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August, 2014 Benefit By Reversing Electronics Manufacturing By Joseph Fjelstad, Verdant Electronics, Seattle, WA


recent years have been related to the solder assembly process. While lead- free solders were touted as drop-in replacements for traditional lead-con- taining solders, field experience has shown this not to be the case. More expensive, lead-free and tin-rich alloys with higher melting tempera- tures have caused the electronics industry to scramble for solutions to a number of new problems (e.g., “head- on-pillow” and pad cratering issues). The use of lead-free solder has also had deleterious spillover effects on printed-circuit-board (PCB) laminate materials due to the higher soldering temperatures required.


M


To fabricate an aluminum circuit, a sheet of alu- minum is prepared and


components placed on it. Sites can be prepared by chemical machining, mechanical machining,


laser cutting, punching, or other methods.


As a result, some efforts have


focused on developing circuit fabrica- tion techniques without solder, by reversing the manufacturing process. Instead of placing components on cir- cuit boards, circuits are built on “component boards” with all compo-


Light-Guided Connector Assembly


Use this new, patented system to double your productivity* when assembling circular and rectangular connectors. The Light Director™ system uses light fibers driven by super-bright LED lamps to individually illuminate target cavities in the connector being assembled. When you enter the wire code printed on unconnected wires or touch a wire terminated at the other end, software turns on the appropriate fiber, thereby causing a bright, flashing light to project from inside the target cavity guiding you to the proper insertion point. Correct insertion is confirmed by the elimination of light from that location, whereas insertion into an incorrect cavity leaves the flashing light visible.


 


® Model M3U PC-based cable test system. Electrical test after build possible.





 Pinning. Probed guided assembly also available.


 and voice commands.


 your mating connector and we will mount and program it at no charge.


www.cableeye.com/LightDirector Tel: (800) 776-0414


 unconnected wire with probe or finger.


*Field testing has shown a doubling of assembly speed while practically eliminating errors.


 flash. Computer also reads pin number in natural voice.


  insertion.


CAMI Research Inc. 


CAMI ®


any of the problems which have confronted the electron- ics manufacturing industry in


nent leads/terminations exposed and interconnected by an additive or semi additive plating process. The new approach is a subset of


solderless assembly for electronics or solder alloy free electronics (SAFE) manufacturing methods. SAFE approaches are cost effective by means of fewer manufacturing steps,


strate due to its various positive properties. It features a coefficient of thermal expansion (CTE) very close to that of copper, with dimensional stability far exceeding that of FR4 circuit materials, low density, good thermal dissipation capabilities, and low cost (about $1.00/lb.). It also com- prises 8.3 percent of the earth’s crust


cutting, punching, or other methods. The aluminum substrate can also be embossed or cast with cavities if required. Aluminum can be ano - dized, so that the surface is noncon- ductive aluminum oxide, or it can be coated with insulating material elec- trophoretically or electrostatically to make its surfaces nonconductive. Cavities can be formed to match the heights of electronic components so that the lead terminations of those components are flush with the sur- face of the aluminum board to facili- tate processing. With aluminum, the overall number of processing steps is significantly reduced from manufac- turing approaches based on conven- tional PCB materials.


Capital Equipment List for Traditional Electronics Manufacture (Abbreviated list)


These basic process steps illustrate the reverse manufacturing of a double-sided aluminum circuit assembled and interconnected with-


out solder. From the top left, aluminum material is provisioned with cavities by milling, etching, or embossing, wherein components are placed and then coated with an insulating material. Holes are


drilled, then filled with insulating material, then redrilled. At the same time, viaholes are formed to access component terminations. The circuit pattern is then plated and circuits sealed after the last


layer is completed leaving open features required for interconnection and power (open features are not illustrated). The metal core can serve both as a heat spreader and a power or ground layer.


but require discipline and attention to detail in component selection and layout. While engineered organic resins can be used alone or with other materials, aluminum is an attractive choice as a circuit sub-


and is highly recyclable. To fabricate an aluminum cir-


cuit, a sheet of aluminum is prepared and components placed on it. Sites can be prepared by chemical machin- ing, mechanical machining, laser


PCB Fabrication: l


l l l l l


Metallization and Plating Equipment


Surface Preparation Equipment (chemical and mechanical)


Drilling Equipment (mechanical and laser)


Shearing Equipment


Photoresist Application Equip ment (includes solder mask)


l Image Development Equipment l Lamination Equipment l Routing Equipment l Cleaning Equipment


Photoimaging Equipment (contact and laser direct print)


Continued onpage 60





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