How to design a PCB( Printed Circuit Board ) ?

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Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. Rub-on dry transfers of common component footprints increased efficiency. Traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout. To fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coated on the blank copper-clad boards.

Nowadays PCBs are designed with dedicated layout software, generally in the following steps:

1.Schematic capture through an electronic design automation (EDA) tool.

2.Card dimensions and template are decided based on required circuitry and case of the PCB.

3.The positions of the components and heat sinks are determined.

4.Layer stack of the PCB is decided, with one to tens of layers depending on complexity. Ground and power planes are decided. A power plane is the counterpart to a ground plane and behaves as an AC signal ground while providing DC power to the circuits mounted on the PCB. Signal interconnections are traced on signal planes. Signal planes can be on the outer as well as inner layers. For optimal EMI performance high frequency signals are routed in internal layers between power or ground planes.

5.Line impedance is determined using dielectric layer thickness, routing copper thickness and trace-width. Trace separation is also taken into account in case of differential signals. Microstrip, stripline or dual stripline can be used to route signals.

6.Components are placed. Thermal considerations and geometry are taken into account. Vias and lands are marked.

7.Signal traces are routed. Electronic design automation tools usually create clearances and connections in power and ground planes automatically.

8.Gerber files are generated for manufacturing.

For further detailes, please contact wonderful09@wonderfulpcb.com.

How to customize a PCB ?

As a customer of PCB industry, you may often ask: How can I customize a PCB board? Why can’t the PCB manufacturer ( or PCBA manufacturer ) follow my requirements?

Actually, you should ask yourself first: Have I got a design document?

Well, to customize a PCB board, you need to offer a design document first which is called a “Gerber file”, it is used to describe your requirements for the PCB board you’d like to customize.

What will be contained in a Gerber file?

① Layer count
② Delivery size
③ Surface finished (such as: HASL, ENIG)
④ Material (such as: FR1, FR4,FR2, CEM-1)
⑤ Board thickness
⑥ Copper thickness
⑦ Solder mask

Items above, they make it each other possible. Otherwise, it may cost engineering problems.

Is it absolutely necessary to have a Gerber file?

Fortunately, it is not if you happened to have a sample PCB board and want a large number of that. You simply send the sample PCB board to the PCB manufacturer works for you, and then all you need to do is enjoying a short wait until the PCB manufacturer send back a host of PCBs, each one of which is the same as the one you send to them.

For PCBA, a BOM list ( BOM-Bill of material ) is necessary during customization.

Pay attention that you should make sure the list providing as many details as possible about the used materials. Otherwise, it may cost engineering problems.

In conclusion, if you want to customize a PCB board or get some PCBA services, you need to find a high quality, experienced PCB manufacturer or PCBA manufacturer and offer your Gerber file, sample PCB board, or BOM list as your requirements.

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The deep BAF process for PCB waste water (3)

3.2 BAF impact on the rest of the water quality indicators

3.2.1 wastewater pH changes

raw water after the factory original coagulation precipitation process preliminary treatment, when entering the BAF system average pH 9.0, basic on the verge of overweight and direct emissions may be the cause of river pollution, soil alkalization, etc. Using BAF process, due to the microbial nitrification system consumes basicity (mainly NH4 +) in waste water, the water pH basic remain at around 7.9, standard ensures water at any time.

3.2.2 the change of ammonia nitrogen in wastewater

Wastewater after treated with BAF system declined, of ammonia nitrogen in water by 19.86 mg/L fell to 13.89 mg/L, but has yet to reach discharge standards, this is due to the best of nitrifying bacteria, proliferation and survival temperature is 25 ℃, while during the experiment system in a row after the water temperature maintained in 11 ~ 16 ℃, under the temperature of BAF in the growth and activity of nitrifying bacteria is restrained, resulting in poor ammonia nitrogen removal efficiency.

3.2.3 waste water in copper complexing state changes

The copper ammonia wastewater mainly complex ion (Cu (NH3) 2 + 4) exist, Cu2 + is very little.BAF role to eliminate the Cu complex in from [Cu (NH3) 2 + 4) isolated Cu2 +, OH - from their response to that of the wastewater generated Cu (OH) 2 precipitate, which was BAF biological flocculation adsorption.

BAF process in the wastewater Cu complexing state overall declining (1.40 mg/L to 0.82 mg/L), but the water was not up to standard. This is because the BAF nitrification and the Cu (OH) 2 is the best temperature flocculation adsorption 20 ~ 30 ℃, and the system straight into the water after the water temperature maintained at 11 ~ 16 ℃, seriously inhibit the adsorption of biofilm activity, lead to the removal of Cu effect is not very ideal.

4. Conclusion

(1) using the depth of the BAF process a printed circuit board factory PCB wastewater treatment, when the water COD load of 0.12 kg/(m3 · d), average inlet COD is 187.8 mg/L, the process average effluent COD can be dropped to 41.8 mg/L; When water COD load up to 0.36 kg/(m3 · d), the average COD water can also fell to 42.1 mg/L, fully meet the local relatively strict wastewater discharge standard requirements.

(2) Because the backwash water quality to suit the requirements of discharge standards, emissions should be to adjust the pool to processing. Backwash cycle is about 15 d.



(3) During the experiment temperature is 11 ~ 16 ℃, BAF in the growth and activity of nitrifying bacteria is restrained, flocculation adsorption activity of the biofilm, ammonia nitrogen and complexing state Cu removal effect is not very ideal. Need to consider to take corresponding measures to improve the filter water temperature or appropriate to ammonia nitrogen in water and Cu for further processing.

PCB Replacement and Repair

The world is changing and technology is always changing too! But sometimes there are certain components which need some minor tweaks and changes to last even longer throughout the years. This can even happen with a client's manufactured electronic products when they need to be upgraded to a newer manufactured device.

When this happens, your manufacturer can help with the entire process of helping all of your clients to prevent sluggish PCB systems. However, there are other reasons why a PCB needs to be repaired, other than having to upgrade the entire system.

Wonderful PCB (HK) Limited is a professional PCB manufacturer with assembly line in house. It provides high quality PCB with good after-sale service. In face of complainant from clients, Wonderful PCB provides completed after-sale service including PCB replacement or repair.

Saving Time, Money & Repairing Defects

When you're going to ship out huge batch orders of units, sometimes taking the extra time to keep account of all of the components and making sure that every single component are finely assembled on the PCB board. And make sure every single one doesn't have a defect which can be very time consuming. However, you can save time from having to recall certain parts or dealing with defunct PCBs by Wonderful PCB when they can correct a design flaw to make sure PCB-repair the system isn't running slow.

This is also good for you, because it means your own clients utilizing PCBs won't be complaining about sluggish systems that can cost them time and money too. You can also implement cost effective solutions when a PCB manufacturer needs to be repaired, which can mean not having to replace an entire batch order and do a complete redesign simply because of a minor defect that can be repaired by the manufacturer.

New Software, New Repairs

When your PCB components and software are due for a brand new update, please don't worry more about it: Wonderful PCB can take care of everything. Sometimes software on the PCB can become slow and sluggish when it is new and the platform it is running on is older than the software itself, making it frustrating for all parties involved.

You or your clients using the PCB components need to stay up with all of the latest software, especially when everything is becoming so fast paced in the technology industry as is. PCB board repair can ensure that everything is fast, highly responsive, and in working order with the best components available on the market.

However, PCB repair and replacement which does mean that the entire batch order will need to be repaired in order to ensure that the software continues to run seamlessly and smoothly. This can take some time to do with bigger orders, but like mentioned earlier, the investment in PCB repair services creates better time management in the long run.