Issue link: https://iconnect007.uberflip.com/i/1513827
JANUARY 2024 I SMT007 MAGAZINE 47 achieved with the proposed repair method was also measured. e positioning and dot accu- racy was assessed against product needs, and the throughput was compared with the current customer experience. All the accuracy data was collected at Essemtec's lab, and the throughput data was collected at the customer's facilities. Even though every soldered component type can be repaired with the proposed method, this work only analyzed two cases. e first one is a product with a TQFP (thin quad flat package) component requiring a type 6 paste with a Sn63Pb37 alloy. is TQFP has 128 ter- minals of 200 μm in width with a pitch of 400 μm and a contact area in the middle of 8.4 x 8.4 mm. e size of the TQFP is 14 x 14 mm. e second case is a product with a BGA using a low temperature soldering type 6 paste with a Sn63Bi37 alloy. is BGA has a total of 1599 terminals with a diameter of 200 μm and a pitch of 400 μm, the size of the BGA is 18.5 x 27 mm. A total of 20,000 dots were jetted to verify the stability of the jetting process. For every 1,000 dots jetted on production, 10 dots were jetted on a separate test plate where the dot's diame- ter and X-Y accuracy was measured. A total of 200 data points were collected per experiment. Positioning accuracy and precision together with the dot diameter were measured utilizing the ePlace soware which is integrated into Essemtec machines. A normality test was per- formed on all data using the Anderson Darling method 6 . A capability analysis was performed on every data set using the Minitab soware version 19. Results Figure 1 shows the first case study of a com- ponent to be repaired—a TQFP. For practi- cal purposes, the component was divided into three zones. Zone A are pads with a width of 200 μm and a pitch of 400 μm. Zones B and C are regions used mainly for thermal dissipation or electrical grounding. It is important to notice that Zone B is not flat. It is an area surrounded by 3D topography with valleys of around 1 mm of the current repair process are the use of the valuable time of expert personnel and that only one component per product can be replaced at a time 4 . Applying solder paste and placing the component is very problematic, especially on fine-pitch components—the risk of short cir- cuits due to misplacements of packages or sol- der paste is high. e proposed method in this work is focused on applying solder paste and placing the com- ponent. By using solder jetting instead of print- ing or dispensing, the time required to deposit solder paste can be significantly reduced. Spe- cial needles were designed to perform the jet- ting process without damaging the already populated components. Another advantage of using a fully programmable jetting system is that the required volume can be customized per pad; for example, pads for a TQFP pack- age with 200 μm width pins and a large pad in the middle can easily be jetted, delivering the correct amount depending on the situa- tion. Pick and place of the components is per- formed with the same instrument as well in a fully automatic way and the throughput is fur- ther improved. e possibility to replace sev- eral components on the same product is also given. ere is no need for an expert operator once the equipment is programmed. e repair process has been implemented with different alloys, including SnPb, SAC305, and SnBi 5 . is work presents the results of products reworked using SnPb and SnBi. e results show that the XY positioning accuracy and dot repeatability exceed acceptable expec- tations for a 400 μm pitch. With this fully auto- matic jetting and pick-and-place method, the repair of a product can be made in a very accu- rate and agile way. is represents remarkable cost advantages for companies performing repairing activities. Experimental Methodology e experimental studies aim to test the positioning accuracy of the solder deposits as well as the dot repeatability. e throughput