Custom PCBA Requirements: 12 Things to Specify Before Requesting a Quote
“I want a custom board” is not a quotable sentence. Not because suppliers are unwilling, but because too much is missing — how many interfaces, what dimensions, which operating system, how many units. Any one of those moves the number completely. Turning the requirement into a list is the fastest route from “let’s talk” to “we can quote.”
Why the List Determines Quoting Speed
Custom work has to be assessed by engineering, and the input to that assessment is the requirement. With gaps, the supplier can only quote on assumptions, the number will be wrong, and after several rounds both sides are exhausted. A complete list compresses quoting from five or six rounds to one or two — and it is also the precondition for not reworking later.
Group 1: Function and Interfaces (4 items)
1. Platform preference — a specified SoC or performance tier, or leave it to the supplier. 2. Interface list and counts — how many Ethernet ports, serial ports (and whether isolated), USB, display outputs, CAN, GPIO; this drives selection more directly than anything else. 3. Memory and storage configuration — minimum requirements and any ceiling. 4. Wireless and connectivity — Wi-Fi, Ethernet, cellular, plus antenna mounting.
The interface list deserves the most time. A board such as the 05A IPA-RK3588 工业控制主板 fits a wide range of applications precisely because the industrial interfaces — isolated serial, multiple Ethernet, CAN — are all present; if your needs fall inside that envelope, adapting an existing model is usually much faster than designing from zero.
The other common shape is a system-on-module: the SoC, memory and storage become a pluggable module while the carrier board is designed in-house or by the supplier. The advantage is that the carrier can be shaped freely around your interface needs while the compute part’s stability is guaranteed by the module itself. If that is the shape you need, a module such as the 01M-M-RK3588S 核心板 is the better starting point — once the module’s pinout and footprint are fixed, the carrier design’s boundaries become clear, and the engineering risk is far lower than redesigning a whole board.
Group 2: Mechanical and Structural (3 items)
5. Dimensions and mounting constraints — maximum outline, mounting hole positions, height limits (note heatsink and connector height especially). 6. Interface placement — which connectors must sit on which edge; this directly affects routing and stack-up. 7. Enclosure and mechanicals — whether a housing is needed, and whether an existing one is reused. These three decide whether tooling is required, and therefore whether one-off charges exist.
Group 3: Environmental (2 items)
8. Operating temperature range — commercial, wide, or more extreme; this drives component selection and the validation plan. 9. Supply conditions — input voltage range, DC or PoE, whether battery operation or power-loss risk applies. These two are the most consistently underestimated constraints: many designs satisfy the functional brief but only a few survive the environmental one.
Group 4: Software and System (2 items)
10. Operating system and version — Android or Linux, which version, and whether long-term maintenance is required. 11. Software deliverables — SDK, BSP, driver source, or simply a bootable image; whether system trimming, boot logo or preinstalled applications are needed. This item largely determines the scale of engineering effort and is one of the biggest drivers of price variation.
If the project also involves compute expansion — for instance adding a module like the RM182X M.2 2280 算力协处理器模组（20TOPS） — then the module’s interface form factor, driver support and thermal conditions belong in the requirements too.
Group 5: Commercial (1 item, but not optional)
12. Volume, cadence and target price — first batch size, projected annual volume, desired lead time, and whether there is a target price. Giving a target price is not “showing your hand”; it tells the supplier which direction to design towards. When target price and configuration are incompatible, knowing early is far cheaper than discovering it after the design is done.
Twelve items, and the requirement has become an assessable document rather than a paragraph. It need not be perfect first time — fill in what you know, mark the rest for the supplier to propose, and even that communicates far better than verbal description alone.
