Pb-Free

Bittele Electronics has a comprehensive lead-free solder solution. Our team has studied every aspect of lead-free solder, including solder alloy selection, solder paste evaluation, wave solder flux evaluation, process optimization, 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.

Our Lead-Free services include:

Lead Free Printed Circuit Boards
Lead Free Rework
Lead free Assembly (SMT or THA)
Lead Free Wave Soldering
Lead-Free Materials Analysis

Our Lead free PCB 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 assembles your lead free boards but also assist you to determine if the materials in your Bill-of-Materials meet lead free PCB manufacturing requirements. 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.

The lead free SMT Assembly Process

The RoHS PCB assembly process requires that none of the hazardous materials listed in the RoHS Directive are used in the boards, components or solders. Bare printed circuit boards used in the typical "leaded process" are often coated with a lead-tin finish, so the finish on the board must be modified significantly to be compliant with lead-free and RoHS standards.

The lead-free prototype process also requires that boards to be assembled at higher temperatures usually 30-50 degrees or higher. The higher temperature may require the substrate of the circuit board itself and various components to 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. The shelf life of the materials used in lead-free boards may also be shorter.

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; i.e. BGAs, heat slug parts, etc. 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. Additionally, suppliers, such as Practical Components provide thermally equivalent parts 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 staffs are trained to IPC-610D standards to ensure that the solder joints are solid and of high quality.

Bill-of-Materials, Board Finish and Components Analysis

It is the customer's responsibility to verify that the Bill-of-Materials is correct for lead-free parts. We can also consult with you if you need help in determining if your board and components meet the requirements. If the components arrive in invalidated moisture package and we determine there might be excess moisture issues, we will notify you that your components need to be baked prior to assembly.

Applying Board Stencil and Solder Paste

We begin 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

Bittele Electronics 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. We uses thermal profile to control the temperature reflow soldering processes and track thermal profiles required for lead-free boards.

Testing

We perform a visual inspection right after soldering to look for manufacturing defects. We use the IPC 610D soldering acceptability standard. Bittele Electronics has trained its staff how to evaluate lead-free solder joints.