Technical sheet of the PCB drilling melamine backup board

2019-12-12 15:25Writer: qyadminReading:
序号
No.
检测项目
Test Items
单位
Unit
技术要求
Standard Requirements
检测结果
Test Results
单项评价
Item Evaluate
1 耐沸水性
Resistance
To boiling water
质量增加百分率, %
Quality percentage increase,%
≤16.0 8.0 合格
Qualified
厚度增加百分率,%
Thickness percentage increase,%
≤19.0 10.6 合格
Qualified
外观等级
Surface Grade
不低于2级
Level 2 and above
1级
Level 1
合格
Qualified
2 耐干热性
Hot & Dry proof
外观光泽等级
Surface Glossy Grade
不低于3级
Level 3 and above
1级
Level 1
合格
Qualified
其它等级
Other Grade
不低于2级
Level 2 and above
1级
Level 1
合格
Qualified
3 抗冲击性能,落球高度100cm
Shock Resistance, Falling Sphere from 100cm High
mm 凹痕直径≤10
Dent dia. ≤10
9 合格
Qualified
4 表面耐磨性能,转
Surface wear-proof, cycles
  ≥350 500 合格
Qualified
5 抗拉强度
Tension Resistance
Mpa ≥45 50 合格
Qualified
6 滞燃性能
Reaction to Fire
氧指数,%
Oxygen Index Value, %
B2级≥27
B2 Level≥27
32.7 合格
Qualified
水平燃烧
Horizontal Firing
B2级,不低于FH-1级B2 Level, Level FH-1 above FH-1级
Level FH-1
合格
Qualified
7 甲醛释放量
Released formaldehyde
mg/L ≤1.5mg/L E1级
Class E1
合格
Qualified
备注            
drilling melamine backup boardmelamine backup board checking

PCB Drilling 

 
      Drilling is the most expensive, irreversible. and time-consuming process in the PCB manufacturing process. The PCB drilling process must implemented since even a small error can lead to a great loss. The drilling process considered the most critical and bottleneck of the manufacturing process.
 
      The drilling process is the foundation for vias. and the connectivity between different layers. If the designer understands the things that happen on the shop floor. they will have a better perception of how their design brought to life. With this insight, the PCB designer ensures the designs are manufacturable. This, in turn, reduces the cost and the product can delivered in a minimum turnkey time.
 
      Basically, there are two kinds of drilling technologies: mechanical and laser drilling.
 
      The mechanical drills are easy to execute. This drilling technology implements drill bits. The smallest hole diameter that can drilled by this operation is about 6 mils (0.006”).
 
      The laser drills are more precise, can drill way smaller holes. Laser drilling is a non-contact process. where the workpiece and the tool do not come in contact with each other. Here, the drill depth can be effortlessly controlled.
 
      The laser technology used to drill blind and buried vias with ease. Here, a minimum hole diameter of 4 mils (0.004”) can lasered with precision.
 
      Unlike the etching and plating process. the drilling process doesn’t have a fixed duration. The drill time varies on the shop floor depending on the number of holes to drilled. This is what happens behind the curtains in a PCB manufacturing unit.

       Laser processing is an efficient technology. for producing drilled microvias with diameters of less than 200 μm..  LPKF ProtoLaser systems. can used for processing of a wide variety of board substrates, e.g., RCC, FR4 and FR5, 
 
      For drilling of FR4 boards with different shapes, resolutions. and densities, LPKF circuit board plotters represent an efficient, low-cost solution. Drill holes with diameters starting at 0.15 mm. LPKF ProtoLaser series laser systems are available if you need even smaller diameters. Our application specialists would be happy to tell you on. which technology is suitable for your application.

How to drill PCB

 
      Drilling is one of the basic, most performed, machining processes. Several methods used for producing micro-holes including conventional punches and dies. electrical discharge machining (EDM), vibration drilling, laser machining, etc.
 
      Electrical discharge machining can used for graphite-epoxy laminates. since the graphite fibers are conductive. Noting that high currents and high temperatures produced. which can cause severe melting of the composite surface. thermal expansion of the graphite fibers in the lateral direction. and debonding between fibers and the matrix. The production rate of an electrical discharge machine is slow .
 
      Vibration drilling is a branch of vibration cutting. which is different from conventional drilling. The conventional drilling is a continuous cutting process. while the vibration-assisted drilling is a pulsed intermittent cutting process. by piezoelectric crystal oscillator. Vibration thrust and torque are smaller than conventional values by 20-30%. under the same drilling condition.  Although vibration drilling can avoid burr and improve cutting stability. there are still a lot of problems to conquer.
 
       Laser machining is a process that no contact between the tool. and the workpiece, and it eliminates the delamination. Laser drilling is being developed as a solution for smaller hole sizes. but there are also problems associated with the process. A PCB made up of three materials ——copper, glass fiber and resin. which have very different material and optical properties. This makes it difficult for a laser beam with particular characteristics to cut.  and through the board. The hole produced by a laser in a standard PCB is sometimes tapered. Also, very small holes produced by laser have limited to a depth equal to the diameter. The main use of lasers seen to be for small blind and buried vias.
 
      to produce through-holes, the main area of interest in the present research. only mechanical drilling is favorable as hole depth increases. because of the need for high accuracy, low temperature and deformation forces. to produce high quality holes on a glass-epoxy composite board. known as the FR-4 board .
 
      Thrust force and Torque In a drilling process, the drill. and workpiece have a relative motion. along with the axis of the hole so that the surplus material removed. To generate and maintain the relative motion, a thrust force and torque applied to the drill.
 
      Bit temperature. When drilling, temperature usually exceeds the glass transition temperature of adhesive matrix. in the laminate base material. Drilling temperature usually increases with wear of the bit. Gross defects such as land tear out are common at high drilling temperature. Lands are small copper rings in conductive planes that surround plated holes. and provide the connection between the holes and circuit t races. that radiate from the holes.
 
      Prior researches have shown that drilling. affects the quality and reliability of plated hole connections. Many defects in plated holes related to the sensitive nature of the lamina. used in modern circuit boards. considered that problems occur. if temperatures in the work material allowed to rise to too high a level. The difference in the coefficients of linear expansion. between the resin and fibers gives rise to residual stresses. which makes it more difficult to meet high dimensional accuracy. with drilled holes showing a smaller diameter than the drill used. Bolton Robert William developed a suitable on-line measurement system with an infrared pyrometer. documented sensor responses and evaluated the sensitivity of temperature. while drilling printed circuit board stacks.
 
      Radial run-out at the drill tip. Ultrahigh rotational spindles have developed for higher precision. and productivity drilling with smaller micro-drills. PCB manufacturers can use commercial spindles rotating as high as 3×105 min−1 or more. but, high rotational speed might cause a radial run-out at the drill tip.
 
      Hidehito Watanabe observed the drilling behavior at contact. with a work surface using a high-speed video camera (drill diameter is 0.1 mm. rotational speed is 3×105 min−1) and proposed a centering model of micro-drills with some run-out. He concluded that:

(1) Orbital revolving drills. with the radial run-out move toward the centripetal direction. after starting contact with a work surface.

(2) The entry sheet intensifies the centripetal action.

(3) The radial run-out is insensitive to drill wear as well as hole quality. because of the centripetal action. A radial run-out at the drill tip might deteriorate hole quality. such as hole location accuracy or surface roughness on a hole wall.

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