• High reliability in multilayer circuit boards:
  • High elongation at elevated temperature prevents foil cracking.
  • Handles as easily as standard copper foil.
• Standard profile for conventional multilayer/mass lamination applications.
• Low profile for high density multilayer boards.

Overview
The growth of multilayer laminates has placed much more emphasis on printed circuit board reliability. This emphasis has been compounded by the direction of the industry to fabricate smaller, denser PCB packages. As the number of layers increased, additional concerns towards maintaining reliability were raised. These concerns involve the Z-Axis expansion or strain of the PCB raw materials. It has been well documented that the raw materials expand under thermal conditions such as PCB soldering processes. PCB reliability after this expansion is especially critical since the manufacturer cannot test the package until the latter stages of the process.

Gould developed JTCS foil, which exhibits excellent ductility at elevated temperature and, therefore, withstands the stress caused by thermal Z-Axis expansion of the laminate. In addition to meeting IPC-4562 requirements and the qualities exhibited by standard Gould foils, JTCS foil withstands the stresses near the edge of plated thru holes without cracking. JTCS copper is produced in a unique manner so there is no sacrifice in handleability, lamination or PCB processing.

Advantages
Grade 3 JTCS foil is available in both standard profile and low profile types. The standard profile product is widely used in conventional multilayer and mass lamination applications, exhibits higher matte side roughness and higher peel strength when compared to the low profile products (see properties and specification sections).

• High Etch Factor and Speeds – Low profile JTCS foil, which is specially tailored for high density multilayer boards, is characterized by higher etch factor (3 or better) and up to 20% faster etch time.
• Resistance to Thru Hole Cracking – Both foils exhibit excellent ductility at elevated temperatures, and eliminate foil cracks near the plated thru holes. Low profile JTCS foil is also available with a minimum elongation value of 6% at elevated temperature, assuring maximum reliability and resistance to foil cracking for dense MLBs with very high layer count.
• Resistance to Recrystallization – Low profile JTCS is formulated to resist recrystallization or grain growth after thermal processing. Recrystallization contributes to dimensional change, warp and twist, and nailheading.

• Resistance to Innerlayer Cracking – JTCS foils are formulated with a balance of tensile strength for handleability and ductility for resistance to innerlayer foil cracks. Tensile strengths equivalent to Grade 1 foils permit JTCS foils to process with handleability and dent resistance of standard Grade 1 foils.

Properties
JTCS foil is routinely available in continuous rolls in thicknesses from 12 µm (0.375 oz)
to 70 µm (2 oz). The 12 µm (0.375 oz) JTCS Foil has a minimum of 2% elongation at 180° C. The following table details the typical properties of JTCS foils in comparison to industry standards.

Specifications
JTCS foils exceed the requirements of all industrial specifications. Results from customer tests are outlined below.