To solve a diamond drilling technique thick backplane PCB drilling , because the need to drill two holes drilled through to complete processing of drill positioning system design , drilling and processing of positive and negative sequence twice drilling drills have special requirements , such as the size of the design . From the above-mentioned aspects of some of the key pairs drilling engineering design are discussed .
Preface:
Generally, we put in 4.0mm thickness above , the board member has a typical crimp hole design called PCB backplane. The main features of the backplane PCB board size is large , the current size exceeds has not uncommon 1000mm; high thickness , typically 4.0-6.0mm, sometimes even up to 10.0mm. In addition , the main row of holes for PCB backplane connector , customers dimensional tolerances that type of hole , hole copper quality , and even shaped hole has very strict requirements . Due to limitations of mechanical drilling capability , PCB backplane drilling technology is the whole process is a key factor . Solutions to technical problems drilling thick PCB backplane lot of drilling is one of them . Mechanical drilling technology breakthroughs for drilling capacity constraints of the problem , the drill can be completed without special custom backplane PCB drilling thick , thick PCB backplane for batch processing obvious advantages .
1 range of applications for drilling
Also known as the pros and cons of diamond drilling industry , is divided into two sides step to complete the drilling of a processing method , the first drill hole is controlled deep drilling , drill through the second hole . The drilling method because of the through holes drilled from the same two complete, requires two drilling location, thus high design requirements for Drill ! Usually due to poorly designed or positioned drilling drills twice the size of the design is unreasonable, there will be " stepped hole " defects have fatal consequences for the PCB assembly crimping devices.
PCB backplane row of jacks are very huge number of drill to drill two holes through the process to complete , in order to produce a reasonable use of resources , through trials to material type ( Our main five categories ) and the thickness of two parameter is the factor we identified in table I need to apply for drilling plate processing technology .
2 the design of the positioning holes drilled
Conventional Drill holes into three general design , but because of the need to change the face of the diamond drilling process , the degree of alignment of the two boreholes demanding initial class board processing, is easy to operate, reducing the positive and negative drill errors caused by switching , we designed four positioning holes for positioning the center of the plate symmetrically . The advantage of this design is the positioning holes : the first controls the drilling depth of the pin hole without re- drilling , drilling only to reload the reverse plate can be eliminated to bring the two positioning pins play error . However, processing results show that four-hole positioning processing methods still have " stepped bore " bad produce .
In order to reduce the " stepped bore " bad , we use is called "over positioning" Drill method . MACHINERY will two or more repeating the positioning element limit the degree of freedom of a workpiece or a phenomenon known as over several positioning. For drilling for , just consider X, Y direction of the positioning method is: the positioning hole is designed to six , six plates are symmetrically positioned holes .
