4 Things Your Boss Expects You to Know About Keyboard PCBA


Background Keyboard PCBA

This project is a Keyboard PCBA. The customer is from Canada, and their company produces video game products.

Actually, in the beginning, the customer produced in other factories.But he said he was very disappointed with the sample.Many details were produced without being clarified.

Therefore, I choose to try my products for the second sample. There have been subsequent changes. Because the customer hasn’t decided whether the keyboard’s green axis or blue axis is yet to be determined, our company currently only provides SMT components.

In the assembling part, customers try different keyboard parts and think it looks like batches. Picture as below, is a beautiful white product:

white background

Keyboard PCBA feature


This is a 2-layer board with a size of 300*100mm. In order to be beautiful, the customer designs white ink and black silk screen.

The copper thickness is normal because it is the design change after the sample. So the surface finish process customers choose LF HASL. After the subsequent product design is stable, it is possible to choose immersion gold or the more commonly used gold plating for the key board PCB part.

As I said at the beginning, our company currently only provides assembly of PCB and SMT components. In order to try the diversification of the keyboard PCBA, the product customers in the picture below choose to assemble it themselves.

Keyboard PCBA feature


The first sample production of the product is black board, as shown in the figure below.Although the texture is good, SMT engineers recommend changing other color PCB because most SMT auto-mount machines do not recognize black.Therefore, the PCB of this sample production is changed to white.

black board

Keyboard PCBA-Production EQ

  1. On PCB part:

As shown in the figure below, the design of the edge welding plate is close to the circuit. Now, to avoid copper exposure, our engineer suggestion is: cutting copper is 0.45mm on one side when V-cut, and the shape routing is 0.25mm on the other side.

So the welding plate near the edge of the plate will be cut. Finally, it was recognized by the customer. The engineer of the customer said that there were too many things to consider in the design at that time and he didn’t pay attention to this problem point.The customer is very grateful and recognized our serious and responsible.

Production EQ


According to our experience, the customer will produce the sample for many times. Finally, the customer himself can not tell which batch of samples, what kind of design. So in order to facilitate the traceability of quality problems, we will add date code in PCB board (position is determined by client).


  1. SMT part Grape Ball


The customer designer commented that there were many small bubbles in the welding area of the previous product, which looked particularly ugly.Ask me if I can avoid this problem.In fact, this is a bad phenomenon of “grape balls” in welding.  What is the grape ball??


The phenomenon of grape ball refers to that solder paste is not fully welded, which makes the welding surface rough and uneven. As picture below.

Reason :

1.Grape balls occur when the flux cannot remove oxides from the surface of the printed solder paste.

2.The less tin is deposited, the easier it is to be oxidized. Therefore, it is easier for 0201 Chip to produce grapefruit phenomenon, so it needs a more active Flux.

3.Halogen-free materials also tend to produce grape ball solder joints.

4.Low temperature solder paste profile is not correct, also easy to produce grape ball phenomenon.

Use the following methods to improve the grape ball phenomenon:

  1. Appropriate use of active solder paste when producing small parts.
  2. Appropriately increase the opening width of steel plate. the opening width increases the volume of flux . The amount of solder paste during printing. so the antioxidant capacity also increases accordingly.

The reflow profile has a heating slope of >1℃/s. When the heating slope is less than 0.7℃/s.the Flux will lose its activity because of the heating time is too long, which greatly improves the probability of producing middle grape ball phenomenon.


steel platesteel plate-


  1. BOM part

The final pre-production problem was that the number of Designators on the BOM was less than the number on the QTY. But the customer forgot to add them.



The customer received the sample and is currently testing it, but soon gave me feedback on their new idea. They want to add a switch to the right arrow below.


The customer’s engineers are so confident in our productivity and resilience that they have started to design another new keyboard.The PCBA.As shown below, the shape is also different from the normal one.

pcba keyboard


The next order may replace the surface finish process, but the customer is concerned about the stability of the welding.I told him that we provide Solderability test

Solderability testing is generally used to make a qualitative and quantitative assessment of the solderability of components. printed circuit boards, solder and flux.


Electronic Product

In the assembly welding process of electronic products, the welding quality directly affects the quality of the whole machine. Therefore, in order to improve the welding quality, in addition to strictly controlling the process parameters. It is also necessary to conduct scientific solderability tests on printed circuit boards and electronic components. The following picture is what it looks like after the test.


Through the implementation of solderability testing, it helps enterprises to determine the quality of solderability after production and assembly and the quality of products.

In practice, micro-spectrum technology has further enriched the solderability test techniques for printed circuit boards other components. clarified the internal factors that affect solderability. Improved product quality and zero defects for technical engineers in the manufacturing industry.


The welding process has given great help..The client was very surprised and said it was an honor to meet us.


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