Thermocompression with non-conductive film

The mechanism

Thermocompression bonding applies controlled temperature, force and alignment to form interconnections. In a TC-NCF route, a non-conductive film occupies the space between the mating dies while metallic bumps and pads carry the electrical connection. The polymer must deform and cure without blocking intended contacts or trapping unacceptable voids. Thin-die handling, film behavior and bump geometry are therefore coupled. TC-NCF is one thermocompression implementation, not a synonym for every bump process or every adhesive. Samsung’s February 2024 HBM3E 12H announcement gives a concrete historical application; it does not make one vendor’s process window universal.

Prepare bumped dies, compatible film and verified surface/handling conditions.
Place the film at its defined wafer or die stage; maintain the intended contact openings and contamination controls.
Align a die to the receiving die and apply the qualified thermal/force cycle for metallic contact and polymer flow/cure.
Repeat the specified stacking sequence while tracking placement error and cumulative warpage.
Inspect continuity, bond-line condition and voids; complete the product-specific reliability qualification.

Science and assumptions

Serial tool occupancy

t_{\mathrm{stack}}\approx N(t_{\mathrm{align}}+t_{\mathrm{bond}})+t_{\mathrm{handling}}

tstack ≈ N (talign + tbond) + thandling

Symbols and units

tstack: Serial tool occupancy per stack
s
N: Placements in the modeled route
count
talign: Alignment/placement time per die
s
tbond: Bond occupancy time per die
s
thandling: Other occupied handling time per stack
s

This estimates occupied tool time for a strictly serial die-placement/bonding sequence.

Assumptions No overlapping stations or batch operations. It is not factory cycle time, and route-specific curing may occupy different equipment.

Engineering example

Synthetic serial flow: 12 placements × (0.3 s alignment + 0.7 s bonding) plus 3 s handling occupy 15 s. A different station layout could overlap work; this calculation predicts neither commercial throughput nor yield.

Distinctions and tradeoffs

NCF supplies insulation and mechanical support; metal joints provide the conductive path.

Sequential local bonding provides process control but tool occupancy, film flow and thin-die stress must close together.

A packaging decision changes manufacturable stack height, test yield and the number of usable HBM stacks delivered.

Specifications and interfaces

Electrical path: Metallic bumps/pads
NCF itself is electrically insulating.
Control variables: Alignment, force, thermal cycle and film state
Values are recipe- and material-specific, not supplied here.

Interfaces

Prepared die and film Input: Surface, metallurgy, rheology and alignment
Bonded die pair Output: Electrical joints and cured/processed polymer interface

Check your understanding

In TC-NCF, what carries current between memory dies?

The metallic interconnections
The non-conductive film
The surrounding air gap

Answer and reasoning

The metallic interconnections

NCF supplies insulation and mechanical support; metal joints provide the conductive path.

Evidence and scope

Historical vendor example: Samsung reported an advanced TC-NCF route for its 2024 HBM3E 12H development. Sampling, qualification and volume production are distinct statuses.

Adjust stack layers, thickness, joint route, interface bandwidth and conditional yield; presets are synthetic, not supplier process windows.