For some PCB’s of large size and thickness, the precision of the gongs slot is not particularly high.However, with the development of electronic products in the direction of thin, small, micro, PCB slot accuracy requirements are also higher.
As PCB board is formed by multi-layer plate pressing, the general operating steps are: pressing – outer hole – initial gong trough – copper sink – electroplating – second gong trough – etching…The initial gongs trough is a one-time gongs trough depth in place, the second trough is mainly to remove the bottom copper.However, for the initial gong slot, the one-step gong slot in place is only theoretical, but in real time it is very easy to damage the bottom plate.For example, there are five layers of plates, and the depth of the gongs groove is four layers, that is, until the surface of the fifth layer. If the gongs groove is put in place, it is easy to damage the surface of the fifth layer.Even some of the high precision gongs trough equipment, but only to improve the accuracy, it is difficult to ensure that the surface and the fifth layer of the board.
Therefore, the company adopts a deep control gong slot process to eliminate the above defects.
Technical implementation elements:
The purpose of the invention is to overcome the defects of the existing technology, and to provide a deep-control trough process with good quality which is not easy to cause damage to the surface of the lower layer plate.
The purpose of the invention is realized through the following technical scheme: A deep control gong slot process, the steps of which are:
S1. After pressing and outer drilling, the first gong slot is conducted with the deep controlling gong slot machine to form the initial slot whose depth is less than the actual slot;
S2. Laser is used to cut the initial groove along the bottom edge of the groove, and the resin is burned off. The processed groove is a forming groove, and the depth of the forming groove is consistent with the actual depth.
S3. Plasma rubber removal equipment is used to remove carbon from the forming tank in step S2.
S4. Then conduct copper sinking, all-plate plating, outer graphic and graphic plating treatment;
S5. After the completion of Step S4, the deep control gong slot machine is used for the second gong slot, and a copper layer is left at the bottom of the slot.
S6. Laser was used to cut the bottom edge of the groove in step S5, but the remaining copper layer was not removed. Laser was used to cut a groove along the bottom edge of the groove on the upper surface of the remaining copper layer;
S7. For drug treatment, spray etchant into the groove with a needle tube and gradually spray etchant into the center, corroding the remaining copper layer and cleaning and drying after the corrosion is completed from the top.
S8. Use weak laser beam to flatten the bottom of the corroded groove, and then remove the glue;
S9, and then etching, screen printing resistance welding, silver sink, detection processing.
Further, in step S1, the head of the deep gong slot is chamfered so that the bottom edge of the initial slot is thickened.
First, in step S1, in the initial gong slot, use the outlet pipe with the air outlet to align with the initial slot and blow away the debris in the initial slot;
In step S2, when the initial groove is cut with laser, the suction tube with suction head is used to align the groove and suck away the debris in the groove to avoid sticking to the melting area of the cut and affecting the cutting.
Preferably, in the step S7, the corrosion time is 3~10min.
Further, in step S1, the underside of the initial groove is higher than the next layer of plates.
Preferably, in step S5, the thickness of the remaining copper layer is 50~100um.
Preferably, in step S8, the flattening time of the weak laser beam is less than 5min.
The invention has the following advantages:
(1) In the first slot of the gongs, the gongs do not reach the surface of the next layer of plates. There is excess material and the residual material has thick material at the edge of the bottom edge of the slots. Then laser cutting the residual material to the surface of the next layer of plates will not cause damage to the surface of the next layer of plates;After the copper sink, the first mechanical gong trough, and there is a residual copper layer, will not damage the next layer of plate surface;
(2) In the treatment of the remaining copper layer, corrosion is followed by normal treatment with weak laser beam. After corrosion, part of copper can be removed and copper becomes loose, which is conducive to weak laser treatment.The reason why a weak laser is used instead of the ordinary laser in the previous step is that the copper has good thermal conductivity, and the general laser will also affect the next layer of surface when it is processed. However, in step S2, due to the short laser cutting time, we are not worried about this risk.
(3) The way of laser cutting to form grooving is to plan the scope for subsequent corrosion and leveling treatment, so as to avoid the occurrence of operation errors to expand the corrosion or leveling scope.
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