HDI soft and hard combination board assembly

HDI (High Density Interconnect) soft-hard board is an advanced electronic manufacturing technology that combines the advantages of soft boards and hard boards and has good mechanical properties, electrical properties and reliability.

HDI rigid-flex boards are widely used in consumer electronics such as mobile phones, tablets, digital cameras, and wearable devices, as well as in communications, medical, aerospace and other fields. This article will introduce in detail the assembly of HDI hard-soft board.


HDI soft-hard board is a multi-layer board, which is made of multiple layers of soft boards and hard boards bonded by adhesives.

Soft boards usually use flexible materials such as polyimide or polyester, while hard boards use rigid materials such as FR4 or CEM-1.

HDI soft and hard combination board assembly

HDI hard-soft board has the characteristics of high-density wiring, high reliability, and high integration, and can meet the requirements of modern electronic products for thinness, miniaturization, and high performance.

HDI soft and hard combination board assembly process

The assembly process of HDI hard-soft board mainly includes the following steps:

  1. Preliminary preparation

Before assembly, the HDI soft-hard board needs to be prepared in advance, including checking the integrity, cleanliness, size, etc. of the board to ensure that there are no defects or problems. At the same time, various assembly tools and materials need to be prepared, such as soldering stations, soldering tin, glue, etc.

  1. Assembly design

According to product requirements and circuit design, carry out assembly design of HDI hard-soft board. The design content includes determining the arrangement sequence, bonding method, wiring layout, component location, etc. of each layer board. In addition, factors such as heat dissipation design and electromagnetic shielding also need to be considered.

  1. patch

To mount electronic components onto the HDI hard-software board, you can use a manual or automatic placement machine. When patching, it is necessary to ensure that the component position is accurate and the solder joint quality is reliable. For small components, they can be fixed by dispensing glue or printing solder paste.

  1. Welding

To weld the mounted components, you can use a hot air soldering station or laser welding machine. Temperature and time need to be controlled during welding to ensure reliable solder joint quality. For some special components, such as BGA chips, special processing and welding are required.

  1. Detection and Debugging

After completing the welding, the HDI hard-software board needs to be tested and debugged to ensure that the circuit function is normal. The inspection content includes testing the electrical performance of the circuit, checking component position and solder joint quality, measuring the voltage and current of each part, etc. If problems are found, adjustments and repairs need to be made.

  1. Packaging and Shipping

Finally, the qualified HDI soft-hard board is packaged and transported to protect the product from damage during transportation. Packaging materials need to be selected according to specific requirements, such as shock-proof pads, blister boxes, etc. It needs to be handled with care during transportation to avoid severe vibration and collision.

Difficulties and precautions in assembling HDI hard-soft board

Difficulties and precautions in assembling HDI hard-soft board

  1. Difficulty Analysis

The assembly difficulties of HDI hard-soft board mainly include the following aspects:

(1) High wiring density: Since the HDI hard-soft board adopts a high-density wiring design, problems such as bridging and virtual soldering are prone to occur during welding.
(2) Material diversity: HDI hard-soft board is composed of a variety of materials. The thermal expansion coefficients of different materials are different, which can easily generate stress during the welding process, leading to warping, cracking and other phenomena.
(3) High assembly accuracy requirements: Since HDI hard-soft board is used in miniaturized, high-performance electronic products, the assembly accuracy requirements are extremely high, and it is necessary to ensure accurate component positioning and reliable solder joint quality.
(4) Electromagnetic shielding and heat dissipation design: Electromagnetic shielding and heat dissipation issues need to be considered in the design of HDI soft-hard board to ensure product performance and reliability.

  1. Precautions

In order to ensure the assembly quality and reliability of HDI hard-soft board, the following points need to be noted:

(1) Strictly control the assembly process: During the assembly process, process parameters such as temperature, time, pressure, etc. need to be strictly controlled to ensure welding quality and placement accuracy. At the same time, the process needs to be recorded and monitored to detect and solve problems in a timely manner.
(2) Select appropriate assembly equipment and materials: Select appropriate assembly equipment and materials according to actual needs, such as automatic placement machines, hot air soldering stations, high-quality solder and glue, etc., to ensure assembly efficiency and product quality.

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