4 Layer - ProtoPro orders have a fixed price of    
    for 4 boards
(plus shipping)
  Manufacturing Specs  
  > ExpressPCB offers a choice of several manufacturing options, including two-layer and four-layer circuit boards. The specifications for each of these choices are listed below.  
4 Layer - ProtoPro Service
> Our 4 Layer - ProtoPro Service is a low cost choice for four layer boards, including the solder mask and silkscreen layers. These are the same professional quality multi-layer boards as our production service, but at a fixed price and quantity. They are shipped in just 3 business days.

Multi-layer boards have many advantages over double-sided boards. They can be designed more compactly, they greatly improve noise immunity and are much easier to lay out.

> 4 Layer - ProtoPro boards have top and bottom copper layers with a tin/lead solder plating over the pads. Sandwiched inside are Ground and Power planes. Through-hole pads can be connected to, or isolated from, the planes. These boards include top and bottom solder masks giving the boards a dark green color. On the top surface is a white silkscreen layer showing the component outlines and text.

ProtoPro designs must fit in a 21 sq-in rectangle and no dimension can exceed 12". With each order, we send you 4 identical boards.

> 4 Layer - ProtoPro orders have a fixed price of $195 (plus shipping).  
> With each order we will send you four identical boards.  
> Orders submitted Monday through Friday by 2:00pm ET are shipped in 3 business days.  
> Paying for your boards is easy by MasterCard, Visa or American Express.  
Manufacturing Specs
> Boards are manufactured with 4 copper layers and plated-through holes.  
> The quantity of boards made is 4. Other quantities are not available.  
> The board size must fit in a rectangle that is 21 square inches or smaller, and the longest dimension can not exceed 12 inches.  
> The minimum board dimension in height or width is 0.35 inches, however the total board area must be greater than 0.4 square-inches. (i.e. smallest square board we can make is 0.64 x 0.64 inches)  
> Our laminate is FR-4 with an overall thickness of 0.058". The two inner layers have a copper weight of 1 ounce. The outer copper layers have a finished copper weight of ~1.25 ounce.  
> The top and bottom solder mask layers are green LPI.  
> Pads on the solder mask layers are grown by 0.003" on all sides. As a result, very fine pitch surface mount components may not include any solder mask between the pins.  
> A white silkscreen is printed on the top side of the board showing component outlines and text. These features are automatically masked to prevent the white printing from overlapping on top of pads (or anywhere there is no solder mask).  
The board finish is the industry standard SMOBC with pads having a tin/lead solder plating. Lead-free is not available with our ProtoPro service.
> Etching resolution is: 0.006" minimum trace width, 0.006" minimum space width.
> Board perimeters are cut to shape using a 0.093" router bit. Slots in the perimeter must be 0.100" or wider. Narrower slots will not be milled correctly. Routing slots or holes in the interior of the board are not offered.  
> The edges of the board are cut with an accuracy of +/- 0.015". A minimum of 0.020" blank space is recommended between the perimeter and all features on the board. Traces placed closer than 0.015" to the board's edge may be routed off.
> Multiple circuits can be pasted together on a single board, but we do not cut them apart. The perimeter of a board cannot include long slots as they can cause manufacturing problems. We regret that we cannot be responsible for any defects that are a result of routing multiple circuits on a single board.  
> Twenty-four hole sizes are available: 0.008", 0.014", 0.020", 0.025", 0.029", 0.033", 0.035", 0.040", 0.043", 0.046", 0.052", 0.061", 0.067", 0.079", 0.088", 0.093", 0.100", 0.110", 0.125", 0.141", 0.150", 0.167", 0.192", 0.251". These sizes are the finished hole diameters after plating. The 0.008" and 0.014" holes may be filled with solder and can only be used as via. The tolerance for the 0.020" hole is +0.003 / -0.005. The tolerance for the other hole sizes are +/- 0.004". Hole sizes other than those list are not offered.  
> A minimum of 0.021" space must remain between adjacent holes. For example, the center-to-center distance between two pads with 0.020" holes must be 0.041" or greater.  
> The maximum number of holes per board is 650.  
> The dielectric spacing between the top layer and the "Ground" inner layer is 0.012" with a dielectric constant of 4.6 +/-0.2. The dielectric spacing between the bottom layer and the "Power" inner layer is 0.012" with a dielectric constant of 4.6 +/-0.2. The dielectric spacing between the "Power" and "Ground" inner layers is 0.028" with a dielectric constant of 4.6 +/-0.2.  
> The two inner layers are solid copper planes. Through-hole pads can either be connected to or isolated from these copper planes. The planes are inset 0.025" from each edge of the board.  
> We do not recommend that users cut apart 4 layer boards because this can result in shorts between the inner layers.  
> The maximum operating temperature is 125 degrees C.  
Pricing and manufacturing specifications are subject to change without
notice. Please check these pages for current information.
Intro to ExpressPCB Free CAD Software PCB Options Production PCBs PCB Design Tips
How it All Works PCB Layout Software Standard PCBs ProtoPro PCBs Resources
How Much it Costs Schematic Software MiniBoard PCBs 4 Layer-Standard PCBs Our Mission
Order PCBs Download CAD Software   4 Layer-Prod PCBs Contact Us