2results about How to "Eliminate precision errors" patented technology

The invention discloses a printed circuit board and a preparation method thereof, and the printed circuit board comprises a plurality of basic conductive layers and a positioning conductive layer clamped between the plurality of basic conductive layers. A plurality of targets are arranged on the positioning conductive layer; wherein the basic conductive layers correspond to different targets respectively, and the basic conductive layers are obtained through pattern preparation after alignment based on the corresponding targets. By means of the mode, the alignment precision of the patterns of the basic conducting layers can be greatly improved, and the structural accuracy and reliability of the printed circuit board are improved.

The utility model provides a kind of floating self-centering type fixture structure for improving bushing press fitting accuracy, including base assembly and upper press head assembly, the base assembly includes the press fitting base for supporting product, the press fitting base is internally provided with the positioning mandrel that can float up and down, the top end of the positioning mandrel can be installed bushing after being passed out the inner hole of product;The upper press head assembly includes upper press head, the upper press head is internally provided with the centre of the top that can float up and down, the tip of the centre of the top projects upper press head setting and can be with the axial center of positioning mandrel cooperation centring, the centre of the top can be driven down after moving down positioning mandrel and bushing is pressed into the inner hole of product.