|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
Placement of ComponentsThe 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
Packaging Fully assembled lead-free Boards are packaged individually in ESD bags for shipment.