Purpose

This study aims to simulate molded printed circuit board (PCB) warpage behavior under reflow temperature distribution. Simulation models are used to estimate dynamic warpage behavior for different form factor sizes.

Design/methodology/approach

This study analyzes warpage during the reflow process. The shadow moiré experiment methodology is used to collect data on the dynamic warpage performance of a model with a form factor of 10mm × 10mm × 1mm. The temperature profile with heating from 25°C to 300°C at intervals of 50°C is used, and the sample is made to undergo a cooling process until it reaches the room temperature. Subsequently, ANSYS static structural simulation is performed on similar form factor models to ascertain the accuracy of the simulation results.

Findings

Results show that the deformation and total force induced by coefficient of thermal expansion (CTE) mismatch are examined based on the warpage performance of models with different sizes, that is, 45mm × 45mm × 1mm and 45mm × 15mm × 1mm. Compared with the experimental data, the simulated modeling accuracy yields a less than 5% deviation in the dynamic warpage prediction at a reflow temperature of 300°C. Results also reveal that the larger the model, the larger the warpage changes under the reflow temperature.

Research limitations/implications

The simulated warpage is limited to the temperature and force induced by CTE mismatch between two materials. The form factor of the ball-grid array model is limited to only three different sizes. The model is assumed to be steady, isothermal and static. The simulation adopts homogenous materials, as it cannot accurately model nonhomogeneous multilayered composite materials.

Practical implications

This study can provide engineers and researchers with a profound understanding of molded PCB warpage, minimal resource utilization and the improved product development process.

Social implications

The accurate prediction of molded PCB warpage can enable efficient product development and reduce resources and production time, thereby creating a sustainable environment.

Originality/value

The literature review points out that warpage in various types of PCBs was successfully examined, and that considerable efforts were exerted to investigate warpage reduction in PCB modules. However, PCB warpage studies are limited to bare PCBs. To the best of the authors’ knowledge, the examination of warpage in a molded PCB designed with a molded compound cover, as depicted in Figure 3, is yet to be conducted. A molded compound provides strong lattice support for PCBs to prevent deformation during the reflow process, which is a topic of considerable interest and should be explored.

中文翻译：

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回流焊工艺下成型PCB的动态翘曲模拟

目的

This study aims to simulate molded printed circuit board (PCB) warpage behavior under reflow temperature distribution. Simulation models are used to estimate dynamic warpage behavior for different form factor sizes.

Design/methodology/approach

This study analyzes warpage during the reflow process. The shadow moiré experiment methodology is used to collect data on the dynamic warpage performance of a model with a form factor of 10mm × 10mm × 1mm. The temperature profile with heating from 25°C to 300°C at intervals of 50°C is used, and the sample is made to undergo a cooling process until it reaches the room temperature. Subsequently, ANSYS static structural simulation is performed on similar form factor models to ascertain the accuracy of the simulation results.

Findings

结果表明，基于不同尺寸模型（即 45mm × 45mm × 1mm 和 45mm × 15mm × 1mm）的翘曲性能，检查了热膨胀系数（CTE）失配引起的变形和总力。与实验数据相比，模拟建模精度在 300°C 的回流温度下动态翘曲预测的偏差小于 5%。结果还表明，模型越大，回流焊温度下的翘曲变化越大。

研究局限性/影响

模拟翘曲仅限于两种材料之间的 CTE 不匹配引起的温度和力。球栅阵列模型的外形尺寸仅限于三种不同的尺寸。假定模型是稳定的、等温的和静态的。该模拟采用均质材料，因为它无法准确模拟非均质多层复合材料。

实际影响

这项研究可以让工程师和研究人员对模制 PCB 翘曲、最小资源利用率和改进的产品开发过程有深刻的了解。

社会影响

准确预测模塑 PCB 翘曲可以实现高效的产品开发并减少资源和生产时间，从而创造可持续发展的环境。

原创性/价值

文献综述指出，已成功检验各种类型 PCB 的翘曲，并且已付出相当大的努力来研究 PCB 模块的翘曲减少。然而，PCB 翘曲研究仅限于裸露的 PCB。据作者所知，如图 3 所示，设计有模塑复合盖板的模塑 PCB 的翘曲检查尚未进行。模塑化合物为 PCB 提供强大的晶格支撑，以防止回流过程中的变形，这是一个非常有趣的话题，应该进行探索。