Investigating the attack angle of squeegees with different geometries

Abstract

Purpose The attack angle of stencil printing squeegees with different geometries was analysed using finite element modelling. Design/methodology/approach A finite element model (FEM) was developed to determine the attack angle during the stencil printing. The material properties of the squeegee were included in the model according to the parameters of steel AISI 4340, and the model was validated by experimental measurements. Two geometric parameters were investigated; two different unloaded angles (45° and 60°) and four overhang sizes of the squeegee (6, 15, 20 and 25 mm). Findings It was found that the deflection of the blade is nearly homogenous along the length of the squeegee. This implies that the attack angle does not change significantly along the squeegee length. The results showed significant differences between the initial and the attack angle. For example, the angle of the squeegee with 15 mm overhang size and with 60° initial angle decreased by more than 5° for a specific squeegee force of 0.3 N/mm; resulting in an attack angle of 53.4°. Originality/value The attack angle during the printing is considerably lower than the initial angle as a result of the printing force. The papers, which were dealing with the numerical modelling of the stencil printing presumed that the squeegees were having their initial angle. This could have led to invalid numerical results. Therefore, we decided to investigate the attack angle during stencil printing for squeegees with different initial geometries to enhance the numerical modelling of stencil printing.

Numerical investigation on the effect of solder paste rheological behaviour and printing speed on stencil printing

“…The geometry of the finite volume model included the loaded angle of the printing squeegee of 53°. This value was found by Krammer et al (2018b) being the actual attack angle for a squeegee with an unloaded angle of 60°, and for the widely used specific printing force of 0.3 N/mm. A no-slip wall boundary condition was set both to the squeegee and the stencil, whereas a free-slip boundary condition was utilised at the paste-air interface.…”

Újraömlesztéses forrasztás stencilnyomtatási folyamatának modellezése

“…A vizsgált nyomtatókés geometriai paraméterei: terheletlen késszög 60°, penge anyaga rozsdamentes acél, penge vastagsága 200 µm, penge magassága 15 mm, kés hossza 300 mm. A numerikus modell érvényességének ellenőrzése után meghatároztuk a szögeket 45°-os terheletlen késszögre, valamint 6, 20, 25 mm pengemagasságokra is [19].…”

Cleaning control of stencil printing subject to performance deterioration

“…Stencil printing is the key process of surface-mount assembly (SMA) (Kay and Marc, 2012;Krammer et al, 2018). During this process, solder pastes are deposited onto the pads of the printed circuit board (PCB) so that when an electrical component is engaged, the deposited solder there between becomes conductive and connects the PCB and the electrical component together.…”