The contents of this repository comprise all the necessary files for the production and assembly of b-parasites. Typically, the fabrication process involves placing an order with a company capable of manufacturing the PCB and performing surface mount technology (SMT) assembly, which consists of mounting various components such as capacitors, resistors & oscillators. This page overviews the required files, functions, and locations.
PCB manufacturing headaches are universally disliked, but there are numerous steps you can take to ensure a smoother production process. By adhering to the following printed circuit board production advice, you can reduce costs, minimize production faults, and enhance the overall quality of your PCBs.
If you have never ordered Printed Circuit Boards for the product before, the process can be pretty daunting.
If you are delegating your electronics layout to an outside engineer, they will typically handle most of this process for you. However, if you plan to undertake this task independently, you will quickly realize that numerous intricate terms & specifications require your comprehension.
Regardless of your approach should possess, at the bare minimum, a fundamental comprehension of the prerequisites to order new PCBs.
This article aims to dissect all of the specifications & terms to assist you in comprehending the different tradeoffs.
While certain manufacturers may employ unique terminology for these specifications, most will apply universally, regardless of the location where you order circuit boards.
Basics of Ordering Printed Circuit Boards
Creating a fully functional PCB comprises two primary phases: the production of the bare board and the subsequent soldering of all the elements. This article categorizes all the diverse specifications into two stages.
To order the printed circuit board fabrication for the bare boards, you must provide the producer with Gerber files, which are made from your printed circuit board layout software.
To facilitate the printed circuit board assembly process, you must provide the manufacturer with a BOM that contains a comprehensive list of all the components. Additionally, a file must be submitted, which includes the exact coordinates of each element that will be employed to program their soldering device. Your printed circuit board layout software creates these files.
PCB with Components
Standard Specifications
- Board type: Typically, you will opt for “single pieces” when placing your order. PCBs are not created individually but produced in large panels with many copies of the circuit board. This approach allows for better production of smaller committees. Following the printed circuit board assembly or final testing, the boards on every panel are depaneled.
- In the majority of cases, penalization will not be a concern for you, as the producer will provide you with fully assembled PCBs that have been separated.
- Different Design in Panel: It is feasible to consolidate various boards on the already present panel. Whether your product necessitates multiple boards, you can place them all on a single panel to reduce costs. However, there is an extra charge for a discussion with diverse board designs.
- Size: If you are ordering single pieces, the dimensions of the PCB are a crucial factor in determining the printed circuit board cost. Alternatively, if you order panels, the panel dimensions will play a significant role.
- Quantity (single): Commence with five boards for your initial version, and gradually escalate the amount as the confidence in the layout improves.
- Layers: The number of routing layers utilized in your printed circuit board design is a crucial factor. Apart from a single layer, it is typically an even number. A basic PCB design employs 1 to 2 layers. Most moderately complex structures, such as those containing microcontrollers, require four to six layers. In contrast, more intricate designs, like those containing microprocessors, necessitate eight layers. The no. of layers directly impacts the price of the printed circuit board.
- Material: The base substance employed in the printed circuit board between stacked layers is the substrate. FR-4 is the most widely used substrate material, which is adequate for most layouts.
- FR-4 is available in various Tg versions, where Tg denotes the transition temperature. It indicates the temperature or heat at which the substance loses its rigidity and becomes more flexible. For most layouts, TG150-160 is the suitable choice without any additional cost. However, upgrading to TG170-180 results in a significant cost increase.
If your design comprises custom RF circuitry, including transmission lines, you may require an RF-specialized substrate material. The substrates from the Rogers R4000 series are widely utilized for RF designs. The R4003C substrate material is halogen-free and more eco-friendly compared to R4350B. Both materials exhibit comparable RF-related specifications.
If your design necessitates effective dissipation of heat, a substrate with a metal core may become imperative. This is exceptionally ordinary in high-power applications, such as LED lighting.
An HDI board is a type of printed circuit board that has a higher trace density, miniaturized features, and more layers than a commonly printed circuit board. This advanced technology is typically used for very complex or small layouts, and it can be considerably more expensive than a standard printed circuit board.
Buried vias and Blind vias are typically utilized when mini size is essential as they increase the cost of the board. In comparison, standard vias are PTHs, meaning they traverse through all layers, even if they are unnecessary on particular layers. Standard vias connect through all layers of the PCB, even when they are not required on specific layers, taking up extra space. Conversely, a blind via establishes a connection from an outer layer to the inner layer and is solely visible on one terminal of the ultimate board. A buried via connects between two inner layers and is completely invisible on a final circuit board. Both blind and buried vias are used when space is critical, but they significantly increase the board’s cost.
- Thickness: The board thickness is the final dimension of the PCB. The most commonly used density is 1.6mm. If space/weight is a critical factor, then a thin board would be preferred. On the other hand, if the strength of a circuit board is a concern, then a thicker board would be the best choice.
- Min track / Spacing: This refers to the minimum width of routing traces or tracks and the less space allowed between them, measured in miles. The standard minimum width is six mils, but in layouts where the area is essential, the minimum width may be reduced to 3-5 mils. However, going below six mils will significantly increase the price of the board.
- Min hole size: The minimum size of the hole refers to the minor diameter that can be pierced on the PCB. This is particularly relevant for creating vias that route connections between layers. A smaller hole size can allow for tight packing of elements and reduce the amount of space taken up by the vias.
- Solder mask: The solder mask is like a coating that is put on the top and bottom layers of the board to protect against oxidation and prevent solder bridges between adjacent pads. Although green is the most ordinary color, you can choose other options.
- Silkscreen: Silkscreen is the coating that allows you to add text and basic images, such as logos, to your circuit board. Its primary use is to indicate component identifiers.
- Gold fingers: If your board includes edge connectors, it is recommended to opt for gold plating to enhance corrosion & abrasion resistance.
- Surface finish: The surface finish is a coating that is put on the metal pads on the outside layers of the PCB to make it easier to attach components and protect them from damage caused by rusting. Previously, Hot Air Solder Leveling (HASL) was the most widely used surface finish, but it has now been replaced mainly by Immersion Gold (ENIG) due to its lead-free nature. Immersion Silver is also a non-toxic option for surface finishing.
- Via Process: Typically, the vias remain unsealed, but there may be situations wherever you need them to be shut. Tenting the via is the simplest & most cost-effective option, as it covers the via with a solder mask coating. However, tenting works best with minimum diameter vias.
- Sometimes, when Ball Grid Array packages are very close together, the tiny holes called vias near the chip pins can cause problems with soldering. This can result in bad connections between the chip and the circuit board. To fix this issue, the vias can be filled with a material to prevent the solder from being drawn away from the chip pins. This solution is more expensive but necessary in some cases.
- Finished copper weight: The copper weight measures how much copper is on each square foot of a circuit board. It tells you how thick the copper is. When we say 1oz of copper, the copper is 1.4 thousandths of an inch thick. In designs with a lot of power, thicker copper makes narrower paths for the current to flow through. This specification is essential for the outside layers of the circuit board.
- Inner copper weight: It is the weight of copper (as described in the Finished copper weight section) for the interior layers of the board. It is generally recommended to route significant current traces on the exterior layers of the board as they offer excellent heat dissipation.
PCB Assembly with Components
Standard Specifications
- Component sourcing options: There are three options available: Turnkey, Kitted, or Combo. Turnkey involves the supplier sourcing and providing all components, Kitted requires the customer to provide the features, and Combo is a blend of both Turnkey and Kitted options.
- Board type: This option determines whether the boards will be assembled individually or as some panel. If the board count exceeds twenty pieces or the board size is smaller than fifty million meters per side, penalization is recommended to optimize the production process for efficiency.
- Quantity:
- This refers to the number of PCBs that will be assembled separately
- The number of Unique Parts: This indicates the number of distinct elements that will require soldering on your PCB. For instance, if your layout utilizes five identical capacitors in different locations, it would be considered one unique element. This count encompasses every discrete chip, resistor, inductor, capacitor, connector, etc.
- Several SMT Parts: This refers to the number of elements necessitating Surface-Mount Technology. This count encompasses all components, not unique. For instance, if you have identical SMT capacitors, it would be counted as 5 SMT parts.
- Many Through-Hole Parts: This indicates the number of components necessitating the through-hole manufacturing procedure. PThs parts are infrequently used in contemporary electronic designs, except when a more robust attachment is required, like for the connector that will endure recurring forces.
Conclusion
Suppose you’re interested in ordering expertly created boards, whether in small numbers for prototyping or larger volumes for creation; my preferred manufacturers include PCB way, Seeed Studio & Bittele, located in China. For manufacturers located in the United States, I would recommend Sunstone Circuits Board.
While you also have the option of manually assembling your boards, I usually don’t advise it unless you possess advanced soldering skills. Most modern microchips are not amenable to manual soldering.
Another major drawback of manual soldering is that if you encounter issues with your layout, it can be difficult to distinguish between poor soldering and fundamental layout problems. By procuring boards & assembly services from an expert manufacturer, it will considerably make simple the testing and debugging of your layout.
While there are numerous technical things that you should be familiar with to place an order for PCBs, this article hopefully assisted you in comprehending those prerequisites more thoroughly.
