Go Down

Topic: How To Check The PCBA Quote From Shenzhen PCBA Factory (Read 305 times) previous topic - next topic

makerfabs

When the project comes to PCBA prototyping& small batch production, the ShenZhen factories is a good way to cost-down and also shorten the lead time.

Of course, the first step is sending the production-related files, include the PCB Gerber file/spec,  and the BOM list, together with the quantity, to the PCB factory for quotation.Normally, the factory will make a PCBA quotation, based on:
1. PCB Cost.
2. Components;
3 . Assembly Cost;
4. Others, such as Testing/Programming/shipping, or your customized services.

1. PCB Cost


The PCB cost is mainly depends on the PCB main spec and area. Besides, the PCB cost also depends on the PCB quality needs, which differs a lot.
 
1. If your PCB design simple(2/4 layer) and do not have detailed request on stack up& impedance control, and some mirror drawback acceptable, there some Shenzhen "Express PCB" works, the price really good and quality remain OK. 

The price from JLC/PCBway/Seeed are good, they can even make the price to $0.99 for the most simple prototyping board (2 layer, small board) . I do not know how could them make the price so low, this should be business Competition, to get more customer for further orders.  For relative larger quantity, the price is depends on the final area, the unit price would be about $100/㎡(including all the fee such as testing fee/tooling fee) for 2 layers,  and $150/㎡ for 4 layer board.

2. If your PCB design relative complicated, more than 6 layers, or you have BGA designs/blind vias/impedance controlling, there the "express PCB" can't not be used. They need to be built by more "Industrial" PCB factory.  There the price would be higher especially the starting fee.  For a 2 layer PCB, the starting fee would be about $50, while maybe only $5 with "express PCB". But the price difference got smaller as the quantity goes bigger… for an order totally 100 ㎡, the price would be almost the same.

3. You need to check with your factory the very detailed spec of the PCB spec, to avoid misunderstanding, includes:
       ● PCB Material:  It would be bad mistake if  you want FPC but the factory quote/produce with FR4
       ● PCB Color: Normally it could be Green/Yellow/Black/White/Red, etc… the most popular used is Green… Personally, I like the Purple color, the OSH Park supports that with a good price.
    Purple PCB Board       Purple PCB Card
       ● PCB layer: Sometime, the inner layer with "Negative film" maybe ignored, check if the factory got your all right, or it may lead to serious problem.
       ● Other PCB spec such as thickness(can be 0.6/0/8/1.0/1.2/1.6..), surface polishing...

4. Lead time. Normally, for "Express PCB" prototyping, 2~3 days OK, while much longer with advanced PCB(normally >10 days) if urgently, ask them to ship the package to you with express shipping but not airmails…the shipping could be 2~4 days from Shenzhen to any place on the world.

makerfabs

2. Components
Double check your BOM before sending it to the factory, and recheck every single components quotation, this is not only ensure you get them get a reasonable price, but also ensures the factory get you all right.

The factory will quotes the components based on the quantity, normally, unit price drops a lot from prototyping to mass production, especially for some cheap connectors, the unit price for 1 pcs would be even 5 times that for 100 pcs.  Check every rows quotation to estimate if the price acceptable:


1. For resistors/capacitors, most of the factory will quote you as substitute items which should be very cheap(less than $0.01) But if you have special request, for example, you need to use a 0.1% resistor, the price would be much higher. Check if the factory price reasonable, if they also quote it as $0.01, it should be them ignored this info, reminds them your request. Of course, a parts number would be a very good way for this.

2. Ask the factory detailed list if they will use the accurate item that listed in your BOM, or some substitute items. Such as a diode, it may be produced by many producers, if you need the ON brand but other brands may not work, you should check if the factory quote you all right.

3. For most factories, normally they will quote the IC original brand, while the passive component with substitute items, if that not acceptable for you, ask them to update.

A final components quotation should be like this:

makerfabs

3. Assembly Cost

This is the core reason that PCBA produced in Shenzhen.  Normally, the factory quote the PCBA assembly as:

1. Starting fee. The starting fee depends on the soldering difficulty, include the components quality/ double side or single side. Arrange from $20~$50 normally.

2. Most boards include the SMD soldering and THT soldering…. for SMD soldering, the  unit price drops a lot as the quantity increase, for example, for 50 pcs, the unit SMD soldering fee would be $10, while for 100 pcs, the fee maybe $7, and even $5 when it comes to 200 pcs.  

3. For THT soldering, with small quantity, the factory may solder them manually, for bigger quantity, maybe wave soldering will be used, which will decrease the cost a lot.
But normally fixture needed for wave soldering.

A finally assembly quotation should be like this:

Go Up