18.104.22.168 Assembly Processes
verification should be made that all manufacturing processes involving
electronic components are mature. Further, the supplier should implement
continuous improvement goals and quality assurance requirements.
Equipment manufacturing processes contribute to equipment
reliability. Thus, when reviewing the process for selecting components, an
assessment of the ability to manufacture the assembly using the proposed
technology should be accomplished. The overall goal is to ensure that
manufacturing processes are mature.
Processes In Manufacturing -
portion of the parts management plan should include a definition of the
manufacturing processes used, how the piece parts flow through these
processes, and where process controls are used. The use of statistical process
control, design of experiments, and other methods of process control should be
Process Maturity - Suppliers
should document their ability to use the proposed processes successfully. If
the proposed manufacturing techniques have been used on other products,
identification of these existing processes, and a simple statement that these
processes are in control and capable, should be adequate. If new techniques
are being proposed (such as a change to surface mount technology),
demonstration of process control and capability should be required. Suppliers
should list the activities performed to identify all of the key process
parameters, measurement criteria, and manufacturing procedures needed to
minimize the learning curve during production. Examples of these activities
||Development of manufacturing
||Identification of process
||Development of pass/fail criteria|
||Design of experiments|
||Product life testing after
Process Control and Capability - The next item that should be demonstrated is a
supplier’s ability to keep their processes in statistical control and capable.
Guidelines are provided in Reference .
Component Packaging - Maintainability of equipment can be enhanced through
the use of standard part package types. Therefore, suppliers are encouraged to
procure components with standard package outlines. Standard package outlines
are contained in Reference
Component Marking - Components
which undergo screening should be permanently marked to indicate the
individual component has received quality assurance testing. Markings should
be visible when components are mounted on the PC board. This helps prevent
components without quality assurance from being accidentally installed at the
factory or at a remote repair facility.
Components should also be
permanently and legibly marked by the manufacturer with the following
information, where space allows:
||Manufacturers name, trademark or
||Manufacturers part number|
||Inspection lot identification or date
||Pin 1 locator or orientation
Components without adequate space for marking should have
provisions to preclude accidental replacement with a different part. All
component marking should be able to withstand normal use in the planned
environment. For military products, marking should be able to pass the
resistance-to-solvents test of MIL-STD-883, Method 2015.
Component Handling - Component
quality assurance measures can be easily compromised by improper handling.
Thus, the contractor PMP plan should reflect practical and proven handling
procedures to maintain component quality. Considerations may include ESD
prevention, lead formation maintenance and automated handling practices for
standard and non-standard packages and humidity control (i.e.,
All components should be shipped in
appropriate packing material. The program plan should address component
handling issues, such as ESD, installation orientation, mounting techniques
(tube, reel, etc.), contamination and humidity.
Procurement and Shipping
Procedures - Component quality should not be degraded during
handling or screening. Handling or screening provisions placed in effect with
third party participants, such as manufacturers, distributors or screening
facilities, should be identified or referenced. Suppliers should be encouraged
to eliminate unnecessary processing which may degrade component
The component manufacturer or
screening house should obtain and keep on file written certification of
specified shipments of components. The shipment certificate should
||Manufacturer name and address|
||Customer or distributor name and
||Date code and latest re-inspection date,
||Quantity of components in the
||Level of screen and specification
To maintain quality as shipped from the part manufacturer, date
codes should be no older than 12 months from receiving date of the purchase
order by the manufacturer.
The supplier should ensure that the components are the correct
type, date code, screening level, and package type prior to stocking. Incoming
inspection is one way to ensure that the components are received with the
proper information. This procedure should be properly identified in the
Discrepancy controls for non-conforming materials should be
implemented. These controls should include flow charts describing corrective
actions, actions taken to prevent recurrence of discrepancies, etc.
Storage Procedures - The PMP
should also address relevant storage and stocking procedures. For instance,
plastic packages absorb moisture over time, which may cause package cracking
during the solder process. Dry storage may be necessary up until the time of
soldering. An alternative process would involve a thermal pre-bake to drive
out excessive moisture.
References  and
 can be used in determining the sensitivity of particular ICs to
moisture-induced package cracking.
Rotation of stock is also an
important function of the storage process. The supplier’s plan should identify
how their process controls stock flow (i.e., First In/First Out, Last In/First
Modification and Repair of PCBs and
Assemblies - Repair and modification techniques for surface mounted
components can be complicated, and may require special tooling and processes.
Thus, the program plan should identify the governing documents and procedures
for the modification and repair of PC