• Poornima Mani

PCB Manufacturing — An Overview

Updated: Nov 28, 2020

A Printed Circuit Board, commonly addressed as a #PCB is a board that allows #electronic designers to use conductive tracks and pads to place electronic components and chips for easy industrial usage. But the question here is: How are PCBs made? So let's get the answer through this article.


Constituents in a PCB Making process


There are multiple components while making a PCB, but the most commonly used one is a fiber-based board called FR4. This is because it provides a stable reasonably good quality product at a cheap price. For the tracks for the components in the PCB, the copper clad board is first obtained. It mainly consists of a copper sheet, hence preferring FR4 for the task.


PCB manufacturing process step - An overview


Now that we have chosen the required PCB boards, we must dive into the next step, creating tracks and eliminating unwanted copper. For this, a photographic process is used in PCB Manufacturing where the whole board is covered in a layer of #photoresist material. This is later brought to sunlight for detailing the tracks. After the completion of this stage, it is kept in a developer such that only the needed parts are covered in the photoresist.


Once this step in PCB making process is completed, these PCB boards are placed in a solution with the right amount of #Ferric Chloride to etch the areas of unwanted copper. There are methods other than photographic processing such as using an accurate quilling machine to mill away unwanted areas using design software. But this method is never an ideal option in cases of high quantities.


Holes, Vias, and Solder in PRINTED CIRCUIT BOARD (PCB)


As you might have seen, the PCB has holes and vias to hold together the components at different points. Usually, the interior surfaces have copper layers to make electrical connections, and drilling is accomplished with multiple drilling machines. The lesser the number of different hole sizes, the lesser the cost of the printed circuit board (PCB).


How a Printed Circuit Board (PCB) looks like?

A solder resist refers to a coating where the unsoldered areas are kept protected by applying a layer of these on it to prevent short circuits.


It is usually composed of a #polymer layer and protects it from solder and other contaminants. The colors of the solder resist commonly used is red or green. Occasionally, if some copper fingers are used for edge connection, the boards are gold plated as the metal won't tarnish at the same time have good conductivity.

How do you Make PCB Silk Screening?


In the PCB making process, there might be times when you have to print the text and other idents onto a PCB to identify the board as well as component fault-finding. A PCB design software is used to add the markings after the completion of the bare board.

PCB with printed text

So now that we have got the PCB ready, how do we know if the PCB is working the way we want it to be? There we go, the final step in the PCB manufacturing process: PCB testing.


Printed Circuit Board (PCB) Testing


After you spend a hefty price on your personalized PCB, the last thing you wish to know is that the PCB is faulty. To prevent this, PCB assembly #pcbtesting methods play an integral role in the manufacturing process. Let us take a look at the common PCB testing process.


How to test a PCB?
  1. Flying Probe Testing: This is an inexpensive method that checks for opens, shorts, resistance, capacitance, and diode issues.

  2. In-Circuit Testing: ICT, also known as the bed-of-nails test is a robust yet expensive way to PCB testing. It involves probes laid out in a layout-matching way to check the integrity of the solder connection. A certain amount of pressure is put to double-check that the connection stays intact.

  3. Burn-in testing: This is a more intense type of PCB testing to detect an early failure. This method is done by pushing a certain amount of power for up to 168 hours. If the board fails, the prevailed condition is called infant mortality and is clearly not an ideal choice for medical application or military.

  4. Functional Testing: This good old-fashioned way takes a little bit of extra time, but can save face from a quality standpoint and save money.

Now you have seen an outlook of how PCBs are made. Check out other articles also to know more about PCB.


SEE ALSO:

  1. PCB Grounding Techniques

  2. Top 5 PCB Designing Software

#PCB

#PCB_Manufacturing

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