Optimization of Solder Paste Printing Parameters Using Design of Experiments (DOE)
Authors: Gopal Sekharan , Mohd Rohani Jafri , Mohd Yusof Shaâ€™ri , Abu Bakar Zailis 
Published: January 2013

Proses mencetak timah merupakan satu proses yang penting dalam pemasangan perkakasan Surface Mount Technology (SMT) menggunakan teknik pencetakan reflow. Terdapat satu persetujuan global di dalam industri di mana proses pencetakan timah melibatkan sebahagian besar kecacatan disebabkan oleh proses pencetakan. Pengalaman dengan proses ini telah menunjukkan bahawa lebih 60% daripada keseluruhan kecacatan pencetakan adalah bergantung kepada masalah yang berlaku pada proses screening. Walau bagaimanapun, operasi dan pemilihan parameter bagi proses pencetakan timah merupakan elemen utama dalam usaha bagi meminimumkan kadar kecacatan tersebut. Parameter seperti tekanan squeegee, kelajuan squeegee, kelajuan pemisahan stensil, snapâ€“off dan sela masa pembersihan stensil merupakan faktor penting dalam proses bagi mencapai keluaran yang lebih baik. Kertas kerja ini menerangkan pendekatan reka bentuk eksperimen bagi proses pencetakan timah. Teknik reka bentuk faktorial digunakan bagi mengkaji kesan parameter proses pencetakan timah. Sebanyak 16 eksperimen telah dijalankan dengan dua tahap bagi setiap faktor. Hasil daripada eksperimen yang dijalankan adalah ketinggian pencetakan timah, dan data telah dianalisis secara statistik menggunakan perisian Minitab. Analisis varians menunjukkan bahawa faktor yang penting bagi ketinggian percetakan timah ialah tekanan squeegee dan snapâ€“off dengan menetapkan kelajuan percetakan, tekanan squeegee, snapâ€“off, pengasingan squeegee dan sela pembersihan pada tahap optimum. Ralat eksperimen antara model regrasi dan pengesahan sebenar ialah sebanyak 1.61% Penggunaan DOE menunjukkan 18% pembaikan ketinggian pencetakan timah boleh dicapai.

Kata kunci: Reka bentuk eksperimen, pencetak timah, analisa varians, analisa regrasi

The solder paste printing process is an important process in the assembly of Surface Mount Technology (SMT) devices using the reflow soldering technique. There is a wide agreement in the industry that the paste printing process accounts for the majority of assembly defects. Experience with this process has shown that typically over 60% of all soldering defects are due to problems associated with the screening process. Therefore, operation and parameter setup of the stencil printing process are the key elements when trying to minimize defects. Parameters such as squeegee pressure, squeegee speed, stencil separation speed, snapâ€“off and stencil cleaning interval are the most important factors in the process to achieve a better yield. This paper describes the experiment design approach for solder paste printing process. A factorial design technique has been used to study the effects of the solder paste printing process parameters. Sixteen experimental trial were carried out in the experiment with two levels for each factor. The output from the experiment is the solder paste height, and the data has been statistically analyzed by using Minitab Software. The Analysis of Variance (ANOVA) showed that the important factors for the solder paste height are squeegee pressure and snapâ€“off with the optimal setting for printing speed, squeegee pressure, snapâ€“off, squeegee separation, and cleaning interval. The experiment error between the predicted regression model and actual verification was found to be 1.61% It is shown that by using DOE 18% improvement of the solder paste height can be achieved.

Key words: Design of experiments, solder paste printing, Analysis of Variance (ANOVA), regression analysis