Issue link: https://iconnect007.uberflip.com/i/1541367
68 PCB007 MAGAZINE I NOVEMBER 2025 A RT I C L E by M a rcy La Ro nt , I - C o n n e ct 0 07 Interposers, Substrates, and Advanced Manufacturing I attend a lot of industry trade shows and confer- ences. Lately, during conversations with tech- nologists, I've noticed that there is some con- fusion about what exactly constitutes an interposer. One question I hear every so often is, "Are all interposers substrates?" The short answer to that question is no. But some interposers are, in fact, full substrates. The following is a brief overview of interposers: their development, composition, function in elec- tronics, and relationship to substrates. A Core Definition In advanced electronics manufacturing, an interposer is a physical interface or intermedi- ate substrate that provides electrical connections between two components that would otherwise be difficult or impossible to connect directly. An interposer is typically a thin layer—often made of silicon, glass, or organic material—placed between a chip (die) and a package substrate, or between a package and a PCB. It acts as a bridge that redistributes signals, power, and ground connections using fine-pitch wiring or through-sili- con vias (TSVs). Interposers allow high-density interconnects and fine-pitch routing from the tiny pads on ICs to larger pads that are manufacturable on PCBs. In advanced packaging, interposers enable multiple chips (logic, memory, etc.) to be mounted side-by-side in one package. This is common in high-performance computing (e.g., GPUs, FPGAs). They help manage differences in pitch and size between chips and substrates, reducing stress and improving assembly reliability. By shortening inter- connect lengths and improving routing density, interposers enhance electrical performance (signal integrity, reduced latency) and can help with heat dissipation. Interposers tend to fall into one of three camps: • Silicon interposers feature TSVs for very fine- pitch, high-performance connections. • Glass interposers offer low cost and good dimensional stability. • Organic interposers are made from advanced laminate materials. They are lower in cost but support less dense routing than silicon inter- posers. In a nutshell, an interposer is an enabling technol- ogy in advanced electronics packaging that serves as a high-density interconnection layer between chips and substrates, and it's crucial for modern semiconductor devices.