Lead-Free and RoHS

 SUNNY PCB Provides Lead-Free Services including:
  • Lead Free Printed Circuit Boards
  • Lead free Assembly (SMT or THA)
  • Lead Free Wave Soldering
  • Lead-Free Materials Analysis

 

RoHS (Restriction of Hazardous Substances) is a European Union directive that restricts the use of lead, mercury, cadmium, chromium (VI), PBBs, and PBDEs in electrical and electronic equipment as of July 1, 2006.
Simply put, RoHS stands for Restrictions of Hazardous Substances.  Often, the term RoHS and Lead-Free are used interchangeably, but this is not technically correct as the restrictions include the six following items and the allowable maximum concentrations:
  • Lead .1%
  • Mercury .1%
  • Cadmium .01%
  • Hexavalent chromium .1%
  • Polybrominated biphenyls (PBB) .1%
  • Polybrominated diphenyl ethers (PBDE) .1%
Lead is the only RoHS-banned substance; therefore lead-free products are also RoHS compliant products. 
SUNNY PCB has a comprehensive lead-free solder solution. Our team has studied every aspect of lead-free solder, including solder alloy selection, solder paste evaluation, design rules, components evaluation, reliability, equipment evaluation, quality inspection and production costs. We have worked actively with industry standard organizations to facilitate the industry-wide transition to lead-free products.
SUNNY PCB Provides Lead-Free services including :
  • Lead Free Printed Circuit Boards
  • Lead free Assembly (SMT or THA)
  • Lead Free Wave Soldering
  • Lead-Free Materials Analysis
Our Lead free MCPCB assembly service utilizes special assembly procedures to assure compliance with Lead-Free and RoHS PCB assembly standards. In addition to lead free PCB assembly, we also provide support to you the transition of RoHS compliant circuit boards.
We not only assemble lead free boards but also assist you to determine if the materials in your Bill-of-Materials meet lead free PCB manufacturingrequirements. We can even search lead-free components for you and send you a Bill-of-Materials with the appropriate components as part of our Turn-Key lead free proto assembly service.

 

Lead Free SMT Assembly Process

The lead-free prototype process also requires that boards be assembled at higher temperatures—usually 30-50 degrees C higher. The higher temperature may require that the substrate of the circuit board itself and various components be modified to withstand the higher temperatures in the oven. In addition, the IC moisture sensitivity level that indicates how long the board can be exposed to the air is approximately 2 classes higher for lead-free boards, so there can be increased moisture sensitivity. The shelf life of the materials used in lead-free boards may also be shorter.

Bill-of-Materials, Board Finish and Components Analysis

It is better for customers to verify that the Bill-of-Materials is correct for lead-free parts. For Consigned material or components, We can also consult with you if you need help in determining if your board and components meet the requirements. If bom is created by us, SUNNY PCB ensures that all are lead free.

Board Stencil and Solder Paste

SUNNY PCB begins the assembly process using a lead-free compatible circuit board and applying a stencil to the board. A lead-free compatible solder paste alloy called SAC305 is applied. The SAC305 solder alloy is used in SMT, Wave Solder and Wire (Hand) soldering processes. After soldering, the board is visually inspected for solder coverage and manufacturing acceptability.

Placement of Components

The next step is placement of parts using a Pick-and-Place machine. The parts that are placed are based on the supplied Bill-of-Materials. Each part has a unique part number assigned to it. When a product is programmed to run on the SMT equipment, the part is assigned and the machine will then pick the correct part. Any component on the board must be lead-free process compatible. These components must be able to withstand the higher solder and manufacturing process temperatures.

Thru Hole and Manual Solder

SUNNY PCB can also perform Thru Hole and Hand / Wire soldering of lead-free boards. Lead-Free Pass Thru and Hand soldering will be performed in areas with no leaded parts. We will use lead-free solder and a lead-free soldering iron.

Placing Board in the Reflow Oven

The final step is placing the board in the oven where the solder paste is melted to form a metallic bond between the component and the circuit board trace. Lead-free and RoHS compliant boards must be processed at higher temperatures in the reflow oven. The process margin (window) is smaller which makes thermal profiling more important for lead-free circuit boards. It is helpful for profiling to have the following: board thickness, board finish, size of the board, and layer count. SUNNY PCB control the higher temperature reflow soldering processes and track thermal profiles required for lead-free boards.

Profiling

To ensure proper oven reflow temperature profiling, we ask for one additional lead free pcb along with an extra set of any temperature critical parts;  These can be actual parts, non-functional actual parts or thermally equivalent dummy parts. Most manufacturers of large and expensive components can supply non-functioning "Mechanical Samples" specifically for this purpose..

Inspection

Due to the metallic composition of lead-free solder, the visual appearance may differ significantly from that of a standard leaded solder joint. Frequently, a first look will give the impression of a cold solder joint. Our inspection technicians are trained to IPC-610D standards to ensure that the solder joints are solid and of high quality.

Packaging

Fully assembled lead-free Boards are packaged individually in ESD BAG /ESD TRAY+INNER BOX+OUTER CARTON for shipment.

Four Common RoHS Concerns Relating to PCB Assembly

You need to consider the following four key areas when readying a project for assembly in a lead-free / RoHS compliant environment:

Base Circuit Board

Industry research has found that the substrate and board finish used on lead-free boards may need to be different than for circuit boards using lead. It's not just the lead. Standard FR4 material will sometimes delaminate during the lead-free reflow process due to the higher temperature profiles required. The problem can be exacerbated if the board has to make multiple passes through the oven for double sided SMT or rework. You may need to be even more cautious with boards that are primarily through-hole. Commonly, wave soldering is more likely to cause delaminating problems than a properly profiled reflow oven.
SUNNY PCB make sure to use materials that can withstand the additional heat and can make multiple passes through processing without problems and specify RoHS compliant boards.

Components

You must verify that all your components meet RoHS standards and do not contain any of the banned substances. Your Bill-of-Materials must specify only RoHS compliant parts and the components in your kit must all meet lead-free and RoHS standards.
Again, it is more than just the lead and other banned substances. The components must also be able to withstand the higher temperatures required in manufacturing. Most standard components will be fine, but some MEMs parts, switches, membranes, LEDs and others may not be able to survive the extra 50 degrees C required. Some can survive the temperatures, but only just barely. Make a note of any components that are heat sensitive, even if RoHS compliant, when you deliver the parts to us..

Moisture Sensitivity

Many components will, over time, absorb small amounts of moisture. RoHS compliant storage packaging will inhibit this and will list an expiration date. If the protective package is past the expiration date or the packaging has been opened, the part may be destroyed during reflow due to the rapidly expanding water vapor. Typically, such a failure would be seen as a crack on the side of the part.
Opened or moisture-expired parts may still be used on your prototype, but they will need to be baked at the assembly house to slowly remove the excess moisture. When confirming the integrity of the moisture protective packaging, we (or any assembly house) may determine that components need to be baked prior to assembly. If parts need to be baked to remove moisture, it takes an additional 72 hours (at Screaming Circuits) for baking. The assembly does not start until the components are baked. (SUNNY PCBwill contact you if we determine your components need to be baked.
Any queries, please talk with us in details.