MHE - RITM

MHE represents The Center for Prospective Technologies and Apparatus which has developed a novel circuit board technology called RITM.

RITM -- A Novel Technology for Multi-Layer PWBs Without Vias

What is RITM:

RITM is a patented family of processes for manufacturing multi- layer PWBs without the need to drill or plate any through holes. RITM, an acronym in Russian, is an abbreviation meaning "selective etching of dissimilar metals". This novel technology is based on clever use of the different physical characteristics of two metals.

Short Summary of the RITM Process:

RITM involves the simultaneous imaging, plating (for example electrochemically deposited copper, 15 to 28 microns), and partial etching of both sides of a thin metal carrier foil (for example aluminum or inexpensive low carbon steel). This foil is then laminated to a substrate with dielectric film. Then the carrier foil is etched again to create the circuit traces, interconnection posts, and pads simultaneously.

This the most basic version of RITM. Other pairs of metals can be selected for the conductor and the carrier foil, depending upon the application. RITM only requires that the metals can be selectively etched to form the inter-connections, as those are the substitutes for the vias.

With RITM many variations are possible, resulting in constructions which cannot be formed with other PWB techniques, including: simulated twisted pairs, meshed conductor or power buss crossovers, micromachine-type circuit elements, inductor components, and relays.

Advantages of RITM:

• Higher reliability due to elimination of vias; relief protrusion of dielectric between the metallizations locks the circuit traces to the board and helps prevent shorts
• Cost savings, due to:

. Lower cost materials * Fewer process steps * Less labor content.

Cost savings can be more than 50% for 2-layer RITM construction as a replacement for a 4-layer PWB

• Improved thermal management -- ICs and other devices can be bonded directly to the metal carrier foil which serves as a heat sink
• Terminals can be integrally incorporated on the carrier foil rather than attached as a separate piece with an additional assembly step
• Separate ground plane can be eliminated, as metal carrier foil can serve as ground plane and can provide electrical shielding
• Size and weight of circuit can be reduced in most cases
• Wide applications -- including high voltage, very high frequency (400 MHz), and high temperature (125o C = 257o F)
• Highly versatile -- base materials for RITM circuits can be metal and composite substrates, ceramics, and some plastics. No need to match thermal characteristics of board and components
• Environmental Impact Reduced -- no plating of through holes
• Wide variety of adhesives can be used: epoxies, polyimides, polyethylene, polypropylene, and non-polar dielectrics such as fluoroplastics
• Flexibility -- the RITM technology has been applied to flexible, rigid flex, and formable circuits
• Resolution -- RITM combines many advantages of thick film with the fine feature resolution of thin film construction
• Compatibility -- RITM is ideal for total surface mount applications, but vias can be included as secondary operations, if needed for special designs
• Two or more RITM boards can be interconnected across the end faces to produce complex, modular structures

Present and Potential Applications:

RITM boards have been utilized in Russia in critical quality military and space electronics and in high volume, low cost children's games. RITM is now being developed and tested for US applications, including several high volume applications where high thermal management and high reliability are required, and cost savings are significant. Other potential applications include: hybrid integrated circuits, micro- assemblies, boards with metal dielectrics and composite bases

Fields of application include: communications, transportation, medical equipment, consumer electronics, microwave devices, and many others.

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