Holiday Notice

Since China’s National Day is approaching, we’d like to inform you that we’ll have a seven-day holiday from Oct. 1st to Oct. 7th (GMT+8) during which your question or email may not be replied immediately. However, quotation or orders can be submitted online as usual.

In order not to get your manufacturing efficiency reduced, we strongly suggest you submit quotation or order in advance so that manufacturing can be done or started at least before our public holiday. We’ll be back at your service on Oct 8th.

PCBCart

Design PCBs to Better Take Advantage of PCBCart's PCB Assembly Capabilities

Never is there an easy way to embrace the conversion from idea to real products, but you deserve that as a creative and efficient engineer. PCBCart is able to assist you to complete this through providing high-quality and instant PCB assembly services. Our professional electrical engineers are always ready to conduct a quick yet careful check on your Gerber files and BOM so that your assembly manufacturing can be smoothly implemented with no defects or issues. When it comes to assembly confirmation items, together in accordance with PCBCart's over 10 years' experience, you should focus on aspects including spacing guidelines and fundamental requirement, part polarity, and footprint or package for assembly.

Spacing Guidelines and Fundamental Requirement

Spacing plays a critical role in determining the reliability of end products. Moreover, dimensions of our assembly equipment have to be taken into careful consideration so as to downsize failure risk of assembly. The following table details spacing guidelines and fundamental requirement, it covers leading ordinary assembly confirmation items that need to be checked by you prior to sending to us.

Confirmation Item Subcategories Specifications
Spacing 0402 and BGA ≥16mil
0201 and BGA ≥12mil
0603 and BGA ≥3mil
Component and internal shield ≥16mil
External edge of frame/cover and component pad (non-module design) ≥16mil
External pad and board edge (module design) ≥1.0mm
Manual soldered components and SMT components >2mm
Manual soldered components and label >10mm
Components mounted through adhesive and gold finger Ordinarily 8mm
Components mounted through adhesive and board edge Ordinarily 3mm
Between manual soldered component holes (pitch: 2mm) >0.88mm
Between ICT point and component pad >1.0mm
Between screw head and SMT components and soldering test points >2mm
Between shielding and nearest SMT component >0.3mm
Between shielding frame and nearest manual-soldered components >3mm
Connector Positioning holes Diameter should be 0.3mm larger than that of pins
Pin-in-paste connector Interference should never be acceptable.
Shield Shield frame or one-piece shield Thickness: ≥0.2mm
Positioning pins Unsymmetrical, Quantity: 2
Hole Diameter should be 0.3mm larger than that of positioning pins.
One-piece shield At least 4 holes that are not regularly distributed are required.
Shield frame or one-piece shield Material suggested to be copper-nickel-zinc alloy
Shield pad Segmental design; width: ≥0.6mm
Transformer Positioning pins Diameter of holes should be 0.3mm larger than that of positioning pins.
Footprint Compatible with lead
Components Components with polarity Should be indicated on PCB
Pin Diameter of component pins should be compatible with that of PCB holes.

Part Polarity

Apart from spacing guidelines and fundamental requirement, part polarity should be also designated in the silkscreen layer, which will help reduce the time taken for DFM checking of PCB assembly. Furthermore, it is better for the polarity to be visible, even after the parts have been soldered on board. The following table demonstrates some common part polarities.

Parts Polarity Markings
Tantalum capacitor Tantalum capacitor polarities for PCB Assembly | PCBCart
Tantalum capacitor polarities for PCB Assembly | PCBCart
Electrolytic capacitor Electrolytic capacitor polarities for PCB Assembly | PCBCart
Electrolytic capacitor polarities for PCB Assembly | PCBCart
Diodes Diodes polarities for PCB Assembly | PCBCart
Diodes polarities for PCB Assembly | PCBCart
LED LED polarities for PCB Assembly | PCBCart
LED polarities for PCB Assembly | PCBCart
Chips Chips polarities for PCB Assembly | PCBCart Chips polarities for PCB Assembly | PCBCart

Footprint or Package for Assembly

Footprint designed in the PCB file should be compatible with the part's package. This effectively means that the copper pads should be of the same size, shape and distance as those suggested in the part datasheet provided by the PCB manufacturer. Otherwise, problems such as empty soldering, cold soldering, less soldering etc. may arise, which can be shown in the following images.


• Sample Problem 1. This image indicates oversized copper pads causing components to shift after being mounted.


Oversized copper pads causing components to shift after being mounted | PCBCart


• Sample Problem 2. This image indicates too small copper pads eventually causing empty soldering.


Too small copper pads eventually causing empty soldering | PCBCart


• Sample Problem 3. This image indicates that component's pin is square while copper pads are round. As such, the hole is smaller than the components' pin, making it impossible for component to be inserted into the holes.


Different shape of component's pin and copper pads will cause trouble during PCB Assembly | PCBCart


Of course, the parameters or specifications displayed above in the table can never limit our capabilities and your design creativity. Therefore, if your design covers items beyond requirement mentioned above, just let our engineers know by leaving a note as you submit an order. We'll definitely try to meet all your design requirement.

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