PWB Fabrication Process

ORDER ENTRY / ENGINEERING PLANNING

• Data package analyzed
• Customer contact if required
• Control number assigned
• Panel layout determined
• Multilayer stackup is selected
• Traveler initiated
• Material ordered
• Inventory updated

PROGRAMMING AND CAM

• Gerber data is used to "cam" the job
• Step and repeat the data for panelization
• Program for drill and rout
• Prepare cam data for photo-plotting
• Prepare data for aoi and test
• Manual jobs(without data) are bombsighted

INNER LAYER PREPARATION

• Layers are cleaned and coated with dry film
• Circuit image(negative) is printed on dry film
• Image is developed
• Layers are etched to remove unwanted copper
• Dry film is removed to expose copper circuits
• Inner layers are "aoi" inspected
• Layers are treated with oxide to promote adhesion

MULTILAYER LAY-UP

• Layers are oriented into the specified stack-up
• Prepreg material is oriented between all of the layers
• Multi-layer book is built containing several panels

MULTILAYER LAMINATING

• Press is loaded with several "books" of multi-layers
• Vacuum is initiated in press
• Temperature and pressure cycle is initiated
• Prepreg liquefies and then gels to bond layers together
• Cure cycle and then cool down

DRILL

• Multi-layers and double sided boards are drilled
• Drill mylar(generated with the f/a) is used to check
• Stack height is based on product and drill size
• Drill bits are inspected and hit count is controlled

PATTERN PLATE

• Imaged panel is electrolytic plated with copper
• The circuit pattern and the holes are plated
• Dry film resists plating between circuits
• Circuit pattern and holes are plated with tin
• Tin acts as an etch resist to protect circuits and holes

STRIP AND ETCH

• Panels are processed through a film strip and etch
• Ammoniacal etch removes all of the unwanted copper
• Tin is removed leaving bare copper and laminate
• If a gold or tin nickel finish is desired, the tin process is eliminated and the gold or tin nickel is the etch resist

SOLDERMASK

• The soldermask screen is made from the film
• Panel surface is scrubbed
• The bare copper panels are coated with soldermask ink
• Panels are cured
• In the case of lpi, panels are printed, developed, & cured

HOT AIR SOLDER LEVEL

• Panels are coated with activating flux
• Panels are inserted into the molten solder chamber
• Solder fills the holes and covers the surface
• Excess solder is blown out of holes and from surface
• Thin coating of solder is left on the surface & in holes

ROUTING

• The individual circuit boards are removed from panel
• Removal is done with numerically controlled router
• Individual boards are sized per the specification

ELECTRICAL TEST

• The individual board is tested electrically
• Test is either reference or net-list
• The test detects shorts and opens

FINAL INSPECTION

• Each board is inspected to ensure compliance with spec
• Samples are taken for all mechanical measurements
• Visual attributes are 100% inspected
• During the manufacturing process, various inspections are made to ensure that the process is intact and product is meeting the requirements.

FIRST ARTICLE INSPECTION

• PTHs are potted, cross sectioned and examined to ensure compliance with spec
• Panels are placed on the Perfect Test equipment to check layer registration