Research
Impractical Stencil Aperture Designs to Enable M0201 Assembly
Effectiveness of I/O Stencil Aperture Modifications on BTC Void Reduction
Microalloyed Sn-Cu Pb-Free Solder for High Temp
Selective Reflow Rework Process
Impact of Thermal Loading on the Structural Intergrity of 3D TSV Package
Design and Fabrication of Ultra-Thin Flexible Substrate
Influence of PCB Surface Features on BGA Assembly Yield
Last Will and Testament of the BGA Void
MORE RESEARCH
Latest Industry News
Print These Electronic Circuits Directly Onto Skin
Compal increasingly asked to diversify production bases
Intel's margins tumble as customers shift to cheaper chips, shares slide 10%
From Foldable Phones to Stretchy Screens
6 Considerations for Integrating Sensors in Vehicles
Bill Gates Says Unhappy Customers Are Good for Your Business. Here's Why.
iPhone 12 review: Upgrade for the camera, not 5G
Apple's shifting supply chain creates boomtowns in rural Vietnam
MORE INDUSTRY NEWS

Manufacture of Aluminum Substrate PCBs



Manufacture of Aluminum Substrate PCBs
A new fab method that uses an aluminum substrates that house fully tested and burned in components to create a component board is described.
Materials Tech

DOWNLOAD

Authored By:


Joseph Fjelstad
Verdant Electronics

Summary


RoHS legislated restrictions on the materials used in electronics manufacture have imparted significant challenges on the electronics industry since their introduction in 2006. The greatest impacts have been felt by the mandated elimination of lead from electronic solder followed by the demand for the elimination of haloids from flame retardants used in traditional PCB laminates.

In the years which have followed the electronics industry has been beset with a host of new challenges in its effort to comply. Failure mechanisms, both new and old, have surfaced which demand solution and the industry suppliers and manufacturing technologists have worked diligently to remedy those vexing faults through the development of a wide range of new materials and equipment for both board manufacture and assembly, along with modifications to the processes used in the manufacture and assembly of printed circuit boards.

Most of the problems which have confronted the electronics manufacturing industry have related to the solder assembly process. Lead-free solders were advertised early on as a drop-in replacement for traditional tin lead solders however field experience proved is not to be the case. The tin rich alloys along with the higher temperatures which were required for assembly cause the industry to scramble for solutions to such problems as champagne voids, poorer wetting, brittle solder joints, copper dissolution, tin whiskers, head in pillow, greater vulnerability to damage caused by explosive outgassing of absorb moisture in packages among others including cleaning of baked on fluxes following the high temperature assembly process. Lead-free solder also had spillover effects on the PCB laminate material itself as manufacturers experienced delamination and degradation of the resins used in circuit construction.

One more recently encountered problem is a phenomenon referred to as pad cratering wherein resin beneath the copper land to which a component is attached is actually torn loose from the surrounding resin breaking through the copper and causing an open.

In this environment, an alternative approach to manufacturing electronic assemblies has been conceived and is presently being developed. The new method in simplest form is one which eschews the use of solder and is predicated on the use of aluminum substrates which house fully tested and burned in components to create what can be best described as a component board wherein the terminations of the components are proximately planar with the surface of the aluminum. In subsequent processing the aluminum component board is first coated with an insulating material and then circuits which interconnect the components are applied using buildup technologies.

Conclusions


Such aluminum circuit structures as have been described in this paper are simple to design and eminently possible to manufacture. They can be easily produced using well-established manufacturing infrastructure tools, equipment and processing techniques which are simply reordered to make highly useful electronic products suitable for use in everything from consumer to high-reliability automotive, military and aerospace products. The limits are likely to be defined more by the imagination of the designer than the limits of the fundamental technology which has been described.

Comments

No comments have been submitted to date.

Submit A Comment


Comments are reviewed prior to posting. You must include your full name to have your comments posted. We will not post your email address.

Your Name


Your Company
Your E-mail


Your Country
Your Comments



Board Talk
Causes of Blowholes
Tips When Moving a Reflow Oven
Assembling Boards with BGAs on Both Sides
Larger Stencil Apertures and Type 4 Paste
5 vs 8-Zone Ovens
Component Moisture Question?
BGA Components and Coplanarity
How To Verify Cleanliness After Rework and Prior to Re-coating?
MORE BOARD TALK
Ask the Experts
Initial Screen Print Test Board
HASL Surface Finish and Coplanarity
Legend Marking Discoloration
Cleanliness Testing
Stencil Cleaning Frequency
Exposed Copper Risk
Spotting After DI Water Cleaning
ESD Grounding - 1 Meg Ohm Resistor
MORE ASK THE EXPERTS