PCB Manufacturing

 

    PCB ( printed circuit board ) is Mechanical Support & electrically wired the electronic components using the copper (conductive path) which is made by etching copper clad. PCB is also called as Printed Wired Board (PWB). The PCB without component is raw PCB & PCB with component is called printed circuit board assembly it means the raw PCB is assembled with electronics components.

            

 Now a day’s PCB (raw) become very inexpensive especially Single sided Board (SSB) & Double Sided Board (DSB). Multi layers PCB are still costly due to its high setup charges.

  • Single Sided PCB (SSB)

 

      PCB which has only one  track (copper) layer is called SSB.

 

  • Double Sided PCB (DSB)

 

      PCB which has two track (copper) layer is called DSB.

 

  • Multi layer PCB

 

     PCB which has more than two copper layers.

Material Used for PCB

 

Conductive Layer is basically is of thin copper foil the base is of glass epoxy (insulating materials) some types are as bellow.

FR 6,FR 4,FR 2,CEM 1,CEM 2,CEM3,CEM4,370HR,BT,FR408,GETEK,Gepeg,HALOGEN FREE FR4,Hybrid,IS410,Nelco13,Nelco ,3 Si, Polyimide,                Rogers 3003,Rogers 4000, Rogers 4003, Rogers 4350,

 

            

Rogers, RT/5880,,Rogers RT/6006,,Rogers RT/6010LM,Rogers Duroid, Taconic 6002, Taconic TLX-9, Thermount

FR-4 PCB material is commonly used Material.

Common Methods of producing PCB

  •       Copper etching (Photo etching)
  •       Screen printing
  •       PCB Milling

From above the first two are widely used for mass production of PCB.


The Last one is using for prototype production of PCB.


Prototype PCB means the limited nos. of PCB which is for R and D purpose of new product or modification of existing product.

The cooper etching (Photo etching) method is widely is used by large scale PCB manufacturing Companies all over world.


Screen printing method is cost saving, but it compromise with quality,also fine PCB with below 10 mil track and same spacing is very hard to achieve with this method. But still some companies are using this to manufacture the low cost PCB.


PCB milling is adopted recently for quick turn PCB manufacturing. The PCBs are milled on cnc machine mechanically with routers (end mill). These methods save lot of time. But this method is not useful for mass production of PCB.


            

The cooper etching (Photo etching) method is widely is used by large scale PCB manufacturing Companies all over world.


Screen printing method is cost saving, but it compromise with quality,also fine PCB with below 10 mil track and same spacing is very hard to achieve with this method. But still some companies are using this to manufacture the low cost PCB.


PCB milling is adopted recently for quick turn PCB manufacturing. The PCBs are milled on cnc machine mechanically with routers (end mill). These methods save lot of time. But this method is not useful for mass production of PCB.



PCB By Photo etching

With the below we will look the steps involved

for PCB manufacturing with photo

etching methods.


Lets Start from beginning how the PCB are manufactured.


Suppose I have requirement of PCB

I will search the Printed Circuit manufacturer in my region

with competitive rates.

Select one from them.

First I have to send the gerber files to him for quotation

in that I have to mention few things about my requirement


Such as Pcb thickness, Pcb finish copper, Masking,

silk screen color ( By default it is masking PISM green,

silk is white), HAL, Lead free, Delivery time.


When this data reach to PCB manufacturer he study the data and give the

quotation.


Factors  which play vital role deciding the price of PCB.


  • Quantity of PCB.
  • Lead Time
  • Minimum track , spacing and minimum drill diameter ( Keep minimum track thickness and spacing between to connection  6 to 8 mill  to reduce cost )

     Alway verify the output ( gerber data ) before

     sending it to manufacturer.


Please read our article on how to avoid cam hold ? 


Manufacturing of PCB.


After accepting quotation the PCB manufacturer goes for pre-engineering of gerber data. This is done in Cam department of the company

or many service beuro are available which provide cost effective service to PCBs Industry.


Why service beuro?


  • Saves expense  on OEM licence cost
  • Saves expense  on Salary, bonus and other benefits of Employee. Also the service beuro provide cost effective
  • solution on the other hand you have to increase salary,
  • bonus and other  benefits of employee on regular basis.


What Cam dept do after getting the customer data?


After getting customer data. Cam dept. carefully study

the gerber data. If found any required missing file the customer  is informed immediately.  After getting all the information and files. The cam dept.

start the pre-engineering of the job. For Pre-engineering  please see the our cam service page click here


In pree-engineering the Engineer checks following things


* Minimum Gap ( pad/pad, pad/trace, trace/trace )

   It should be 0.006" ( 0.15 mm ) to avoid expensive PCB


* Minimum Track Width

   It should be 0.006" ( 0.15 mm ) to avoid expensive PCB


* Copper Voids

   The acceptable size is over 0.006" , Voids below this  should be patch with  

   copper fills.


* Annular Ring

   It should be 0.008" either side this should be check with drill dia not finished


* Masking openings

   The mask opening minimum 0.002" either side. Oversize masking should be

   modified so that track exposure avoided.


* Undetermined traces

   Some times in hurry designer skip the connection and in gerber unterminated traces occur.



Next to this the PCB data is panelized according to order quantity. These details also can be found on cam service under the heading Penalization Of PCB Drill file rout file is extracted ( prepared )


Penalization includes step and repeat. The data is multiple and venting and thieving bars are added around borders of panel.


After completion of the software work the gerber data is generated for required films. The films (plots) required to be plotted. We recommend get your plots from qualified service beuro if in house laser photo plotting facility is not available.


Benefits of outsourcing


You will have to pay only for your plots (Rates are very competitive), Need not worry about quality if choose right service beuro (We recommend choose service beuro which have experience in PCB). No extra cost for Laser Photo plotter (approx USD 10K TO 20K), Save cost for special employee for the photo plotting department (employee salary, bonus and other facilities). If you have any problem with quality of plots service beuro will replace it free of cost.


We strongly recommend get your Photo plots from Laser Photo plotting Beuro only as after all it is matter of quality.



Some service beuro provide free DRC service which is another great benefit. We get appreciation from our clients for this service many times.


Our belief that client want his product quick but he will not happy at all if he get rejected board quickly. This will cause more delay. We think PCB manufacturers should plan their work and do not hurry to just finishing work as early as possible. The clients are totally depending on you when he gives his work to you. Give appropriate delivery time. (Such as for SSB: - 2 days, DSB 3 to 4 days for MLB 10 days). We think client will have not bothered if PCB manufacturer take one more day to deliver the PCB (Ok PCB).   Golden Rule of R.T.O ‘it is better to delay than accidents’ here we can say “it is better to delay than rejection.


Let’s move on


 Films required for Single Side Board are as below


  1. Bot side artwork
  2. Bot side mask
  3. Top side silk

Films required for Double Side Board are as below


  1. Top side artwork
  2. Bot side artwork
  3. Top side mask
  1. Bot side mask
  2. Top side Silk
  3. Bot Side Silk


Films required for Multilayer Board (4 layer) are as below


  1. Top side artwork
  2. Bot side artwork
  3. Inner Layer 1
  1. Inner Layer 2
  2. Top side mask
  3. Bot side Mask
  1. Top side silk
  2. Bot side silk

In multilayer PCB as no. of layer increases no of film increases.

  • PCB Manufacturing

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