PCB Technical - The most easily lost information when requesting a PCB quotation

Once the board designer is ready to design, the next step is to find a manufacturer to turn it into a finished product. To manufacture the circuit board, an estimate or PCB quotation is required. The main purpose is to manufacture and assemble circuit boards with the least cost and process steps.

Only when the PCB designer provides all the important information related to the specific board, the manufacturer can give an accurate quotation. Let's take a look at the basic information that is often missed when requesting a quote.

What is PCB quotation?

The PCB quotation is a general estimate, describing the time, cost, and ability of the manufacturer to convert the submitted design into a physical board. It is not necessarily related to the manufacture of individual circuit boards. A quotation for information related to PCB design, manufacturing or assembly can be requested.

What is the quotation for the prototype board?

Most contract manufacturer (CM) websites have a section for requesting quotations for prototype boards. This provides the option to obtain prototype PCB information. These types of circuit boards are used to check whether the concept/design is valid. Usually, the timetable for prototyping is shorter and the turnaround is faster. The number generated during the prototyping process is generally 5-10.

How to get an accurate PCB quotation

The quotation from CM is not only information indicating the cost of the number of circuit boards required, but also provides ideas about the manufacturer's time requirements and capabilities to include all the technologies involved in the circuit board design.

The accuracy of the quotation simplifies the manufacturing process. In order to make the process faster and without delays, it is best to include all the necessary details at once. If any important information is missing, the CM will have to contact the designer. During this communication, the order will be suspended. If the order is placed on hold for too long, some internal manufacturing deadlines may be missed. Therefore, production may take longer than estimated.

The key information required for an accurate quotation is as follows:

Board type (rigidity, flexibility, rigid-flex combination, etc.)

Number of layers

Board size

Material

Minimum hole size

Number of holes

Minimum trace width

Minimum spacing between traces

Outer copper finish

Ring requirements

How to create a circuit board design quote

When the requester does not have the ability to design the layout or does not have sufficient resources, a quotation for PCB design (schematic and layout) will be presented

You can add up to 5 files when quoting design services. Usually, the important files uploaded are BOM, schematic, circuit board outline and mechanical details (DXF files). You must also write down the design requirements. The design service quotation will include PCB design cost and estimated time frame.

From the design service, you can expect the following:

Expected results of PCB design services

Selection of design tools: CM also provides a variety of design tools for customers to choose from. The selected tool will be used to create the schematic and all other design-related files.

Selection of PCB design tools

Schematic: When submitting a quotation, any rough schematic can be added, and then the design team will convert it to the preferred CAD format.

PCB schematic

Reduce costs: The manufacturer will focus on the submitted design work and optimize it to reduce costs and improve process efficiency.

Reverse engineering: Various CMs provide the option to create all design files for the new PCB based on the detailed information of the existing circuit board upon request. These details can be bare boards, filled boards, or just design documents or drawings. The designer must specify the difference with the existing circuit board, and accordingly, a new design file will be generated.

How to get a quotation for PCB manufacturing services

Documents required for PCB manufacturing quotation

For manufacturing quotations, the following documents are essential:

Gerber files with English units in RS-274X format or ODB++ format. These files should be generated for each circuit board layer.

Manufacturing printing/drawing (Gerber format), should include circuit board outline, drilling pattern and hole size.

Excellon drilling file (ASCII format), which contains detailed information such as units, tool units, coordinates, and number formats.

A Readme.txt file containing detailed board and file information and layer stacking information.

The IPC netlist describes a list of nets for establishing a conductive interconnection scheme for circuit boards.

How to request a PCBA quotation

Circuit board assembly quotations generally require the following documents:

The BOM file is necessary for CM to understand and obtain an estimate of component pricing.

Gerber/ODB++ files are essential for PCB manufacturing and assembly. It provides information about each layer of the circuit board.

An XY position data file and component layout help together with assembly drawings.

The top 6 most frequently lost data during the inquiry period

Although most designers are careful in providing all the major details discussed above, some people may miss some minor details. These details are also important for calculating total cost and time estimates and should be submitted when requesting a quotation (RFQ). The general omissions are as follows:

1. Solder mask details

In addition to clicking "Yes" for the solder mask, there are some basic details that need to be shared with CM. These details include:

Solder mask (top, bottom or top and bottom)

Solder mask type (LPI-liquid light imaging)

Solder mask color (green, blue, black, red, white or transparent)

Solder mask finish (semi-gloss or matte)

2. Surface treatment

The type of surface finish on the board is used to affect its operation. Commonly used surface treatments include hot air solder leveling (HASL), electroless nickel immersion gold (ENIG), electroless nickel palladium immersion gold (ENEPIG) and so on. Therefore, if it is not specified correctly, the wrong surface treatment type will have a negative impact on PCB efficiency. This is an important detail that is often missed when requesting a quote.

3. Silkscreen

Another detail that is often overlooked is screen printing. Just like the solder mask, it is not enough to click "Yes" in the silk screen options. You should also answer questions about whether you need double-sided and what color is needed.

4. Impedance details: The controlled impedance requirements of the circuit board determine the choice of various parameters. Therefore, if it is not provided, the quotation will be delayed.

5. Stacking details: the number of layers, the stacking sequence, the thickness of each layer, the total thickness of the stack, etc., are all details about the stacking and should not be missed.

6. Opening: Any opening on the board that is not mechanically drilled is called an opening. The size and position of the cuts are also part of the information provided when requesting a quote.

How to avoid delays in the circuit board quotation process

Sometimes, quotations for PCBs designed, assembled, or manufactured may be delayed from the manufacturer's end. There are some common reasons for this to happen:

Damaged or missing files

Any of the following important information is missing from the fab drawings/prints: material type

Finished board thickness

Circuit board shape and size

Cutout/slot details

Differences between fab drawings and Gerber files

Undefined board structure

Lack of surface treatment details

No drilling file provided

Gerber files are not scaled one-to-one

Drill file is not in ASCII format

The hole is gone

Missing layer stacking information

Plated holes and non-plated holes are not clearly defined

Missing aperture list

Plane layer without thermal connection

All plane layers should be submitted in negative format (plane layer). The negative plane includes data including elements such as heat dissipation, anti-pad, and splitting. The data in the front plane layer will show copper features. Compared with the positive plane layer, the negative plane layer has the following advantages:

Reduce file size

Analyze faster

Reduce test time

There should be no polygons in the plane layer/signal layer, because the CAD program may miss filling these areas, resulting in poor circuit board function.

To reduce latency, it is recommended to provide an IPC netlist for boards that require electrical testing.

All the facts mentioned above provide a general idea of what should be included and what is usually missed when requesting a board quote. Small negligence will eventually become the cause of production delays. Therefore, the more accurate the quotation, the faster the circuit board manufacturing speed.