis of area light resist under the pattern line, therefore also not protection.Therefore these regional copper can be by etching away.This etching process uses a kind of ferric chloride solution to finish.

After copper is removed, can find out that the zone that before has been positioned at below mask graph lines and the rectangle lines does not cover fully from Fig. 5 and 6.And these zones comprise the

zone

28 and 30 of clean epoxy resin now.

Again the copper facing plate 20, put into chemical bath then, remove all residue sclerosis photoresists in the previous hardening region with this plate 20 certainly.

Consider from the purpose of this specification, being called between two adjacent notches 14 on sheet material 20 parts is with 26.Length according to dimension D (as shown in Figure 4) device for limiting of this band.After these operations described in finishing this specification, be with 26 to cut into a plurality of sticks this, each stick in these little sticks just becomes an ESD/SMD according to the invention or protective device 60.

Can find out that also the zone along periphery of the downside 58 with 26 still comprises the copper facing part from Fig. 6.These neighboring areas 34 of downside 58 with 26 and 36 form a dististyle part.These dististyles are finally as the device that the whole protective device of making 60 is fixed on the PC plate.

Fig. 7 overlooks the perspective view of top side 57 from Fig. 6 with 26 tops.With the usually corresponding intersection of these below mid portions 28 with 26 be the zone 40 of marking at end face 38 upper edge straight lines.These direct zones 40 are to be delimited by the dotted line among Fig. 7.

The next step of manufacture process of the present invention is discussed referring now to Fig. 7.In this next step, along each zone coating light resist polymer with the linearity region 40 of 26 top sides 57.After applying these linearity regions, also will resist the photetching polymer along the gap 25 and electrode 21 coatings.These electrodes 21 are made by conducting metal (using copper herein).Use this photoresist of UV optical processing then, the result is hardened photoresist in linearity region 40.

As the result that this photoresist hardens on linearity region 40, when immersing the electrolytic cell preparation plating that comprises metal with 26, metal can not be built-up on this linearity region 40.

In addition, as explained above, when being with 26 to immerse in the metallide ponds, can not plate metal with the mid portion 28 of 26 downsides 58 yet.The previous copper metal that covers this metal part comes out the naked epoxy resin that is used to form plate 20 bottoms by eating away.Metal can not attach or be plating on this naked epoxy resin in the metallide process.

Entire belt 26 is immersed the electrolytic copper plating pond, and then immerse the electrolytic ni plating pond.Its result can find out in Fig. 8 that copper layer 46 and nickel dam 48 are deposited on the basic copper layer 44.After these copper layers 46 and nickel dam 48 deposits, by the additional tin lead layer 52 of the plumbous pond of electrolytic tin deposit one deck on same area, as shown in Figure 9.Remove the sclerosis light resist polymer on the linearity region 40 then.

As shown in Figure 10 and 11, apply again and add polymeric material 43.Available multiple mode is applied addition polymerization compound 43.For example, wire printer shown in available Figure 14 applies addition polymerization compound 43 in the mode that is similar to the template printing that will be further described below.In addition, available hand formula mode coats with the pipe of polymer 43.Also can use automation coated polymeric 43.In case coat polymer 43 and attached in 41 the zone 42, zone the time, plate 20 promptly by thermmohardening so that polymer 43 is solidified, obtain its outer appearnce be similar among Figure 11 with 26 be with 26.

The next step of making protective device 60 is to add layer protective layer 56 (Figure 12) applying on the most length of 26 end faces 57.This protective layer 56 is the 3rd subassemblies of protective device 60 of the present invention, and forms sealant comparatively closely on electrode 21 and polymer belt 43 zones.Thus, protective layer 56 provides the protection that avoids oxidation and protects when installing on the PC plate it to avoid impacting.This protective layer also can lay by absorption at use vacuum suction instrument it is contained on the surface.

This protective layer 56 helps to be controlled at fusing, ionization and the starting the arc phenomenon that occurs in the circuit fusing portion 42 under the current overload situation.Protective layer 56 or covering layer material have required blow-out characteristic, and this is even more important when fusing in circuit fusing portion.

Apply and in a procedure of processing, to use simple anchor clamps to form the apparatus main body shape when adding cover layer 56.With current method relatively, the advantage of this manufacture method is can guard electrode 21, gap 25 and polymer 43 are avoided physics and damage environment.As it is identical to adopt die pressing or mould to annotate method, and when adopting the conformal method to apply to add the operation of cover layer 56, the physical location of electrode gap 25 does not have the danger that suffers damage.Before deposited adding, the conformal covering can be mixed with dyestuff, form the protective device 60 that a kind of color code is represented voltage rating.

When using stencil printing covering being applied add process, the polymer that preferably adds polyurethane adhesive or cream is made protective layer 56, and when using the deposited enrobe of injection molding the most handy Merlon adhesive.It is to be made by Dymax that a kind of optimization polyurethane is arranged.Add process according to different coverings is deposited, other similar glue, cream and adhesive are also applicable to the present invention.Except that polymer, protective layer 56 also can be made up of plastics, conformal coating and epoxy resin.

Be added to when being with on 26, comprise the use of common wire printer shown in Figure 14 in that the using stencil typography is applied protective layer 56.Found that other is used for applying the process that adds cover layer 56 faster than some in the template printing, for example uses injection molded process.Specifically, found to use the quantum of output of the template printing process of wire printer to be the twice of injection molding.This wire printer is by the A ffiliated Manufacturers of New Jersey, Inc.of Northbranch manufacturing, and production number is CP-885.

Add at the template printing process, simultaneously material is applied that all are with on 26 in the quadrant adding to plate 20.Cladding material directly is exposed under the UV irradiation in the using stencil printing process owing to make, so hardened material speed is more faster than injection molding, and UV light must pass through filter in injection molding.In addition, the template printing process is more more even than adopting injection molding aspect the height of cover layer 56 and width.Because its uniformity, its meltability can test and encapsulate in the relatively fast automation process.In injection molding,, may be difficult in test and encapsulation accurately with protective device 60 centerings because cover layer 56 is slightly inhomogeneous on height and width.

This wire printer comprises cover 78 at the bottom of 74, one squeegee rollers 76 of 72, one extrusion arms of 70, one bases of a slide plate and.End cover 78 is contained on the base 72, and movable squeegee roller 76 is contained on the extrusion arm of base 72 and 78 tops, chassis.Plate 70 can cover 78 slip underneath at the base 72 and the end.End cover 78 has row's parallel open 80, and its width is corresponding to the width of cover layer 56.

When the template printing process begins, an adhesive tape is attached to below the plate 20.The plate 20 that posts adhesive tape is put on the plate 70, and this adhesive tape is placed between plate 70 and the fuse 20.Cover layer 56 materials are added to an end of end cover 78 with irrigator.Be pushed into plate 70 below the end cover 78 and below end cover 78, plate 20 alignd with parallel open 80 centerings.Then fall squeegee roller 76, contact end cover 78 makes it cover on the end and covers 78 tops but do not touch cladding material.Then begin mobile squeegee roller 76 and slip over end cover 78 with opening 80, thus with layer of cover material 56 from opening 80 extrusion coated on plate 20 with 26 in every tape on.Therefore, the existing coated electrode 21 of this cover layer, gap 25 and polymer belt 43 (Figure 12 and 13).Then squeegee roller 76 is lifted, and plate 20 is taken out below end cover 78.Opening 80 in the end cover 78 has enough width so that protective layer partly covers dististyle 34,36, shown in Figure 12 and 13.In addition, should be in cream or glue scope as the viscosity of tectal material, thereby so that this material compress can be with the mobile upper surface 49 that form a general planar after on plate 20, but this material 56 can not flow in the notch 14 again.To put into the UV chamber with 26 plate 20 then and carry out the UV sclerosis.This polyurethane adhesive or cream have been solidified to form protective layer 56 (Figure 12 and 13) after sclerosis finishes.

Though see that from aesthetic view point colourless clean cover layer is pleasing, also available other alternative has a color cover layer.For example, available coloured, clean or transparent cover layer.Simply dyestuff is added clean covering layer material and can make these colored materials.Can use these colored materials as color code.In other words, tectal different colours can provide a kind of ready-made decision means to the user corresponding to different rated values, is used for judging the rated value of any given protective device 60.These two kinds tectal transparencies allow the user before assembling and in use by visual inspection polymer belt 43.

Be with 26 to prepare to accept so-called cutting operation then, be used for being with 26 to be divided into single fuse sheet these.In this cutting operation, use diamond saw or similar tool to be cut into single film surface along parallel plane 61 (Figure 12) fuse sheet 60 (Figure 13) is installed with 26.These otch are divided the breach in the electrode 21 23 equally.In this, the metallic compound that is more readily understood electrode 21 cuts away from breach 23 or relief area 23.Specifically, the not electroded relief area 23 of cutting will be more easier.In addition, in when cutting, may be along the hardening phenomenon of otch generation metallic compound, thus make metal fillings (part of electrode) fall into interstitial area, and reduce gap effective width W2.This way that breach 23 is placed on the position of cutting can be alleviated problem and other problem that may occur that may occur thus.Should be noted that breach 23 can be further stretches to the direction of

dististyle

34,36, and can do the angle 19 of breach 23 in the arc-shaped in another embodiment.

Just finished the manufacture process of film protective device 60 of the present invention (Figure 13) through this cutting operation.

All above characteristics combination get up to form a kind of ESD/SMD device assembly, and geometric figure and the composition of polymer 43 of this assembly by regulating electrode and gap just can provide better control to triggering and clamping voltage characteristic.To the size Control of deposit and photoetching process, uniform triggering and clamping voltage are provided together with the suitable selection of electrode and polymer 43 materials.Yet be appreciated that and under the situation that does not deviate from essence of the present invention or central feature, implement the present invention by also available other concrete form.Therefore can think that these examples and embodiment are descriptive rather than restrictive in every respect, the present invention also is not limited to the details that goes out given herein.

Claims

1. film-type mounted on surface circuit protection device, comprising:

A substrate carrier;

The a pair of electrode that is positioned on the substrate surface, these electrodes are made by first conducting metal, and are separated by a gap; And

A kind of be positioned in the gap interelectrode with the voltage variable polymeric material.

2. the mounted on surface protective device of claim 1, wherein said first conducting metal is selected from and comprises copper, silver, nickel, titanium, aluminium or their alloy are in interior element set.

3. the mounted on surface protective device of claim 1 further comprises a pair of dististyle that is connected to the PC plate that is suitable for, and first conductive metal layer of electrode forms the part of dististyle.

4. the mounted on surface protective device of claim 3, wherein first conductive metal layer of electrode and a dististyle part are the continuous layers of one deck.

5. the mounted on surface protective device of claim 1, wherein these electrodes traverse on the width of circuit protection device basically.

6. a film surface is installed circuit protection device, comprising:

First subassembly that comprises substrate, dististyle and electrode, these electrodes separate each other, form a gap; And

One comprises second subassembly with the voltage variable polymeric material that is deposited in the gap.

7. the mounted on surface protective device of claim 6 further comprises the 3rd subassembly that comprises layer protective layer, and this protective layer is covered in on voltage variable polymeric material and the electrode, avoids impacting and oxidation to protect them.

8. the mounted on surface protective device of claim 7, wherein said protective layer is made by polymeric material.

9. the mounted on surface protective device of claim 6, wherein said support substrates is made by FR-4 epoxy resin or polyimides.

10. the mounted on surface protective device of claim 7, wherein protective layer is transparent and colourless.

11. the mounted on surface protective device of claim 7, wherein protective layer is transparent in painted.

12. one kind is used to make the method that film surface is installed circuit protection device, comprising the step of while deposit pair of electrodes and a pair of dististyle on the substrate end face.

13. the method that proposes in the claim 12 further is included in the step that deposit and electrode on the side of substrate and the bottom surface have being electrically connected and be used for described mounted on surface protective device is connected to the dististyle of printed circuit board.

14. the method that proposes in the claim 12, wherein electrode and dististyle are with steaming the sedimentation deposit.

15. the method that proposes in the claim 12, wherein electrode electrochemical method deposit.

16. method that is used for protective film mounted on surface circuit protection device; this protective device have a pair of be positioned at the electrode that separates by the gap on the substrate end face and be deposited on the gap with the voltage variable polymeric material, described method comprises layer protective layer is laid in step on electrode, variable voltage polymer and the gap.