The wafer level chip scale package (WLCSP) is a variant of the flip-chip interconnection technique where all packaging is done at the wafer level. With WLCSPs, the active side of the die is inverted and connected to the printed circuit board (PCB) using solder balls.

The WLCSP die has a first layer of organic dielectric (Polyimide 1), a metal redistribution layer (RDL) to re-route the signal path from the I/O to a new desired location, and a second polyimide layer (Polyimide 2) to cover the RDL metal, which in turn is patterned into the solder ball array.

Aug 26, 2024 · RDL的全称是（ReDistribution Layer）重布线层，RDL重布线层作为晶圆级封装中的核心技术，起着XY平面电气延伸和互联的作用。 RDL是将原来设计的芯片线路接点位置 (I/O pad)，通过晶圆级金属布线制程和凸块制程改变其接点位置，使芯片能适用于不同的封装形式。 基于明阳在半导体领域的布局，先进封装载板与测试板进行工艺技术研发。 当前工艺主要分为tenting，mSAP，SAP三种，Tenting制程由于蚀刻工艺的限制， 通常难以制作线宽/线距小 …

WLCSP includes wafer bumping (with or without pad layer redistribution or RDL), wafer level final test (probe), device singulation and packing in tape & reel to support a full turnkey solution.

WLCSP Construction Figure 2 below outlines a typical representation of a WLCSP package with Redistribution Layer (RDL) and Under Bump Metallization (UBM) structures.

To prevent diffusion and enable solder wetting, an under-bump metallization (UBM) layer is deposited on the RDL. The solder ball is a lead-free alloy. Backside wafer lamination, a protective polymer film, is optional for WLCSP productions.

PCB LAND PATTERN GUIDELINES The WLCSP is a surface-mountable package with bot-tom ball termination of its external connections. The land pattern design for all WLCSP type packages is based on IPC-7351 and IPC-7095 standards. A Non-Solder-Mask Defined (NSMD) pad design is recom-mended for all board pads, as shown in Figure 2.

There are exciting interconnect technologies in wafer level packaging such as wafer level chip scale packaging (WLCSP) or fan-out wafer level packaging (FO-WLP) solutions such as embedded Wafer Level Ball Grid Array (eWLB) to meet these needs.

Oct 5, 2023 · This article explores the process stages of wafer-level packages including the fan-in WLCSP, fan-out WLCSP, RDL package, flip chip package, and TSV package.

A typical WLCSP die has a first layer of dielectric, conductive metal RDL to redistribute the signal path from the die peripheral to a solder ball pad, and a second dielectric layer to cover the RDL metal, which in turn is patterned into the solder ball array.