A kind of multi-layer printed circuit board machining process
Technical field
The present invention relates to a kind of printed circuit board machining process, especially design a kind of multi-layer printed circuit board machining process.
Background technology
Present multi-layer printed circuit board machining process is made figure to copper-clad plate, and pressing is milled then except that frame.Technology mainly contain two kinds:
A kind of is " gummosis point jigsaw frame ", and another kind is " a big copper sheet jigsaw frame ".
Gummosis point jigsaw frame is outside the design configuration 1 of copper-clad plate as shown in Figure 1, and the copper face that covers that will be except that line pattern is made into one by one circle and covers copper point 21 and also claim " gummosis point ", and the copper sheet etching that circle is covered outside the copper point 21 is removed, exposed substrate.Use gummosis point frame, help avoiding the effect of contraction of frame, and the effect of a little residual copper of gummosis point reservation is to reduce multi-layer sheet pressing process prepreg filler demand, help improving reliability figure in the plate.But because in the copper-clad plate course of processing, the material contracts rate iso-stress parameter of substrate and copper sheet is inconsistent, causes producing stress between the copper sheet of copper-clad plate and the substrate.Usually the contraction or expansion coefficient ratio of substrate is bigger; copper sheet is relatively stable; single gummosis point jigsaw frame can be because residual copper rate be low; the gummosis point frame convergent-divergent degree of independent separate design is bigger; thereby cause inner line pattern 1 to be subjected to the pulling force of the pressure of gummosis point frame contraction or expansion and cause big shearing; it is the possible difference of ratio that each layer copper-clad plate expanded or shunk; so just influenced the contraposition between each layer in the pressing process, so aligning accuracy is low between each layer of gummosis point frame.
Big copper sheet jigsaw frame then is a reservation copper sheet 4 in the copper-clad plate line pattern 1 outside, or copper sheet 4 simply is divided into the copper sheet of several bulks, it is very high that it covers the copper rate, so adopt the outside frame of the copper-clad plate of " big copper sheet jigsaw frame " more stable, when pressing, aligning accuracy height between each layer, but after pressing, mill except that behind the part frame, the wiring board periphery still needs the remaining part frame to be used for subsequent handling, for example make via, outer graphics, make solder mask etc., though if adopt big copper sheet frame, this moment, inner active graphical part wiring board was still pind down by the big copper sheet frame of external stabilization, so the not variation of its size, but stress is very big between frame and the internal wiring figure 1, and line pattern 1 produces stress in the other direction in the ductor.After all process steps is finished, we mill when removing remaining frame, in case original frame pins down or limits removal to enclose pattern, the wiring board that comprises enclose pattern at once since before the internal stress contraction or expansion that exists, cause the size of final finished and original different design to close.
Summary of the invention
It is low that the technical problem that the present invention mainly solves provides a kind of deformation degree, the multi-layer printed circuit board machining process that aligning accuracy is high.
For solving the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of multi-layer printed circuit board machining process may further comprise the steps:
1) make line pattern and frame figure in copper-clad plate, described frame figure is made up of frame pattern I and frame pattern I I, outwards is followed successively by by the central area of copper-clad plate: line pattern, frame pattern I, frame pattern I I; The residual copper rate of frame pattern I is less than the residual copper rate of frame pattern I I;
2) be multilayer circuit board with copper-clad plate lamination, mill off comprises the multilayer circuit board outer rim of frame pattern I I;
3) via of making multilayer circuit board, outer graphics, solder mask;
4) multilayer circuit board is milled for the design finished size.
Wherein, technical scheme is preferably, and the residual copper rate of described frame pattern I is 34.9%~57.7%, and the width of frame I is 5mm~10mm, and the residual copper rate of frame pattern I I is 69.4%~92.4%;
Wherein, technical scheme is preferably, and described frame pattern I structure is the circular copper point that covers, and circular covers the substrate for exposing between the copper point; Described frame pattern I I structure is the copper billet that covers of rhombus, and covering of rhombus is exposed substrate between the copper billet.
Wherein, technical scheme is preferably, and circular covering is spaced apart 0.5mm~1mm between the copper point, and the circular copper spot diameter that covers is 2mm~3mm; The copper billet length of side of covering of rhombus is 15mm~50mm, rhombus cover between the copper billet 2mm~3mm at interval.
Wherein, technical scheme is preferably, and copper-clad plate is provided with location hole in the described printed circuit board machining process, described location hole be arranged in frame pattern I I rhombus cover copper billet.
Wherein, technical scheme is preferably, and copper-clad plate is provided with location hole in the described printed circuit board machining process, and described location hole is arranged in the zone that the frame figure is covered with copper billet.
Wherein, technical scheme is preferably, in step 2) and step 3) between further comprising the steps of:
Measure lined with copper plate shrinkage rates with X-RAY behind the mill off frame pattern I I, do contrast, adjust the bore position of subsequent handling and the contraposition ratio of subsequent handling according to the shrinkage rates of copper-clad plate and the design size value of customer requirement.
Residual copper rate of the present invention is defined as: the gross area that is covered with the area/plate face zone of copper face in residual copper rate=100% * plate face zone.
Adopt processing technology of the present invention, because described frame figure is made up of frame pattern I and frame pattern I I.The outside residual copper rate of frame pattern I I height, the harmomegathus of copper is more much smaller than base material, so the large tracts of land copper sheet to pin down lower frame pattern I I relative stability higher, such core material is in carrying out multilayer pressing process, although bear 20~220 ℃ high temperature and the pressure of 0~500PSI, thermal expansion also appears in sheet material under this temperature and pressure, produce because heat causes stress at different directions, but because the residual copper rate of frame pattern I I height, the thermal coefficient of expansion of copper is little, the very little and stable height of harmomegathus after outer frame is heated, thus limited the deformation of interior layer pattern, so can keep putting in order the high aligning accuracy of plate.Overcome the coarse problem of contraposition in the gummosis point frame lamination process.
After lamination finishes, mill and remove the multilayer circuit board outer rim that comprises frame pattern I I, at this moment the plate internal stress is released, some variations take place in the circuit board size, and therefore the palette internal stress also obtains discharging, in subsequent technique, the size of plate no longer changes, and does not have internal stress.At the cloth via, make outer-layer circuit, after technologies such as making solder mask are finished, again the circuit board frame is milled to remove and be processed as final design size, at this moment, circuit board can not contract and rise, and has overcome big copper sheet frame circuit board plate size in this step and has not allowed manageable problem.
Description of drawings
Fig. 1 is " gummosis point jigsaw frame " described in the utility model board face schematic diagram;
Fig. 2 is " big copper sheet jigsaw frame " described in the utility model board face schematic diagram;
Fig. 3 is the utility model embodiment embodiment 1 plate face schematic diagram.
Description of reference numerals:
1, line pattern 2, frame pattern I 21, the circular copper point that covers
3, frame pattern I I 31, rhombus covers copper billet 4, copper sheet
5, location hole
Embodiment
By describing technology contents of the present invention, structural feature in detail, realized purpose and effect, give explanation below in conjunction with execution mode and conjunction with figs. are detailed.
See also Fig. 3
The multi-layer printed circuit board machining process that present embodiment provides may further comprise the steps successively:
1) make line pattern 1 and frame figure in copper-clad plate, described frame figure is made up of with frame pattern I I3 frame pattern I 2, outwards is followed successively by by the central area of copper-clad plate: line pattern 1, frame pattern I 2, frame pattern I I3.Described frame pattern I structure is the circular copper point 21 that covers, and circular covering between the copper point 21 is the base material that exposes; Described frame pattern I I structure be rhombus cover copper billet 31, covering of rhombus is exposed base material between the copper billet 31.Wherein, circular covering between the copper point 21 is spaced apart 0.5mm~1mm, and to put 21 diameters be 2mm~3mm to the copper that covers of circle, and frame pattern I 2 width are 5mm~10mm; Copper billet 31 length of sides of covering of rhombus are 15~50mm, rhombus cover between the copper billet 31 2~3mm at interval.Wherein, copper-clad plate is provided with location hole 5 in the described printed circuit board machining process, described location hole 5 be arranged in frame pattern I I rhombus cover copper billet 31.The copper billet 31 that covers of rhombus has higher residual copper rate, can intersect the fixedly location hole 5 of edges of boards, can reduce inherent strain again, satisfies multi-layer sheet contraposition requirement technology, guarantees that course of processing dislocation is little.
Adopt as above design, the copper rate of covering of pattern I is calculated as follows:
Cover copper rate=π * round diameter
2/ [(spacing between round diameter+circle)
2* 4]
So according to the technical scheme of present embodiment, it is 57.7% that frame pattern I maximum is covered the copper rate, it is 34.9% that minimum is covered the copper rate.
Frame pattern I 2 is covered the copper rate and is calculated as follows, and when described rhombus is square, covers the copper rate and reaches maximum, covers copper rate=length of side this moment
2/ (length of side+rhombus spacing)
2
When rhombus length of side minimum, during spacing maximum layout, cover copper rate minimum this moment under the situation of each limit angle unanimity of rhombus, even get each limit of rhombus vertically for square, covers copper rate maximum and also only can reach 69.4%;
When rhombus length of side maximum, during spacing minimum layout, to cover copper billet simultaneously and be square, cover copper rate maximum and can reach 92.4% this moment.
When rhombus no longer is a square, and when becoming " flat ", cover the copper rate just to descend, so in the operating process,, except the length of side and spacing of noting the control rhombus, also will consider the angle on each limit of rhombus for the copper rate of covering that keeps stipulating thereupon.To satisfy technical scheme to covering the requirement of copper rate.
In operation, why frame pattern I I respectively covers needs separation between the copper billet, that is because substrate can produce some gases in the course of processing, needs the channel connection atmosphere of exhaust, otherwise the pressing process causes the plate performance failure because of can't exhaust causing after the pressing bubble being arranged.
2) be multilayer circuit board with copper-clad plate lamination, mill off comprises the multilayer circuit board outer rim of frame pattern I I3.
When skin mills the limit, will have the frame pattern I I3 mill off that covers copper billet 31 of rhombus after, the stress that can discharge frame pins down line pattern 1, makes the inherent strain of whole plate obtain discharging before boring, reduces the influence of frame pattern I I to subsequent handling.Measure whole plate shrinkage rates behind the mill off frame again, the processing ratio of contraposition requirement technology is arranged, make the plate and the client's design size value difference value that finally process littler, improve and put in order the plate aligning accuracy according to shrinkage rates adjustment boring, outer-layer circuit figure etc.And mill off part frame reduces the plating area, the saving electroplating cost.With the frame mill off, can reduce the difference between frame and the line pattern 1, help improving the rate of finished products of outer-layer circuit figure pad pasting.
3) measure the copper-clad plate shrinkage rates with X-RAY behind the mill off frame pattern I I, according to the bore position of operation after the shrinkage rates adjustment of copper-clad plate and the ratio of back operation.Make the via of multilayer circuit board, outer graphics, solder mask;
4) multilayer circuit board is milled for the design finished size.
In actual mechanical process, adopting the circular copper billet 31 that covers that covers copper point 21 and rhombus is because these two kinds of relatively good making of shape, but in fact be made as other shape, for example will cover copper billet in the frame pattern I 2 and be designed to ellipse, strip etc., cover copper billet among the frame pattern I I3 and be designed to triangle etc., also can realize goal of the invention, as long as the residual copper rate of frame pattern I 2 is less than the residual copper rate of frame pattern I I3.
The above only is embodiments of the invention; be not so limit claim of the present invention; every equivalent structure or equivalent flow process conversion that utilizes specification of the present invention and accompanying drawing content to be done; or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present invention.