Where the relay sits in an ICT
An in-circuit tester checks every component on an unpowered PCBA and verifies the connectivity of each net, flagging missing, wrong or marginal parts together with opens and shorts. It is fast and it points at the faulty node rather than just the faulty board, which is why it sits between assembly and functional test as a production gate. Structurally, an ICT is a large switching matrix, and the matrix is built from relays.
The 50 PPM arithmetic behind a 20,000-relay tester
A fully loaded tester can hold around 20,000 relays, and that count sets the component quality bar on its own: at 20,000 parts, a single defective relay is already a 50 PPM failure rate. To ship a matrix without a latent bad channel, the relay itself has to be built to better than 50 PPM. Material choice alone does not get there — the parts need automated, tightly controlled production and dynamic screening so that early-life and latent failures are caught before they reach the matrix.
Four families, one density ladder
SHR AUTOSENSOR supplies four reed relay families for ICT matrices — SIP, MSIP, VSIP and VN — all built on automated lines and dynamically screened. Each step roughly halves the board area of the previous package.
- SIP — single-in-line; 1A (SPST) and 1C (SPDT) forms; the general-purpose channel part.
- MSIP — 1A; about half the SIP footprint, which halves the area cost of an expensive test-head board.
- VSIP — 1A; halves the MSIP footprint again for high-density matrices.
- VN — the newest package at 4.4 × 4.4 mm, for the densest tester builds.
Shared electrical characteristics
- Insulation resistance above 1010 Ω for clean open-circuit readings
- Microsecond-class switching with long-life sealed contacts
- Low, stable contact resistance for low-level measurement
- Automated manufacture with dynamic screening for early-failure detection
Choosing a family for the matrix
The decision trades channel count, board area and contact form. Designs that need a 1C/SPDT channel for guard or discharge routing start from SIP, since the denser families are 1A. Density-driven designs move through MSIP and VSIP, where the area freed by each shrink is reinvested in more channels and therefore more coverage per fixture; the 4.4 × 4.4 mm VN is reserved for space-bound adapters such as flying fixtures over dense consumer boards. Across all four, the electrical requirements do not change — above 1010 Ω insulation, fast switching to hold down per-board test time, and sealed contacts that tolerate production-volume actuation.
Why reed contacts hold up in this duty
An ICT matrix switches hundreds of thousands of cycles a shift, so contact life and speed set both throughput and cost of ownership. A sealed reed contact gives microsecond-class operate times, billions of signal-level operations and no exposed armature to oxidize or collect contamination, and its small package is what lets the density ladder keep stepping down from SIP toward VN. Kept under a 50 PPM defect budget, the matrix finds faults on the PCBA instead of becoming a fault source itself.
About SHR AUTOSENSOR
SHR AUTOSENSOR TECH LIMITED (SHR AUTOSENSOR) manufactures high-voltage reed relays, mercury wetted relays and high-voltage DC contactors. Contact: [email protected] | +86 13761571029 | www.reed-relay.com