PCB Assembly

TURNKEY, CONSIGNED & PARTIALLY CONSIGNED ASSEMBLY

PCB Assembly Manufacturing Design Tips

CHOOSING BETWEEN ROHS (LEAD-FREE) OR STANDARD (LEADED) SOLDER

Sierra is able to produce both RoHS and Leaded Solder boards. In terms of rework and removing components,leaded solder is easier to deal with. It also offers a cleaner, shinier finish.

RoHS is used most frequently when shipping to Europe. As RoHS and Leaded solder temperatures are different, boards must either be completely soldered with RoHS or Lead. This includes BGAs. Non-RoHS components can withstand RoHS process. Avoid mixed process; that is, mixed solder. For example, a standard HASL bare board should not use a RoHS assembly process. Learn more about RoHS and Lead-Free PCBs.

Water Clean

Aqueous clean process uses water soluble flux during soldering. The board is cleaned using water. This process yields shinier solder joints and an overall cleaner looking PCBA, without any flux residue.

Use No Clean Flux only if your PCBA has some parts (batteries, microphones, speakers, relays, etc...) that can be damaged if submerged in a water wash. No Clean Flux leaves flux residue on the finished PCBA; however, flux is non-corrosive and non-conductive.

If a few components are water sensitive, you may choose to have the PCBAs processed with water soluble flux without initially soldering the water sensitive components. Make sure include specific instructions to hand solder these few components after cleaning with No Clean Flux.

SILKSCREEN

If silkscreen for assembly is not provided, full assembly drawing is required. While we assemble boards without silkscreen, we will have to bypass inspection. Errors may occur.

Placement (X-Y) Centroid Files

If you do not send centroid files with you CAD data, we can extract them for an extra fee.

SHORTAGES

Kit audit reports are given within 24 hours.

FIDUCIAL

1mm circular pad on board. Ideally, three anywhere on board -- as far away from each other as possible. They should not form an isosceles triangle. For arrays, it's preferred that they are not on rails.

MOISTURE PROCEDURE

Inspect parts indicators: whether parts are usable straightaway. If they are not, Sierra Circuits uses a baking procedure to remove all moisture.

PASTE LAYERS

We will use customer-supplied paste layers, when present. If they are not provided, we will create them. When creating paste, Sierra Circuits does not require customers' approval before usage.

MULTI-PART ASSEMBLY ORDERS

Generally, we do not allow multi-part assembly orders. For an acceptable multi-part assembly order, combine BOMs and Centroid Files, and make sure reference designations are not duplicated.

SUBSTITUTIONS

Sierra Circuits will notify and seek approval from customers before making substitutions for components.