TABLE I.
Common Process Step Order in Circuit Board Manufacture at the FacilityA
| Process | Description | Typical Chemicals Used Historically |
|---|---|---|
| Treater | Manufacture of prepreg from resin-impregnated fiberglass cloth | Epoxy resin; methyl ethyl ketone; ethylene glycol monomethyl ether; fiberglass; methylimidizole, dicyandiamide |
| Core lamination | Prepreg and copper sheets are layered, laminated and trimmed to form raw boards (cores). | NAB |
| Apply resist | After pre-cleaning core, sheets containing photoresist are applied and fixed using heat and pressure (start of internal circuitize steps). | Pumice, dry film resist |
| Expose | Glass artwork of the desired circuitry is cleaned and placed over the core which is exposed to ultraviolet light. | Isopropyl alcohol, trichlorotrifluoroethane, methanol, methyl ethyl ketone |
| Develop resist | Unexposed resist is removed. | Potassium carbonate, sodium carbonate, methyl chloroform, trichloroethylene |
| Etch | Unprotected copper is removed. | Cupric chloride, hydrochloric acid |
| Strip resist | Exposed resist is removed uncovering the remaining copper circuit. | Sodium hydroxide, potassium permanganate, sulfuric acid, methanol, methylene chloride |
| Drill | Holes are drilled in board. | NA |
| Surface prep | Hole surface is prepared for plating and burrs and debris removed. | Sodium hydroxide, sulfuric acid, benzotriazole, dimethyl aminoborane, hydrochloric acid, sodium carbonate |
| Copper plating | Holes are plated to create electrical connections through the board. | Sodium carbonate, sodium permanganate, sulfuric acid, cupric chloride, hydrochloric acid, copper sulfate, dimethylaminoborane, formaldehyde, sodium hydroxide, acetic acid, methanol, phosphoric acid, potassium hydroxide |
| Composite lamination | Circuitized cores are laminated together to form multi-layered boards. | NA |
| External circuitize | Previous process steps are repeated to create circuitry on the exterior and through the board. | (Same chemicals as above in process steps apply resist through copper plating) |
| Component placement | Components are mounted and soldered. | Isopropyl alcohol, perchloroethylene, flux, lead, tin |
| Inspection, testing and repair | Inspection is conducted at various points in the process and hand soldering is performed for repairs. | Isopropyl alcohol, flux, lead, tin |
A
Adapted from Pinkerton(2).
B
NA = Chemical use not identified.