PCB News - How to ensure the quality of HDI circuit boards

How to ensure the quality of HDI circuit boards

In order to ensure the production quality of HDI circuit boards, manufacturers have gone through a variety of inspection methods during the production process, and each inspection method will target different HDI circuit board defects.

1. Solderability test of HDI circuit board

The solderability test of HDI circuit board focuses on the test of pads and plated through holes. Standards such as IPC-S-804 stipulate the solderability test method of HDI circuit boards, which includes edge immersion test, Rotary dipping test, wave dipping test and solder bead test, etc.

2. Detection of internal defects in HDI circuit boards

The detection of internal defects of HDI circuit boards generally adopts microsection technology, and the specific detection methods are clearly stipulated in relevant standards such as IPC-TM-650. The main inspection items for microsection inspection include the thickness of copper and tin-lead alloy coatings, the alignment of the internal conductor layers of the PCB multilayer circuit board, the laminated voids and the copper cracks.

3. HDI circuit board size and appearance inspection

The content of HDI circuit board size detection mainly includes the directness of processing holes, spacing and tolerances, and the edge size of HDI circuit boards. The content of appearance defect inspection mainly includes: the alignment of the solder mask and the pad; whether the solder mask has abnormal conditions such as impurities, peeling, wrinkles, etc.; whether the reference mark is qualified; whether the circuit conductor width (line width) and spacing are consistent Requirements; Whether the multilayer board is peeled off, etc. In practical applications, special equipment for HDI circuit board appearance testing is often used to detect it. Typical equipment is mainly composed of computers, automatic workbenches, and image processing systems. This system can detect the inner and outer layers of the multilayer board /////, single/dual panels, and base image films; it can detect broken lines, overlapping lines, scratches, pinholes, line width and line spacing, Rough edges and large-area defects, etc.

4. HDI circuit board solder mask integrity test

HDI circuit boards generally use dry film solder mask and optical imaging solder mask. These two kinds of solder mask have high resolution and immobility. Dry film solder mask is laminated on the PCB under pressure and heat. It requires a clean HDI circuit board surface and an effective lamination process. The surface of the solder mask tin-lead alloy has poor viscosity. Under the impact of thermal stress caused by reflow soldering, the phenomenon of peeling and breaking from the surface of the HDI circuit board often occurs. This kind of solder mask is also brittle, and may cause micro-cracks under the influence of heat and mechanical force during leveling. In addition, physical and chemical damage may also occur under the action of cleaning agents. In order to find out these potential defects of the dry film solder mask, the HDI circuit board should be subjected to a strict thermal stress test in the incoming material inspection. When the solder mask peeling phenomenon is not observed during the test, the HDI circuit board test piece can be immersed in water after the test, and the capillary action of the water between the solder mask and the PCB surface can be used to observe the solder mask peeling phenomenon. It is also possible to immerse the HDI circuit board specimen in the SMA cleaning agent after the test to observe whether it has physical and chemical effects with the solvent.

Shenzhen Zhongke Circuit Technology Co., Ltd. is a high-precision PCB multi-layer circuit board manufacturer, focusing on PCB circuit boards, HDI circuit boards, flexible and rigid boards, high frequency boards/high frequency circuit boards, PCB blind buried vias, Long strip boards, extra long circuit boards, long strip circuit boards, double-sided extra long boards, extra long circuit boards, special circuit boards, etc. The factory has imported and domestic plates all year round: the dielectric constant ranges from 2.2 to 10.6. FR4/Glass fiber board/ rogers/Rogers/PTFE/taconic/Taconic/arlon/Teflon/f4b high frequency board. Have many years of production experience in medical/security/industrial control/automotive/communication/military industry. It includes core businesses such as SMT patch/PCBA processing for mid-to-high-end electronic products. Our delivery speed is faster at the same cost, and our cost is lower at the same delivery speed. At present, Zhongke Circuit has a PCB circuit board production base and technology research and development base, and has set up service centers in many major domestic electronic product design centers, and has provided rapid electronic manufacturing services to more than 2,000 customers around the world.