SA Electronics INC., USA BEST PCB SMT AND PROTOTYPE

SMT Assembly

Prototype PCB Assembly:

With prototyping, flexibility is the key. We can put just about any part on just about any board in as little as 24-hours. To do this, we give each prototype pcb assembly order personal.

Repeat Prototype Assembly:

Generally, we treat a repeat prototype assembly order the same as an initial prototype order. To maintain the maximum level of flexibility and responsiveness, we don’t develop and keep a specific process for prototype pcb assembly orders. Each one gets personalized attention.

Pilot Production:

A short run of boards assembled in a standard manufacturing process prior to turning on volume production. It is designed to ensure the reliable manufacturability of the boards. A pilot production run would typically be followed up with long-term volume production.

Short-Run Production:

Like a prototype, short-run production could be just a few boards to just a few hundred per month. It could also be a single run.

Volume Production:

Our volume production process is optimized for quality and cost. We offer electrical testing if requested.

Files We Need for SMT Assembly

Bill Of Materials(BOM) - We need a BOM listing the required circuit board and all component parts in Microsoft Excel or delimited format. Please highlight in red any components we will not be placing, or any parts that are not included in the kit. BOM should include: Part #, Reference Designator, Description, and footprint (package).

Gerbers- Please send us all gerber files generated by your CAD program, we will need these files for fabrication PCB.

Centroid data or Pick-and-place or XY data - This is the machine file, which should include: X, Y, Theta, Side of Board (Top or Bottom), and Reference Designator. If you cannot generate this file, we can generate from the gerber files.

Assembly Drawings - Are required for assembly, they do help to ensure all special PCB Assembly instructions are properly or PCBs have a silkscreen which indicates polarity and 1st-pin markings.

Components - We request 5 extra minimum for discrete parts(for 0402 and smaller we request 10 extra), for ICs, QFPs and BGAs we ask for 1 extra per components. We can place parts on cut tape of any length so there is no need to buy reels.

SA Electronics are the experts in protoype pcb assembly - as fast as 24-hour turn times. We can put just about any part, from tiny 0201 passives up to 1,700+ ball BGAs, on just about any board. And we can assemble your prototype with traditional lead-based solder or in a complete lead-free process.

SMT assembly is described as where components are to be placed, the printed circuit board normally has flat, usually tin-lead, silver, or gold plated copper pads without holes, called solder pads. Solder paste, a sticky mixture of flux and tiny solder particles, is first applied to all the solder pads with a stainless steel or nickel stencil using a screen printing process. It can also be applied by a jet-printing mechanism, similar to an inkjet printer.

After pasting, the boards then proceed to the pick-and-place machines, where they are placed on a conveyor belt. The components to be placed on the boards are usually delivered to the production line in either paper/plastic tapes wound on reels or plastic tubes. Some large integrated circuits are delivered in static-free trays. Numerical control pick-and-place machines remove the parts from the tapes, tubes or trays and place them on the PCB

The boards are then conveyed into the reflow soldering oven. They first enter a pre-heat zone, where the temperature of the board and all the components is gradually, uniformly raised. The boards then enter a zone where the temperature is high enough to melt the solder particles in the solder paste, bonding the component leads to the pads on the circuit board. The surface tension of the molten solder helps keep the components in place, and if the solder pad geometries are correctly designed, surface tension automatically aligns the components on their pads.

If the circuit board is double-sided then this printing, placement, reflow process may be repeated using either solder paste or glue to hold the components in place. If a wave soldering process is used, then the parts must be glued to the board prior to processing to prevent them from floating off when the solder paste holding them in place is melted.

After soldering, the boards may be washed to remove flux residues and any stray solder balls that could short out closely spaced component leads.

Finally, the boards are visually inspected for missing or misaligned components and solder bridging. If needed, they are sent to a rework station where a human operator repairs any errors. They are then usually sent to the testing stations (in-circuit testingand/or functional testing) to verify that they operate correctly.

Flex

Our Manufacturing and Engineering Teams have developed specific processes and procedures for flex circuit board assembly to closely monitor and control temperature exposure, handling requirements and storage conditions. Because flex PCB assemblies are so difficult to repair once damaged, we exercise extreme care and quality control during the manufacturing process.

Rigid/Flex

Rigid-flex PCB assembly requires special handling during the assembly process that is not normally encountered with a traditional rigid PCB assembly. Prior to actual assembly, our Engineering Team will review your design to make manufacturing and assembly recommendations based on component footprints, appropriate cover layer capture, and ideal stiffener support. For many flex assemblies appropriate panelization, and even pallet design, is crucial in order for the boards to be processed on our manufacturing equipment. It is preferred to engage with us during the early design phase to ensure the most cost effective and robust quality manufactured product.