CN1960595B - Flexible circuit board with structure for shielding electromagnetic wave - Google Patents
Flexible circuit board with structure for shielding electromagnetic wave Download PDFInfo
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- CN1960595B CN1960595B CN2005100220318A CN200510022031A CN1960595B CN 1960595 B CN1960595 B CN 1960595B CN 2005100220318 A CN2005100220318 A CN 2005100220318A CN 200510022031 A CN200510022031 A CN 200510022031A CN 1960595 B CN1960595 B CN 1960595B
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- electromagnetic wave
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Abstract
The invention comprises: a basal body with a welding zone, on which circuits are formed; a masking film and a silver foil sequentially overlapped on the basal body; and a protection layer with high temperature resistant and heat rejection property used for separating the silver coil from the welding zone. The invention has either good electromagnetic wave shielding property, anti-flexing property, or has good heat resistant property so as to avoid the silver foil floating up and breaking off in process of attaching FPC to PCB.
Description
[technical field]
The present invention relates to a kind of flexible print circuit board, relate in particular to a kind of flexible circuit board with electromagnetic wave screening structure.
[background technology]
As everyone knows, various electronic equipments are being realized miniaturization and light-weighted while, to multifunction and high speed development.When work, can produce and launch the electromagnetic wave of different frequency and form cross interference.Therefore the effective measures of anti-electromagnetic wave interference are to shield to electronic equipment.This not only can prevent and control the interference of outside incident electromagnetic wave to the electronic equipment of working, and can also stop these equipment launching electromagnetic wave when work to remove to disturb the various electronic equipments of other running status effectively.In this case, the FPC (flexible circuit board) that is used for electronic equipment assembling also more and more requires to take the electromagnetic wave shielding measure.Electromagnetic wave shielding is mainly used to prevent the influence of high frequency magnetic field, thus effectively control electromagnetic wave from a certain zone to another regional radiation propagation.Adopt low-resistance conductor material that electromagnetic energy is had reflection and guiding function, produce electric current and the magnetic polarization opposite, thereby weaken the radiation effect of source electromagnetic field with the source electromagnetic field in conductor material inside.And utilize electromagnetic wave to produce reflection on shielded conductor surface and absorb and repeatedly reflect and play shielding action inner generation of conductor.Electromagnetic Interference belongs to noise jamming in fact, its unit of measurement is a decibel (dB), according to Schelkunoff electromagnetic shielding theory, screening effectiveness (SE) should be made up of absorption of electromagnetic wave loss value A, reflection loss value R and internal reflection loss value B three parts, and expression formula is as follows:
SE＝SEA+SER+SEB
In the formula, SE is an effectiveness, and A is attenuation by absorption; R is surperficial individual reflection decay; B is inner multiple attenuation (only just meaningful under the situation of A＜15dB).
The electromagnetic wave shielding performance is to estimate in the electric field of KEC method, and promptly testing wave frequency respectively is the screening effectiveness value of the product under 10MHz and the 1GHz.
At present, the method for the electromagnetic wave shielding of FPC has:
Copper Foil mode, such as U.S. Pat 6,768,052B2 realizes electromagnetic shielding method to the FPC product by hot pressing Copper Foil on product, and this method has shield effectiveness and bending performance preferably preferably, but thickness is big, need be through repeatedly hot pressing, and the cycle is long, the cost height.
The conductive coating mode, such as disclose in the patents such as JP2001207143, JP2000290616, JP4353575,2004-353575: evenly apply one deck conduction seal coat such as the silver-colored electromagnetic wave shielding of realizing the FPC product of starching by modes such as printings the surperficial of product.It is low that this method has a cost, the advantage that bending performance is good, but shield effectiveness is relatively poor, easily comes off, and needs technologies such as printing and curing, and the cycle is long;
Silver foil mode, such as Japan Patent 2000-269632,2003-095566, a kind of novel shielding material of TATSUTA company exploitation has excellent shield effectiveness and bending performance, and the number of times of pressing simultaneously is few, the cycle short, the production efficiency height.But since FPC all to pass through SMT (surface mount) element pasted on surface or and PCB welding etc. have the technology of high temperature, and owing to the outer field insulating barrier thermal endurance of silver foil problem carry out FPC and PCB be connected and assembling process such as SMT in will occur that silver foil floats or phenomenon such as come off.
[summary of the invention]
Main purpose of the present invention is exactly in order to solve prior art problems, a kind of flexible circuit board with electromagnetic wave screening structure is provided, existing good shield effectiveness and bending performance, simultaneously can be high temperature resistant, avoid carry out FPC and PCB be connected and assembling process such as SMT in occur that silver foil floats or bad phenomenon such as come off.
For achieving the above object, the invention discloses a kind of flexible circuit board with electromagnetic wave screening structure, be formed with the matrix of circuit above comprising, cover epiphragma and silver foil on the matrix successively, have on the described matrix and be used for crossing the weld zone that welding substance links together with extraneous conductor dbus, also comprise be used for silver foil and weld zone are separated, can be high temperature resistant and the protective layer of heat rejection; The longitudinal cross-section of described protective layer is shaped as " L " shape with horizontal edge and longitudinal edge, and described horizontal edge covers the silver foil upper surface, and described longitudinal edge covers the side of silver foil near the weld zone; The thickness of described protective layer is more than or equal to 27.5 μ m
The invention has the beneficial effects as follows: silver foil forms with wiring board and is electrically connected the electromagnetic wave shielding of realizing product; and silver foil has good bending performance; protective layer covers the part of silver foil near the weld zone by hot pressing; silver foil and weld zone are separated; because protective layer material has excellent heat resisting and excellent heat rejection performance; wait in the high temperature assembling process the protection of silver foil thereby be implemented in welding, obtain excellent electromagnetic wave shielding and bending performance simultaneously.
Feature of the present invention and advantage will be elaborated in conjunction with the accompanying drawings by embodiment.
[description of drawings]
Fig. 1 is the structural representation of a kind of embodiment of the present invention;
Fig. 2 is the position and the size schematic diagram of protective layer.
[embodiment]
As shown in Figure 1, 2, be formed with the matrix 1 of circuit above flexible circuit board comprises, cover epiphragma 2 on the matrix 1 and silver foil 3, protective layer 4 successively, matrix 1 is generally the copper-clad plate that etching has circuit; Epiphragma 2 covers on the matrix 1, and matrix 1 is play a part and external insulation and protection, can be made up of the polyimide film that has adhesive, and thickness is 20～50 μ m; Silver foil 3 covers on the epiphragma 2, form by the silver layer 31 with electromagnetic wave shielding function, anisotropy conductiving glue 32, diaphragm (PPS or resin) 33 3 parts, the thickness of silver foil 2 is: 20 μ m～40 μ m, epiphragma 2 has hole 5 on the earth connection of copper-clad plate, the conducting resinl 32 of silver foil 3 is connected silver layer 31 by this hole with earth connection on the matrix 1, realization is to the electromagnetic wave shielding of product; Have weld zone 6 on the matrix 1, do not have epiphragma 2 and silver foil 3 above the weld zone 6, be used for crossing welding substance (such as scolding tin) and link together, play circuit conducting effect with extraneous conductor dbus; Protective layer 4 is positioned at the part of silver foil 3 near weld zone 6, is used for silver foil 3 and weld zone 6 are separated, and is made up of the material of the heat rejection performance with excellent heat resisting and excellence, such as polyimides.In order not only to save cost but also can to have good effect of heat insulation; protective layer is designed to its longitudinal cross-section and is shaped as " L " shape with horizontal edge and longitudinal edge; horizontal edge is meant the protective layer part that covers silver foil upper surface (one side of the epiphragma of promptly getting along well contact), and longitudinal edge is meant and covers the lateral parts of silver foil near the weld zone.As shown in Figure 2, the width a＞=0.3mm of horizontal edge in the time of a＜0.3mm, because the subsides of polyimide film are inclined to one side, will cause silver foil exposed in the course of processing, and silver foil will come off and melt when high-temperature operation, causes the function of shielding reduction.The width b of longitudinal edge is 2～20mm, and 2～8mm is better, and is when b＜2mm, because product is narrow, relatively more difficult in processing and assembling process; When b＞20mm, will increase cost on the one hand, protective layer is distinguished the bending that will influence product between bending and is waited other functions on the other hand.C is the thickness of protective layer, and its scope is: 27.5 μ m or more than, generally speaking the high more heat-proof quality of the thickness of protective layer is good more, but protective layer will increase the thickness of entire product, so the thickness of protective layer can not surpass the requirement of product specification book.
With the heat resistance of object lesson explanation diaphragm various sizes, the sample of getting equal number carries out the processing and the test of following five kinds of situations respectively below.
Sample one, under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, (model is platform rainbow FD0515HL with protective layer under hot pressing condition subsequently, thickness is 27.5 μ m) be hot-pressed onto on the silver foil, protective layer is of a size of: a=0.4mm, b=4mm; After the punch forming, product is carried out heat-resisting test and bending test and shield effectiveness test;
Sample two, under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, (model is platform rainbow FD0515HL with protective layer under hot pressing condition subsequently, thickness is 27.5 μ m) be hot-pressed onto on the silver foil, protective layer is of a size of: a=0.3mm, b=1.5mm; After the punch forming, product is carried out heat-resisting test;
Sample three, under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, (model is a platform rainbow FD0515HL thickness with protective layer under hot pressing condition subsequently, be 27.5 μ m) be hot-pressed onto on the silver foil, protective layer is of a size of: a=0.2mm, b=1.8mm; After the punch forming, product is carried out heat-resisting test;
Sample four, under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, (model is a platform rainbow FD0515HL thickness with the PI protective layer under hot pressing condition subsequently, be 27.5 μ m) be hot-pressed onto on the silver foil, protective layer is of a size of: a=0.2mm, b=10mm; After the punch forming, product is carried out heat-resisting test and bending test;
Sample five, under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, (model is a platform rainbow FD0515HL thickness with the PI protective layer under hot pressing condition subsequently, be 27.5 μ m) be hot-pressed onto on the silver foil, protective layer is of a size of: a=0.4mm, b=20mm; After the punch forming, product is carried out heat-resisting test.
The test result of above-mentioned five samples is as shown in table 1.
Table 1
| Project | Sample one | Sample two | Sample three | Sample four | Sample five |
| Come off/number of melted product | No | 13 | 24 | 5 | No |
As shown in Table 1, the test result of sample one and sample five is best, and the width a of visible protective layer horizontal edge is a very crucial value.
Sample one and sample five are contrasted with the FPC comparative example made from existing operation and method again.
Comparative example one: under hot pressing condition, Copper Foil (model is platform rainbow XIR050513HJY) is hot-pressed onto on the epiphragma of FPC product, under hot pressing condition, epiphragma (model is platform rainbow FD0515HL) is hot-pressed onto on the Copper Foil subsequently, after the punch forming, product is advanced the test of thermal endurance test, bending test and screening effectiveness;
Comparative example two: by silk screen printing with silver slurry (model be gold century DE-427SS silver slurry thickness for) be printed onto on the epiphragma of FPC product, solidify the back punch forming after, the test of product being advanced thermal endurance test, bending test and screening effectiveness;
Comparative example three: under hot pressing condition, silver foil (model is TATSUTA PC1000) is hot-pressed onto on the epiphragma of FPC product, after the punch forming, product is advanced the test of thermal endurance test, bending test and screening effectiveness.
The test result of sample one and sample five and three comparative examples is as shown in table 2.
Table 2
As shown in Table 2, flexible circuit board of the present invention is compared with existing flexible circuit board, not only have excellent electromagnetic wave shielding and bending performance, and thermal endurance is fine, thereby avoided FPC be connected with PCB and assembling process such as SMT in occur that silver foil floats or bad phenomenon such as come off, reduced cost.
Claims (4)
1. flexible circuit board with electromagnetic wave screening structure, be formed with the matrix of circuit above comprising, cover epiphragma and silver foil on the matrix successively, have on the described matrix and be used for crossing the weld zone that welding substance links together, it is characterized in that with extraneous conductor dbus: also comprise be used for silver foil and weld zone are separated, can be high temperature resistant and the protective layer of heat rejection; The longitudinal cross-section of described protective layer is shaped as " L " shape with horizontal edge and longitudinal edge, and described horizontal edge covers the silver foil upper surface, and described longitudinal edge covers the side of silver foil near the weld zone; The thickness of described protective layer is more than or equal to 27.5 μ m.
2. flexible circuit board as claimed in claim 1 is characterized in that: the width of described horizontal edge is more than or equal to 0.3mm.
3. flexible circuit board as claimed in claim 2 is characterized in that: the width range of described longitudinal edge is 2～20mm.
4. flexible circuit board as claimed in claim 3 is characterized in that: the width range of described longitudinal edge is 2～8mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2005100220318A CN1960595B (en) | 2005-11-02 | 2005-11-02 | Flexible circuit board with structure for shielding electromagnetic wave |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2005100220318A CN1960595B (en) | 2005-11-02 | 2005-11-02 | Flexible circuit board with structure for shielding electromagnetic wave |
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| Publication Number | Publication Date |
|---|---|
| CN1960595A CN1960595A (en) | 2007-05-09 |
| CN1960595B true CN1960595B (en) | 2010-11-10 |
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|---|---|---|---|
| CN2005100220318A Active CN1960595B (en) | 2005-11-02 | 2005-11-02 | Flexible circuit board with structure for shielding electromagnetic wave |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102209428B (en) * | 2010-03-29 | 2013-03-06 | 富葵精密组件(深圳)有限公司 | Circuit board with electromagnetic shielding structure |
| CN105657958B (en) * | 2015-12-29 | 2018-09-04 | 广东欧珀移动通信有限公司 | Mobile terminal, flexible PCB and its manufacturing method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1376019A (en) * | 2002-03-08 | 2002-10-23 | 启亨股份有限公司 | Printed circuit board and its production process |
| CN2571138Y (en) * | 2002-09-28 | 2003-09-03 | 天瑞企业股份有限公司 | Electromagnetic interference (EMI) shielding layer structure |
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2005
- 2005-11-02 CN CN2005100220318A patent/CN1960595B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1376019A (en) * | 2002-03-08 | 2002-10-23 | 启亨股份有限公司 | Printed circuit board and its production process |
| CN2571138Y (en) * | 2002-09-28 | 2003-09-03 | 天瑞企业股份有限公司 | Electromagnetic interference (EMI) shielding layer structure |
Non-Patent Citations (1)
| Title |
|---|
| 崔永丽,张仲华,江利,欧雪梅.聚酰亚胺的性能及应用.塑料科技.2005,50-53. * |
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| CN1960595A (en) | 2007-05-09 |
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| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: Shenzhen BYD Electronic Component Co., Ltd. Assignor: Biyadi Co., Ltd. Contract fulfillment period: 2008.4.25 to 2015.11.14 Contract record no.: 2008440000067 Denomination of invention: Flexible circuit board with structure for shielding electromagnetic wave License type: Exclusive license Record date: 20080504 |
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Free format text: EXCLUSIVE LICENCE; TIME LIMIT OF IMPLEMENTING CONTACT: 2008.4.25 TO 2015.11.14 Name of requester: BIYADI ELECTRON MEMBER CO., LTD., SHENZHEN CITY Effective date: 20080504 |
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Effective date of registration: 20201202 Address after: No. 99, South Ring Road, Jingjiang City, Taizhou City, Jiangsu Province Patentee after: Jingjiang Shunhai Automobile Trade Co.,Ltd. Address before: 518119 BYD Industrial Park, Yanan Road, Kwai Chung Town, Longgang District, Guangdong, Shenzhen Patentee before: BYD Co.,Ltd. |
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Effective date of registration: 20220217 Address after: 214500 No. 96, Xingye Road, Jingjiang City, Taizhou City, Jiangsu Province (in Chengnan Incubation Park) Patentee after: Jingjiang Defang Technology Service Co.,Ltd. Address before: 214500 No.99, South Ring Road, Jingjiang City, Taizhou City, Jiangsu Province Patentee before: Jingjiang Shunhai Automobile Trade Co.,Ltd. |
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