What is PCB fabrication process?
Below there is the main steps of PCB fabrication process:
Step 1. Circuitry Images creation
The transfer of PCB design circuitry image data from the manufacturing files provided by the CM to the board is the initial stage in the production of a circuit board. Data typically comes in the Gerber file format, while other formats and databases can be utilized.
A multilayer circuit board is made up of several layers of metal conductors and dielectric material. It is made up of layer pairs that are sandwiched together by two layers of copper foil and an epoxy resin and glass fiber core material known as FR-4. FR-4 is the most widely used core material in PCB manufacture, however there are alternative dielectric materials available.
A multilayer board’s layer stackup is constructed by laminating a thinner variation of the core structure used to make a double-sided board with additional core structures. For a high-quality finished product, each layer’s breadth, copper weight, and layer-to-layer alignment must be rigorously regulated.
Step 2. Inner Layer printing
Circuitry pictures are printed on the surface of the inner layer cores as the initial stage in PCB construction.
- A layer of photoresist material is placed on top of the core’s copper foil.
- Either an ultraviolet light is shone through the photo tooling on the photoresist or a laser is used for direct imaging.
- Only the copper circuitry’s pads and traces are exposed, which causes the photoresist covering the circuitry designs to polymerize, or harden.
- The still-pliable unexposed photoresist is chemically removed from the copper.
- Only the circuitry portions shielded by the polymerized photoresist remain after the copper layers of the core have been removed.
- The copper circuitry remains after the photoresist is removed.
After this procedure is finished, an AOI system (automated optical inspection) will check the layers of the core for flaws. The inner layer pairs of the board are ready to be bonded together to form a single circuit board once each pair has undergone this identical procedure.
Step 3. Layers Laminating
Layer pairs are layered to form a PCB “sandwich,” along with thin layers of copper foil to cover the outside surfaces of the top and bottom sides of the board. Each layer pair will have a sheet of “prepreg” put between them to aid in the bonding of the layers. A fiberglass substance known as prepreg has been injected with epoxy resin, which will melt when exposed to the pressure and heat of the lamination process. The layer pairs will be joined together when the prepreg cools.
To ensure the proper alignment of the circuitry on the various layers when putting the board together at this step, much care must be used. The sandwiched layers are laminated when stackup is complete, and the pressure and heat of the lamination process will fuse the layers into a single circuit board.
Step 4. Holes Drilling
Drilling through-hole vias, non-plated holes for mechanical characteristics, and holes for component mounting are the following steps in PCB construction. In order to accommodate plating, the majority of the thru-holes used in a circuit board are typically drilled 0.005″ bigger than the required final hole size. Any laser-drilled microvias or blind and buried vias that are present in the design are constructed prior to the board being laminated. The additional manufacturing stages for these vias may increase the cost of the board but may be necessary for electrical performance or dense circuitry.
Once holes have been drilled, they are cleaned using mechanical and chemical procedures to get rid of drilling debris and glue stains. Then, a thin coating of copper is chemically deposited over the board’s whole exposed surface, including the interior of the holes. In the following stage, more copper will be electroplated onto the surface and into the holes to produce a metallic basis.
Step 4. Outside Layers creation
The circuitry images for the board’s top and bottom may now be printed. The circuitry has to be exposed and plated with extra copper to do this, using the same photoresist as with the inner layers.
- A sheet of photoresist material entirely covers the top and bottom surfaces of the board, including the plated-hole drill holes.
- Contrary to the inner layers, all of the board’s surface regions are revealed when the photoresist is exposed by UV or laser, with the exception of the circuitry designs.
- The circuitry designs of bare copper are electrically plated with more copper to increase their metal weight after the unexposed photoresist has been chemically removed.
- The remaining portion of the board’s photoresist is then scraped away in order to prepare it for etching. After that, tin is protectively plated onto all of the copper circuitry.
- All of the copper on the board is etched away, leaving just the tin-protected metal circuitry sections.
- After the tin has been removed, the copper pads, traces, and thru-holes are left intact.
The board’s circuitry is finished at this stage, but there are still a few steps to do to finish the board’s construction.
Step 5. Solder Mask printing, Silkscreen marking, and Surface Finishes
The solder mask material is placed using a UV exposure procedure identical to how the photoresist was done in order to protect the board during assembly. All of the board’s surface will be covered by this solder mask, with the exception of the metal pads and solderable features. Component reference designators, additional board marks, and the solder mask are silk-screened onto the board. The circuit board is baked in an oven to cure the solder mask and silkscreen ink.
The exposed metal surfaces of the circuit board will also receive a surface treatment. This aids in the soldering process during assembly and helps to preserve the exposed metal. The surface finish of hot air solder leveling is one instance (HASL). The board is dipped into a bath of molten solder after being initially covered with flux to prepare it for the solder. A high-pressure burst of hot air is used to smooth the solder on the surface of the metal and remove excess solder from the holes as the board is taken out of the solder bath.
Step 5. Inspection
The preparation of the circuit board for assembly is done at the last stage of PCB production. The panels are readied for breakout following assembly or, if necessary, the circuit boards are routed out of the manufacturing panels. This is accomplished by either routing the board except for the little breakout tabs or scoring a V-cut on the board’s outline.
The completed board is put through continuity testing using automated test tools like a flying probe test system or a bed of nails test fixture. Testing looks for any accidental shorts between nets that might render the board useless. The board is transported back to the PCB contract maufacturer for component assembly when testing is finished and inspections are successful.
How to Choose the Best PCB fabricator?
Selecting the ideal printed circuit board fabricator is not always simple.
After the PCB design has been created, the board has to be built, which is often done by a specialized PCB fabricator.
Selecting the proper PCB manufacturer can greatly simplify the process, but picking the incorrect one might cause significant problems.
It is time well spent to do some study on the various PCB manufacturers, but it frequently helps to have some guidelines and judgments.
1. company ability
It is important to match the PCB fabricator’s capabilities with the anticipated quantity of printed circuit boards that will need to be provided. It might be that only few prototype PCBs are needed, or it could be that just a small number of production runs are required. In some situations, it could be necessary to use a lot of PCBs.
A small business that is typically set up to produce prototype PCBs or small production quantities of PCBs may be easily overwhelmed by a large order. Conversely, a company that is set up to manufacture huge quantities of PCBs for large production runs will not be able to accommodate small quantities.
It is worthwhile to attempt to match the requirements with the PCB fabricator’s capabilities.
2. Testing ability
Boards may be tested as samples by higher grade PCB fabricators and manufacturers to ensure compliance. Verify that the business has the capacity to handle this in the required manner.
3. quality Materials
Where the materials are obtained will be an important consideration for many businesses wanting to choose the best PCB manufacturing.
Some low-cost fabricators could seek for the lowest sources for their ingredients, which could lead to inconsistent boards that operate differently from batch to batch.
Lead, mercury, cadmium, and a few other hazardous compounds that are prohibited from use in manufactured electronics, as well as a few additional fire retardants, are likely to require board-specific laws that regulate their usage.
4. Efficient communication and coordination ability
the capacity of a corporation to cooperate and create a partnership is another crucial component. It is tough to measure, but if the PCB fabricator can collaborate with the design and assembly teams, this may bring about considerable benefits and can be a key consideration when choosing the best PCB fabricator.
Cooperation between parties may help problems get handled more quickly, can assist offer input on how to enhance workflow and productivity, and can be advantageous to both sides in many ways.
5. avoid selecting brokers
Many of the so-called PCB manufacturers are really just brokers that collect orders and then pass them on to a firm to build, which could surprise you. Be careful since it might not be able to ensure the requirements and standards that should be listed on the board.
Although some competent brokers might be able to put up a useful order, it is generally preferable to work directly with the PCB fabricator to guarantee that contact is possible.
6. lead time
The length of time it takes to produce a PCB might not always be a big deal. However, the majority of PCB assembly firms want boards by specific dates. When choosing a PCB fabricator, it is important to make sure that these dates can be reached.
While being able to depend on a PCB fabricator to stick to deadlines is helpful, having the capacity to provide boards quickly is also helpful. This is often done at a premium price, and if the turnaround time is too short, it could result in more mistakes.
7. Good cost
Cist is a crucial consideration. Making a product effective requires cutting costs, but caution must be used to avoid cutting expenses too much.
Although finding the best deal is always important, it has been stated that the ecstasy of a bargain is forgotten before the pain of subpar quality is fully endured.
To get the lowest price but for the essential goods, cost and quality must be balanced.
8. manufacturing ability
The first thing to check is if the PCB fabricator can adhere to the necessary requirements. Basically, they need to be able to accept the files in the formats that they will be given (normally, this shouldn’t be an issue since formats are generally standard) and produce a board that meets the necessary specifications, such as the required number of layers, type of PCB material, tolerances, special requests, etc.
To ensure that they are able to satisfy them all, it is essential to go through a thorough checklist.
9. PCB Quality
A crucial consideration in choosing the best PCB fabricator is quality. The term “quality” is ambiguous, undefined, and perhaps even a little abstract. It can refer to a wide range of things.
The PCB quality, however, primarily denotes that the board arrives as required and according to drawing – without defects.
After the major orders have been successfully obtained, the quality shouldn’t deteriorate and should remain high.
Why choose us?
one stop service
Since our founding in 2000, we have been one of China’s leading suppliers of professional PCB fabrication and assembly services to specialists, engineers, and manufacturers all over the world. With more than ten years of experience in the design, production, testing, and assembly of customized printed circuit boards, we can now offer a full range of services, including rapid PCB prototyping, circuit board manufacturing, PCB assembly, and component sourcing, all with a guarantee of high quality and reasonable cost.
You cannot afford to make any quality compromises when it comes to your printed circuit boards, which are crucial to the dependable, successful operation of your electronic components as well as the overall success of your manufacturing process. When you pick INTOPCB as your circuit board fabricator, you get a business with a ten-year history of offering top-notch PCB solutions to a diverse clientele. Quality is our primary focus throughout every stage of our business, including PCB design, production, and assembly.
We adhere to the strict quality requirements that are applicable to every aspect of our business, which is one of the main reasons why we are a favored PCB fabricator for clients from across the world. For instance, although our proto boards are produced to attain IPC1 compliance, our standard PCBs adhere to the strict IPC2 quality standard. Our assembly services also satisfy the IPC3 standard’s requirements. We adhere to quality management systems that are completely compliant with ISO 9001, TS16949.
To ensure the quality of our procedures and PCBs, we take a number of proactive measures. Prior to production/assembly, our technical staff reviews each PCB design to make sure there are no innate faults and that the design complies with the client’s particular requirements. We go above and above by doing a Design for Manufacturing (DFM) test at no extra cost. Before sending the final product to your site, we also have a full quality control department on staff to carry out thorough inspections and testing, including Electrical Test, Automated Optical Inspection (AOI), Automated X-ray Inspection (AXI), etc. Your PCB’s performance and quality are completely reliable.
Full Turnkey PCB Assembly is a service we provide, and it entails PCB fabrication, component sourcing, and PCB assembly. Your productivity and cost-effectiveness will increase as a result of not having to handle several vendors across varied schedules thanks to our one-stop service. We can deliver a quick and individualized service that larger businesses cannot match since we are a medium-sized business that is completely sensitive to our clients’ demands. Our outstanding client satisfaction record is evidence of our capacity to wow.
We aim to provide seamless and effective customer care together with the highest quality PCB services and the best trade experience. In our more than ten years of business, we have learnt how to service our clients and do it effectively. Each year, we deal with thousands of part numbers.