Discuss simply the mobile phone uses the design of FPC multilayer board
In recent years, FPC relies on its one's own characteristic, in the designs of slide phone and folding mobile phone, playing a more and more important role.
Slide phone board and order quantity of multilayer board of folding mobile phone are increasing constantly, how control quality manufacturer of FPC, finish product this kind of cause, imprison important in craft
First, preface
One that is with electronic product miniaturizes, melting at a high speed, digitization, development and information intelligence terminal (the computer, TV, telephone, fax) at full speed in personal communication terminal, the mobile phone and 3G communication of mountain fastness Under the networked demand, carry FPC life-span and impedance required in sliding closure type mobile phone and folding mobile phone of the mobile phone industry and require refinement more and more with the suitable communication, in FPC maker manufacturer, how go, control, it finishes product this kind of to be to cause, imprison not important in craft.
FPC (Flexible Printed Circuit can oar p-c board,can also call it FWPC) Characteristic following without being had mainly for several respect:
(1)It is good flexibly: But arbitrarily crooked to deform, twine radius to be little, can move freely along X. Y. Z three directions; (2) The space usage is small: Light and thin, make the narrow space of the instrument fully utilized, has responded to the request that the electronic product is miniature and light and small; (3) Light: The flexible slab is designed by the mechanical strength according to current-carrying capacity, so the weight is relatively light; (4) The leak tightness is good: Adopt low tension to seal and design, can tolerate the severe environment; (5) The transmission characteristic is steady: The wire interval can be designed freely according to the electric parameter, the general domain finalizes a text; (6) The manufacturability of assembly is good: Products free head joint and whole head joint characteristic are good, are accommodated and welded. Insertion, and stereoscopic routing and three-dimensional spatial join,etc.; (7) Good insulating property: The high molecular material of substrate PI and PETs,etc. that the flexible slab adopts has higher insulating strength, and the general circuit covers the membrane to protect, so improved insulating property greatly.
In recent years, FPC relies on its one's own characteristic, in the designs of slide phone and folding mobile phone, playing a more and more important role. The requirements for of people are stricter and stricter. Also, the slide phone board of our company and order quantity of multilayer board of folding mobile phone have increased recently, in order to strengthen the quality and training of personnel, specially and such respects as the craft in the production process is maintained are controlled to the slide phone board and design composing idea, selecting suitable materials of the multilayer board of the folding mobile phone, in order to reduce bad emergence, increase a percentage of the qualification rate.
Second, make the requirement:
1,Design and select suitable materials
The first step is very important. What substrate if the customer does not reflect or is appointed to use, should consider mangling copper, because it is good that its curved sex ratio electrolytic copper wants. But the substrate has glue and has no glue to have greater influence on the fluting characteristic, have the intersection of glue and substrate able to bear curved sex ratio, have the intersection of glue and substrate able to bear getting curved to take kind generally speaking.
The classification of the substrate:
1.1 Copper foil:
1.1.1 Mangle copper.
It mangles copper to be to electrolyze the intersection of negative pole and copper, settle, smelt slug, through prolong, pigeonhole, take shape, because of the reason of smelting, the composition is more single and crystallization is distributed evenly. Because the crystallization direction is parallel to the flexible slab, is suitable for the transmission of the high signal of the frequency. It is good to mangle copper characteristic ratio electrolytic copper. Its thickness is several kinds 1/4OZ, 1/3OZ, 1/2OZ, 1OZ, 2OZ.
1.1.2 Electrolytic copper:
The electrodeposited copper foil utilizes the electric plating principle to make copper ion deposit on smooth negative pole drum wheel rotated, then separate and get have grain side and maos of the intersection of Taxi and copper foil from gyro wheel of negative pole copper foil, can use after surface treatment. Electrodeposited copper foil and negative pole drum contact surface are very smooth, but because the other side keeps in touch with plating the liquid, will be coarse under the function of high current density. This mat surface can increase the superficial contact area and help to improve the cohesion with the protective film after surface treatment. Its thickness is several kinds 1/4OZ, 1/3OZ, 1/2OZ, 1OZ, 2OZ.
Often adopt PI (gather drunk imide) . PET (polyethylene) Or GE (glass fibre) . PI characteristic, preferably, price great among them. The thickness is several kinds 1/2mil, 1mil, 2mil.
1.3 Select suitable materials to match while designing
Because the slide phone characteristic is expected relatively much, on the choice of the material no matter substrate or CVL should be towards " thin " Direction go consider.
1.4 Design the composing
1.4.1 The regional circuit of the fluting is required:
a)There can't be via hole in fluting part to need; b)The needing to add extra and protect the copper wire on both sides the most of the circuit, if the space is insufficient, should choose to add extra protecting the copper wire on the angle of fluting partial inner R; c)The joint part in the circuit needs to design into the arc line.
1.4.2 Area of fluting (air gap) Requirement: The area of fluting needs to stratify, remove the glue, it is easy to disperse in conformity with the action of force. The larger the better on condition that influence assembly the curved area is.
2,Preparation method
After the material is chosen, control slippery cover plate and multilayer board to seem even more important from the preparation method. Increase the number of times of the fluting, especially sink electric copper process and especially control while making soon. General slippery cover plate and a point of plywood of the multilayer board have a life-span requirement, the general minimum exigency fluting of the mobile phone trade reaches for 80,000 times.
Because the general craft that FPC adopts is a electric plating craft of the whole plate, will not pass the electricity of picture of once as the hard board, so copper is too thick to demand to plate too thick in the copper plating, a piece of copper is the generally most suitable for 0.1~0.3 mil. (the intersection of hole and copper compare with deposition of surface copper about 1:1 at copper plating) But the copper and substrate are not stratified in order to guarantee the hole at the time of hole copper quality and SMT high temperature, and put conductivity and communication at the goods in process, copper thick thickness demand, up to or more 0.8~1.2mil.
In this case will produce a question, perhaps someone will ask, a piece of copper demands to have 0.1~0.3mil only, (do not add the substrate copper) Does hole copper require that how to accomplish in above 0.8~1.2mil? This needs to increase a process: General FPC process chart on board (if only demand to plate 0.4~0.9mil) For: Cutting Bore hole Sink copper (the black hole) Electric copper (0.4~0.9mil) Figure And then the process.